(Beyond Pesticides, November 9, 2018) A Tunisian study (published in January 2018) on the effects in pre-pubertal mice of exposure to malathion — an organophosphate pesticide first registered for use in the U.S. in 1956 — demonstrates significant distortion of liver and kidney biochemistry and function in the animals. Deleterious effects include compromise of feeding ability, metabolism performance, neurologic deficits, reduction of overall body weight, and simultaneous increases in the weights of livers and kidneys, with structural anomalies and lesions in those organs. Organophosphates (OPs) have raised alarm bells for years. Some, such as chlorpyrifos and diazinon, have had their registrations cancelled for household uses because of the extreme health risks to children, but agricultural, golf course, and “public health” (mosquito control) uses remain commercially available and in use. Recently, Beyond Pesticides reported on research whose investigators support — and called publicly for — a worldwide ban on the compounds because of the serious health and environmental risks they pose, particularly for children. Beyond Pesticides has written extensively on OP pesticides, including malathion and chlorpyrifos. Both are used widely in agriculture. Chlorpyrifos has been the subject of quite a ping-pong match in recent years: a scheduled ban by the Environmental Protection […]

(Beyond Pesticides, November 2, 2018) A group of leading toxics experts, who published a paper in the journal PLOS Medicine on their research on organophosphate exposure during pregnancy and impacts on child development, are calling for a ban on organophosphate pesticides. The study evaluates current science on the risks of this class of compounds, produced by Corteva Agriscience (formerly Dow AgroSciences); its conclusions warn of the multitude of dangers of organophosphates for children, and makes recommendations for addressing these risks. The experts conclude that: (1) widespread use of organophosphate (OP) pesticides to control insects has resulted in ubiquitous human exposures; (2) acute exposures to OPs is responsible for poisonings and deaths, particularly in developing countries; and (3) evidence demonstrates that prenatal exposures, even at low levels, put children at risk for cognitive and behavioral deficits, and for neurodevelopmental disorders. Among the authors’ recommendations are these: Governments and subsidiary agencies, including the Environmental Protection Agency (EPA), should phase out chlorpyrifos and other organophosphate pesticides; ban non-agricultural uses of OP pesticides (including in household products); monitor watersheds and drinking water sources of human exposure; promote the use of integrated pest management (IPM) through incentives and training; and establish pesticide use and illness reporting […]

(Beyond Pesticides, September 15, 2017) Illegal cannabis grow operations are polluting California waterways with banned pesticides, according to reports from Reuters. Despite recent legalization of recreational marijuana in the state, California still accounts for over 90% of illegal grow operations within the U.S. The extent of contamination puts wildlife and drinking water at risk, necessitating increased monitoring and enforcement to stop ongoing ecological damage. Unreleased reports obtained by Reuters indicate the presence of pesticides, such as diazanon and carbofuran, which have been linked to a range of adverse human health outcomes. Both chemicals inhibit acetylcholinesterase (AChE), an enzyme important for the transmission of nerve impulses. When AChE is inhibited, acetylcholine accumulates leading to overstimulation of neurotransmitters, resulting in muscle weakness, confusion, and paralysis, among other symptoms. Both chemicals have also been shown to be highly toxic to birds. According to EPA reports from the 1980s, carbofuran applications contributed to the death of between one and two million birds each year. Diazinon has likewise been linked to hundreds of bird kill incidents, with reports in the 1980s involving over 23 bird species in 18 states. Reuters reports that law enforcement officers have been hospitalized from only touching plants or equipment contaminated […]

