Mammals
Impacts of Pesticides on Mammals
Mammals can be directly exposed to pesticides, but are most commonly affected indirectly, through groundwater contamination and runoff, or through secondary poisonings such as ingesting prey that has been exposed to pesticides.
- In 2014, a mountain lion in California was found to be experiencing mange (parasitic mites) as a result of pesticide poisoning due to rodenticides moving up the food chain.
- In 2012, the U.S. Fish and Wildlife Service (FWS) announced a proposal to list the fisher (part of the weasel family) as threatened under the Endangered Species Act (ESA) due to the impact of rodenticides used in illegal marijuana operations.
- Neurotoxicology and Teratology published a study on the neurobehavioral toxicology of pyrethroid insecticides in 2008. Researchers found that decreased motor skills and coordination, slow response rates, and startle responses to noise are other possible effects of pesticide exposure in mammals.
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Research summarizing toxicological data on the effects of the organochlorine pesticides DDT, and its metabolites, found that these organochlorine compounds can impair female fertility by altering ovarian development and function in mammals.
Atlantic Bottlenose Dolphins. Photo by Pete Markham - Banned in 1972 for its toxic and deadly effects, DDT still persists in the environment and impacts wildlife. Levels of DDT remain dangerously high in some species of marine mammals, such as the short beaked common dolphin, killer whale, and common bottlenose dolphin
- Evidence, published in Human and Ecological Risk Assessment, has shown that aquatic mammals exposed to general levels of DDT and other, newer pesticides, have impacted reproductive, immune and endocrine function.
[See More Scientific Studies Below]
Economic Cost
Mammals provide many ecosystem services. Some mammals provide food, clothing, and other materials that are used by humans. They provide the opportunity for recreational activities, such as zoos, horseback riding, hunting or animal watching. Other mammals, such as the cow, are revered and worshiped in certain communities for their religious affiliation. All mammals are responsible for ecologic biodiversity in some way, whether it be large or small. For example: bears eat berries and then travel, excreting the berries farther away, which gives plants the ability to spread and grow where they otherwise could not.
Pesticides can and do negatively impact mammals and the ecosystem services they provide, but the full economic impact can be difficult to define. The services listed above may not have a direct price associated with them, but it can be assumed that the impacts of pesticides on mammals cause some economic burden due to loss of ecosystem services. One can assume that prices will climb as mammal populations decline while the demand for the services they provide remains constant. If domesticated mammals that humans depend on for food decline due to pesticide exposure, society would experience an increase in the price of food. Similarly, if there is a drop in the number of mammals that provide biological diversity, ecological stability could easily be threatened, which in turn would affect human life.
Litigation & Lawsuits
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| Indiana bat. Photo by USFWSmidwest. |
In 2015, EPA was sued for violating the Endangered Species Act (ESA). The lawsuit documents EPA’s failure to consult with the U.S. Fish and Wildlife Service (FWS) regarding the impact of the herbicide on two endangered species: the Indiana bat (and the whooping crane). A motion was filed against EPA after the decision was made to expand the use of Enlist Duo to nine additional states.
Quick Links
- EPA Approves Enlist Duo®, Opens Gate to New Wave of GE Woes (Oct. 2014)
- Farmers and Environmental Groups to Challenge EPA over Herbicide Approval (Oct. 2014)
- EPA Sued for Violating Endangered Species Act with Allowance of New 2,4-D/Roundup Pesticide (Feb. 2015)
- EPA’s Expansion of 2,4-D Enlist Duo Challenged (Apr. 2015)
What Can You Do?
- Learn about the Hazards and Alternatives to using lawn pesticides.
- Go Organic – Visit our Eating with a Conscience page to learn why eating organic foods is the right choice.
- Visit our Tools for Change page to learn how to organize your community against pesticide use.
- Sign up for Beyond Pesticides’ Action Alerts to stay up-to-date on the latest petitions and news.
Scientific Studies:
Plastic pollution is an increasing global health concern, particularly the ever-increasing amount of tiny plastic particles commonly referred to as micro- and nanoplastics (MNPs). Most research to date on MNP exposure and hazards has focused on environmental species such as aquatic organisms and, more recently, humans, leaving impacts on farm animals largely unstudied. MNPs have been detected in all environmental compartments, including agricultural environments, farm animals and food products originating from them. The health of farm animals can be directly affected by MNPs, while humans can be affected by MNPs present in animal-derived food products. In this perspective article, we argue that MNP research should give more attention to farm animals forming a critical link between the environment and human health. Here, we summarize evidence on sources, exposure routes, levels in farm animals, and potential health effects of MNPs on farm animals, and identify knowledge gaps for future research, such as effects of MNPs on reproduction and development. In particular, the bovine embryo model is a promising model to study effects of MNPs on early development of both farm animals and humans. This perspective article signals the need for follow up studies that will increase our understanding of the transfer of MNPs between environment, farm animals, and humans, and the potential of farm animals to serve as an indicator for other animals, including humans. The control of tick and flea burdens in dogs and cats has become essential to the control of important and emerging vector borne diseases, some of which are zoonoses. Flea worry and flea bite hypersensitivity are additionally a significant disease entity in dogs and cats. Owner compliance in maintaining the pressure of control measures has been shown to be poor. For these reasons efforts are continuously being made to develop ectoparasiticides and application methods that are safe, effective and easy to apply for pet owners. A new polymer matrix collar has recently been developed which is registered for 8 months use in cats and dogs. The basic properties of this collar have been investigated in several in vitro and in vivo studies. The effects of imidacloprid, flumethrin and the combination were evaluated in vitro by means of whole cell voltage clamp measurement experiments conducted on isolated neuron cells from Spodoptera frugiperda. The in vitro efficacy of the two compounds and the combination against three species of ticks and their life stages and fleas were evaluated in a dry surface glass vial assay. The kinetics of the compounds over time in the collar were evaluated by the change in mass of the collar and measurement of the surface concentrations and concentrations of the actives in the collar matrix by HPLC. Hair clipped from collar treated dogs and cats, collected at various time points, was used to assess the acaricidal efficacy of the actives ex vivo. An in vitro isolated insect nerve model demonstrated the synergistic neurotoxic effects of the pyrethroid flumethrin and the neonicotinoid imidacloprid. An in vitro glass vial efficacy and mortality study against various life stages of the ticks Ixodes ricinus, Rhipicephalus sanguineus and Dermacentor reticulatus and against the flea (Ctenocephalides felis) demonstrated that the combination of these products was highly effective against these parasites. The release kinetics of these actives from a neck collar (compounded with 10% imidacloprid and 4.5% flumethrin) was extensively studied in dogs and cats under laboratory and field conditions. Acaricidal concentrations of the actives were found to be consistently released from the collar matrix for 8 months. None of the collar studies in dogs or cats were associated with any significant collar related adverse event. Here we demonstrated the synergism between the pyrethroid flumethrin and the neonicotinoid imidacloprid, both provided in therapeutically relevant doses by a slow release collar matrix system over 8 months. This collar is therefore a convenient and safe tool for a long-term protection against ectoparasites.
Anticoagulant rodenticides (ARs) are widely used for pest control, resulting in their pervasive presence in the environment and posing significant toxicological risks to a range of predatory and scavenging species. Our study mainly aimed to evaluate AR exposure and effects in nestlings of eagle owl (Bubo bubo) from the Region of Murcia (southeastern Spain). We analysed ARs in blood samples (n = 106) using high-performance liquid chromatography-triple quadrupole (HPLC-TQ), assessed the influence of potential anthropogenic (presence of livestock farms, landfills and human population density) and environmental (land uses and proximity to watercourses) variables, and measured prothrombin time (PT) and plasma biochemical parameters as biomarkers of effects. Our results showed the presence of AR residues in 91.5% of the nestlings, with 70.8% exhibiting multiple ARs (up to six compounds in a single individual). Second-generation ARs (SGARs) were the most prevalent compounds. The analysis of biochemical parameters indicated that the sampled individuals were in good physiological condition. Although PT was positively correlated with total AR concentration (ΣARs), the relationship was not significant (Rho = 0.04; p = 0.49). Regarding environmental factors, higher ΣARs were associated with the most urbanised study site and the presence of landfills, likely due to the increased availability of rodent prey. The prevalence of two SGARs (brodifacoum and difenacoum) was linked to closer proximity to riverbeds, suggesting a contamination pathway associated with inland aquatic ecosystems, where these AR compounds may concentrate due to water scarcity. This study underscores the widespread exposure of eagle owls to ARs and highlights the importance of effective monitoring and management of these pollutants to protect conservation-concern wildlife in Mediterranean semiarid regions.
[Spadetto, L., Gómez-Ramírez, P., León-Ortega, M., Zamora-López, A., Díaz-García, S., Zamora-Marín, J. M., Tecles-Vicente, F., Pardo-Marín, L., Fenoll, J., Calvo, J. F., & García-Fernández, A. J. (2025). Exploring anticoagulant rodenticide exposure and effects in eagle owl (Bubo bubo) nestlings from a Mediterranean semiarid region. Environmental research, 264(Pt 2), 120382. https://doi.org/10.1016/j.envres.2024.120382]
Triazole pesticides are widely used throughout the world, but their abuse causes toxic effects in non-targeted organisms. In the present study, the cytotoxic effect of the triazole ipconazole was evaluated in porcine and ram spermatozoa. Ipconazole significantly reduced sperm viability, increased ROS levels, altered catalase and SOD enzyme activity, and caused alterations in the molecular mRNA expression of structural biomarkers (PRM1, ODF2, AKAP4, THEG, SPACA3 and CLGN) related to fertility in males, as well as the overexpression of BAX (cell death) and ROMO1 (oxidative stress) mRNA. Our results indicate that the fungicide triazole is involved in cellular, enzymatic and molecular alteration of porcine and ram spermatozoa, and is possibly a factor in the development of infertility in male mammals.
