28
Apr
Organophosphate (OP) Pesticides in Agricultural Area Residents’ Urine Year Round
(Beyond Pesticides, April 28, 2023) A study published in Science of The Total Environment finds agricultural communities encounter chronic and measurable pesticide exposure regardless of seasonal pesticide applications. Several biomonitoring studies demonstrate people living adjacent to or within agricultural areas often experience elevated levels of organophosphate (OP) insecticides, even while not working directly with OPs. Six dialkyl phosphate (DAP) metabolites (breakdown products) of OPs persist in urine during the spraying and non-spraying seasons. Despite 75 percent of OPs metabolizing into one or more of the six DAPs and excreting within six to 24 hours after exposure, the consistent levels of DAPs in urine highlight continuous exposure beyond regular seasonal pesticide applications.
OP compounds have a global distribution, with evaporation and precipitation facilitating long-range atmospheric transport, deposition, and bioaccumulation of hazardous chemicals in the environment. OPs are highly toxic and, as this study shows, residues are consistently present in human and animal urine, as well as blood, tissues, and milk. Considering 90 percent of Americans have at least one pesticide compound in their body, primarily stemming from dietary exposure, including food and drinking water, advocates maintain that current restrictions on their use must adequately detect and assess total chemical contaminants. The study notes, “We suggest that among agricultural communities that experience chronic exposure to nearby pesticide applications, OPs may persist in indoor and outdoor environments. The results of the current analysis provide additional evidence to suggest that residents of agricultural communities experience OP exposure even when [a] recent application has not occurred.”
Researchers gathered data from agricultural community members in the Central Valley of California to determine important factors associated with urinary DAPs levels among these high-exposure communities. The cohort included 80 children and adults who lived within 61 m (200 ft) of agricultural fields in the Central Valley of California in January (pesticide non-spraying season) and June (pesticide spraying season) 2019. The researchers collected one urine sample per participant during each visit to measure DAP metabolites. Additionally, researchers gathered supplementary data with in-person surveys to identify health, household, sociodemographic, pesticide exposure, and occupational risk factors. Using a data-driven, best-subsets regression approach, researchers identified key factors that influence urinary DAP levels.
The results find those with seasonal employment, likely to be in agriculture, have higher DAPs concentration in urine than those who do not work seasonally. However, the subset regression identifies numerous individual- and household-level factors that influence total DAPs: “the number of years spent living at the current address, household use of chemical products to control mice/rodents, and seasonal employment status.” Among adults, those with education on pesticide exposure mitigation and age are significant factors associated with total DAPs in urine. Among adults only, the study identifies educational attainment (for total DAPs) and age category (for EDM) as significant factors.
Numerous occupational hazards are associated with chemical exposure, especially among individuals with occupations that involve regular exposure to xenobiotic (foreign substance) compounds. The agricultural sector has a long-standing history of synthetic chemical use, which disproportionally affects farmworkers‘ health. Furthermore, farmworkers’ children are at greater risk as their immune system response is immature and especially vulnerable to stressors from pesticide exposure. Synthetic chemicals in pesticides can accumulate in bodies, causing an amalgamation of health effects. These effects can range from heightened risks of various cancers (e.g., prostate, hepatic, liver, etc.) and endocrine disruption to mental health problems (e.g., depression), respiratory illnesses (asthma), and many other pesticide-induced diseases. However, pesticide exposure is ubiquitous and not confined to where it is applied. Pesticides and other toxic chemicals can enter homes from the workplace via clothes, shoes, and home-based personal protective equipment (PPE) and accumulate residues on laundry, on carpets, and in art/house dust. Some cases demonstrate that levels of chemicals transported into the house can be high enough to cause an adverse health effect in a resident child or spouse. Although pesticide exposure through the skin or inhalation is most prevalent among individuals working around these toxic chemicals, the general population also experiences pesticide exposure through residues in food and water resources. Many of these chemical compounds remain in soils, water (solid and liquid), and the surrounding air at levels exceeding U.S. Environmental Protection Agency (EPA) standards. The increasing ubiquity of pesticides concerns public health advocates as current measures safeguarding against pesticide use do not adequately detect and assess total environmental chemical contaminants. Therefore, individuals will continuously encounter varying concentrations of pesticides and other toxic chemicals, adding to the body’s burden of current-use chemicals.
