A pesticide used on thousands of acres of specialty crops in Michigan that was expected to be banned by the United States Environmental Protection Agency (EPA) due to potential developmental issues in children will remain in use under a decision by the federal department's new administrator, Scott Pruitt, but continued debate over the chemical's use has both sides claiming their positions are backed by science.
Sold under more than 50 different product names, chlorpyrifos is one of the most widely used insecticides in the world, targeting insects, arachnids and other pests that destroy hundreds of different crops, including apples, cherries and other fruit, corn, onions, nuts and specialty crops. The pesticide is also used to control mosquitos at some golf courses, as well as ants, cockroaches and other pests. Chlorpyrifos was also used for residential pesticide control prior to heavy restrictions imposed by the EPA in 2001 due to concerns about health risks.
Additional research since the EPA's 2001 ban on residential use of chlorpyrifos has indicated the pesticide is linked to developmental delays in children, including autism, attention deficit disorders and decreased or delayed cognitive ability. While federal law requires the EPA to consider a pesticide's risk to children when reauthorizing the use of each pesticide registered with the agency on a 15-year basis, health and environmental advocates say the EPA ignored such evidence when its new administrator reversed the agency's previous decision in 2015 to ban the use of chlorpyrifos for agricultural use.
Praised by those in the farming and pesticide industry who are in favor of more relaxed regulations, the move has been dubbed a return to "sound science" by the new EPA under the Trump administration, and serves as an example of how science has become a politicized issue in the country's regulation system that pits those helping to feed the population against those in the public health realm who are trying to protect it.
In Michigan, pesticide applicators purchased about 3,387 pounds of chlorpyrifos in 2013, 2014 and 2015 across the state, according to the Michigan Department of Agriculture and Rural Development.
"Its a widely used organophosphate that is in many farmers' toolboxes," said Kevin Robson, horticultural specialist with the Michigan Farm Bureau, who focuses on specialty crops in the state, such as apples, cherries, onions, cranberries and others.
Specialty crops, which also include foods such as turnips, carrots, cabbage, asparagus, and brassica crops, such as broccoli and cauliflower, account for about 159,000 acres of farmland in Michigan. Robson said chlorpyrifos is used as a one-time treatment application for many of those crops. Without the use of the pesticide, he said, growers estimate they could lose 50 to 95 percent of their crops to pests.
For instance, onion growers, who use the chemical for protection against a specific onion maggot, say the effect on the industry would be particularly severe, starting at the transplant and seed production stage. Likewise, many asparagus growers use chlorpyrifos as a one-time application prior to harvest to control the invasive cutworm, which the Farm Bureau said would ruin at least 20 percent of their crop if the pesticide was banned from use.
"There are some other options, but we in American agriculture like to see the right treatment at the right place and time," Robson said of alternatives to chlorpyrifos. "There are older technologies that are less efficient, and you have to use more to be as effective. At the end of the day, there are some (crops) that don't have alternatives, like onions."
Further, the Michigan Farm Bureau and other industry organizations say limitations on the use of chlorpyrifos imposed by the EPA throughout its use, as well as longstanding scientific data have shown chlorpyrifos is safe when used properly.
"This has been around since the 1960s and has been tried and tested based on science. All chemicals go through the EPA's review process," Robson said. "For our growers that don't have another option, if the EPA would have revoked all tolerances (banned chlorpyrifos), basically, you wouldn't have onion growers growing onions anymore because it's the only thing that basically works.
"Apples growers are utilizing it, but people think they are putting this on the food that our children eat, and that's not true."
Apple growers may use chlorpyrifos as a pre-emergent pest control product that is applied just as trees start to bloom.
When compared to other pesticides that were used for many years before the EPA banned their uses due to health and environment concerns – such as DDT – Robson points to other chemicals that pose potential risks if used improperly.
"Bleach is in every household, and if it's not used correctly it can kill you – and it's in every home with every child," he said. "Any chemical can be harmful or fatal if swallowed... when people compare it to DDT, I compare it to bleach or anything that is within reach of a child."
Chlorpyrifos belongs to a class of pesticides called organophosphates, which operate by blocking an enzyme that controls what travels between nerve cells. When the enzyme is blocked, the nervous system fails to operate properly and kills the pest. The pesticide is considered a distant cousin to some other organophosphates that have been used as nerve agents, such as sarin and other chemical weapons, albeit far less toxic. For instance, a lethal dose of chlorpyrifos is considered to be between 92 and 276 milligrams per kilogram of body weight, while sarin is toxic at .071 to .285 milligrams per kilogram of body weight.