[Falero, C. et al. (2025) Oxidative and Molecular–Structural Alterations of Spermatozoa in Swine and Ram Exposed to the Triazole Ipconazole, Toxics. Available at: https://www.mdpi.com/2305-6304/13/3/176. ]
Anticoagulant rodenticides (ARs) have been detected in non-target wildlife species worldwide but information on exposure in Australian mammals is extremely limited. To address this, we analysed liver tissue from the five largest sized species of native Australian carnivorous and scavenging mammals for all SGARs currently used in Australia. A total of 52 individual animals from five dasyurid species were tested for exposure to ARs with 26 individuals (50 %) testing positive. Eleven individuals (21 %) tested positive for more than one AR compound, and two individuals tested positive for three types of AR. This study is the first to document widespread and pervasive AR exposure in native Australian marsupial carnivores, including those in remote locations away from towns. The frequency and severity of exposure, sometimes from multiple ARs suggest potential population-level impacts on these threatened species. These findings provide further evidence that ARs should be listed as a key threatening process under state and federal legislation and that the federal regulator (Australian Pesticides and Veterinary Medicine Authority) should restrict the widespread sale of SGARs in line with other countries.
[Lohr, M. et al. (2025) Widespread detection of second generation anticoagulant rodenticides in Australian native marsupial carnivores, Science of The Total Environment. Available at: https://www.sciencedirect.com/science/article/pii/S004896972500467X.]
Clothianidin (CLO), a neonicotinoid that is widely used in forests and agricultural areas, was recently reported to cause toxicity in mammals. Although sensitivity to chemicals varies between sexes and developmental stages, studies that comprehensively evaluate both males and females are limited. Therefore, in this study we utilized murine models to compare the sex-specific differences in behavioral effects following CLO exposure at different developmental stages. We orally administered CLO to male and female mice as a single high-dose solution (80 mg/kg) during the postnatal period (2-week-old), adolescence (6-week-old), or maturity (10-week-old), and subsequently evaluated higher brain function. The behavioral battery test consisted of open field, light/dark transition, and contextual/cued fear conditioning tests conducted at three and seven months of age. After the behavioral test, the brains were dissected and prepared for immunohistochemical staining. We observed behavioral abnormalities in anxiety, spatial memory, and cued memory only in female mice. Moreover, the immunohistochemical analysis showed a reduction in astrocytes within the hippocampus of female mice with behavioral abnormalities. The behavioral abnormalities observed in female CLO-treated mice were consistent with the typical behavioral abnormalities associated with hippocampal astrocyte dysfunction. It is therefore possible that the CLO-induced behavioral abnormalities are at least in part related to a reduction in astrocyte numbers. The results of this study highlight the differences in behavioral effects following CLO exposure between sexes and developmental stages.
[Kaku, K. et al. (2024) A single dose of clothianidin exposure induces varying sex-specific behavioral changes in adulthood depending on the developmental stage of its administration, The Journal of Toxicological Sciences. Available at: https://www.jstage.jst.go.jp/article/jts/49/7/49_301/_article. ]
Chlorpyrifos is an organophosphate insecticide used to control pests in crops. Thus, humans are constantly exposed through ingestion of contaminated food or water, inhalation of contaminated air, and through the skin. The juvenile and peripubertal periods comprise a window of development of the reproductive system, sensitive to toxic agents. Considering the scarcity of data on exposure to the insecticide during these periods, the aim of this study was to evaluate the effects of chlorpyrifos on the testis during the juvenile and peripubertal periods. Thirty Wistar rats with an initial age of 25 days were distributed into 3 groups: control, which received corn oil (vehicle); CPS5, which received 5 mg/Kg b.w. of chlorpyrifos; and CPS15, which received 15 mg/Kg b.w. of chlorpyrifos. The groups were treated via gavage daily for 40 days and on the 41st experimental day, the animals were anesthetized and submitted to euthanasia to collect the organs. Blood was collected to obtain plasma and testosterone measurement. The testicles were removed, weighed and used for sperm count analyses, histopathological and morphometric analyzes and for oxidative stress analyses. Spermatozoa from the vas deferens were collected for analyzes of sperm morphology and acrosome integrity. The results showed that the two concentrations of chlorpyrifos caused a decrease in the number of Leydig and Sertoli cells and germ cells and increased the number of morphologically abnormal sperm and sperm with acrosomal damage. Furthermore, a decrease in lipid peroxidation was observed in the CPS5 and CPS15 groups, and a decrease in glutathione-S-transferase activity in the CPS5 group. We conclude that exposure to chlorpyrifos harms the daily production of sperm, as well as their quality, in addition to causing an imbalance in the oxidoreductive balance of the testicle.
[da Costa, I. R., Quadreli, D. H., da Silva, L. M. M., de Andrade, F. G., & Fernandes, G. S. A. (2024). Chlorpyrifos impairs sperm parameters and number of Sertoli and Leydig cells in rats after exposure during the peripubertal period. Toxicology, 504, 153789. https://doi.org/10.1016/j.tox.2024.153789]Abstract
[Aardema, H. et al. (2024) ‘Farm animals as a critical link between environmental and human health impacts of micro-and nanoplastics’, Microplastics and Nanoplastics, 4(1). doi:10.1186/s43591-024-00082-w. ]
Anticoagulant rodenticides (ARs) are an effective tool used to suppress rodent populations in urban and agricultural settings to reduce human disease risk and economic loss, but widespread use has resulted in adverse effects on predators globally. Attention has largely been focused on impacts of ARs on raptors, although there is increasing evidence that mammalian carnivores are also impacted. We conducted a literature review to assess the extent to which ARs have been documented in wild mammalian carnivores globally and identify potential overlap with imperiled carnivores. We found a small but growing body of literature documenting exposure to ARs in 8 Carnivora families, with Mustelidae (64% of studies), Canidae (44%) and Felidae (23%) most represented. At least 11 different AR compounds were documented in carnivores, and authors claimed that exposure caused mortality of at least one individual in 33.9% of species studied. ARs were listed as a threat for 2% of Red List carnivores, although we found that 19% of Red List carnivores had ranges that overlap countries that have documented AR exposure in carnivores. Collectively, our review highlights the need to prioritize conservation attention on the potential role of ARs on global carnivore declines. We suggest (1) expanding AR monitoring and research outside of the northern hemisphere, (2) supporting long-term AR monitoring to understand the spatial and temporal variation of AR use and exposure risk, (3) expanding research across trophic levels and across the urban–wildland gradient and 4) research to further our understanding of the point at which morbidity and mortality occur.
[Keating, M.P., Saldo, E.A., Frair, J.L., Cunningham, S.A., Mateo, R. and Jachowski, D.S. (2024), Global review of anticoagulant rodenticide exposure in wild mammalian carnivores. Anim Conserv, 27: 585-599. https://doi.org/10.1111/acv.12947]
Neonicotinoids are the most widely used class of insecticides in the United States (U.S.). and the world. Consistent with their high use and persistence, neonicotinoids are often found contaminating drinking water and food. They are also detected in human urine, breast milk, amniotic and cerebrospinal fluids, as well as the brains of treated rodents. Neonicotinoids were once thought to pose little neurotoxic risk to humans, but a growing body of research challenges that assumption. In this study we provide the first comprehensive assessment of unpublished rodent developmental neurotoxicity (DNT) studies on five neonicotinoids that were submitted to the U.S. Environmental Protection Agency (EPA) by neonicotinoid manufacturers. Groups of female rats were administered three different doses of a neonicotinoid during pregnancy and lactation, and their offspring subjected to various neurological tests and brain measurements. We identified nicotine-like effects such as reduced brain size, indicative of neuronal cell loss. Statistically significant shrinkage of brain tissue was observed in high-dose offspring for five neonicotinoids: acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam. Two brain regions reduced in the rodent studies–the corpus callosum and caudate-putamen–tend to be smaller in people diagnosed with attention-deficit hyperactivity disorder (ADHD), and in children of mothers who smoked during pregnancy, suggesting a possible link between perinatal neonicotinoid exposure and ADHD. A decreased auditory startle reflex was reported for acetamiprid at all doses and was statistically significant in the mid- and high-dose offspring, and for clothianidin in juvenile high-dose females. No mid- or low-dose brain morphometric data were submitted for acetamiprid, imidacloprid, or thiacloprid. Thiamethoxam mid- and low-dose brain morphometric data were provided to EPA upon request. Only partial mid-dose brain morphometry data were submitted for clothianidin, but no low-dose data. Yet despite this lack of data, EPA concluded that only the high-dose brain morphometric effects were treatment-related–setting the mid-dose as the study’s No Observed Adverse Effect Level (NOAEL) or failing to find a definitive NOAEL for acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam. We found numerous deficiencies in EPA’s regulatory oversight and data analyses. EPA dismissed statistically significant adverse effects, accepted substandard DNT studies despite lack of valid positive control data, and allowed neonicotinoid registrants to unduly influence agency decision-making. We conclude that perinatal exposure to neonicotinoids and their metabolites induces adverse, nicotine-like neurotoxic effects in rodent bioassays, and that the exposure limits set by EPA for human exposure are either not protective or not supported by available neurotoxicity data. We propose regulatory changes to empower EPA to better protect public health from developmental neurotoxins like neonicotinoids.
