Agrichemical and Environmental News -- Feb96
A monthly report on pesticides and related environmental issues

Issue No. 120, February 1996

Open Forum:
In an attempt to promote free and open discussion of issues, The Agrichemical and Environmental News encourages letters and articles with differing views. To include an article, contact:
Catherine Daniels, Food and Environmental Quality Laboratory, Washington State University, Tri-Cities campus, 2710 University Drive, Richland, WA 99352-1671. Phone: 509-372-7495. Fax: 509-372-7491. E-mail:

In This Issue

News and Notes Pesticide Training Season Here
WSDA Minor Crop Workshop Scheduled for March Methyl Bromide Happenings
A Rebuttal Allan Felsot
Registration Proposals Due USGS Releases Results of Agrichemical Studies
The Status of 2,4-D Comply for Overwintering Adult Pear Psylla Control
Officially Unofficial Federal Issues
State Issues Available Reports

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News and Notes

Note: The AENews is now accessible from the World Wide Web via the Washington State Pesticide Page. The address for the page is:

Enter this address carefully, paying close attention to punctuation and spacing (no spaces between parts of the address). Some readers may experience difficulties accessing the site. These are believed to be related to the Internet and to on-line services, not the web site. If you are having a problem accessing the web page, please inform Catherine Daniels (ph: 509-372-7495, fax: 509-372-7491, E-mail:

Clarification: The May 22 meeting of the Washington State Commission on Pesticide Registration, reported in the January issue as being in the WSU Extension Office in the courthouse, will be held at the WSDA Pesticides Branch Conference Room at 2015 S. 1st St. in Yakima.

Colombia changes policy on U.S. fruit

The government of Colombia on January 26, 1996 suspended its fumigation requirement for U.S. fresh fruit imports originating in states where Oriental fruit fly has not been detected. The requirement had been instituted on December 28, 1995 in a response to several fruit fly detections in California and Florida.

This change in policy, particularly as it affected impending apple and pear shipments from the Pacific Northwest, was achieved through the intervention of U.S. Agriculture Secretary Dan Glickman and the efforts of the Foreign Agricultural Service (FAS) and Animal and Plant Health Inspection Service (APHIS) representatives in Bogota, Colombia.

Wine making may cut residues

Researchers in Italy have studied the influences of wine making techniques on pesticide residues. The fate of five insecticides, including chlorpyrifos (Lorsban), fenthion (Baytex), methidathion (Supracide), methyl parathion (Penncap-M), and quinalphos (Ekalux, not registered in the U.S.), applied to the fruit of vines destined for wine was studied.

According to the report, insecticide residues on grapes showed high degeneration rates soon after treatment, with half-lives ranging from 0.97 to 3.27 days.

Processing the grapes into wine caused considerable residue reductions (more than 80%) for chlorpyrifos, methyl parathion and quinalphos; moderate reduction (about 50%) for methidathion; and almost no reduction for fenthion. The two wine making techniques, with and without maceration, had the same influence on pesticide residue concentrations.

Food Chemical News, Nov. 27, 1995

Crawford named CSANR director

Phil Crawford, currently interim assistant director of Cooperative Extension for Agriculture and Natural Resources, on January 2 became director of the Center for Sustaining Agriculture and Natural Resources.

IR-4 schedules research projects

IR-4 field, laboratory, ARS and headquarters coordinators met November 14-16 in New Brunswick, NJ to schedule projects for the 1996 research season. IR-4 will work on 148 projects, with 22 of these dedicated toward registration. Nine of the projects do not involve field work and consist of transfer of samples to other laboratories. Twenty of the projects are for efficacy and phytoxicity purposes only.

Douglas Rothwell, minor use coordinator for Health Canada, participated in the meeting. Canada will cooperate in the 1996 IR-4 program and is scheduled for six field trials, which will be analyzed at IR-4 laboratories. Canada will analyze one group of IR-4 samples. The venture with Canada is part of the harmonization called for under the guidance of the US-Canada Free Trade Agreement. A total of 496 field trials for 1996 are distributed as follows:


California delays methyl bromide ban

Legislation to "roll back" a scheduled ban of the use of methyl bromide in California was approved by the State Assembly's Toxics Committee on January 10.