(Beyond Pesticides, January 25, 2017) A study conducted at the University of Buffalo recently revealed a connection between two common insecticides and an increased risk for certain metabolic diseases, including diabetes. Researchers found that by binding to and disrupting melatonin receptors that control numerous physiological functions, chemicals such as insecticides can affect melatonin levels, creating a higher risk for metabolic diseases to develop. The study, Carbamate Insecticides Target Human Melatonin Receptors, was published in Chemical Research in Toxicology and was funded by a grant from the National Institute of Environmental Health Sciences, which is part of the National Institutes of Health. The implicated chemicals in this research, carbaryl and carbofuran, are notoriously dangerous carbamate insecticides. Carbamates share structural characteristics and an ability to inhibit acetylcholinesterase (AChE), an enzyme important for the transmission of nerve impulses. When AChE is inhibited, acetylcholine accumulates leading to overstimulation of neurotransmitters, resulting in muscle weakness, confusion, and paralysis, among other symptoms. Carbaryl is said by EPA to be “one of the most widely applied insecticides in the U.S.,” since use began in 1959, with 10-15 million pounds used annually. It is a broad-spectrum insecticide used on a variety of crops, in forestry and on ornamentals, in […]

(Beyond Pesticides, February 26, 2013) The world’s most commonly used synthetic insect repellent is not  as effective as it once was, according to scientists at the London School of Hygiene and Tropical Medicine. While researchers found DEET to be an effective repellent after an initial application, subsequent rounds of testing mere hours later showed mosquitoes to be unaffected by its presence. The study, published in the journal PLOS One, underlines the need to develop safe, natural, effective alternative preventions to this hazardous chemical. To perform their experiment, researchers took the mosquito species Aedes aegypti, a carrier for dengue and yellow fever, and exposed it to a human arm covered in DEET. A few hours later they repeated the experiment, but this time the mosquitoes largely ignored the presence of the chemical. To find out what caused this to occur, researchers placed electrodes on the antennas of the insects. “We were able to record the response of the receptors on the antenna to DEET, and what we found was the mosquitoes were no longer as sensitive to the chemical, so they weren’t picking it up as well,”   co-author James Logan, PhD told the BBC.  “There is something about being exposed […]

(Beyond Pesticides, April 13, 2012) A study has found that the children of flower plantation workers in Ecuador are neurologically affected by the pesticide residues that their parents unwittingly carry home on their clothes, tools, and skin. The study documents significantly reduced activity for the essential enzyme acetycholinesterase (AChE) in children whose parents work on flower plantations compared to others whose parents do not. The two main classes of pesticides that the researchers identify as used in the region’s flower production, organophosphates and carbamates, are known to suppress the enzyme’s activity. AChE activity is crucial to healthy neurological functioning in humans and its suppression during childhood can hinder nervous system and cognitive development causing immediate and long-term impairment. In the study, Lower acetylcholinesterase activity among children living with flower plantation workers (Environ Res. 2012 Apr;114:53-9. Epub 2012 Mar 10), children whose parents work on a flower plantation are more than three times more likely to be in the group of lowest AChE activity. Additionally, the children who live the longest with a flower plantation worker are four times more likely to have lower enzyme activity than children who never live with a plantation worker. The researchers obtained their results by […]

(Beyond Pesticides, January, 21, 2009) A new study concludes that exposures during pregnancy and childhood to insecticides that target the nervous system, such as organophosphates (OPs) and carbamates, are associated with childhood brain tumors. The researchers hypothesize that this susceptibility might be increased in children with genetic variations that affect the metabolism of these chemicals. The study, “Childhood Brain Tumors, Residential Insecticide Exposure, and Pesticide Metabolism Genes,” examines whether childhood brain tumors (CBT) are associated with the functional genetic variations. The study provides evidence that exposure to insecticides, paired with specific metabolism gene variants, may increase the risk of CBT. DNA was extracted from archival screening samples for 201 cases ≤ 10 years of age and born in California or Washington State between 1978 and 1990. Insecticide exposures during pregnancy and childhood were classified based on interviews with participants’ mothers. The children’s mothers reported whether they or anyone else had chemically treated the child’s home for insects including termites, fleas, ants, cockroaches, silverfish, or “other” pests. The results are consistent with the possibility that children with a reduced ability to metabolize organophosphate and carbamate insecticides might be at increased risk of CBT when sufficiently exposed. The researchers observed multiplicative interactions […]