[Sass, J.B., Donley, N. and Freese, W. (2024) Neonicotinoid pesticides: evidence of developmental neurotoxicity from regulatory rodent studies, Frontiers in Toxicology. Available at: https://www.frontiersin.org/journals/toxicology/articles/10.3389/ftox.2024.1438890/full. ]
Secondary exposure to anticoagulant rodenticides (ARs) causes the death of mammalian predators and scavengers directly and indirectly through sublethal effects that reduce fitness. Poisoning by ARs has been proposed to be a significant source of mortality for coyotes (Canis latrans), a medium-sized canid that thrives at the urban–wildland interface and may prey upon species targeted by pest control efforts. However, only 1 study, with a relatively small sample size, documented the prevalence of AR exposure in a free-roaming coyote population. We quantified AR exposure in carcasses of 365 urban and suburban coyotes in southern California, USA, and compared AR prevalence and hepatic residue concentrations to those of 120 rural coyotes collected elsewhere in the state. For urban coyotes, we also examined demographic (sex, age, body mass, cause of death) and environmental factors (season, degree of urbanization, diet) that could influence the number of AR compounds and residue concentrations. Nearly all urban coyotes (98.1%) were exposed to at least 1 AR, compared to 41.7% of rural coyotes, and most individuals had residues of both first-generation (FGAR) and the more potent second-generation (SGAR) compounds, often at concentrations exceeding thresholds considered lethal in other mammals. Anticoagulant rodenticide exposure of urban coyotes did not vary by sex or season, but the number of compounds detected increased with mass, and adults tended to have residues of more compounds and at higher concentrations than juveniles, suggesting repeated and chronic exposure. Livers of road-killed coyotes had higher SGAR concentrations than those euthanized as nuisance animals, which had lower SGAR concentrations in intensively urbanized areas. Concentrations of SGAR and FGAR residues were highest in suburban areas with natural open space and lower intensity development, and stable isotope values suggested that these coyotes were exposed to ARs by consuming commensal rodents and possibly mesocarnivores. In contrast, coyotes from urbanized areas had lower AR concentrations possibly because less AR is applied in these settings or because coyotes consumed foods with less AR, such as domestic cats and anthropogenic resources. Although some coyotes showed evidence of internal bleeding consistent with AR toxicosis and were in poorer body condition, there was no clear relationship between the extent of hemorrhaging and AR exposure. Despite statewide legislation to restrict their use and mitigate non-target impacts, AR exposure remains ubiquitous in southern California and represents another stressor of urban life to which coyotes have successfully adjusted, making them a potential sentinel of environmental contamination.
[Stapp, P. et al. (2024) Patterns of exposure of coyotes to anticoagulant rodenticides in California, USA, The Journal of Wildlife Management. Available at: https://wildlife.onlinelibrary.wiley.com/doi/abs/10.1002/jwmg.22696.]
Chronic exposure to glyphosate-based herbicide (Gly) has been associated with neurological disorders. Tannic acid (TA) is an antioxidant with attenuating action against neuroinflammation-associated conditions. This study evaluated the effect of Gly on pain perception alongside antinociceptive and anti-inflammatory actions of TA in Gly-exposed mice. Male Swiss mice were randomly divided into six groups (n=8): control (distilled water 0.2 ml/kg), Gly (Gly 500 mg/kg), Pre-TA + Gly (TA 50 mg/kg pre-treatment, afterwards Gly-administered), TA + Gly (TA 50 mg/kg and Gly co-administered), Pre-AA + Gly (ascorbic acid (AA) 10 mg/kg pre-treatment, afterwards Gly-administered), and AA + Gly (AA 10 mg/kg and Gly co-administered). Mechanical, thermal, and chemical pain were evaluated six weeks post vehicle/drugs administrations orally, followed by brain biochemical measurements. TA treatment alleviated Gly-induced hyperalgesia in similar version to the values of control and AA groups by increasing significantly (p < 0.05) nociceptive thresholds. Moreover, TA-treatment significantly decreased malondialdehyde (MDA) and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) levels, significantly increased anti-inflammatory cytokines (IL-10, IL-4, and TGF-1β) levels, and antioxidant enzymes, catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities compared to Gly-treated mice (p < 0.05). Conclusively, TA treatment exerted antinociceptive and anti-inflammatory actions, possibly through its antioxidant and anti-inflammatory actions in Gly-exposed mice. Notably, TA pre-treatment showed a better response than TA and Gly co-administration. We propose the potential neuroprotective and ameliorative functions of TA in Gly-induced hyperalgesia. This merits further clinical research into protective roles of TA against pesticide-related conditions.
[Abolarin, P.O. and Owoyele, B.V. (2024) Tannic acid inhibits pain mediators, inflammation and oxidative stress in mice exposed to glyphosate-based herbicide, Environmental Analysis Health and Toxicology. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11294660/. ]
Organochlorine pesticides (OCPs) show differences in their chemical structure, mechanism of toxicity, and target organisms. However, OCPs also have some common characteristics such as high persistence in the environment, bioaccumulation, and toxicity which lead to health issues. Nowadays, the toxicity of OCPs is well known, but we still do not know all the specific molecular mechanisms leading to their toxicity in mammalians. Therefore, this review aims to collect data about the mode of action of various classes of OCPs, highlighting their differences and common behavioural reactions in the human and animal body. To discuss the OCPs molecular pathways and fate in different systems of the body, three organochlorine insecticides were selected (Dichlorodiphenyltrichloroethane, Hexachlorocyclohexane and Chlordecone), regarding to their widespread use, with consequent effects on the ecosystem and human health. Their common biological responses at the molecular scale and their different interactions in human and animal bodies were highlighted and presented.
[Baratzhanova, G. et al. (2024) The mode of action of different organochlorine pesticides families in mammalians, Environmental Toxicology and Pharmacology. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1382668924001546?via%3Dihub. ]
Antimicrobial resistance is a global public health threat. Antimicrobial-resistant infections are on the rise and are associated with increased morbidity, mortality, and health care costs. Infants and children are affected by transmission of antimicrobial-resistant zoonotic pathogens through the food supply, direct contact with animals, environmental pathways, and contact with infected or colonized humans. Although the judicious use of antimicrobial agents is necessary for maintaining the health and welfare of humans and animals, it must be recognized that all use of antimicrobial agents exerts selective pressure that increases the risk of development of resistance. This report describes historical and recent use of antibiotics in animal agriculture, reviews the mechanisms of how such use contributes to development of resistance and can adversely affect child health, and discusses US initiatives to curb unnecessary use of antimicrobial agents in agriculture.
[Katz, S.E. and Banerjee, R. (2024) Use of Antibiotics in Animal Agriculture: Implications for Pediatrics: Technical Report, Pediatrics. Available at: https://publications.aap.org/pediatrics/article/doi/10.1542/peds.2024-068467/199441/Use-of-Antibiotics-in-Animal-Agriculture. ]
While anthropogenic pollutants are known to be a threat to primates, our understanding of exposure to pollutants in situ and their sub-lethal effects is still limited. We used non-invasive biomonitoring to examine associations between faecal concentrations of 97 chemical pollutants and faecal hormone metabolites of cortisol and oestradiol in four primate species inhabiting Kibale National Park, Uganda (chimpanzees—Pan troglodytes, olive baboons—Papio anubis, red colobus—Piliocolobus tephrosceles and red-tailed monkeys—Cercopithecus ascanius). Across all species (n = 71 samples), results demonstrated positive associations of organochlorine pesticides (OCPs) (β = 0.143, p = 0.020) and organophosphate esters (β = 0.112, p = 0.003) with cortisol in adult females. Additionally, we observed positive associations of OCPs (β = 0.192, p = 0.013) and brominated flame retardants (β = 0.176, p = 0.004) with cortisol in juveniles. Results suggest that cumulative pesticides and flame retardants are disruptive to endocrine function in these populations, which could have implications for development, metabolism and reproduction. Our study further demonstrates that faeces can be an important, non-invasive matrix for examining pollutant–hormone associations in wild primates and other critical wildlife populations.
[Steiniche, T., Wang, S., Chester, E., Mutegeki, R., Rothman, J.M., Wrangham, R.W., Chapman, C.A., Venier, M. and Wasserman, M.D., 2023. Biology Letters, 19(5), p.20230005.]