The bill is part of a legislative package moving through a special session of the California Legislature called into session by Gov. Pete Wilson to make enactment possible without the two-thirds vote required of urgency measures.

Unless long-awaited health impact studies are completed, suspension of methyl bromide use takes effect March 30. An extension of the deadline was sought by grower groups when it became apparent the studies would fail to appear on time.

Pesticide training season here

Washington State University has mailed out its Pre-License and Recertification brochures to all licensed pesticide applicators. Recertification courses offer six recertification credits per day. For copies of the brochures, contact one of the following:

Programs for Western Washington

OlympiaFeb. 28
SilverdaleMar. 4, 5
BellevueMar. 6, 7

Integrated Plant Health Workshop,
PuyallupMar. 5-8 (5 credits per day)

PRE-LICENSE Courses in Western Washington

OlympiaFeb. 26, 27, 28

Report says synthetic chemicals
less likely than diet to cause cancer

The National Research Council, a 20-member research arm of the National Academy of Sciences, recently released a report on carcinogens in the U.S. diet. The report, "Carcinogens and Anticarcinogens in the Human Diet," was based on an extensive review of reports on cancer-causing and cancer-fighting substances in foods. The report states that about one-third of the 1.35 million new cancer cases in the U.S. each year are linked to diet, but very few are linked to synthetic chemicals. A quote from the report states, "The great majority of individual naturally occurring and synthetic food chemicals are present in the human diet at levels so low that they are unlikely to pose an appreciable cancer risk."

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WSDA minor crop workshop scheduled for March

The Washington State Department of Agriculture plans a minor crop registration workshop for March 18 in room 252 at the Tri-Cities branch campus of Washington State University.

The free workshop will focus on how to apply for Section 18 emergency exemptions and Section 24(c) Special Local Needs registrations. No lunch is provided, but light refreshments are provided for the morning session.

Registration forms must be returned by March 8. These forms, directions and more information may be obtained from WSDA Minor Crop Program coordinators Michele Hauff at 509-575-2595, Robin Schoen-Nessa at 360-902-2027 or from the WSDA Registration Branch at 360-902-2030.

Minor Crop Registration Workshop II Agenda

Ted Maxwell, WSDA Program Manager, Registration
8:30-9:00Overview of Section 18 Process _ Explanation of a Section 18 review, time frames, and Section 18 definitions. _ Michele Hauff, WSDA Registration & Minor Crop Program Coordinator
9:00-9:45EPA Perspective _ An overview of how EPA processes Emergency Exemptions, agency reviews, and how to improve submissions to speed review. EPA materials and information presented at October 1995 workshop will be presented. _ Robin Schoen-Nessa, WSDA Registration & Minor Crop Program Coordinator
10:00-11:00Data Generation - Choices _ Discussion of how to meet
Section 18 Exemption and 24(c) Registration research requirements. Discussion of WSU research programs, IR-4 Program and how the new Washington State Commission on Pesticide Registration can be an asset
11:00-12:00Panel Discussion - Overview Section 18 Guidance Package & Problem Areas _ Discussion of the Section 18 process: The applicant's request submission to WSDA - WSDA's request to EPA - Successfully receiving an exemption; Challenges of past Section 18s and future proposals including industry/grower perspective. _ Robin Schoen-Nessa, Michele Hauff, & Rocky Lundy - Mint Industry Research Council
1:30-2:00Overview of SLN Process _ Explanation of a 24(c) request review, time frames, 3rd Party 24(c)s and the differences in WSDA and EPA roles _ Michele Hauff, WSDA Minor Crop Registration Coordinator
2:00-3:00Panel Discussion - Overview 24(c) Guidance Package & Problem Areas _ Explanation of how a crop protection need/pest problem becomes a Special Local Need. Discussion of information needed to receive a successful 24(c) review. Discussion of challenges to receiving a 24(c), including an industry perspective. _ Robin Schoen-Nessa, Michele Hauff, & John Shipley - Asgrow Seed
3:00-3:30Experimental Use Permits _ The importance of EUPs in generating data to support future registration needs. _ Steve Foss, WSDA Agricultural Chemical Specialist, Registration

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Methyl bromide happenings

Senior advisers in the EPA Office of Air and Radiation say a lack of adequate substitutes for the fumigant, methyl bromide, should not delay the 2001 phase_out date for the pesticide. They also say, however, that the lack of substitutes should prompt more research into alternatives.

