Dr. Allan S. Felsot, Environmental Toxicologist, WSU
The following testimony was presented to Dr. Lynn Goldman, at the EPA FQPA Hearings in Yakima, Washington on May 30, 1998
My name is Allan Felsot, and I am a Professor and Extension Specialist in the Department of Crop & Soil Sciences at Washington State University. I am assigned to the Food and Environmental Quality Lab at our branch campus in Richland. My specialty is environmental toxicology, the area to which much of my extension work is devoted. My research is devoted largely to environmental chemistry. Prior to starting my tenure at WSU in 1993, I had been on the faculty of the University of Illinois since 1978 in the Office of Agricultural Entomology, where I was project leader of the Pesticide Chemistry and Toxicology Lab. Combined with my doctoral training, I have spent the last 23 years studying just about every aspect of pesticide technology.
I have seen the technology change. I have seen the attitude of manufacturers change. I have seen the attitude of growers change. I have seen an honest ethic of environmental stewardship infuse every aspect of agricultural production. When agronomic tools have advanced, growers have adopted them, as well as innovating many themselves. New crop protection tools have been developed, and growers have adopted them. I doubt if there is a single grower in our diverse state who would refuse to adopt a new technology if shown it to be a superior way of farming while maintaining long-term soil and water quality. After all, every grower knows that good soil and water are the basic capital of their livelihood.
But new technologies do not grow overnight. They are cultivated from the creativity of many people throughout the greater agricultural community over time. Some ideas take hold right away; others await development and fine-tuning. Others are yet to be discovered. But whatever technology is adapted, one guiding principle must hold if it is to be sustainable: The growers must make a profit.
Which brings me to my perception of why we are here today. The Food Quality Protection Act was partly a response to the National Academy of Sciences Report, Pesticides in the Diet of Infants and Children. The FQPA was also partly a response to the Clinton Administration's goal of reducing pesticide use, a goal seemingly driven by the perception that we are slowly harming ourselves because we still use pesticides as a mainstay of crop protection. If there is anything that surprises me most over the last 23 years of my studies, it is the ramping up of the rhetoric against a technology that humans have employed for thousands of years. Furthermore, the rhetoric has increased despite the tremendous changes in the types of chemistries employed in modern crop protection. Because many of the recommendations of the NAS report bore fruit in provisions of the FQPA, it is appropriate that we should not forget the following statement about pesticides at the very beginning of that report: "Their application has improved crop yields and has increased the quantity of fresh fruits and vegetables in the diet, thereby contributing to improvements in public health."
Now, this statement of endorsement of a technology is not to say that the tools comprising that technology should not change or evolve as new knowledge accrues. Indeed, I thank Rachel Carson in her time for kicking us into paying attention to certain issues that were not given due attention. Fortunately, our scientists, our manufacturers, our growers, indeed our community heeded this call after some initial recalcitrance, but the nature of the tools changed. But let me remind you and everyone here today that Rachel Carson relied on the science of the time to write her book. Indeed, her book is heavily referenced with citations of studies from the 1940s and '50s that we would now call environmental chemistry and toxicology. Ironically, many of those studies were published by agricultural scientists in agriculturally oriented journals, illustrating that the agricultural community has always been as concerned about safety as it is today.
The point is that science drove the perception of risk, not some feeling that something is good or bad, certainly not public pressure. Informed science gave Ms. Carson the impetus to write her vision of risks presented at that time by DDT use. While we can agree or disagree on how this science was interpreted, the point is that we need to use the science as we move to assess the risks of the currently used technology. At this junction is where I believe the conflicts are sparking.
Here is the problem as I see it, and it is time for me to be very specific. EPA seems to be acting as if there is a public health crisis caused by the use of organophosphate insecticides. The rumor that the agency was determined to rescind the uses of these compounds set off alarm bells around the community, as if someone had tossed a match into the middle of cheat grass-infested land in July. But how did the agency expect the community to react? It is the minor crop growers who would be hit hardest, not because they want to cling to a tool they know has seen its best days. Rather, alternatives are scarce and very, very expensive by comparison. Remember the first maxim of sustainable farming: Thou shall make a profit.
