For years, U.S. regulators relied on falsified data provided by Dow Chemical to allow unsafe levels of the chemical chlorpyrifos into American homes, according to a new analysis from University of Washington researchers.
The analysis reexamines work from the 1970s sponsored by Dow and submitted to the Environmental Protection Agency (EPA) to guide the agency in establishing what scientists refer to as a “no-observed-adverse-effect-level” or NOAEL. Such thresholds are used to determine what types of use and at what level a chemical exposure can be allowed and still be considered “safe.”
According to the new analysis, published online July 3 in the journal Environmental International, the inaccurate findings were the result of a chlorpyrifos dosing study conducted by researcher Frederick Coulston and colleagues from the Albany Medical College in the early 1970s for Dow.
The authors of the new paper reexamining that prior work are Lianne Sheppard, Seth McGrew and Richard Fenske of the Department of Environmental and Occupational Health Sciences, School of Public Health at the University of Washington.
While the study was authored by the Coulston group, the analysis was completed by a Dow statistician and concluded that 0.03 mg/kg-day was the chronic NOAEL level for chlorpyrifos in humans. But the new analysis by the University of Washington researchers found that wildly overstated the margin of safety. Had the data been properly analyzed a lower NOAEL of 0.014 mg/kg-day would have been found, they said.
The Coulston study did not undergo peer review but still was used by the EPA for risk assessments throughout much of the 1980′s and 1990′s, the University of Washington researchers reported.
The researchers concluded: “During that period, EPA allowed chlorpyrifos to be registered for multiple residential uses that were later cancelled to reduce potential health impacts to children and infants. Had appropriate analyses been employed in the evaluation of this study, it is likely that many of those registered uses of chlorpyrifos would not have been authorized by EPA. This work demonstrates that reliance by pesticide regulators on research results that have not been properly peer-reviewed may needlessly endanger the public.”
Commonly known as the active ingredient in the brand name Lorsban, chlorpyrifos insecticides were introduced by Dow Chemical in 1965 and have been used widely in agricultural settings. The largest agricultural market for chlorpyrifos is corn but the pesticide is also used by farmers growing soybeans, fruit and nut trees, Brussels sprouts, cranberries, and cauliflower, as well as other row crops. Residues of the chemical are commonly found in food. Non-agricultural uses include golf courses, turf, green houses, and utilities.
Despite the science promoted by Dow, independent scientific research has shown mounting evidence of the dangers of chlorpyrifos, particularly to young children. Scientists have found that prenatal exposures to chlorpyrifos are associated with lower birth weight, reduced IQ, the loss of working memory, attention disorders, and delayed motor development.
The American Academy for Pediatrics, which represents more than 66,000 pediatricians and pediatric surgeons, has warned that continued use of the chemical puts developing fetuses, infants, children and pregnant women at great risk.
Chlorpyrifos is so dangerous that the European Food Safety Authority has stated that there is no safe exposure level.
The EPA reached an agreement with Dow in 2000 to phase out all residential uses of the chemical because of research showing the chemical is dangerous to the developing brains of babies and young children. In 2012, chlorpyrifos was banned from use around schools.
In February 2020, after pressure from consumer, medical, scientific groups and in face of growing calls for bans around the world, Corteva AgriScience, a successor corporation to a merger of Dow and DuPont, said it would phase out production of chlorpyrifos. The chemical, however, remains legal for other companies to make and sell.
The study that is the subject of the new paper by the University of Washington researchers was overseen in 1971 by the Albany Medical College’s Institute of Experimental Pathology and Toxicology. The study included 16 healthy adult male inmates from a pool of volunteers at Clinton Correctional Facility, a maximum-security prison in Dannemora, New York.
The volunteers were randomized into four experimental groups, including one control group, whose members received a daily placebo. The members of the three other groups received daily chlorpyrifos treatments at three different doses. The study took place over 63 days.
The new analysis found several problems with the study, including the omission of eight valid baseline measurements for one of the three treatment groups.
“Such an omission of valid data without justification is a form of data falsification that violates all standard codes of ethical research practice and is classified as outright research misconduct,” the University of Washington researchers concluded.
The researchers said that chlorpyrifos “passed through the regulatory process without much debate,” even though there was “growing evidence that it might pose a health hazard in residential environments.”
“The Coulston Study misled regulators by omitting valid data,” and “may have adversely impacted public health” for several years, the University of Washington paper concludes.