The global surge in disinfection practices from the COVID-19 response has raised concerns about the marine exposure to the hazardous ingredients in disinfectant products, including triclosan (TCS) and triclocarban (TCC). However, there are very limited studies on the response of marine TCS and TCC (TCs) loading to the COVID-19 pandemic. Here we used cetaceans as bio-indicators for a long-term retrospective analysis of TCs loading to the South China Sea (SCS) between 2004 and 2022. Hepatic TCs was 100% detected in all nine cetacean species (n = 120). Interestingly, TCS concentrations decreased in Indo-Pacific humpback dolphins (IPHD) before the pandemic from 2010 to 2017. However, after 2019, TCS concentrations in IPHD significantly increased several-fold. Similarly, post-pandemic TCS concentrations in Indo-Pacific finless porpoises (IPFP) and two fish species were significantly higher than pre-pandemic levels. There were significant relationships between thyroid hormones (THs) and TCs in IPHD and IPFP, suggesting that increased TCs may worsen the interference of THs homeostasis and nutritional conditions in cetaceans. These findings demonstrate the profound impact of the surging use of TCs-containing products from the COVID-19 response on marine ecosystems.
[Guo, Y., Shi, W., Liu, Z., Sun, X. and Wu, Y., 2023. Journal of Hazardous Materials, 459, p.132289.]
Alternatives to pesticides are urgently needed to meet sustainable agriculture goals but few options are available for many systems. Here we test how a form of olfactory misinformation on a newly sown wheat crop can prevent wild house mice (Mus musculus) from finding buried seeds. Our misinformation tactic, odour camouflage, reduced seed loss by >63%, providing a simple, non-lethal and ethical way to reduce seed damage and avoid rodenticide use.
[Parker, F.C., Price, C.J., Bytheway, J.P. and Banks, P.B., 2023. Nature Sustainability, pp.1-4.]
Piperonyl butoxide (PBO) is a popular insecticide synergist present in thousands of commercial, agricultural, and household products. PBO inhibits cytochrome P450 activity, impairing the ability of insects to detoxify insecticides. PBO was recently discovered to also inhibit Sonic hedgehog signaling, a pathway required for embryonic development, and rodent studies have demonstrated the potential for in utero PBO exposure to cause structural malformations of the brain, face, and limbs, or more subtle neurodevelopmental abnormalities. The current understanding of the pharmacokinetics of PBO in mice is limited, particularly with respect to dosing paradigms associated with developmental toxicity. To establish a pharmacokinetic (PK) model for oral exposure, PBO was administered to female C57BL/6J mice acutely by oral gavage (22–1800 mg/kg) or via diet (0.09 % PBO in chow). Serum and adipose samples were collected, and PBO concentrations were determined by HPLC-MS/MS. The serum concentrations of PBO were best fit by a linear one-compartment model. PBO concentrations in visceral adipose tissue greatly exceeded those in serum. PBO concentrations in both serum and adipose tissue decreased quickly after cessation of dietary exposure. The elimination half-life of PBO in the mouse after gavage dosing was 6.5 h (90 % CI 4.7–9.5 h), and systemic oral clearance was 83.3 ± 20.5 mL/h. The bioavailability of PBO in chow was 41 % that of PBO delivered in olive oil by gavage. Establishment of this PK model provides a foundation for relating PBO concentrations that cause developmental toxicity in the rodent models to Sonic hedgehog signaling pathway inhibition.
[Jenkins, A. et al. (2023) Pharmacokinetic analysis of acute and dietary exposure to piperonyl butoxide in the mouse, Toxicology Reports. Available at: https://www.sciencedirect.com/science/article/pii/S2214750023001099. ]
Persistent organic pollutants (POPs) are lipophilic compounds that can accumulate in high concentrations in the blubber of marine mammals, which are long-lived, top-level predators in their ecosystems. These compounds, which include DDTs, PCBs, PBDEs, HCHs, and CHLDs, impact mammalian health, including neurological effects, reduced immune system efficiency, and reproductive failure. POPs are transferred from females to their offspring during gestation and lactation, which have implications for the health of newborn marine mammals, particularly first-born offspring who receive higher concentrations. The dynamics of POP transfer during lactation have been studied in a few pinniped species, but there are no comparable studies on living cetaceans. Because life history strategies and behavior of lactating phocids differ from dolphins, a study on delphinid maternal transfer is warranted. To accomplish this, placenta and longitudinally collected blood and milk samples were taken concurrently from trained bottlenose dolphin, Tursiops truncatus, mother/calf pairs to assess the dynamics of maternal contaminant transfer. Initial POP levels in placenta, blood serum, and milk varied by individual and were related to the age and reproductive history of the females. Regardless of initial POP levels, maternal serum and milk concentrations decreased while calf serum POP levels increased over time. Pollutant transfer varied by POP class and by congener. Contaminant transfer efficiency to calves was most apparent for 4- to 6‑chlorine PCBs, DDT isomers p,p'-DDD, p,p'-DDT, o,p'-DDD, and o,p'-DDE, trans-nonachlor, cis-nonachlor, heptachlor epoxide, nonachlor III, and oxychlordane. By the end of the lactation period, calf serum POP levels were considerably greater than those of their mothers, particularly for compounds with fewer chlorines. POP levels were most biomagnified in the calf born to the primiparous female. These results provide critical information on one component of contaminant transfer in the marine ecosystem and for understanding potential risks of POP exposure to developing odontocete calves.
[Noren, D.P., Johnson, S., Boyd, D., Ylitalo, G.M., Lundin, J., McCormley, M. and Jensen, E.D., 2023. Science of The Total Environment, p.167888.]
Non-market natural capital provides crucial inputs across the economy. In this paper, researchers use land rental market data to calculate the welfare impacts of a change in an unpriced natural capital using well-identified causal impact estimates while accounting for spatial spillovers. The researcher apply the welfare analysis to examine the cost of whitenose syndrome (WNS) in bats, which provide pest control services to agricultural producers. WNS, a disease that decimates infected bat populations, began spreading through the US starting in the mid-2000s. We find that the loss of bats in a county causes land rental rates.
[Manning, D. and Ando, A.]
Although neonicotinoids are among the major classes of pesticides that affect mammalian nervous systems, little is known about sex differences in their effects. This study aimed to examine whether the neurobehavioral effects of a neonicotinoid, clothianidin (CLO), differed between sexes. Male and female C57BL/6N mice were orally administered CLO (5 or 50 mg/kg) at or below the chronic no-observed-adverse-effect-level (NOAEL) and subjected to behavioral tests of emotional and learning functions. Changes in neuroactivity in several brain regions and the concentrations of CLO and its metabolites in blood and urine were measured. Acute CLO exposure caused sex-related behavioral effects; decreases in locomotor activities and elevation of anxiety-like behaviors were more apparent in males than in females. In addition, male-specific impairment of short- and long-term learning memory by CLO exposure was observed in both the novel recognition test and the Barnes maze test. Male-dominant increases in the number of c-fos positive cells were observed in the paraventricular thalamic nucleus in the thalamus and in the dentate gyrus in the hippocampus, which are related to the stress response and learning function, respectively. The concentrations of CLO and most metabolites in blood and urine were higher in males. These results support the notion that male mice are more vulnerable than females to the neurobehavioral effects of CLO and provide novel insights into the risk assessment of neonicotinoids in mammalian neuronal function.
[Kubo, S. et al. (2022) Sex-specific behavioral effects of acute exposure to the neonicotinoid clothianidin in mice, Toxicology and Applied Pharmacology. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0041008X22004288?via%3Dihub. ]
Sixty years ago, Rachel Carson published her book Silent Spring, which focused the world's attention on the dangers of pesticides. Since that time human impacts on the environment have accelerated and this has included reshaping the chemical landscape. Here we evaluate the severity of exposure of tropical terrestrial mammals to pesticides, pharmaceuticals, plastics, particulate matter associated with forest fires, and nanoparticles. We consider how these environmental contaminants interact with one another, with the endocrine and microbiome systems of mammals, and with other environmental changes to produce a larger negative impact than might initially be expected. Using this background and building on past conservation success, such as mending the ozone layer and decreasing acid rain, we tackle the difficult issue of how to construct meaningful policies and conservation plans that include a consideration of the chemical landscape. We document that policy solutions to improving the chemical landscape are already known and the path of how to construct a healthier planet is discernible.
[Chapman, C.A., Steiniche, T., Benavidez, K.M., Sarkar, D., Amato, K., Serio-Silva, J.C., Venier, M. and Wasserman, M.D., Biological Conservation, 269, p.109522.]