An EPA panel released a statement declaring that "the critical issue is not whether adequate alternatives for all methyl bromide uses are available now, but whether they will be available by the time the phase-out deadline arrives. EPA knows that it will be a combination of chemical and nonchemical methods that replaces the many uses of methyl bromide, not a single chemical." The panel also stated that eliminating methyl bromide "could reduce future atmospheric loading of ozone-depleting chemicals by 13%, making this the single most significant policy action that can be taken" to reduce risks associated with a thinning ozone layer.

In the European Community, the European Union Council of Ministers adopted a position favoring an accelerated phase-out of methyl bromide and hydrochlorofluorocarbons under the Montreal Protocol, in order to protect stratospheric ozone. These accelerated schedules would outpace existing law in the European Union, as well as timetables established under the international treaty.

The European Union Commission officials criticized recent U.S. congressional hearings as counterproductive to the need to hasten the phase-out of ozone-depleting chemicals. Commission officials said the U.S. hearings were especially damaging to efforts to get developing countries to phase-out exemptions on use and production of ozone-depleting chemicals.

The Commission stated that "this is extremely disappointing, because we certainly need the full support of the U.S., both the executive branch and the Congress on this issue. It is really hard to understand those who question the validity of the ozone issue. Certainly, these people are not scientists."

The December 7 Journal of Commerce reported that U.S. farmers are unlikely to succeed in having other countries ban use of methyl bromide by Jan. 1, 2001, the date when the fumigant is set to be phased out in the U.S. Growers claim they will be overrun with imported produce, if all countries do not ban the pesticide. The article says the farmers' problems reflect deep divisions within the administration, where USDA opposes any reduction in methyl bromide's use before 2001 and others are offering an earlier reduction to gain concessions. Farmers are expected to turn to Congress, where legislation is proposed to lift the ban's deadline until the secretary of agriculture determines either that an effective and affordable substitute to methyl bromide has been found or that a uniform international phase-out date has been set. The article notes support for the legislation by President Clinton and Sec. Glickman.

Chemical Regulation Reporter, Oct. 27 and Dec. 15, 1995.

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A rebuttal

Note: The December 1995 issue of National Geographic contained an article on sustainable agriculture. Leonard Gianessi and Richard Bonanno were so incensed that they sent a letter to the editor of National Geographic regarding the article. Their letter is reprinted, with permission, here in its entirety.

The article, "A Farming Revolution," starts with a legitimate and exciting notion that farming in the U.S. is changing and moving toward a more sustainable ideal. The author, Verlyn Klinkenborg, defines this as being agriculture that is "economically viable, environmentally sound, and socially responsible". However, the author co-opts this idea to promote the interests of "organic agriculture" and portray more "conventional agricultural" practices as ignorant and shortsighted. In doing so, the terms "sustainable agriculture" and "organic agriculture" are often confused, the facts about the farming practices used as examples are distorted, and a link between modern farming practices and the decay of rural communities is contrived. The limitations and risks associated with many of the practices hailed by the author are not recognized, and the benefits of many existing practices are ignored. His conclusion, based on a few examples of organic farming, is naive and seriously misleading. Not only does he play upon nostalgia to frame his premise that agriculture is rushing to organic farming, he also ignores the economic and social costs should such a "revolution" ever take place.