(Beyond Pesticides, December 18, 2009) Biologists are finding that short-term, seasonal exposure to pesticides in rivers and basins limit the growth and size of wild salmon populations. Along with the widespread deterioration of salmon habitats, these findings show that exposure to commonly used pesticides continue to detriment the recovery of the salmons’ populations. The findings can be found in the study, “A fish of many scales: extrapolating sublethal pesticide exposures to the productivity of wild salmon populations,” in the December 2009 issue of the Ecological Society of America (ESA) journal, Ecological Applications. “Major efforts are currently underway to restore Pacific salmon habitats in an effort to recover depressed populations,” says David Baldwin, Ph.D., of the National Oceanic and Atmospheric Administration (NOAA), who co-authored the study with NOAA colleagues, “However, not much research has been done to determine the importance of pollution as a limiting factor of ESA-listed species.” The researchers studied the impact of pesticides, such as diazinon and malathion, on individual salmon using pre-existing data, and then devised a model to calculate the productivity and growth rate of the population. They used several exposure scenarios to reflect realistic pesticide use across various landscapes and over time. “An important aim […]

(Beyond Pesticides, December 1, 2009) A new study published in the November 2009 issue of Occupational and Environmental Medicine, adds rhinitis, the inflammation of the mucous lining of the nose, to the long list of ailments linked to pesticide exposure. “Rhinitis associated with pesticide exposure among commercial pesticide applicators in the Agricultural Health Study,” examined data from 2,245 Iowa commercial pesticide applicators and evaluated the association between rhinitis and 34 pesticides used in the past year. Seventy-four percent of commercial pesticide applicators in the study reported at least one episode of rhinitis in the past year (current rhinitis), compared with about 20-30% of the general population. Pesticide exposure and rhinitis were assessed at enrollment using two self-administered questionnaires. The first, completed at enrollment, obtained detailed information on use of pesticides on the market at the time of enrolment as well as smoking history, current agricultural activity and demographics. The second questionnaire, sent one month later, more detailed information on the pesticides, as well as medical history, including rhinitis, conjunctivitis, sinusitis and asthma. Respondents reported using 16 herbicides, 11 insecticides, five fungicides and two fumigants in the past year. Five of the pesticides were significantly positively associated with current rhinitis: the […]

(Beyond Pesticides, November 12, 2009) Scientists from McMaster University in Hamilton, Ontario have developed a dipstick test that can detect minute amounts of toxins and pesticides in foodstuffs that is slated to be less costly than current pesticide testing methods and can produce results within minutes. Their paper-strip test produces results in minutes rather than hours by means of an easy-to-read color-change. Published in the November 1 issue of the American Chemical Society’s Analytical Chemistry, a semi-monthly journal: “Reagentless Bidirectional Lateral Flow Bioactive Paper Sensors for Detection of Pesticides in Beverage and Food Samples,” study author, John Brennan, PhD, and colleagues note that conventional tests for detecting pesticides tend to use expensive and complex equipment and in some cases can take several hours to produce results. They cite a growing need for cheaper, more convenient, and more eco-friendly tests for pesticides, particularly in the food industry. A 10 cm-long bioactive paper-based solid-phase biosensor was developed to detect acetylcholinesterase (AChE) inhibitors, including organophosphate pesticides. The researchers tested this sensor using food and beverage samples intentionally contaminated with common pesticides. The strip accurately detected trace amounts of the chemicals within five minutes, according to the scientists. The test strip changes color shades […]