At high exposure levels, organophosphorus insecticides (OPs) exert their toxicity in mammals through the inhibition of brain acetylcholinesterase (AChE) leading to the accumulation of acetylcholine in cholinergic synapses and hyperactivity of the nervous system. Currently, there is a concern that low-level exposure to OPs induces negative impacts in developing children and the chemical most linked to these issues is chlorpyrifos (CPF). Our laboratory has observed that a difference in the susceptibility to repeated exposure to CPF exists between juvenile mice and rats with respect to the inhibition of brain AChE. The basis for this difference is unknown but differences in the levels of the detoxification mechanisms could play a role. To investigate this, 10-day old rat and mice pups were exposed daily for 7 days to either corn oil or a range of dosages of CPF via oral gavage. Four hours following the last administration of CPF on day 16, brain, blood, and liver were collected. The inhibition of brain AChE activity was higher in juvenile rats as compared to juvenile mice. The levels of activity of the detoxification enzymes and the impact of CPF exposure on their activity were determined in the two species at this age. In blood and liver, the enzyme paraoxonase-1 (PON1) hydrolyzes the active metabolite of CPF (CPF-oxon), and the enzymes carboxylesterase (CES) and cholinesterase (ChE) act as alternative binding sites for CPF-oxon removing it from circulation and providing protection. Both species had similar levels of PON1 activity in the liver and serum. Mice had higher ChE activity in liver and serum than rats but, following CPF exposure, the percentage inhibition was similar between species at an equivalent dosage. Even though rats had slightly higher liver CES activity than mice, the level of inhibition following exposure was higher in rats. In serum, juvenile mice had an 8-fold higher CES activity than rats, and exposure to a CPF dosage that almost eliminated CES activity in rats only resulted in 22% inhibition in mice suggesting that the high serum CES activity in mice as compared to rats is a key component in this species difference. In addition, there was a species difference in the sensitivity of CES to inhibition by CPF-oxon with rats having a lower IC50 in both liver and serum as compared to mice. This greater enzyme sensitivity suggests that saturation of CES would occur more rapidly in juvenile rats than in mice, resulting in more CPF reaching the brain to inhibit AChE in rats.
[Sette, K. N., Alugubelly, N., Glenn, L. B., Guo-Ross, S. X., Parkes, M. K., Wilson, J. R., Seay, C. N., & Carr, R. L. (2022). The mechanistic basis for the toxicity difference between juvenile rats and mice following exposure to the agricultural insecticide chlorpyrifos. Toxicology, 480, 153317. https://doi.org/10.1016/j.tox.2022.153317]
A wide range of chemicals have been identified as endocrine disrupting chemicals (EDCs) in vertebrate species. Most studies of EDCs have focused on exposure of both male and female adults to these chemicals; however, there is clear evidence that EDCs have dramatic effects when mature or developing gametes are exposed, and consequently are associated with in multigenerational and transgenerational effects. Several publications have reviewed such actions of EDCs in subgroups of species, e.g., fish or rodents. In this review, we take a holistic approach synthesizing knowledge of the effects of EDCs across vertebrate species, including fish, anurans, birds, and mammals, and discuss the potential mechanism(s) mediating such multi- and transgenerational effects. We also propose a series of recommendations aimed at moving the field forward in a structured and coherent manner.
[Robaire, B. et al. (2021) A cross-species comparative approach to assessing multi- and transgenerational effects of endocrine disrupting chemicals, Environmental Research. Available at: https://www.sciencedirect.com/science/article/pii/S001393512101358X. ]
Habitat alteration for agriculture can negatively affect wildlife physiology and health by decreasing diet diversity and increasing exposure to agrochemicals for animals foraging in altered landscapes. Such negative effects may be mediated by the disruption of the gut microbiota (termed dysbiosis), yet evidence for associations between habitat alteration, wildlife health, and the gut microbiota remains scarce. We examine the association between management intensity of banana plantations and both the body condition and gut microbiota composition of nectar-feeding bats Glossophaga soricina, which commonly forage within banana plantations across Latin America. We captured and measured 196 bats across conventional monocultures, organic plantations, and natural forests in Costa Rica, and quantified gut microbiome bacterial phylogenetic diversity using 16S rRNA amplicon sequencing. We found that gut microbiota from bats foraging in conventional monocultures were overall less phylogenetically diverse than those from bats foraging in organic plantations or natural forests, both of which were characterized by diverse bacterial assemblages and individualized microbiota. Despite lower diversity, co-occurrence network complexity was higher in conventional monocultures, potentially indicating altered microbial interactions in agricultural landscapes. Bats from both organic and conventional plantations tended to be larger and heavier than their forest counterparts, reflecting the higher food supply. Overall, our study reveals that whilst both conventional monocultures and organic plantations provide a reliable food source for bats, conventional monocultures are associated with less diverse and potentially dysbiotic microbiota, whilst organic plantations promote diverse and individualized gut microbiota akin to their natural forest-foraging counterparts. Whilst the long-term negative effects of anthropogenically-altered microbiota are unclear, our study provides further evidence from a novel perspective that organic agricultural practices are beneficial for wildlife health.
[Alpízar, P., Risely, A., Tschapka, M. and Sommer, S. Frontiers in Ecology and Evolution, p.608.]
Chlorpyrifos (CPF), the most used insecticide in Argentina, can act as an endocrine disruptor at low doses. We previously demonstrated that chronic exposure to CPF induces hormonal imbalance in vivo. The aim of this work was to study the effects of low concentrations of CPF (0.01 and 1 mg/kg/day) on the reproductive system of virgin adult rats. In the ovary, we studied the effects of CPF on steroidogenesis by determining steroid hormone content by RIA and CYP11 and CYP19 enzyme expression by qRT-PCR. The estrous cycle was evaluated by microscopic observation of vaginal smear, as well as by changes in uterine histology. In endometrium, we determined the fractal dimension and expression of PCNA, ERα and PR by IHC. Our results showed that chronic exposure to CPF affects ovarian steroid synthesis, causing alterations in the normal cyclicity of animals. In addition, CPF induced proliferative changes in the uterus, suggesting that it could affect reproduction or act as a risk factor in the development of uterine proliferative pathologies.
[Ramos Nieto, M. R., Lasagna, M., Cao, G., Álvarez, G., Santamaria, C., Rodriguez Girault, M. E., Bourguignon, N., Di Giorgio, N., Ventura, C., Mardirosian, M., Rodriguez, H., Lux-Llantos, V., Cocca, C., & Núñez, M. (2021). Chronic exposure to low concentrations of chlorpyrifos affects normal cyclicity and histology of the uterus in female rats. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 156, 112515. https://doi.org/10.1016/j.fct.2021.112515]
The testicular deficiency associated with exposure to three widely used insecticides in Egyptian agriculture was evaluated. Animals were orally treated with sub-lethal dose (1/50 of the oral LD50) of cypermethrin (CYP), imidacloprid (IMC), and chlorpyrifos (CPF) at 5, 9 and 1.9 mg/kg/day, respectively, five times a week for one month. The CYP, IMC, and CPF exposure resulted in a significant decline in animal body weight, sperm count, motility, normality, and viability with increased head and tail deformities. Significant reduction in serum testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), testis superoxide dismutase (SOD), and reduced glutathione (GSH) levels. In contrast, catalase (CAT), lipid peroxidation (LPO), and protein carbonyl content (PCC) levels were significantly stimulated. Jointly, obtained results were confirmed by microscopic examination of testis sections. The present data concluded that the CYP, IMC, and CPF have a public health impact and violently interferes with male rat reproductive system.
[Abdel-Razik, R. K., Mosallam, E. M., Hamed, N. A., Badawy, M. E. I., & Abo-El-Saad, M. M. (2021). Testicular deficiency associated with exposure to cypermethrin, imidacloprid, and chlorpyrifos in adult rats. Environmental toxicology and pharmacology, 87, 103724. https://doi.org/10.1016/j.etap.2021.103724]
Anthropogenic contaminants in the marine environment often biodegrade slowly, bioaccumulate in organisms, and can have deleterious effects on wildlife immunity, health, reproduction, and development. In this study, we evaluated tissue toxicant concentrations and pathology data from 83 odontocetes that stranded in the southeastern United States during 2012–2018. Mass spectrometry was used to analyze blubber samples for five organic toxicants (atrazine, bisphenol-A, diethyl phthalates, nonylphenol monoethoxylate [NPE], triclosan), and liver samples were analyzed for five non-essential elements (arsenic, cadmium, lead, mercury, thallium), six essential elements (cobalt, copper, manganese, iron, selenium, zinc) and one toxicant mixture class (Aroclor1268). Resultant data considerably improve upon the existing knowledge base regarding toxicant concentrations in stranded odontocetes. Toxicant and element concentrations varied based on animal demographic factors including species, sex, age, and location. Samples from bottlenose dolphins had significantly higher average concentrations of lead, manganese, mercury, selenium, thallium, and zinc, and lower average concentrations of NPE, arsenic, cadmium, cobalt, and iron than samples from pygmy sperm whales. In adult female bottlenose dolphins, average arsenic concentrations were significantly higher and iron concentrations were significantly lower than in adult males. Adult bottlenose dolphins had significantly higher average concentrations of lead, mercury, and selenium, and significantly lower average manganese concentrations compared to juveniles. Dolphins that stranded in Florida had significantly higher average concentrations of lead, mercury, and selenium, and lower concentrations of iron than dolphins that stranded in North Carolina. Histopathological data are presented for 72 animals, including microscopic evidence of Campula spp. and Sarcocystis spp. infections, and results of Morbillivirus and Brucella spp. molecular diagnostic testing. Sublethal cellular changes related to toxicant exposure in free-ranging odontocetes may lead to health declines and, in combination with other factors, may contribute to stranding.
[Page-Karjian, A., Lo, C.F., Ritchie, B., Harms, C.A., Rotstein, D.S., Han, S., Hassan, S.M., Lehner, A.F., Buchweitz, J.P., Thayer, V.G. and Sullivan, J.M., 2020. Frontiers in Marine Science, 7, p.630.]
