April 13 — In recent months, the pesticide industry has been advancing a series of arguments calling into question a significant shift in how the Environmental Protection Agency assesses the health risks of pesticides.
The arguments criticize from a number of different angles recent EPA actions that suggest that the agency is giving more weight to scientific studies of human exposure to chemicals in the environment rather than laboratory-based studies conducted on test animals.
In response to a number of these human-exposure studies published in recent years, the EPA is moving toward enacting sweeping new restrictions on a widely used class of insecticides called organophosphates. The studies found that perinatal exposure to these chemicals may damage the neurological and cognitive systems of children more than was originally thought.
The restrictions could have seismic effects on the use of dozens of chemicals contained in hundreds of pesticide products sold by large companies like Bayer, Dow Chemical and BASF, as well as many other smaller companies. If the EPA reduces the maximum amount of organophosphates that can be safely used, it would essentially lower the ceiling on the sales-generating potential of these products as farmers discover that they are now legally prohibited from using the pesticides they've been spraying for decades.
Though the EPA is still months if not years away from enacting these restrictions, industry trade groups are already laying the groundwork to challenge the legitimacy of any future decision.
The dispute centers on a disagreement about what types of scientific evidence the EPA should rely on when it assesses the risks of a pesticide.
In the past, the vast majority of data used in an EPA risk assessment has come from toxicology studies, which are typically conducted by exposing animals to pesticides in a highly controlled laboratory setting.
However, when it comes to organophosphates, the EPA is now relying heavily on epidemiology studies, which observe how humans have been exposed to pesticides within their everyday environment.
Some of the most influential of these epidemiology studies originated from Columbia University's Center for Children's Environmental Health, or CCCEH.
For more than a decade, CCCEH scientists have been following a cohort of several hundred New York City children with varying degrees of exposure to chlorpyrifos, one of the most widely used organophosphate insecticides. In the past, the chemical was used to kill nearly any insect on farms, in homes and within standing waters. Now, chlorpyrifos is primarily used by the agriculture industry only, as safety concerns led to the phasing out of residential uses.
CCCEH scientists have published numerous journal articles over the years based on health data from the children in their cohort—for example, a 2012 article linking high levels of prenatal exposure to chlorpyrifos with abnormalities in brain development and IQ levels.
Virginia Rauh, a perinatal epidemiologist with CCCEH and the lead author of many of these articles, said human studies have some advantages over animal studies in providing a more realistic view of the effects of a chemical.
“I think of it as a more complete picture about what does a kid look like who has early exposure,” she told Bloomberg BNA.
As a part of its ongoing science review of all pesticides, the EPA is currently conducting a health and safety overview for all organophosphate chemicals.
Last fall, the EPA released a document summarizing published literature on the health effects of exposure to these chemicals. The agency relied heavily on the Columbia cohort studies, as well as those of two other human studies, and concluded that this research indicates the need for new safeguards to protect children (80 Fed. Reg. 57,812).
If the EPA were to implement these safeguards, it would represent a sea change in the way the agency interprets scientific data, rejecting decades of findings from lab-based toxicology studies, according to Tamika Sims, director of human health policy with the pesticide industry trade group CropLife America.
“What seems to be happening now is that the EPA is sidestepping the toxicology data and using the epidemiology data,” Sims told Bloomberg BNA. “You have to be cautious in how you potentially sidestep one set of data for the other, which is what we feel like is happening. It doesn’t seem like a logical integration [of the two] is occurring.”
Sims also said her group has been unable to determine whether the EPA has full access to the raw data from the Columbia cohort studies.
She said, when asked about this, EPA officials provided CropLife with shifting answers—first telling the organization that they received no data from Columbia, then saying that they had received some of the data.
“It’s all hearsay,” Sims said. “EPA is saying they don’t need access to all the raw data. … That’s not been said in writing.”
Peter Taback, a spokesman with the Columbia's Mailman School of Public Health, told Bloomberg BNA in an e-mail that Columbia's scientists have been working with the EPA on chlorpyrifos for years.
He said the school has offered to make its data available “under protocols that ensure the confidentiality of the children who are the subjects of our research. If we have a formal request from EPA, we will, of course, share all data that were gathered with the support of the U.S. government.”Scientific Advisory Panel
The EPA is convening a three-day meeting of its Scientific Advisory Panel later this month to look at biomonitoring data on exposure to chlorpyrifos. The meeting will take place at the agency's Arlington, Va., facilities from April 19 to 21. More information, including an agenda for the meeting, is available on the EPA's website.
The EPA did not make anyone available to Bloomberg BNA to answer questions for this story. EPA spokeswoman Melissa Harrison said in a statement to Bloomberg BNA that her agency plans to launch a formal public comment period this spring to get feedback on its use of epidemiology data in regulating chlorpyrifos.
But Harrison also said the EPA didn't want to comment too far beyond this because the agency is convening a panel of independent scientists later this month to review the chlorpyrifos data and it does not want to “preempt or influence the discussion before it occurs.”
However, a recent letter from Jack Housenger, head of the EPA's pesticide regulatory programs, to a pesticide industry executive sheds more light on the situation.
In an April 7 letter to Cindy Baker Smith, senior vice president of the pesticide company AMVAC, rejecting her request to postpone the scientific advisory panel meeting, Housenger tacitly acknowledged that his agency does not have all of the Columbia data.
“The EPA is not required to disregard—nor will it disregard—such a study solely because the EPA does not possess the raw data underlying that peer-reviewed research,” Housenger wrote.
The quandary about whether and how to use epidemiology data in regulatory decisions is a relatively recent one.
Melissa Perry, an epidemiologist at The George Washington University, said recent advances in data analysis and in chemical measurement have allowed scientists to collect extremely high-quality human data. Within the past 15 years, Perry said, the quality of this data has reached a point where the connections one can make with it rival in strength those one can make from toxicology data.
“The EPA hasn’t been accustomed to incorporating epidemiology data in the past,” she told Bloomberg BNA.
Perry said she hopes the EPA won't be pilloried for attempting to incorporate this data into its regulatory process.
“I don’t see any justifiable arguments to say they have to ask for permission for that,” she said. “If they have to act in a forthright way to protect the public health, they shouldn't be expected to be worn down in the process.”
For her part, Rauh said she hasn't had any interactions with the EPA about access to her data and that she's focused on continuing to study how pesticides affect children. She also said she's glad she's a scientist gathering data, not a regulator looking at the data to try to figure out what should be done.
“The EPA has a hard job and I don’t know how they’re able to actually put it together,” Rauh said. “They select the evidence, we provide one piece. The rest of it is on their shoulders.”
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