Despite the longstanding use of chlorpyrifos, health and environment concerns about the risks of exposure to the pesticide began rising in the late 1990s, and have continued in more recent years. Human health incidents led the EPA in 2001 to ban the use of chlorpyrifos in residential settings. Researchers in the 2000s also started to find an increasing amount of evidence that linked the chemical to severe developmental issues in children, including autism spectrum disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD) and other issues.
Researchers at the University of California Davis' Department of Public Heath Sciences and the university's Medical Investigations of Neurodevelopmental Disorders Institute, in Sacramento, found that mothers who lived less than a mile from agricultural organophosphate pesticide application, particularly chlorpyrifos, during pregnancy had a 60 percent increased risk of having children with Autism Spectrum Disorder.
A series of studies by researchers at Columbia Center for Children's Environmental Health with Columbia University's Mailman School of Public Health were influential in the EPA's 2015 decision to ban all uses of chlorpyrifos, which has recently been overturned by the agency's new administration.
A 2010 study examined the association between chlorpyrifos exposures and mental and physical impairments in children in low-income areas of New York City neighborhoods in the South Bronx and Northern Manhattan. Chlorpyrifos was commonly used in the neighborhoods until it was banned for household use in 2001. Researchers said their findings indicate high chlorpyrifos exposure, as illustrated in umbilical cord blood at birth, was associated with a 6.5-point decrease in the Psychomotor Development Index score and a 3.3-point decrease in the Mental Development Score in three-year-olds.
"Although this pesticide has been banned for residential use in the United States, chloryprifos and other organophosphorus insecticides are still commonly used for a variety of agricultural purposes," said the deputy director for the center, Virginia Rauh, who co-authored the study.
Rauh said researchers hoped the study would show the neurotoxicity of the pesticide "under a range of community conditions" and "inform public health professionals and policy-makers about the potential hazards of exposure to this chemical of pregnant women and young children."
The EPA in 2011 estimated people consume about .009 micrograms of chlorpyrifos per kilogram of their body weight per day from food residues, while children typically consume more residues, with toddlers taking in about .025 micrograms per kilogram of their body weight per day. Additional ingestions may also occur from drinking water and residue in food handling establishments. The EPA's acceptable daily dose is .3 micrograms per kilogram of body weight per day.
The Pesticide Action Network's "What's On My Food" database estimates the percent of crops with specific pesticides on them, and typical amounts. While the database doesn't break down figures by locations or region of the country, it does give some data on domestic versus imported foods, and organic versus traditionally farmed foods. For instance, the database found chlorpyrifos is found in about 35.7 percent of almonds, with a maximum level 4.8 micrograms per 100 grams of the food. The pesticide was found in about 12.4 percent of apples tested in 1999, with an average of 1.1 micrograms per 100 grams of apples and a high level of 54 micrograms.
In addition to health risks posed by chlorpyrifos, the pesticide can disrupt aquatic life and other insects, such as bees. Environmental studies indicate the threat to aquatic wildlife is greatest from misapplication of chlorpyrifos.
A 2014 study found that exposures from surface water concentrations in the United States decreased after the pesticide's use was restricted in the early 2000s, which included changes in the concentrations and uses of the chemicals during application, as well as the prohibition of domestic sales of the pesticide.
The Washington State Department of Agriculture has said the application of chlorpyrifos is highly toxic to honey bees and have a residual hazard for an estimated four to six days. In general, the department advises against applying chlorpyrifos to blooming fruit trees or allowing pesticide drift onto blooming trees or blooming broadleaf weeds in order to prevent bee kills.
John Stone, program coordinator for Michigan State University's Pesticide Safety Education Program, said chlorpyrifos residue resides on the skin of most fruit, rather than contaminating the entire food.
"Most fruit with a skin, like an apple or cherry, the molecule doesn't make it through there," he said "It's a contact insecticide, opposed to a systemic one that is absorbed through the plant. And part of the Food Quality Protection Act is how much pesticide can actually be on those fruits."
The amount of the pesticide and when it may be applied is spelled out by the type of use or crop receiving the treatment, with restrictions ranging from less than 24 hours for Christmas trees to 365 days prior to harvest for ginseng. Non-food uses include golf courses, industrial sites, greenhouses, nursery production, sod farms and wood products.