Use of the herbicide atrazine (ATR) is banned in the European Union; yet, it is still widely used in the USA and Australia. ATR is known to alter testosterone and oestrogen production and thus reproductive characteristics in numerous species. In this proof of concept study, we examined the effect of ATR exposure, at a supra-environmental dose (5 mg/kg bw/day), beginning on E9.5 in utero, prior to sexual differentiation of the reproductive tissues, until 26 weeks of age, on the development of the mouse penis. Notably, this is the first study to specifically investigate whether ATR can affect penis characteristics. We show that ATR exposure, beginning in utero, causes a shortening (demasculinisation) of penis structures and increases the incidence of hypospadias in mice. These data indicate the need for further studies of ATR on human reproductive development and fertility, especially considering its continued and widespread use.
[Govers, L. et al. (2020) Atrazine induces penis abnormalities including hypospadias in mice, Journal of developmental origins of health and disease. Available at: https://pubmed.ncbi.nlm.nih.gov/31475654/. ]
Cypermethrin (CYP) is a ubiquitously present synthetic pyrethroid insecticide. It has endocrine disrupting activities which may adversely affect reproductive development and functions of offspring if exposed during critical developmental period. The present study was undertaken to delineate the effects of CYP exposure in pregnant female rats during perinatal period on the sexual maturation, hormonal regulation, reproductive development and fertility of F1 female offspring and its molecular mechanism of action. Pregnant rats (F0) were gavaged daily with 0, 1, 10, 25 mg/kg bw/day CYP and 10 μg/kg bw/day Diethylstilbestrol (DES; positive control) from gestation day (GD) 6 to postnatal day (PND) 21. The reproductive development and function parameters were evaluated at PND 45 and 75. Reduced body weight, delayed vaginal opening, and disrupted estrous cyclicity were observed at 25 mg/kg CYP dose. CYP exposure significantly affected the reproductive organ development and their functions at all doses. Significant alterations in ovarian and uterine histology such as luteinization, reduction of primordial follicular reserves, presence of multi-oocyte follicles and thin degenerative luminal and glandular uterine epithelium were observed at adulthood. Altered circulatory steroid hormone levels and expression of ovarian and uterine steroid hormone receptors were observed at PND 75 in the F1 female offspring. Expression of HOXA10 and α-SMA which are important for uterine integrity and functions, were found to be altered at PND 75. Increased pre-implantation loss (PIL%), post-implantation loss (POL%), and reduced litter size in F1 females when cohabitated with unexposed fertile male rats were observed. Overall, perinatal exposure of pregnant rats to CYP led to significant long lasting effects on the reproductive functions of F1 female offspring. The adverse effects were passed on to F2 generation via female germ line and posed developmental anomalies. The present finding necessitates additional molecular studies to understand its trans-generational mechanism of action via female germline.
[Singh, D., Irani, D., Bhagat, S., & Vanage, G. (2020). Cypermethrin exposure during perinatal period affects fetal development and impairs reproductive functions of F1 female rats. The Science of the total environment, 707, 135945. https://doi.org/10.1016/j.scitotenv.2019.135945]
Marsupials are experiencing devastating population declines across Australia. Exposure to environmental endocrine disruptors, through ingestion of contaminated resources in the environment, could be contributing to this decline. Atrazine (ATZ), a widely used herbicide in Australia, is an endocrine disruptor with the ability to cause reproductive abnormalities in a diverse range of vertebrates. We exposed adult female wallabies (Macropus eugenii) to drinking water containing ATZ (450 p.p.m) throughout pregnancy, parturition and lactation. We assessed the outcome of this exposure to the reproductive development of their young by assessing gonad and phallus development. Both these organs are especially sensitive to perturbations in the hormonal environment during development. Although no gross abnormalities were seen in gonad structure, exposure to ATZ did alter the expression of genes required for normal testis function. Furthermore, long-term exposure to ATZ resulted in a significant reduction in penis length. These results demonstrate that ATZ exposure during gestation and lactation can significantly affect the development of male young by affecting virilisation. Given the known vulnerability of macropodid marsupials to endocrine disruption, as well as their overlapping distribution with agricultural areas, these data raise major concerns for the use of pesticides in areas with fragile marsupial populations.
[Cook, L.E., Chen, Y., Renfree, M.B. and Pask, A.J., 2020. Reproduction, Fertility and Development, 32(13), pp.1168-1168.]
Bats play a vital role in our ecosystems and economies as natural pest‐control agents, seed dispersers, and pollinators. Agricultural intensification, however, can impact bats foraging near crops, affecting the ecosystem services they provide. Exposure to pesticides, for example, may induce chromosome breakage or missegregation that can result in micronucleus formation. Detection of micronuclei is a simple, inexpensive, and relatively minimally invasive technique commonly used to evaluate chemical genotoxicity but rarely applied to assess wildlife genotoxic effects. We evaluated the suitability of the micronucleus test as a biomarker of genotoxicity for biomonitoring field studies in bats. We collected blood samples from insectivorous bats roosting in caves surrounded by different levels of disturbance (agriculture, human settlements) in Colima and Jalisco, west central Mexico. Then, we examined the frequency of micronucleus inclusions in erythrocytes using differentially stained blood smears. Bats from caves surrounded by proportionately more (53%) land used for agriculture and irrigated year‐round had higher micronucleus frequency than bats from a less disturbed site (15% agriculture). We conclude that the micronucleus test is a sensitive method to evaluate genotoxic effects in free‐ranging bats and could provide a useful biomarker for evaluating risk of exposure in wild populations. Environ Toxicol Chem 2021;40:202–207.
[Sandoval‐Herrera, N., Castillo, J.P., Montalvo, L.G.H. and Welch, K.C., 2020. Environmental Toxicology and Chemistry.]
Paraquat was the most successful nonselective herbicide in Korea due to its rapid herbicidal activity. However, its high mammalian toxicity, frequent self-poisoning incidents, and a lack of effective antidotes led to a paraquat ban in Korea in 2012. Therefore, this review was conducted to revisit the toxicological profile of paraquat and to investigate the impacts of the paraquat ban on human health and agriculture in Korea. A review of toxicological information reconfirmed that paraquat is highly acutely toxic to humans, and ingestion, inhalation, or dermal administration of the herbicide can cause severe clinical signs and inevitably lead to death by respiratory failure. In Korea, the paraquat ban immediately decreased the suicide rate due to pesticides (mainly paraquat) by 46.1%, resulting in a 10% decrease of the total suicide rate. However, this also led to an increase in suicide attempts with other poisons such as carbon monoxide, suggesting that suicide attempts and rates of suicide by poisoning depend on not only the toxicity of the poison but also the accessibility of the poisoning agents. In agriculture, paraquat was quickly replaced by other nonselective herbicides such as glufosinate and glyphosate. Thus, the paraquat ban did not have a significant impact on agricultural practices but influenced the nonselective herbicide market; the use of glufosinate was higher than use of glyphosate due to glufosinate’s rapid herbicidal activity, which is similar to that of paraquat. Though the paraquat ban can be considered as a national strategy to lower suicide rates, the increase in suicide attempts with other poisons suggests that multilateral efforts are required for not only keeping suicidal agents away from people but also minimizing motives for suicide.
[Kim, J. W., & Kim, D. S. (2020). Paraquat: toxicology and impacts of its ban on human health and agriculture. Weed science, 68(3), 208-213. https://www.cambridge.org/core/journals/weed-science/article/abs/paraquat-toxicology-and-impacts-of-ban-on-human-health-and-agriculture/0E4589AEC0B5B84F5D46587C0640B235 ]
Thiazole-Zn is a systemic fungicide synthesized and developed in China that has been used for the prevention and treatment of bacterial and fungal diseases on fruits and vegetables. Thiazole-Zn is a new thyroid disruptor chemical. The purpose of this study was to clarify the thyroid-disrupting property of thiazole-Zn and the mechanism responsible for thyroid hormone (TH) biosynthesis inhibition in male rats induced by thiazole-Zn. First, the effects of different thiazole-Zn doses and exposure times on the thyroid weights, thyroid morphology and serum hormone levels of rats were investigated. The results showed that thiazole-Zn increased thyroid weights and serum thyroid-stimulating hormone (TSH) levels and induced thyroid cell hypertrophy and hyperplasia in a dose-related and time-related manner. Furthermore, measurement of thyroid radioiodine uptake in vivo in rats confirmed that thiazole-Zn inhibited active iodide uptake into the thyroid, which reduced circulating levels of serum T3 and T4. Decreases in circulating THs resulted in a compensatory increase in serum TSH levels through a negative feedback system. Subsequently, sustained excessive stimulation of the thyroid gland by TSH led to thyroid follicular cell hypertrophy and hyperplasia. In addition, thiazole-Zn increased sodium/iodide symporter (NIS) expression in the rat thyroid, and the increased NIS expression promoted and restored iodide uptake into the thyroids of rats. The risk of iodine intake inhibition by thiazole-Zn to humans, especially susceptible individuals, such as children and pregnant women, warrants additional attention.
