Kristen Taylor/FlickrMethyl iodide, a pesticide used primarily by strawberry growers, may cause brain damage in developing fetuses.
California’s former top pesticide regulatory official dismissed safety guidelines suggested by her own staff scientists on the grounds that they were "excessive" and too onerous for the pesticide manufacturer, recently released internal documents show.
In response, the scientists lodged a formal protest, calling the official’s actions “not scientifically credible,” according to the documents released by court order last week.
The documents amount to a “smoking gun,” says Paul Blanc, a professor of occupational and environmental medicine at UC San Francisco. Last year, Blanc helped advise the staff scientists on their evaluation of the pesticide, methyl iodide.
“The decision by the regulatory superiors was not science-based," Blanc said.
In one of the documents, Mary-Ann Warmerdam, who led the state's Department of Pesticide Regulation until this year, weighs a recommendation from her staff that farm workers be exposed to no more than a trace amount of methyl iodide per day. The recommendation – intended to protect farm workers from cancer and miscarriage – is "excessive and difficult to enforce," Warmerdam wrote in April 2010, about two weeks before the department made its recommendation that California approve methyl iodide. If the restrictions on methyl iodide were approved, she wrote, the pesticide manufacturer might find the recommendations "unacceptable, due to economic viability."
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"(Warmerdam's) method was to consult with the pesticide manufacturer and determine what was acceptable to them, and then decide on what an acceptable level of exposure was," said Susan Kegley, a consulting scientist for the Pesticide Action Network, a group suing the state.
Department spokeswoman Lea Brooks declined to comment on the documents, citing the pending litigation. "It is inappropriate to try this case in the media," Brooks said.
Warmerdam resigned from the department in January. Gov. Jerry Brown has yet to appoint a successor.
Methyl iodide was approved in December 2010, at the tail end of the Schwarzenegger administration. It's a chemical fumigant used primarily by strawberry growers. A coalition of environmental and farm-worker groups has sued the state to try to ban the chemical.
As part of the suit, the groups asked the Department of Pesticide Regulation to release documents explaining how the agency decided to approve the chemical. The plaintiffs wanted to know how the agency had settled on exposure levels more than 100 times higher than what scientists within the agency believed were safe.
When pressed for documents that might reveal the agency's rationale, Warmerdam declined to release them, citing the "deliberative process" exemption, which allows government agencies to keep the thought process behind a decision private. A public records act request filed by California Watch and KQED QUEST elicited the same response.
Earlier this month, a judge disagreed, ordering the department to release the documents, which plaintiffs shared with reporters on Thursday.
"DPR has an obligation to explain to the public the basis for its decision," said Earthjustice attorney Greg Loarie, who is representing the plaintiffs. "The public has every right to know that DPR approved methyl iodide over the objections of its own staff scientists."
That rift between scientists and regulators first became public last year, in an e-mail exchange unearthed by KQED QUEST and California Watch's Public Records Act request. In the e-mails, two staff toxicologists – Lori Lim and Ruby Reed – said they had not been part of the decision to approve methyl iodide, and they stood by their original work.
"We had to read between the lines to figure out how the target levels were calculated," they wrote. Both Lim and Reed have since resigned from the department.
The new documents show staff scientists sending their complaints up the department’s chain of command.
"I am puzzled by the numbers," staff scientist Jay Schreider wrote in a memo to the state's top toxicologist, Gary Patterson. Approving methyl iodide was "management's prerogative," Schreider wrote. But he said managers should not imply that the scientists' findings "are the basis for that decision, or that the apparent 'mix and match' approach provides a scientifically credible basis for the decision."
In his order, Judge Frank Roesch of the Alameda County Superior Court found that the "great majority" of the department’s documents should never have been withheld in the first place. As for the rest, Roesch found "the interest in public disclosure clearly outweighs agency interest in non-disclosure."
The documents reveal a rare point of agreement between the department’s scientists and its managers: that methyl iodide may cause brain damage in developing fetuses.
When California first began evaluating methyl iodide, it took the unusual step of bringing in an outside group of scientists, hired to work alongside department scientists, as an independent peer-review group. The scientists, including UCSF’s Blanc, worried that methyl iodide could drift up from strawberry fields and be inhaled by pregnant farm workers or children playing nearby, causing subtle effects such as IQ loss, which might never be detected or traced back to the chemical.
"Methyl iodide concentrates in the fetal brain to levels well above those in the mother," they wrote in their assessment. "There is a high likelihood that methyl iodide is a developmental neurotoxin."
The new documents show department managers also contending with the lack of data about methyl iodide's potential effects on developing brains. In animal tests, they wrote, "several measures of neurological deficiency were measured. … Overall, there is a need for a more thorough investigation into developmental neurotoxicity in pre- and post-natal exposures to methyl iodide, because the existing data do not address these exposures."
Given the lack of data, the panel scientists recommended that a 10-fold "uncertainty factor" be added into the calculations about how much methyl iodide to which a worker could be safely be exposed. Toxicologists use uncertainty factors to help them quantify the amount of a chemical that might be determined “safe.” In this case, the added uncertainty factor would have left managers with a lower number, which would have put greater restrictions on methyl iodide’s use.
Department managers chose to drop the uncertainty factor. An internal document shows that they debated where, and how, to explain that decision.
"Hello Gary!" reads a memo from Marylou Verder-Carlos to Patterson, the lead toxicologist. "If you could please look over this document and see how and where we could explain dropping the additional 10X for the lack of DNT (developmental neurotoxicity) study."
Ultimately, department managers chose not to mention the uncertainty factor in the approval notice at all.
Ted Slotkin, a pharmacology and cancer biology professor at Duke University who served on the peer-review panel, says the documents show that the Department of Pesticide Regulation has no way of knowing whether methyl iodide is safe.
"DPR has no benchmark with which to establish the limits of exposures that could be deemed as 'safe' for pregnant women and children living in agricultural communities or attending schools adjacent to fields where methyl iodide will be applied," he said.
Some farmers in California already are starting to use the chemical, and they are expected to ramp up its use sharply in the fall, during strawberry planting season.