Additionally, Stone said the university's pesticide safety program works with farmers on overall pest management programs.
"We also educate about timing applications for when pest levels reach losses that would be greater than the cost of application," he said. "They don't spray just because a good integrated pest management system is monitoring the system to see if there are pests building up or if you have to take action because you're going to have losses."
The Michigan Department of Agriculture and Rural Development (MDARD) is responsible for registering about 15,500 pesticide products in the state, which includes about 600 that are classified as "restricted use" pesticides. Of those 600, about 59 insecticides registered in Michigan contain chlorpyrifos as an active ingredient. An additional three products containing chlorpyrifos aren't considered to be registered use products, but are products that are used in the industry as an ingredient in other products and wouldn't be used directly by consumers, said Brian Verhougstraete, pesticide registration program specialist with the Michigan Department of Agriculture.
The restricted use designation requires those working with the product to attain a special certification. Certification is required for the sale, use or purchase of all restricted use pesticides.
Stone, with Michigan State University's pesticide program, said the EPA in 1996 made chlorpyrifos a restricted use pesticide.
The MDARD said about 3,387 pounds of chlorpyrifos were sold in 2013 through 2015 throughout the state, with 90 pounds sold in Macomb County. There were no sales of chlorpyrifos in Oakland, Livingston or Wayne counties during the same three year period. Data for 2016 and 2017 was not available.
Verhougstraete said the amount sold in each county doesn't necessarily mean that amount is being applied in each county. In fact, he said Oakland County has the highest number of commercial pesticide applicators per capita in the state, along with Macomb and Livingston counties. However, the majority of applications are typically made in more rural counties.
"That data is for 'sales' of chlorpyrifos and doesn't necessarily equate to use – it's possible that some people bought the product and either didn't use it or used it over the course of several years," he said. "The data also only tells us what county the chlorpyrifos was purchased in, not where it was ultimately used. In other words, it's possible that chlropyrifos that was purchased in Macomb could have been used in another county or that chlorpyrifos purchased in another county was used in Macomb."
Pesticide regulations are prescribed by the EPA under the federal Federal Insecticide, Fungicide and Rodenticide Act, commonly referred to as FIFRA. Under the law, the EPA must re-evaluate each pesticide registered with the department on a 15-year basis. Chlorpyrifos was first registered for use in 1965, with its last reauthorization by the EPA under FIFRA completed in 2006.
For public health advocates, the 2006 re-authorization has become an area of contention. The issue, they say, stems from a change in 1996 to the Food Quality Protection Act, which is a part of the FIFRA, and which requires the EPA to consider special protections for infants and youngsters when assessing a pesticide for re-authorization.
In 2007, the Natural Resources Defense Council and the Pesticide Action Network of North America (PANNA) filed a petition with the EPA asking it to re-evaluate the pesticide's impact in the context of food consumption and request the agency to remove all tolerance levels for the pesticide and effectively ban all uses of chlorpyrifos.
Miriam Rotkin-Ellman, senior scientist with the Natural Resources Defense Council, said the EPA's own restrictions and the addition of new research shows the EPA didn't follow the rules properly. "That act said that the EPA needed to take a closer look at pesticides and how they relate to children," Rotkin-Ellman said.
It was about 2001 when the EPA banned chlorpyrifos for use in residential settings, such as sprays and granular products used by exterminators in cracks and crevices, as well as foggers and pest control products. The chemical is, however, permitted to be used in child resistant bait traps for ants and roaches.
"Because the literature and the EPA's own studies at the time suggested there's a mismatch, and at very low levels kids are at risk of learning disabilities, the EPA didn't consider that," Rotkin-Ellman said. "That was the main part to our 2007 petition. They left out what the science is pointing to."
The petition eventually ended up landing in the federal Ninth Circuit Court, which in 2015 ordered the EPA to respond to the groups' petition, meaning it must either accept or deny the petition's request. The EPA subsequently announced in October it would remove all tolerances of the pesticide.
The decision drew tens of thousands of comments to the EPA, both lauding the decision and rebuking the agency's method used in its revised health assessment, which led to the decision and relied heavily on epidemiological studies that linked chlorpyrifos to health concerns in children.
