02
Nov
Scientists Call for Ban on Organophosphate Pesticides
(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 programs.
- Healthcare professions and training institutions should implement training and curricula on the health impacts from OP exposures, how to treat acute exposures, and how to educate patients and the public about these hazards and the best means for avoiding them.
- Schools of nursing and medicine should incorporate curricula on environmental hazards (including pesticides), and medical boards ought to include environmental health in their examinations.
- Agricultural entities should provide training on the handling and application of pesticides, and on worker protection standards; accelerate the development of nontoxic approaches to pest control through IPM; and ensure worker safety through appropriate protective equipment and training.
Developed approximately eight decades ago, initially as nerve gas agents for military use, and later amended for use (at reduced concentrations) as pesticides, organophosphates are widely used for agricultural pest control, but also, in hospitals and other healthcare institutions, schools, and public spaces (e.g., parks, golf courses, playing fields), and for mosquito control. The best-known among the organophosphate pesticides (OPs) — some of which have been proscribed or limited in the past decade or so — are probably chlorpyrifos, malathion, and diazinon. The study authors note that the extensive use of OPs has “led to ubiquitous human exposure.” A recent example of that ubiquity — in which every single home in rural New York State counties showed the presence of pesticides, often including the organophosphates malathion and/or chlorpyrifos — was covered by Beyond Pesticides.
High-dose exposure to OPs causes “acute poisoning from the irreversible inhibition of the enzyme acetylcholinesterase (AChE), resulting in cholinergic syndrome (including narrowed pupils, excessive salivation, bronchoconstriction, mental confusion, convulsions or tremors, and in some cases, death). Additionally, delayed polyneuropathy has been described in association with high exposures.” Farmworkers and pesticide applicators are generally most at risk for these kinds of exposures, but they are not the only victims. In 2013, for example, at least 25 children in India died after an acute dietary exposure to high levels of organophosphates. In addition, children, who are most vulnerable to the harmful effects of OPs, may be exposed if they live near, and/or their parents work in, agricultural fields treated with the compounds.
Lower-level exposures, even those previously considered safe, and to which many members of the public are subject, can lead to myriad neurodevelopmental, reproductive, and respiratory health problems. A plethora of studies, including the subject investigation, has linked exposures during fetal development with neurodevelopmental issues, i.e., poorer cognitive, behavioral, and social development in children. Cognitive problems may include reduced IQ, developmental delays, and greater risk for learning disabilities; numerous investigations, cited in the subject research paper, have implicated OPs in the development of autism spectrum disorders.
The EPA stated in 2016 that there was sufficient epidemiologic evidence of “neurodevelopmental effects occurring at chlorpyrifos exposure levels below that required to cause acetylcholinesterase inhibition.” Chronic, low-level exposure is a huge concern, particularly prenatally and for young children, given their rapid development and the potential deleterious effect during multiple developmental windows. Such exposures get insufficient research and clinical attention, and are often dismissed because pregnant women and fetuses may not show obvious clinical symptoms or signs, and developmental deficits may not manifest until months or years later.
Frighteningly, the study notes that outcomes related to fetal exposures to OPs seem to persist, with associations observed into middle and late childhood. It further pointed out that neuroanatomic alterations (such as differences in brain volume in regions responsible for attention, receptive language processing, social cognition, and regulation of inhibition) were seen in children with high levels of OPs in their umbilical cord blood. These observed associations may “potentially constitute a pathway from pesticide exposure to the associated behavioral and cognitive deficits [and] may be permanent.”
More than 40 organophosphate pesticides are considered, by the EPA and World Health Organization (WHO) Food and Agriculture Organization, to be moderately or highly hazardous to human health. These toxic compounds are used on a huge array of agricultural crops, as well as for the uses noted above. The EPA moved in 2016 to ban chlorpyrifos for agricultural uses; the Trump administration reversed that decision in 2017. In August 2018, the NInth Circuit Court of Appeals ruled that the ban must executed, based on “scientific evidence that its residue on food causes neurodevelopmental damage to children” — a decision the Trump administration has said it will appeal. Some countries have instituted bans on a few OPs, the European Union has denied approval of 30+ OP compounds, and early in 2018, Hawaii became the first state to ban chlorpyrifos.
Beyond Pesticides has written extensively on organophosphates and their implications in human health problems and diseases, including those related to reproductive, cognitive, and respiratory function. These compounds are implicated, as well, in the dysregulation and dysfunction of bodily systems because of their impacts on endocrine function. Through its Pesticide-Induced Diseases Database, Beyond Pesticides keeps track of emerging research on pesticide exposure and human health.
Several study co-authors have been quite direct in their commentary on the research results. Past president the American College of Obstetricians and Gynecologists, and president-elect of the International Federation of Gynecology and Obstetrics Jeanne Conry, M.D said, “Health care professionals are on the front line of responding to organophosphate pesticide exposure, but the only way to make sure families aren’t exposed in the first place is to ban them completely.”
Bruce Lanphear, M.D., physician-scientist at Simon Fraser University in Vancouver, BC noted, “We found no evidence of a safe level of organophosphate pesticide exposure for children. Well before birth, organophosphate pesticides are disrupting the brain in its earliest stages, putting them on track for difficulties in learning, memory and attention, effects which may not appear until they reach school-age. . . . Government officials around the world need to listen to science, not chemical lobbyists, and protect our children from chlorpyrifos and all organophosphate pesticides.”
“Alternatives to these toxic pesticides exist, and many farmers have successfully eliminated use of organophosphate pesticides. The agricultural community has a responsibility to use these alternatives. We need federal support for research on less toxic pest management and support to our farmers so they can farm sustainably and profitably, as well as alternatives to organophosphate use to control mosquitos and other public health threats,” said Asa Bradman, Ph.D., environmental health scientist at UC Berkeley.
Lead author, director of the UC Davis Environmental Health Sciences Center, and co-director of Project TENDR (Targeting Environmental Neuro-Development Risks) Irva Hertz-Picciotto, Ph.D. opined, “Children deserve to be healthy and safe from exposure to toxic chemicals. We have compelling evidence from dozens of human studies that exposures of pregnant women to very low levels of organophosphate pesticides put children and fetuses at risk for developmental problems that may last a lifetime. . . . Current U.S. EPA policy is failing to protect children and fetuses here in the U.S. from these dangerous chemicals. By law, the EPA cannot ignore such clear findings: It’s time for a ban not just on chlorpyrifos, but all organophosphate pesticides.”
EPA’s decision in 2000 and subsequent action removed chlorpyrifos’ residential uses and retains all agricultural uses except tomatoes (allowable residues on apples and grapes were adjusted), golf course and public health mosquito spraying. The agency argued at the time of its decision that it had adequately mitigated risks through the removal of high exposure uses to children in the residential setting, but ignored the special risks to farmworker children’s exposure as well as the availability of alternative agricultural practices and products that made chlorpyrifos unnecessary and therefore its risks unreasonable. The decision at the time was hailed as a victory for the public because it eliminated high hazard exposures and showed that EPA could remove uses of a widely used chemical. Except, it did not do the job. The risk assessment process does not force a consideration of those who suffer disproportionate risk or groups of people (such as those with neurological diseases in this case who are disproportionately affected).
Beyond Pesticides welcomes the recommendations of this paper, and in particular, the enthusiasm of several of its authors for banning these compounds and transforming agricultural practices to less toxic, sustainable methods. Keep abreast of developments on the organophosphate issue, and pesticides generally, via Beyond Pesticides’ Daily News Blog, its journal Pesticides and You, its Safer Choice pages, and its coverage of the need for a transition to organic approaches for the sake of human and environmental health.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002671