[Honglian, Y. et al. (2020) Thyroid-disrupting effects and mechanism of thiazole-Zn-induced thyroid cell hypertrophy and hyperplasia in male Sprague-Dawley rats, Ecotoxicology and Environmental Safety. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0147651320303833. ]
Neonicotinoids are now the most widely used insecticides in the world. They act systemically, travelling through plant tissues and protecting all parts of the crop, and are widely applied as seed dressings. As neurotoxins with high toxicity to most arthropods, they provide effective pest control and have numerous uses in arable farming and horticulture. However, the prophylactic use of broad-spectrum pesticides goes against the long-established principles of integrated pest management (IPM), leading to environmental concerns. It has recently emerged that neonicotinoids can persist and accumulate in soils. They are water soluble and prone to leaching into waterways. Being systemic, they are found in nectar and pollen of treated crops. Reported levels in soils, waterways, field margin plants and floral resources overlap substantially with concentrations that are sufficient to control pests in crops, and commonly exceed the LC50 (the concentration which kills 50% of individuals) for beneficial organisms. Concentrations in nectar and pollen in crops are sufficient to impact substantially on colony reproduction in bumblebees. Although vertebrates are less susceptible than arthropods, consumption of small numbers of dressed seeds offers a route to direct mortality in birds and mammals. Synthesis and applications. Major knowledge gaps remain, but current use of neonicotinoids is likely to be impacting on a broad range of non-target taxa including pollinators and soil and aquatic invertebrates and hence threatens a range of ecosystem services.
[Goulson, D. (2013) An overview of the environmental risks posed by neonicotinoid insecticides, Journal of Applied Ecology. Available at: https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2664.12111. ]
Chlorpyrifos (CPF) is an organophosphate (OP) insecticide extensively used in agricultural and domestic settings. Healthy adult female albino rats were divided into three groups of six rats in each. Two groups were dosed orally with CPF in vegetable oil (0.1 and 2.5 mg/kg/day) and third group was given vegetable oil for 8 weeks. Non-significant changes were observed for body weight and feed intake. A disruption in estrous cyclicity was observed with a prolonged metestrous. Erythrocyte osmotic fragility and lipid peroxidation levels increased significantly. Mammary gland whole mounts revealed a significant (P<0.05-0.0001) increase in the ductal thickness, number of branches, alveolar and terminal end bud number and terminal end bud diameter. A significant increase in ovarian surface epithelium height, follicular diameter and follicular atresia was observed in treated rats (P<0.05-0.0001). A similar significant increase in the uterine surface epithelium height, endometrial gland epithelium height and myometrium thickness in higher dose group was recorded (P<0.05-0.0001). Luminal epithelium height and endometrial gland diameter was increased significantly in both the treated groups (P<0.05-0.0001). The results indicate that sub-chronic exposure of CPF causes oxidative stress and negative effects on the reproductive organs of female rats, which may be a pointer towards beginning of cancer incidence.
[Nishi, K., & Hundal, S. S. (2013). Chlorpyrifos induced toxicity in reproductive organs of female Wistar rats. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 62, 732–738. https://doi.org/10.1016/j.fct.2013.10.006]
Organophosphorus pesticide residues are found in many food samples due to increasing use of multiple organophosphorus pesticides (OPs) in agriculture. Toxicity of individual organophosphorus has been well-studied in previous epidemiological and laboratory investigations. This study focused on reproductive toxicity of perinatal exposure to the mixture of organophosphorus pesticides (MOPs). The MOPs consists of three most commonly used pesticides, i.e., Dichlorovos, Dimethoate, and Malathion which individually does not cause significant effects on the reproductive system at the similar concentration levels based on previous studies. Using the Sprague-Dawley rats, we established a perinatal exposure model by oral gavage and observed significant endometrial hyperplasia and thickened uterine walls in the F0 rats after administration of high doses of the MOPs. We further monitored several key developmental and behavioral indices in the F1 generation after maternal exposure to the MOPs, and observed significantly delayed physical development and weakened mental development. Moreover, we found increased weights of the reproductive organs (the uterus and the testis) and abnormal levels of key sex hormones (progestin and testosterone) in the MOPs groups. It is more important that we observed a significantly lower pregnancy rate and live birth rate in the high-dose MOPs group. These results indicate that the MOPs may be more detrimental to the maternal endometria and the reproductive functions in the offspring than individual organophosphorus.
[Yu, Y., Yang, A., Zhang, J., & Hu, S. (2013). Maternal exposure to the mixture of organophosphorus pesticides induces reproductive dysfunction in the offspring. Environmental toxicology, 28(9), 507–515. https://doi.org/10.1002/tox.20741]
In this study, 70 Wistar rats were randomly divided into seven equal groups (six experimental and one control), which consisted of animals belonging to both sexes. Different combinations of insecticides were administered daily to the experimental groups (group 1: cypermethrin + piperonyl butoxide (PBO); group 2: alphacypermethrin + PBO; group 3: deltamethrin + PBO; group 4: cypermethrin + PBO + tetramethrin; group 5: alphacypermethrin + PBO + tetramethrin; and group 6: deltamethrin + PBO + tetramethrin) for 28 days. During the study period, mortality and serious clinical findings were not observed in any animal. However, feed consumptions decreased in groups 1 and 3 (p < 0.05). Red blood cells, white blood cells, and hemoglobin levels, especially in cypermethrin and alphacypermethrin groups (groups 1, 2, and 4), were found to be higher than the control group (p < 0.05). Furthermore, biochemical changes related to liver, kidney functions, and protein metabolism occurred in males of almost all the groups. Relative liver and kidney weights of the male animals increased in the cypermethrin and alphacypermethrin groups (p < 0.05). The most common finding observed during the histopathological examination of all the experimental groups was centrilobular degeneration in the liver. It was concluded that although clinical symptoms were not observed, synthetic pyrethroid, synergist, and knockdown agent combinations might cause serious abnormalities when administered in certain doses in mammalians.
[Yavuz O, Aksoy A, Das YK, et al. (2013). Subacute oral toxicity of combinations of selected synthetic pyrethroids, piperonyl butoxide, and tetramethrin in rats. Toxicology and Industrial Health. https://journals.sagepub.com/doi/abs/10.1177/0748233712469651]
Administration of 5 mg methomyl (40%) kg(-1) b.wt. mouse(-1) (equal to 50% of LD50 dose), every day for 90 days to adult female mice resulted in a significant decrease in body weight, relative weight of the ovary, uterus and fallopian tube; mean number of small, preantral, antral and pre-ovulatory follicles and fertility compared to controls. On the other hand, total duration of the estrous cycle was significantly increased compared to controls. One month after the cessation of the treatment (a commercial methomyl preparation-lannate) the effect on estrous cycle and organ weight was not restored. Treatment of 2.5 mg or 1 mg lannate kg(-1) b. wt., although did not alter duration of the estrous cycle; relative weight of the ovary, uterus, and fallopian tube and fertility, caused a significant decrease in mean number of small follicles compared to controls. All the groups of mice treated with lannate showed loss in body weight (15.15% in 1 mg, 6.61% in 2 mg and 12.16% in 5 mg treated groups) whereas controls showed a gain in body weight (20.02%) during the period of experimentation. The results indicate that 5 mg lannate kg(-1) b. wt causes loss of follicles and infertility, whereas lower dosages (2.5 and 1 mg) reduce the number of small follicles which might shorten reproductive life span of mice.
[Shanthalatha, A., Madhuranath, B. N., & Yajurvedi, H. N. (2012). Effect of methomyl formulation, a carbamate pesticide on ovarian follicular development and fertility in albino mice. Journal of environmental biology, 33(1), 33–37.]Abstract
Background
Methods
Results
Conclusion
[Stanneck, D. et al. (2012) ‘The synergistic action of imidacloprid and flumethrin and their release kinetics from collars applied for ectoparasite control in dogs and cats’, Parasites & Vectors, 5(1). doi:10.1186/1756-3305-5-73. ]
Effect of chlorpyrifos pesticide on testicular oxidative damage was studied in Sprague-Dawley rats at varying doses. At lower doses (5 and 10 mg/kg body weight/30 days), reduction in plasma levels of testosterone and follicular stimulating hormone (FSH) and luteinizing hormone (LH) along with significant shrinkage of seminiferous tubules and drastic changes in germ cells were seen. But these adverse changes of testes were restored with the revival of serum testosterone and FSH and LH at higher doses (20 and 30 mg/kg body weight/30 days). Similarly, levels of testicular lipid peroxidation and diene conjugates were elevated whereas activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), steroidogenic (Δ5, 3β-HSD and Δ5, 17β-HSD) enzymes and angiotensinogen-converting enzyme and glutathione content including lipid–protein content of testes were decreased at low doses. But at higher doses, reductions in level of lipid peroxidation (as revealed by malondialdehyde [MDA] value) and conjugated dienes were found and on the contrary, revivals of testicular antiperoxidative/antioxidant enzymes defense systems, angiotensinogen-converting enzyme (ACE), steroidogenic enzymes, lipid–protein and antioxidant glutathione content were observed. Therefore, the present study indicated from the results that chlorpyrifos had a dual effect at both doses on oxidative stress changes, but at higher doses, the cells were triggering its natural defense mechanism to combat the insult of lower doses of chlorpyrifos and became operative possibly through corrective measure of antioxidant enzymes defense system and pituitary gonadotropins hormones feedback mechanisms on testes.