"We support a withdrawal of all uses of chlorpyrifos because the EPA determined over 10 years ago that chlorpyrifos was too dangerous to be used around kids and cancelled all homeowner uses; chlorpyrifos remains one of the most widely used agricultural insecticides in the United States, at over five million pounds applied annually; across the country, rural families, farmworkers and families of farmworkers are regularly exposed to chlorpyrifos, resulting in poisoning incidents each year and medical problems from acute and chronic exposure to this hazardous insecticide; chlorpyrifos is linked to brain and neurodevelopmental damage in children in extensive peer-reviewed studies; and the EPA continues to leave rural children and the children of farmworkers in harm’s way because they are exposed to chlorpyrifos through drift, volatilization and take-home exposure from farmworker family members," stated a group of doctors and health professionals in a letter to the EPA. The group included representatives from Physicians for Social Responsibility, Wake Forest University's department of community medicine, the Institute for Health and the Environment at the University of Albany, Clinica Sierra Vista, the University of California, and several others.
The decision also drew praise from environmental groups.
"We like to give credit where credit is due and the EPA and the services deserve credit for finally putting together a robust process to analyze harms to endangered and threatened species due to pesticide use," the Center for Biological Diversity said in its comments to the EPA. "Endangered species are extremely sensitive to environmental stressors. In fact, exposures that may not have much of an effect on the population of a heathy species could profoundly impact the population of endangered or threatened species. The Endangered Species Act represents the institutionalization of caution – it was enacted to keep species from going extinct, and it has been so successful at this because it unambiguously mandates a precautionary approach."
Those opposing the decision, including Dow AgroSciences; CropLife America; the American Farm Bureau Federation; and others, said the decision was based on faulty science that relied on unproven epidemiological studies. Central to the opposition was the inclusion of those studies in the EPA's revised health assessment, which wasn't fully published until after the 2015 announcement.
The EPA's health assessment's inclusion of epidemiological studies, rather than its previous use of neurotransmission disruption, was a specific objection.
The review, published on November 3, 2016, explained that previous health tolerances for chlorpyrifos relied on risk assessments that measured the estimated amount of chemical exposure to inhibit blood and the body's ability to function correctly. However, the revised health study, which the EPA used to base its planned ban on the pesticide, also relied on evidence from the Columbia Center for Children's Environmental Health Study on pregnant women, which reported an association between fetal cord blood levels of chlorpyrifos and neurodevelopmental outcomes.
Based on the total risks, the EPA published a proposed rule on November 6, 2015 for revoking all tolerances for chlorpyrifos. While the EPA at that time didn't yet have data for exposure from drinking water, the agency found overall exposure from food was high enough to proceed with the decision.
Exposure from food alone, the EPA's assessment found, is a concern at the 99.9 percentile of exposure to all populations, with the highest risk to children who are one to two years of age. Essentially, the health assessment found the limit of chlorpyrifos in drinking water should be set at zero, after considering the average amount of total exposure to chlorpyrifos from other sources.
While indoor residential uses are prohibited, outdoor exposure from chlorpyrifos is still possible. The EPA's assessment stated that exposure to golf courses treated with chlorpyrifos can occur, particularly within the first 24 hours of treatment.
"This assessment indicates that all residential post-application exposures are of concern on the day of application; further, all exposure scenarios assessed following aerial and ground mosquitocide applications result in risks of concern," the EPA stated in its review.
"Because dietary risk from food exposure alone and from residential exposure along are of concern, it's not possible to calculate DWLOC (Drinking Water Levels Of Comparison)," the EPA assessment stated. "The steady state aggregate of DWLOC is zero after accounting for food and residential exposures."
While the EPA's revised health assessment still weighed the risk of chlorpyrifos on the chemical's inhibition of AChE, which is a primary neurotransmitter in the body, the new assessment method also relied heavily on the Columbia University study and others.
"In summary, the EPA's assessment is that the Columbia Center for Children's Environmental Health study, with supporting results from the other two U.S. cohort studies and the seven additional epidemiological studies reviewed in 2015, provides sufficient evidence that there are neurodevelopmental effects occurring at chlorpyrifos exposures below that required for AChE inhibition."
Despite the heath assessment, incoming EPA administrator Pruitt in March of this year reversed the agency's decision and rejected the petition from the Natural Resources Defense Council and the Pesticide Action Network. While Pruitt said the EPA would conduct its own analyses with the potential to take further action, no additional considerations are expected to occur prior to the pesticide's next re-evaluation, which is required under FIFRA in 2022.