Early in the article, hoeing and cultivation are cited as means of weed control that do not rely on synthetic chemicals. Although these practices can be substituted for herbicide applications, they do not come without their own drawbacks. Large-scale adoption of hoeing and cultivation would cause more farm worker accidents, increase the use of petroleum, increase erosion, and require millions of laborers to return to the fields. Instead of the charming picture of the father and his sons, hoes at the ready, "marching to battle weeds," why not show the much less idyllic view of millions of black workers in the 1920s-1930s hoeing weeds out of Southern cotton fields? Synthetic chemicals to kill weeds substituted for millions of hours of drudgery in the fields.

Cultivation generally requires several passes over a field in a single growing season to obtain effective weed control. Herbicides often provide control for long periods of time and reduce the number of passes necessary to control weeds. Consequently, less time is spent by the growers operating dangerous farm equipment, and less fuel is consumed. Also, cultivation can increase soil erosion by continually disrupting the surface of the soil. The author does not mention the major reductions in soil erosion that have resulted as farmers have substituted herbicides for mechanical cultivation in control of weeds and adopted conservation tillage practices.

The picture of the Wisconsin farmer using a propane flamer is a great misrepresentation. Nowhere in the article does it point out the risk of operating a tractor with large propane tanks attached to it. The author writes that flame cultivators use only "a few gallons of fuel instead of oceans of herbicides." The comparison is not accurate. The chemical herbicides are typically used at rates of quarts per acre mixed into a hundred gallons of water. Use of fossil fuels is higher for the propane weeder versus the few grams, ounces or pounds of chemical herbicides applied per acre. Did the author watch or talk to pesticide applicators who accurately spread eight ounces of a chemical evenly over an entire acre?

The author misrepresents several facts in discussing organic agriculture. We understand that the Gallo winery's organic-trial, 15,000-acre vineyard noted in the article has since been returned to conventional farming methods supported by Integrated Pest Management. Purportedly, severe weed control problems, a drop in soil fertility and attendant costs of organic methods led to the decision. The article's picture of the Gallo vineyard clearly shows that cover crops were not being used between all the rows. How much water did the cover crops consume?

The article does not mention that organic farming operations typically use large amounts of pesticides that are certified organic. Often, these pesticides are used at much higher rates than synthetic compounds and don't work as well. Compounds of sulfur, and copper are regularly sprayed on organic grapes and potatoes to control diseases. The rise in the use of synthetic chemicals since World War II is also distorted. It is not mentioned that, prior to that time, growers used crude chemical compounds, such as lead-arsenic, cyanide gas, copper and sulfur to control pests. Synthetic pesticides replaced these chemicals, many of which were harshly toxic. The idea that growers obtained good yields, and maintained profitable farming operations without pesticides, was almost as untrue in the early part of this century as it is today. Although it may be true that his "granddad didn't use chemicals", certainly many growers of his generation did to control agricultural pests. What were his granddad's yields? In many cases, the amount of pesticide used decreased when synthetic chemicals were introduced. Coincidentally, yields of crops such as apples increased dramatically because the synthetic chemicals were less harsh on the trees and the environment than the lime sulfur and lead-arsenic previously used.

Dr. David Pimental's claims about percentage crop losses from pests being the same now as before the advent of modern pesticides are suspect and misleading. The true value of modern crop production technology, such as pesticide use, is reflected in crop yield. U.S. farmers produce four times as much per acre now than 50 years ago.

Many other modern farming practices are also distorted by the author. For example, the hybrid corn that he disdains for taking jobs and knowledge away from the farmer is largely responsible for the huge increase in corn yields in the last 40 years. Also, the use of fungicides to control diseases of corn is almost zero due to the continual development of resistant varieties of corn. The contour farming in Vernon County, Wisconsin, touted as revolutionary, is used by most growers in areas where erosion is a problem, especially on the hilly fields and light soils of southern Wisconsin. Farmers in this area regularly rotate corn with alfalfa, since both are used to feed livestock. Contour farming and rotations are farming practices widely adopted by all farmers, not just "organic" or "sustainable" ones. The use of manure as a source of nitrogen for the soil is also common, since livestock are present. However, this does not totally negate the need for fertilizer to be applied for other plant nutrients.