(Beyond Pesticides, August 12, 2009) A new study examining the effects of the mosquito repellent DEET on insects, mice and human proteins reports that the chemical interferes with a prominent central nervous system enzyme. This effect is magnified when exposure to DEET is combined with exposure to certain other pesticides. Entitled, “Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet,” and published in BioMed Central (BMC) Biology, the study utilized toxicological, biochemical and electrophysiological techniques to show that DEET is not simply a behavior-modifying chemical, but that it also inhibits cholinesterase activity in both insect and mammalian neuronal preparations. The researchers examined DEET’s effects on mosquitoes, cockroach nerves, mouse muscles, and enzymes purified from fruit flies and humans. Applications of DEET slowed or halted the actions of the enzyme acetylcholinesterase. This enzyme is crucial for regulating nerve impulses in both insects and mammals, and once its functions are disrupted, neuromuscular paralysis, leading to death by asphyxiation result. In humans, symptoms include headache, exhaustion and mental confusion together with blurred vision, salivation, chest tightness, and muscle twitching and abdominal cramps. The study also investigated the consequences of DEET interactions with carbamate insecticides on the […]

(Beyond Pesticides, March 5, 2009) A new study published in the March 2009 issue of Environmental Health Perspectives finds that pesticide combinations cause more harm to endangered salmon than ndividual pesticide exposure. This means that single-pesticide risk assessments required by the Environmental Protection Agency (EPA) inadequately assess hazards. Mixtures of organophosphate and carbamate pesticides are commonly detected in freshwater habitats that support threatened and endangered species of Pacific salmon. According to the researchers from the National Oceanic and Atmospheric Administration (NOAA) Fisheries and Washington State University, these pesticides inhibit the activity of acetylcholinesterase (AChE) and thus have potential to interfere with behaviors that may be essential for salmon survival. The researchers measured brain AChE inhibition in juvenile coho salmon exposed to sublethal concentrations of the organophosphates diazinon, malathion, and chlorpyrifos, as well as the carbamates carbaryl and carbofuran. The pesticides were tested individually and in combination. They plotted AChE levels on a curve to determine whether the toxicologic responses to binary mixtures were additive, antagonistic (lesser than additive) effect, or synergistic (greater than additive). The authors observed addition and synergism, with a greater degree of synergism at higher exposure concentrations. Several combinations of organophosphates were lethal at concentrations that were […]

(Beyond Pesticides, June 10, 2008) According to scientists at Simon Fraser University in British Columbia, Canada, real-world pesticide combinations, such as those found in Canada’s Nicomekl River, may contribute to latest decline in the region’s endangered salmon populations. The study, published in Environmental Science and Technology (ES&T), a publication of the American Chemical Society, examines the impact by simulating the river’s low-level pesticide mixture to examine its effects on fish. The study used steelhead trout, a member of the salmon family, and found that the pesticide mix can deaden the trout’s sense of smell. This could harm the fish’s ability to avoid predators, find mates, and migrate back to sea, the researchers say, and could contribute to the threatened and endangered status of salmon species. “Most laboratory studies examine the effects of a single chemical, often at high concentrations, but real-world streams contain a mixture of chemicals at very low concentrations,” Keith Tierney, Ph.D., the study’s coauthor, told ES&T. Dr. Tierney and his colleagues re-created river water in the laboratory under controlled conditions with carefully measured levels of the 10 most frequently occurring pesticides in British Columbia’s Nicomekl River. The mixture contained four major classes of pesticides, including the commonly […]

(Beyond Pesticides, March 13, 2008) Exposure to certain chemicals, including pesticides and nerve agents, explains the high rates of illness in Persian Gulf War Veterans, according to a new study published in the Proceedings of the National Academy of Sciences. Veterans from the 1990-91 conflict have a higher rate of chronic, multi-symptom health problems than either non-deployed personnel or those deployed elsewhere. Symptoms routinely reported by these veterans include fatigue, muscle or joint pain, memory problems, trouble sleeping, rash and breathing problems. Due to the findings, the study author, Beatrice Golomb, M.D., Ph.D., associate professor of medicine at the University of California, San Diego School of Medicine, warns of the potential risk to civilians exposed to pesticides.“Health issues among Gulf War veterans have been a concern for nearly two decades. Now, enough studies have been conducted, and results shared, to be able to say with considerable confidence that there is a link between chemical exposure and chronic, multi-symptom health problems,” said Dr. Golomb. “Furthermore, the same chemicals affecting Gulf War veterans may be involved in similar cases of unexplained, multi-symptom health problems in the general population.”The study synthesized evidence regarding a class of chemicals known as acetylcholinesterase inhibitors (AchEs), including […]