[Mandal TK, Das NS. Correlation of testicular toxicity and oxidative stress induced by chlorpyrifos in rats. Human & Experimental Toxicology. 2011;30(10):1529-1539. doi:10.1177/0960327110392400]
Fenvalerate is a synthetic pyrethroid insecticide used in agriculture and domestic insect control. Some studies have proposed that it may act as an environmental estrogen; other studies suggest possible genotoxicity in germ cells. This study aimed to evaluate the effects of fenvalerate on the female reproduction in rats whose mothers were exposed during gestation and lactation. Pregnant Wistar rats were exposed to fenvalerate (40 mg/kg) or corn oil (vehicle) orally from gestational day 12 until the end of lactation. The dose selection was based on previous studies, whereas this was considered an effective dose. Results showed decreases in ovarian weight, pre-antral follicles and corpora lutea at PND 75 and an increase in the resorption number, when fertility test was performed at PND 80. Under some experimental conditions, fenvalerate may impair reproductive development of female offspring, manifested as reduced fecundity and ovulation number, resulting from the impairment in corpora lutea counting.
[Guerra, M. T., de Toledo, F. C., & Kempinas, W.deG. (2011). In utero and lactational exposure to fenvalerate disrupts reproductive function in female rats. Reproductive toxicology (Elmsford, N.Y.), 32(3), 298–303. https://doi.org/10.1016/j.reprotox.2011.08.002]
Biomonitoring surveys of wild cetaceans commonly utilize blubber as a means to assess exposure to persistent organic pollutants (POPs), but the relationship between concentrations in blubber and those in blood, a better indicator of target organ exposure, is poorly understood. To define this relationship, matched blubber and plasma samples (n = 56) were collected from free-ranging bottlenose dolphins (Tursiops truncatus) and analyzed for 61 polychlorinated biphenyl (PCB) congeners, 5 polybrominated diphenyl ether (PBDE) congeners, and 13 organochlorine pesticides (OCPs). With the exception of PCB 209, lipid-normalized concentrations of the major POPs in blubber and plasma were positively and significantly correlated (R(2) = 0.828 to 0.976). Plasma concentrations, however, significantly increased with declining blubber lipid content, suggesting that as lipid is utilized, POPs are mobilized into blood. Compound- and homologue- specific blubber/blood partition coefficients also differed according to lipid content, suggesting POPs are selectively mobilized from blubber. Overall, these results suggest that with the regression parameters derived here, blubber may be used to estimate blood concentrations and vice versa. Additionally, the mobilization of lipid from blubber and concomitant increase in contaminants in blood suggests cetaceans with reduced blubber lipid may be at greater risk for contaminant-associated health effects.
[Yordy JE, Wells RS, Balmer BC, Schwacke LH, Rowles TK, Kucklick JR. 2010. Environ Sci Technol. 15;44(12):4789-95]
Atrazine (ATR), a widely used chlorotriazine herbicide, inhibits a number of endocrine-dependent processes, including gonadotrophin surges and mammary gland development in rats. Chlorotriazine herbicides are rapidly metabolized in plants and animals to form a group of metabolites that are detected both in the environment and in exposed animals. The extent to which these metabolites are responsible directly for the observed health effects is not understood. Our goal was to determine if a mixture of ATR metabolites, in proportions found in the environment, might produce developmental effects in Long-Evans rats following exposure late in pregnancy. We administered an ATR metabolite mixture (AMM) containing ATR, hydroxyatrazine, diaminochlorotriazine, deethylatrazine, and deisopropylatrazine orally to pregnant Long-Evans rats at 0.09, 0.87, or 8.73 mg/kg body weight (bw)/day, on gestation days 15–19, using 0 and 100 mg ATR/kg bw/day as negative and positive controls, respectively. We observed no significant effect of acute AMM exposure on body weight gain in dams during the dosing period, weight loss in pups on postnatal day (PND)4, or pubertal timing, as is seen with ATR alone. However, as with ATR, we detected delayed mammary gland development, evaluated by whole mount analysis, as early as PND4 in all treatment groups. Our data suggest that acute exposure to AMM at levels as low as 0.09 mg/kg bw during late pregnancy causes persistent alterations in mammary gland development of female offspring, and that these effects do not appear to be related to bw or associated with pubertal timing.
[Enoch R.R., et al. 2007. Environmental Health Perspectives, 115(4).]
Dimethoate, a widely used organophosphate insecticide, was administered orally (28 mg/kg body weight) to hemicastrated (HC) virgin mice on day 1 and for 5, 10, and 15 days. Hemicastrated untreated control mice showed a significant increase in relative ovarian weight, with 42.74% hypertrophy and an increase in healthy and atretic follicles when compared with those of sham-operated control animals. The HC mice treated for 1 day or for 5 days showed no significant change in ovarian weight (36.64% and 25.19% hypertrophy, respectively) or in healthy and atretic follicles, when compared with HC-control mice. Treatment with dimethoate for 10 or 15 days, however, resulted in a significant decrease in ovarian weight (19.84% and 0.76% hypertrophy, respectively), a significant decrease in the number of healthy follicles, and a concomitant significant increase in the number of atretic follicles when compared with those in HC control animals. No significant change occurred in the number of estrous cycles or duration of each phase of the estrous cycle in HC mice treated with dimethoate for either 1 or 5 days. In HC mice treated with dimethoate for 10 or 15 days, however, a significant decrease in the number of estrous cycles, duration of proestrus, estrus, and metestrus, a concomitant significant increase in the diestrus phase, when compared with HC control animals. In mice receiving dimethoate for 15 days (but not for 1, 5, or 10 days) a significant decrease occurred in body weight and in the weights of the uterus, kidney, spleen, and liver when compared with the parallel weights in HC control animals. The overall findings suggest that following dimethoate treatment, a significant decrease in ovarian weight with a concomitant increase in compensatory ovarian hypertrophy and in the number of healthy follicles, with a concomitant increase in the number of atretic follicles and interrupted estrous cycles, may be due to the direct effect on the ovary or may be due to a hormonal imbalance in any stage of the hypothalamo-hypophysial ovarian axis.
[Mahadevaswami, M. P., & Kaliwal, B. B. (2002). Effect of dimethoate administration schedules on compensatory ovarian hypertrophy, follicular dynamics, and estrous cycle in hemicastrated mice. Journal of basic and clinical physiology and pharmacology, 13(3), 225–248. https://doi.org/10.1515/jbcpp.2002.13.3.225]
In order to address data gaps identified by the NAS report Pesticides in the Diets of Infants and Children, a study was performed using methoxychlor (MXC). Female rats were gavaged with MXC at 0, 5, 50, or 150 mg/kg/day for the week before and the week after birth, whereupon the pups were directly dosed with MXC from postnatal day (pnd) 7. Some dams were killed pnd7 and milk and plasma were assayed for MXC and metabolites. For one cohort of juveniles, treatment stopped at pnd21; a modified functional observational battery was used to assess neurobehavioral changes. Other cohorts of juveniles were dosed until pnd42 and evaluated for changes to the immune system and for reproductive toxicity. Dose-dependent amounts of MXC and metabolites were present in milk and plasma of dams and pups. The high dose of MXC reduced litter size by approximately 17%. Ano-genital distance was unchanged, although vaginal opening was accelerated in all treated groups, and male prepuce separation was delayed at the middle and high doses by 8 and 34 days, respectively. In the neurobehavioral evaluation, high-dose males were more excitable, but other changes were inconsistent and insubstantial. A decrease in the antibody plaque-forming cell response was seen in males only. Adult estrous cyclicity was disrupted at 50 and 150 MXC, doses which also showed reduced rates of pregnancy and delivery. Uterine weights (corrected for pregnancy) were reduced in all treated pregnant females. High-dose males impregnated fewer untreated females; epididymal sperm count and testis weight were reduced at the high, or top two, doses, respectively. All groups of treated females showed uterine dysplasias and less mammary alveolar development; estrous levels of follicle stimulating hormone were lower in all treated groups, and estrus progesterone levels were lower at 50 and 150 MXC, attributed to fewer corpora lutea secondary to ovulation defects. These data collectively show that the primary adult effects of early exposure to MXC are reproductive, show that 5 mg/kg/day is not a NO(A)EL in rats with this exposure paradigm (based on changes in day of vaginal opening, pubertal ovary weights, adult uterine and seminal vesicle weights, and female hormone data) and imply that the sites of action are both central and peripheral.
[Chapin, R. E., Harris, M. W., Davis, B. J., Ward, S. M., Wilson, R. E., Mauney, M. A., Lockhart, A. C., Smialowicz, R. J., Moser, V. C., Burka, L. T., & Collins, B. J. (1997). The effects of perinatal/juvenile methoxychlor exposure on adult rat nervous, immune, and reproductive system function. Fundamental and applied toxicology : official journal of the Society of Toxicology, 40(1), 138–157. https://doi.org/10.1006/faat.1997.2381]
Thiophanate methyl a carbamate compound is an effective plant fungicide, used
for controlling pests on fruits and vegetables. The only report available on the toxicological aspects of the compound is from Nippon Soda Company Ltd. Tokyo, Japan which produces and markets it (Hashimoto et al., 1972). The present study was taken with a view to explore toxicological effects of thiophanate methyl in rats.
[Singh, T., Garg, B. and Verma, P. (1987) Thiophanate methyl acute, subacute and chronic toxicity in rats, Indian Journal of Pharmacology. Available at: https://journals.lww.com/iphr/citation/1987/19020/thiophanate_methyl_acute,_subacute_and_chronic.15.aspx. ]