Certainly, one of the most important measures of success of any farming system is its profitability. Here again, the author misleads the readers that organic farming operations are as profitable as conventional operations.

One organic vegetable grower is quoted as reporting that she grosses $10,000 an acre from her vegetables. The article claims that this is far above the average for conventional crops. While strictly accurate, the statement is misleading _ the $10,000 per acre is not uncommon gross revenue for "wholesale" fresh vegetables. This amount is only greater than the average for conventional growers, because field crops, which garner a much lower price, are included in this average. Eastern lettuce growers typically receive $16,000 per acre for their wholesale lettuce (two crops per season), which then retails at $34,000 per acre.

A similar distortion is made in discussing organic rice production. The author refers to organic rice production in California with a somewhat favorable comparison of yields and costs of production. But he fails to understand that the organic rice field is only productive every other year. This is because weed pressure becomes so bad that the ground is kept fallow for an entire year, so that flooding and cultivation can be used to control the weeds. Therefore, the profitability of this farming operation is severely overstated. Organic growers who are profitable usually are so by taking advantage of the price premiums that their produce receives in the market place or by adopting very low input management practices that minimize inputs while sacrificing some yield. It is not accurate to say that organic agriculture can compete in the common market with other production methods.

Although the author points out a growing interest in sustainable agriculture and an increased awareness of environmental and community concerns in shaping farming practices, he uses them to promote a set of farming practices beset with its own problems, and to dispel many of the gains agriculture has made in the last 50 years. The new vision of farming he is searching for will be one of continual technological advancement, with the adoption of integrated pest management, precision farming, biotechnology, and the continued judicious use of synthetic chemicals for pest control. These advancements will reduce the amount of land needed to grow crops, keep people from the laborious and dangerous tasks of farming, and reduce the impact of pesticides on the environment.

U.S. farmers use hundreds of millions of pounds of synthetic chemicals every year. That is reality. Organic growers use pesticides, too, and often at higher per-acre amounts than do conventional farmers. The problem is pest control, not pesticides. Weeds, plant pathogens, nematodes, plant viruses, and insects are a constant threat to U.S. food production. Synthetic chemicals have reduced the risk of crop losses dramatically. The article, "A Farming Revolution," presents a distorted, naive view of the reality and future of U.S. agriculture.


Leonard P. Gianessi National Center for Food and Agricultural Policy 1616 P Street, N.W., First Floor Washington, D.C. 20036

A. Richard Bonanno Bonanno Farm Trust 255 Merimack Street Methuen, MA 01844

Note:Leonard Gianessi is a senior research associate with the National Centers for Food and Agricultural Policy, a Washington, D.C. think tank on agricultural policy issues.

Richard Bonanno, on faculty at University of Massachusetts, operates a diversified vegetable farm and serves on the IR-4 Commodity Liaison Committee.

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The missing link

What we think we still don't know
after 25 years of water quality research funding

...Allan Felsot

During the last five years, the Washington Department of Ecology (DOE) and the U.S. Geological Survey (USGS) have reported detections of pesticide residues in surface and ground water collected from around Washington. Reported pesticide concentrations were mostly at or below trace levels, which can be considered nominally as values 10-100 times greater than the detection limits. While one cannot dispute the presence of residues of agricultural chemicals in water systems, the agriculture industry and the public are at odds largely because the biological effects of such contaminants are commonly thought to be very uncertain. Certainty about exposure on the one hand and uncertainty about the effects of that exposure on the other obscure the impact of agriculture on human health and environmental quality.

The ability to detect pesticide residues at levels of parts per trillion has fostered the idea that water is highly contaminated with pesticide residues. Mere detections, regardless of quantity, are now perceived inherently as unwelcome risks. The fear of constant threats to human and ecological health from exposure to synthetic contaminants seems on the verge of overwhelming society. But, is there really a link between pesticide residue detections at environmentally characteristic levels and biological effects that justifies focusing attention on the very low levels found in water?