The EPA, in announcing its reversal, said the 2015 ban "relied on certain epidemiological outcomes, whose application is novel and uncertain, to reach its conclusion. Pruitt's decision also signaled that the agency would be moving in a new direction when considering regulations.
"We need to provide regulatory certainty to the thousands of American farms that rely on chlorpyrifos, while still protecting human health and the environment," Pruitt said. “By reversing the previous administration's steps to ban one of the most widely used pesticides in the world, we are returning to using sound science in decision-making – rather than predetermined results."
Administrator Pruitt in his decision to deny the petition said the public record lays out "serious scientific concerns and substantive process gaps" in the proposal to ban the pesticide. And, that "reliable data, overwhelming in both quantity and quality, contradicts the reliance on – and misapplication of – studies established to end points and conclusions used to rationalize the proposal."
The two groups that filed the petition have since appealed the EPA's decision in federal court. Meanwhile, while no states have gone beyond the EPA's regulations and banned chlorpyrifos on their own, seven have submitted legal objections to the EPA's March 29 decision, requesting immediate action to vacate the order and take final action on the EPA's proposed rule to revoke tolerances on the pesticide. Those states include New York, Washington, California, Massachusetts, Maine, Maryland and Vermont.
With both sides of the issue clinging to scientific evidence to back up their claims, the general public may be left wondering who to believe.
"The rhetoric that you're hearing now, what the EPA released and Scott Pruitt said in his letter denying our petition offering no new science contradicting the EPA's own findings, is that this is 'a return to sound science,’” Rotkin-Ellman said. "What Pruitt said – who I might add, is not a scientist – is that there is uncertainty. And based on that, he said the EPA shouldn't act on a ban approved by the previous administration. In doing so, he didn't cite any specific science."
By playing on the uncertainties that are inherent in epidemiological studies, such as those used in the EPA's health assessment of chlorpyrifos, as well as other environmental issues, opponents of tighter regulations and restrictions claim faulty science is at play. However, proponents of stronger regulation say that view ignores strong evidence from studies.
“Where we are on pesticides and many other environmental issues is looking at patterns of disease, so that if you understand those patterns you might be able to do something about it," Rotkin-Ellman said. "We don’t intentionally expose disease to people anymore because that's unethical, so we look at diseases and we better understand them and (their) risk factors, and can hopefully show positive results. That has happened with lead in water. That's epidemiology.
"For pesticides, you look at animal (testing) literature, which is mostly on rats, and sometimes you don't see it. And there are two different places you can go with that: the public health community says that if we have evidence of effects on animals and humans and it's not lining up, maybe that's because animals and rats aren't the same. That could be why human studies show a connection and animals not as much... The industry argument is that there is something wrong with the epidemiology and that we should basically ignore it."
Raising doubts to discredit epidemiological studies has proven to be one of the most effective ways for industry to avoid regulations, as former Assistant Secretary of Labor for the Occupational Safety and Health Administration (OSHA) David Michaels pointed out in his 2008 book, "Doubt is Their Product: How industry's assault on science threatens your health." The book documents the tobacco industry's tactics to create doubt and controversy over the hazards of smoking, and explains how scientific uncertainty has been used to keep the public confused about asbestos, lead, plastics and other toxic materials in order to disrupt the country's regulatory system by politicizing science.
"The question about what kind of science is the backstory argument that is happening," Rotkin-Ellman said.
"If you stop anyone on the street and give them evidence of something toxic to their food based on studies, but those studies don't show it in rats, most people are going to be worried about the thing that effects humans. And on that side of the argument, you have doctors and pediatricians and people that worry the most about kids," she said. "The people that oppose that literature are people that represent the industry, by and large. From a parent's perspective, if there's something showing up in children, then we should be doing something about it."
Still, the impact of banning one of the most widely used pesticides in the country remains unknown. In addition to the monetary impact it could have on the pesticide and agricultural industries, heavily restricting pesticides such as chlorpyrifos could have on the food supply as more invasive species continue to find their way into the country is a mystery.
"Some of the announcements that Pruitt has put out is a flagship and a breath of fresh air for American agriculture and Michigan agriculture," said Robeson with the Michigan Farm Bureau. "In terms of the Pesticide Action Network of North America and the Natural Resources Defense Council, they are petitioning and they are an equal-opportunity petitioner. They want all pesticides gone... You can't feed the world with organic practices alone. There's just no other way."