30
Aug
Brain Function Damage from Exposure to Organophosphate Pesticides, including Chlorpyrifos, Documented with Imaging
(Beyond Pesticides, August 30, 2019) The indictment of organophosphate pesticides gained more traction with the publication, in the Proceedings of the National Academy of Sciences, of a new research study out of the University of California, Berkeley. The research, among the first to use advanced brain imaging to assess cortical activation, shows altered brain activity, during tasks that call on executive function, in teenagers from California’s Salinas Valley (the site of significant organophosphate use) whose mothers were exposed prenatally. The UC Berkeley study underscores the slow-motion calamity of the Trump administration Environmental Protection Agency’s (EPA’s) failure to ban the use of this class of pesticides, and of chlorpyrifos in particular, which compounds carry extreme risks for children. The effects of this prenatal exposure continue to unfold during children’s critical developmental periods.
Researchers used fNIRS (functional near-infrared spectroscopy) imaging to monitor blood flow in the brains of the teens, 15–17, born and raised in the Salinas Valley. They used data from the California Pesticide Use Reporting program (which documents locations and times of pesticide spraying) to estimate the subjects’ mothers’ proximity to organophosphate (OP) applications during pregnancy. The subject adolescents — estimated to have relatively high levels of prenatal exposure to organophosphates — showed aberrant brain activity in executive function, attention, social cognition, and language comprehension, compared to their peers. The fNIRS found less blood flow to the frontal cortex during tasks using cognitive flexibility and visual working memory, and increased blood flow to the parietal and temporal lobes during tests of linguistic working memory.
The teens were part of the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a longitudinal study, begun two decades ago, that examines impacts of pesticides (and other environmental toxins) on children’s development. UC Berkeley’s Berkeley News reports, “Previous CHAMACOS work has linked prenatal organophosphate exposure with attention problems and lower IQ in children.”
Beyond Pesticides covered previous CHAMACOS work on health impacts of pesticides in the Salinas Valley: “Researchers looked at pregnant women living within one kilometer of agricultural fields where organophosphate pesticides were used. They found that at age 7, the children of those women had declines of approximately two IQ points and three verbal reasoning points per 522 pounds of pesticides applied nearby.”
Associate adjunct professor of epidemiology at UC Berkeley and lead author of the new study, Sharon Sagiv, PhD, said, “These results are compelling, because they support what we have seen with our neuropsychological testing, which is that organophosphates impact the brain.” The seemingly odd results of both reduced and increased blood flow are apparently not entirely unusual; such patterns show up in conditions such as Alzheimer’s and Parkinson’s diseases, and with Type 1 diabetes, according to Allan Reiss, co-author of the study, Howard C. Robbins Professor of Psychiatry and Behavioral Sciences, and a professor of radiology at Stanford University.
He elaborates: “The brain has a remarkable ability to utilize compensatory mechanisms to counteract long-term insults. Higher activation may represent the recruitment and utilization of extra neural resources to address functional inefficiency related to a long-term insult, and lower activation, then, could be related to the eventual failure to recruit these resources after continued exposure or disease exhausts the brain’s ability to bring compensatory responses online.”
Organophosphates, which include chlorpyrifos, are the most commonly used class of insecticide in agriculture. They are endocrine disrupting compounds that can affect children’s neurodevelopment, possibly due to neurotoxicity induced by acetylcholinesterase (AChE) inhibition, and may affect boys more than girls. Exposure to OPs is widespread and occurs primarily via ingesting food contaminated with OP residues, but those who work in or live proximate to agricultural sites are also exposed through residue on clothing and in households, and through drift from sprayed applications. In 2018, a group of leading toxics experts called for a ban on OPs, primarily because prenatal exposures, even at low levels, threaten children with cognitive and behavioral deficits, and neurodevelopmental disorders.
Beyond Pesticides has called attention to the toxicity of organophosphates, and chlorpyrifos in particular, for many years. For example, in 2011, it noted links between organophosphate exposure and lowered IQ in children, and provided more evidence of risks of prenatal exposure and lower IQs in 2016. In 2018, it reported on the inadequacy of the evaluations used to justify EPA registration of chlorpyrifos — one in a series of examples of EPA’s poor oversight, corruption, and collaboration with industry to prioritize its concerns over the public’s safety and well-being.
The story of chlorpyrifos is illustrative. Pursuant to a lawsuit filed by environmental groups, in 2015 EPA proposed a rule change revoking food residue tolerances of chlorpyrifos — a move that would effectively have banned use of the pesticide in agriculture (residential insecticide uses had been proscribed in 2000). Then, early in 2017, with a new administration in place, then-EPA Administrator Scott Pruitt reversed the agency’s own proposal to ban the pesticide — a decision that happened just weeks after Mr. Pruitt met with the head of Dow Chemical Company, maker of the compound. Mr. Pruitt then claimed, without scientific justification, that the science on chlorpyrifos was “unresolved” and said EPA would study the issue — with no planned action — until 2022.
Next, in the summer of 2018, the U.S. Court of Appeals for the Ninth Circuit issued its decision in a suit, brought by a plethora of health, environmental, and labor groups represented by Earthjustice, asking that the 2017 Pruitt EPA order reversing the ban be vacated. (The attorneys general of New York, California, Washington, Massachusetts, Maine, Maryland, and Vermont also filed their own appeal calling for a ban.) The court ordered EPA to finalize its proposed ban on chlorpyrifos. In July 2019, EPA declined to do so and, rather than offer justification for why the pesticide should remain on the market, as the court had ordered it to do, EPA attacked the science the plaintiffs had urged EPA to review and consider as “not . . . valid, complete, and reliable.”
Scientists and many regulators understand that chlorpyrifos (and other organophosphate pesticides) need to come off the market altogether, for food and non-food uses. Most recently, Beyond Pesticides reported on an announcement, from the European Union and the European Food Safety Authority, that essentially said that chlorpyrifos should no longer be used. Given the current administration and its EPA actions, states have been pursuing bans and other constraining actions: Hawai’i banned chlorpyrifos more than a year ago, and New York and California followed suit in spring 2019.
Chlorpyrifos is one of many toxic pesticides that are central to conventional, chemical-intensive agricultural practices that threaten human health and the environment. Beyond Pesticides has long sought a broad transition to organic practices, which disallow the use of toxic pesticides and synthetic inputs, and enact a systems-based approach that is protective of health and the environment. A transition to organic advances a viable, scalable path forward for growing food.
Clearly, members of the public cannot rely on this EPA to act in the best interests of children, all people, and the environment. But they can work to ban chlorpyrifos and other neurotoxic insecticides in a number of ways:
• learn more about impacts of pesticides and related developments with the Beyond Pesticides factsheet, Children and Pesticides Don’t Mix, and through its Daily News Blog and journal, Pesticides and You
• help support an organic agricultural system that does not rely on toxic chemicals by buying organic whenever possible
- insist that purveyors provide organic foods
- advocate for organic with elected officials and advocacy organizations in local communities and at the state level
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources: https://news.berkeley.edu/2019/08/27/prenatal-pesticide-exposure-linked-to-changes-in-teens-brain-activity/ and https://www.pnas.org/content/early/2019/08/20/1903940116