(Beyond Pesticides, February 20, 2008) Pesticides that run off agricultural land and mix in rivers and streams combine to have a greater than expected toxic effect on the salmon nervous system, according to researcher Nathaniel Scholz, PhD, a zoologist with the National Oceanic and Atmospheric Administration (NOAA) in Seattle. Dr. Scholz, who presented his findings at the symposium entitled From Kitchen Sinks to Ocean Basins: Emerging Chemical Contaminants and Human Health,  which was organized by NOAA and hosted at the American Association for the Advancement of Science (AAAS) Annual Meeting, had previously looked at the effects of individual pesticides. However, to get a more realistic idea of exposure, combinations of several pesticides were used and juvenile salmon exposed to them two at a time. The results surprised Dr. Scholz and his team. The total impact observed from combined pesticides was greater than the sum of the individual pesticides, demonstrating a synergistic effect. Some pesticides that were not deadly when tested in individual trials killed all salmon exposed to combinations. A mixture of the pesticides diazinon and malathion, exhibited the greatest synergistic effect and killed all the salmon exposed to them, even at the lowest concentrations. “It was eye opening,” Dr. […]

(Beyond Pesticides, July 5, 2007) A new study showing that the order of exposure to multiple pesticides may be just as important as the dose, timing and length of exposure adds another dimension to the complex task of risk assessments. Using carbaryl and chlorpyrifos, University of York scientists have observed significant differences in mortality rates of freshwater invertebrates depending on the order of exposure to these frequently used agricultural chemicals. The study, Modeling Combined Effects of Pulsed Exposure to Carbaryl and Chlorpyrifos on Gammarus Pulex, suggests the sequence of pesticide exposure may be just as important of a variable as the dose, the timing of the dose and the length of exposure when factoring environmental and health endpoints. The researchers conducted the study by exposing the freshwater invertebrate Gammarus pulex — a tiny shrimp — to pulses of the two insecticides (both of which affect the nervous system through acetylcholinesterase inhibition) mimicking exposure to chemical mixtures in the environment — for example, farmers may apply several different pesticides over the growing season that run off into the aquatic environment. After receiving a pulse of one pesticide, the shrimp were given 14 days, a time period chosen based on previous experiments, […]

(Beyond Pesticides, June 4, 2007) The breakdown products (oxons) of the three most commonly used organophosphate pesticides in California’s agricultural Central Valley — chlorpyrifos, malathion and diazinon – are 10 – 100 times more toxic to amphibians than their parent compounds, which are already highly toxic to amphibians, according to a study released last Wednesday by scientists of Southern Illinois University, Carbondale, and the U.S. Geological Survey (USGS) Western Ecological Research Center. The results of the laboratory experiments on the toxicity of the three breakdown products were published in the journal Environmental Pollution. The title of the article is “Comparative toxicity of chlorpyrifos, diazinon, malathion and their oxon derivatives to larval Rana boylii.” “Since some of the parent pesticide compounds are already at concentrations sufficient to cause significant amphibian mortality in the Sierra Nevada, the higher toxicity of the breakdown products poses a serious problem,” said Gary Fellers, Ph.D., coauthor of the study. Donald Sparling, Ph.D., a research biologist and contaminants specialist at Southern Illinois University, and Dr. Fellers, a research biologist and amphibian specialist at the USGS Western Ecological Research Center in California, conducted laboratory tests to determine the acute toxicity – the lethal dosage causing death in 96 […]