The OP insecticides are tools that have been used since the 1950s. Indeed, they were hailed as replacements for the dreaded DDT. We all know these are hazardous if handled as the mixed formulation. We all know that field workers must be given due protection in fields recently sprayed. But there is not a shred of evidence, and I reiterate, not a shred of credible evidence that implicates OP residues in food as a cause of acute or chronic toxicity. Even if one desires to cumulate the exposure of all OPs in the diet together, exposure is still so low as to be trivial. From a biochemical viewpoint, despite OPs having a common mode of toxicity, cumulating their exposure is fraught with problems. Cumulating exposure of disparate compounds with different pharmacokinetic parameters cannot logically be made by linear extrapolations, especially from doses that are too low to even cause a measurable response of the biochemical target, the acetylcholinesterase enzyme.
Now, I realize that some advocates are saying that OP residue exposure during pregnancy or perhaps after birth may cause neurodevelopmental effects. And I know these same advocates are pressuring the agency to use yet another 10-fold safety factor over and above the 100-fold safety factor used to determine the reference dose, because they claim there are no data. And the law says that, in the absence of data, EPA may use an extra safety factor. As a student of the toxicology literature, I am happy to inform you there are plenty of data. Indeed, one of the advocacy groups, Environmental Working Group, in one of their recent reports cites quite a bit of it. It turns out that the so-called neurodevelopmental toxicity only seems to happen when neonate rats have been exposed to doses at the maximum tolerated level. Just because a rat cannot tell you it's feeling nauseous today doesn't mean that rat is not one sick puppy. In other words, those maximum tolerated doses routinely used in mechanistic studies are astonishingly high compared to environmental levels of residues. Biochemical reactions do have thresholds according to kinetic theory. For that reason, the dose does make the poison, regardless of the effect measured.
But some might say that we have to look at the worst case. Well, for OPs we actually have human testing data, and human cholinesterase seems to be the most sensitive biomarker of probable effects. Cholinesterase sensitivity is a key predictive parameter, because the neurodevelopmental effects seen in rat neonates are accompanied by significant cholinesterase depression. Indeed, it is excessive acetylcholine at the synapse which seems to be a factor affecting neurodevelopment. Thus, if we have human data that are predictive of the doses that could cause neurodevelopmental hazard, why does an extra 10-fold safety factor need to be applied? Our food residues do not cause cholinesterase depression, even in the young, so there is no public health crisis.
I am sure EPA reads the USDA Pesticide Data Program reports and knows that residues of OPs in food are barely 10% of the tolerances. My analysis of all pesticide residues in apples shows that the average maximum residues have declined by over 50% between 1993 and 1996. Violations of tolerances only rarely occur due to the magnitude of residues. Usually, they occur because of off-label use. These observations suggest that growers are actually reducing usage and following recommended application rates. If anything, the labels need improvement so users can more easily determine legal crop uses.
Despite the good news indicating dietary exposure is trivial, with maximum food residue levels declining and levels mostly at just a small fraction of the tolerance, EPA decided to shrink the risk cup by lowering the reference doses of the OPs by at least 10 to 50 fold. Now the Reference Doses are even further from the Acceptable Daily Intakes that are used in the rest of the world to set tolerances. Chances of harmonization with the rest of the world are even less likely, and the implications for trade are troublesome. No wonder growers believe that EPA's efforts to remove OPs from the U.S. market could be economically disastrous at this point in time.
Some people say that perhaps tolerances will need to be lowered so the risk cup does not overflow. But lowering tolerances by 10 fold will not change dietary exposure, because nearly 99% of residues are one tenth of the tolerance already. Lowering these even further will require enforcement of tolerances nearly equal to, and in some cases below, practical method detection limits and certainly below statistical quantitation limits. Moves to significantly lower the Reference Dose in the absence of convincingly critical interpretations of the data on
neurodevelopmental effects and proposals to control OPs by lowering tolerances logically suggest that EPA is ready to cancel the OPs.
Having made this argument, do not misunderstand me and think that I am not for change. I do realize that the time for OP pesticides is nearly up, and new technologies must be developed and marketed. But time is required to find these replacements. There is no health crisis regarding these compounds. Thus, there is no need for the EPA to act hastily. Ample lead time is needed to allow compounds to be developed and tested under various IPM programs and in diverse environmental conditions characteristic of our rugged, diverse terrain. So I end with a plea to the EPA. Time is needed for growers to make the transition. But first, the technological alternatives must be developed and repeatedly proven.
On behalf of my fellow agricultural scientists at WSU, we stand ready to help industry and growers develop and adopt the new technologies. These efforts will take resources. But most of all, for now, let's leave the crisis mentality behind and allow enough time for the changes to come. Thank you.
Return to the Table of Contents for the July 1998 issue
Return to the Agrichemical & Environmental News Index