Organophosphate (OP) insecticide use is widespread, while the industry promotes the chemicals as having greater efficiency and lesser environmental persistence. However, OPs are a class of insecticides known to have adverse effects on the nervous system, having the same mode of action as nerve agents for chemical warfare. OPs originate from the same compounds as World War II nerve agents, adversely affecting the nervous system. Chemical exposure can cause a buildup of acetylcholine (a chemical neurotransmitter responsible for brain and muscle function) and lead to acute impacts, such as uncontrolled, rapid twitching of some muscles, paralyzed breathing, convulsions, and, in extreme cases, death. The compromise of nerve impulse transmission can have broad systemic impacts on the function of multiple body systems. In addition to being highly toxic to terrestrial and aquatic organisms, human exposure to organophosphates can induce endocrine disruption, reproductive dysfunction, fetal defects, neurotoxic damage, and kidney/liver damage. Exposure can increase vulnerability to deadly diseases, including COVID-19. Furthermore, OPs are one of the leading causes of intentional poisoning globally, as pesticide toxicity makes them potentially lethal substances.
Urinary OP biomarker levels did not vary, and the risk was the same throughout all seasons. OP metabolites are typically excreted in the urine within a 6- to 24-hour period, so the study concludes that participants who had detectable levels of urinary DAPs had a recent exposure to OPs, regardless of seasonal spraying. There are other more prominent sources of OP contamination. For instance, diet accounts for a considerable proportion of people’s exposures to pesticides in the U.S.; 2016 data from the United States Department of Agriculture (USDA) show that 47% of domestically produced foods and 49% of imported foods had detectable pesticide residues. A number of studies point to organics as protective as studies confirm that urinary DAP levels reduce after a week-long shift to an organic diet; a 2015 study that found that adults who consumed organic produce had lower urinary levels of organophosphate residues (as detected via levels of DAPs); and another in 2015 that concluded that a switch to an organic diet reduced the body burden of pesticides in children, especially in low-income urban, marginalized, and agricultural communities. Considering this study finds urinary OP metabolites among children and household dust OP levels increase as residential distance to orchards decreases, the study identifies important factors that influence pesticide exposure among agricultural communities. Given proximity to applications, take-home exposure from occupational workers, and residual environmental exposures, a majority of pesticide exposure disproportionately burdens Hispanic/Latino(a) communities, which contain most of the population in the study area. However, the study suggests future research establishes exposure routes that put agricultural communities, and others at risk.
The study concludes, “We suggest that future research should explore more refined exposure assessment methods to evaluate unique routes of exposure (i.e., inhalation, ingestion, or dermal contact). These efforts will support strong epidemiologic research to identify health impacts of OPs. Findings may also support community education about effective and personalized exposure mitigation strategies for agricultural community members to promote environmental justice.”
Although most OP uses in the U.S. are now agricultural, toxicity experts recommend banning all OPs for agricultural use. EPA and the World Health Organization (WHO) consider over 40 OPs that are moderately or highly hazardous to human health. EPA classifies as probable carcinogens some commonly used OPs like malathion, a popular mosquito control, and tetrachlorvinphos, a common flea and tick killer in pet collars and shampoos. States, including Hawaii, California, New York, and Maryland, had already adopted plans to phase out uses of the OP chlorpyrifos, to different degrees, in agriculture following evidence of neurotoxic effects on children. EPA announced the cancellation of all chlorpyrifos food production uses in the U.S., as chemical contamination among the general population remained considerable even after implementing residential use restrictions over two decades ago. However, even with the agency announcement of agricultural use cancellations, chlorpyrifos will still remain available for golf courses and as mosquito adulticide.
The pesticide marketplaces still contain many chemicals that cause similar endocrine-disrupting, cancer-causing, neurotoxic health effects. Additionally, imported goods can still contain chemical residues as chlorpyrifos residues do not disappear immediately after end-use and will persist in our environment for quite some time.
Therefore, policies should enforce stricter pesticide regulations and increase research on the long-term impacts of pesticide exposure. Beyond Pesticides tracks the most recent studies related to pesticide exposure through our Pesticide Induced Diseases Database (PIDD). This database supports the clear need for strategic action to shift away from pesticide dependency. For more information on the many harms of pesticides on health, see PIDD pages on body burdens (urine and other compartments), endocrine disruption, cancer, and other diseases. Learn more about how inadequate pesticide use regulations, including organophosphates, can adversely affect human and environmental health; see Beyond Pesticides,’ Pesticides and You article “Highly Destructive Pesticide Effects Unregulated.”
Beyond Pesticides advocates a precautionary approach to pest management in land management and agriculture by transiting to organic. Buying, growing, and supporting organic can help eliminate the extensive use of pesticides in the environment and from your diet. For more information on how organic is the right choice for consumers and the farmworkers who grow our food, see the Beyond Pesticides’ webpage, Health Benefits of Organic Agriculture.
Spring is here, so grow your spring garden the organic way by Springing Into Action, pledging to eliminate toxic pesticide use.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Science of The Total Environment