This question needs analysis from both human health and ecological health perspectives. Unfortunately, information about the health effects of exposure to agricultural chemicals has been derived from results of high dose exposures in acute and chronic toxicity testing. For example, in the joint WSU-WA Toxics Coalition publication, The State of Our Groundwater, readers learn that they risk exposure to a variety of chemical contaminants, but the accompanying tabulation of health effects information is based strictly on high dose feeding studies in rodents, not on environmental exposures.

The debate about health effects of exposure to residues in drinking water has been directed essentially by concerns of chronic toxicity, namely carcinogenicity. Herbicides are the most frequently detected pesticides in water systems throughout the U.S., and many of these compounds, including atrazine, have been labeled by the U.S. Environmental Protection Agency (EPA) as carcinogenic. As discussed in past issues of this newsletter, the whole system of carcinogenicity assessment has come under scrutiny. The biggest problem is testing carried out with maximum tolerated doses (MTD) administered over a rodent's normal two-year life span. But the National Academy of Science report, Issues in Risk Assessment, has pointed out that, although the MTD technique may currently be the only viable one to test carcinogenicity, the results are probably irrelevant to environmental exposures. Furthermore, given the current state of knowledge about the multi-step processes involved in the development of cancer, the EPA assumption of no-threshold for a carcinogenic effect has become archaic. Even the EPA is revamping its own guidelines for scaling the carcinogenicity of a substance, by incorporating more information from metabolic and physiologic (i.e., pharmacokinetic) studies.

To address whether there is a missing link between residue detection and biological effect, I will focus first on health-based risk assessments of atrazine. The USGS will soon be reporting numerous detections of this compound in Washington's surface and ground water; indeed, it will be the most frequently detected compound. The differences in perception about the risks posed by atrazine in drinking water can be highlighted by comparing the assessment by the environmental advocacy organizations, the Environmental Working Group (EWG) and Physicians for Social Responsibility, with that of Heidelberg College and Ciba-Geigy researchers who have been monitoring water quality in the Midwest.

The independently published EWG report, Tap Water Blues, purports to be a risk assessment of exposure to triazine and chloroacetamide (such as alachlor, metolachlor) herbicides in drinking water sources of the Midwest, where these compounds are used heavily on corn and beans. The total cancer risk associated with exposure was estimated by multiplying a routinely used cancer potency factor derived from high dose rodent studies by the average water concentrations. Although assumptions by EWG are basically the same as those used by the EPA, they present the risk as multiples above the "federal standards for acceptable cancer risk", which is nominally "one additional cancer per million exposed individuals." Using this benchmark, EWG reaches the alarming conclusion that "3.1 million individuals in 23 cities with populations over 25,000 are exposed to cancer risks from herbicide contaminated drinking water that exceed federal cancer standards by a factor of 10 or more." The 23 cities were in Illinois, Missouri, Iowa, Ohio, Kansas and Nebraska.

The Heidelberg College/Ciba-Geigy (HC) collaborative report was published in Environmental Science and Technology (ES&T). The researchers' risk assessment focused solely on atrazine exposure to total populations in Ohio, Illinois and Iowa. They segregated herbicide residue data and population exposure by type of drinking water source, because sources like groundwater and large lakes tend to have significantly lower pesticide concentrations than rivers. The benchmark of risk was the EPA health advisory level (HAL) designated for atrazine. The HAL is the pesticide concentration in drinking water at which health effects would not be expected to occur from lifetime exposure. The atrazine HAL of 3 ppb represents the No Observed Adverse Effect Level (NOAEL) estimated from animal tests as adjusted by a 5,000-fold safety factor (i.e., 1/5,000 times a water concentration of 15 ppm). The authors of the study concluded that less than 0.25% of the assessed populations was exposed to concentrations exceeding the HAL. Although EWG lumped all herbicides together, assuming the additive effect is biologically reasonable, atrazine levels still comprise nearly 50% of the average residue. The Heidelberg College focus on atrazine thus gives valid information for extrapolating risk assessment to exposures from all herbicides.

