04
Sep
Pesticide Drift from Greenhouses Adversely Affects Children Living Nearby
(Beyond Pesticides, September 4, 2020) When pesticide drift is investigated, it is most often drift from agricultural fields that is examined. A new study shows that off-target drift of pesticides from greenhouses is also a reality. This research deduced such drift of organophosphate and carbamate pesticides from crop applications done in Ecuadoran floriculture greenhouses by evaluating the acetylcholinesterase enzyme (AChE) activity, necessary to the transmission of nerve impulses, in children residing nearby. The team finds that children living in homes near greenhouses in which these insecticides (widely recognized as cholinesterase inhibitors) are used exhibit reduced activity of this enzyme and abnormal functioning of the nervous system. Beyond Pesticides has monitored the pesticide drift issue intensively, and has long advocated for far better protections for farmworkers. This new information connects those issues, and expands the “drift” concerns to include risks to people working in greenhouses, and to those, especially children, who happen to live near greenhouse-type structures in which these toxic chemicals are used.
The study evaluates data during three separate periods (2008, April 2016, and July–October 2016) on 623 children, aged 4–17, living in floricultural communities in Ecuador. The research is part of the study of the Secondary Exposure to Pesticides among Children and Adolescents (ESPINA) project. The study data comprises metrics on both AChE activity in the children, and the magnitude of pesticide drift as a function of distance between residences and floriculture greenhouses.
The study analyzes both the distribution of areas of flower crops within “buffer zones” of various sizes around children’s homes, and the “correlation coefficients” (statistical measures of the strength of the relationship between two variables) between household proximity to the nearest treated greenhouse crops and to variously sized areas of flower crops within 1,000 meters of homes. Proximity of children’s homes to such greenhouses, especially within 275 meters, is associated with lower AChE activity, reflecting greater cholinesterase inhibitor exposure from pesticide drift. Reduced AChE activity is also associated with larger crop areas within 500 meters of residents, and especially so for those within 150 meters. In typically understated academic parlance, the study concludes, “mitigation of off-target drift of pesticides from crops onto nearby homes is recommended.”
Carbamates and organophosphates, like chlorpyrifos, are insecticides that have long been used on agricultural crops, as well as to kill a variety of insects: cockroaches, ants, fleas, crickets, aphids, bedbugs, sand fleas, and mosquitoes. Residential uses of organophosphate pesticides have been highly restricted by the US. Environmental Protection Agency [EPA] over the last two decades ago, but both continue to be used widely in agriculture. (There is evidence of some shift in agricultural use from these classes of pesticides to synthetic pyrethroids and neonicotinoids, which come with their own significant risks and harms.)
These two classes of pesticides share (with some others) a common mode of toxic action in the body: they are cholinesterase inhibitors, which means that they bind to receptor sites for the enzyme acetylcholinesterase, or AChE, which is essential to normal nerve impulse transmission. Basically, after a neurotransmission, the “spent” neurotransmitter, acetylcholine, must be cleared away from the synaptic cleft (the space between two neurons); otherwise, new signals would be unable to launch. Following transmission of a nerve impulse by acetylcholine, AChE breaks it down — a critical process that prevents what would otherwise be constant stimulation of the post-synaptic cell. In binding to those receptor sites, cholinesterase inhibitors inactivate AChE, and prevent that important clearing.
When AChE is inhibited, the buildup of acetylcholine can lead to acute impacts, such as uncontrolled, rapid twitching of some muscles, paralyzed breathing, convulsions, and, in extreme cases, death. Because of their common mode of action, both carbamates and organophosphates can have significant impacts — apart from episodes of acute poisoning — on the functioning of multiple bodily systems. The brain and central nervous system, after all, direct and/or mediate virtually all activities in the body, so compromise of neural transmission can have broad systemic impacts.
Exposures to these pesticides have been associated with myriad health anomalies and outcomes, including: metabolic diseases (including diabetes); non-Hodgins Lymphoma; childhood brain tumors; infant leukemia; endocrine disruption; reproductive impacts; hepatic (liver) function; a variety of cancers; Parkinson’s Disease and other neurological impairments; respiratory impacts; and developmental delays, impaired cognitive development, and a host of learning/behavioral problems in young children. Beyond Pesticides wrote about a call, from leading toxicologists, for a ban on organophosphates because of the multitude of dangers of organophosphates to children.
Of course, residents near greenhouses are not alone in their exposures. A 2020 study on pesticide exposures of people working in “non-organic” greenhouses found that those a who apply pesticides within them commonly report “reproductive disorders, respiratory symptoms, neurological symptoms, and skin irritations.” Common sense would suggest that such impact might well extend to those working in similar closed agricultural structures, such as hoop houses and high tunnel growing systems. That study also asserts that inadequate ventilation of such structures contributes to the problem, noting that the “ventilation systems and indoor environmental conditions of greenhouse farms were not designed according to specifications of the American Society of Heating, Refrigerating and Air-Conditioning Engineers.”
Another 2020 study of greenhouse worker exposure to pesticides in China, said of the study’s objective: “Greenhouse workers are considered a special occupational group who are exposed to more toxic and harmful substances than ordinary farmers. The health problem of this group is a public health problem that warrants attention.” The research results shows, though varied across levels of exposure, increased prevalence of cardiovascular diseases, skeletal muscle system diseases, and digestive diseases. The researchers’ summary said, “Long-term and high-intensity pesticide exposure, coupled with the high temperature and humidity in greenhouses, has caused different degrees of damage to the health of practitioners, involving various systems of the human body, such as the nervous, reproductive, respiratory, circulatory, digestive, [and] endocrine systems.”
The use of greenhouses and similar structures is increasing significantly with demand for local food production, and with growing concerns about stability of food supplies because of climate change and now, impacts of the current or future pandemics. With the increasing use of such systems, concerns about pesticide exposures — if these systems are used for non-organic crop production — will also likely grow, for both those working in them and those living nearby.
Absent EPA’s cancellation of the registration of these classes of pesticides, the public is left to avoid exposures to these chemicals by making the best choices they can, such as: avoiding use of pesticides in homes and gardens; purchasing organic food as much as possible; and insisting that community leaders opt for nontoxic solutions for schools, playgrounds, athletic fields, parks, and other common spaces. Members of the public can advocate, through Beyond Pesticides and other organizations, and in their own lives, for nontoxic, organic, and regenerative agricultural systems that do not put the health of people, wildlife, and ecosystems at such grave risk.
Source: https://www.sciencedirect.com/science/article/abs/pii/S0013935120306216?via%3Dihub
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