My perspective on the potential risk of consuming atrazine-contaminated water was derived from combining HC and EWG report data and focusing on the HAL as a safety benchmark. When 0.25% of the population of the reported six Midwestern states was exposed to atrazine levels exceeding the HAL, then 3,100 individuals, rather than 3.1 million (a 1,000-fold difference), may have increased health risks. But, recall that the HAL is 5,000 times less than the safe level as determined from the NOAEL. Even the highest atrazine concentration exceeding the HAL (13.5 ppb) reported in the HC study was 1,000 times less than the NOAEL. Thus, exposure assessment data suggest that no one is exposed to residues that have a biological effect.

Further evidence of an absence of human health effects from atrazine exposure in drinking water comes from a review of atrazine epidemiology published recently in Reviews of Environmental Contamination and Toxicology. The author concludes that epidemiological studies of individuals occupationally exposed to atrazine showed no increased incidence of cancer. Furthermore, the author also states that epidemiological studies of farmer exposure and incidence of cancer were too inconclusive to reliably prove a link between atrazine and carcinogenicity. Bear in mind that the exposures in these epidemiological studies would be thousands of times the exposures in drinking water.

In addition to human health effects, new concerns are being voiced about the effects of pesticide residues on aquatic organisms. The benchmark currently used for safety is the 96-hour LC50 determined on the most sensitive aquatic organisms (usually a crustacean or insect). The toxicity estimate is divided by a factor of 100, to calculate an ecologically based water quality criterion. Thus, residues below the criterion would be considered to have no adverse effect on the most sensitive species. None of the herbicide detections being reported for surface waters in Washington exceeded the ecological safety criteria. An aquatic risk assessment for atrazine was published recently in Environmental Toxicology & Chemistry. The assessment concluded that atrazine "does not pose a significant risk to the aquatic environment."

Although many may agree about the lack of adverse biological effects from atrazine and other herbicides, the outcome of an ecological risk assessment for insecticides is less certain. Chlorpyrifos, diazinon and azinphos-methyl are of primary concern, with chlorpyrifos dominating the number of detections in the USGS database. These organophosphorus insecticides have the highest toxicities to fish and aquatic invertebrates. The chlorpyrifos ecological water quality criterion is 0.04 ppb (or 40 ppt). Some of the detections that the USGS will report for Washington are above this level. For the following reasons, however, it would be wrong to interpret these detections as hazardous. First, the specific level detected is important; in Washington the highest level in the USGS database (0.120 ppb) is only three times higher than the water quality criterion. Second, the safety criteria are close to the analytical limit of detection, which makes residue numbers close to this level unreliable. Third, hazard could only be characterized if we knew how long the exposures lasted and how they fluctuated over time. Fourth, the toxicity bioassays do not use natural waters that contain dissolved organic matter. Numerous studies have shown that organic matter in water can significantly reduce toxicity. Finally, if the chlorpyrifos data are eliminated from the USGS database, insecticide detections in state waters are infrequent.

Despite 25 years of water quality funding to identify problems and develop best management practices, agricultural chemicals are still detected in aquatic systems. I believe now that ever lower detection limits will continue to yield detections, despite our best attempts to keep the chemicals on the farm. But the issue is not detections; the real issue should be biological effects. As shown in this essay, different researchers report different assessments of potential biological impacts, especially for human health. One can take the same set of pesticide residue numbers and obtain two entirely different perspectives.

I believe the uncertainty in risk assessments of very low levels of pesticide residues is analogous to a phenomenon known from analytical chemistry. For the analysis of any chemical in a sample of water, soil, plant, etc., the closer the concentration is to zero, the more unreliable the result and the more likely two different laboratories will report different results. Could it be that the myriad of studies about the biological effects of exposure to trace concentrations of pesticides in water produce contentious risk assessments, because the concentrations are effectively close to that point where there is no biological effect? If so, then perhaps we actually know more than we think we do.

Note:Allan Felsot is an environmental toxicologist at the Food and Environmental Quality Laboratory.

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Registration proposals due!

Note: To obtain a copy of the WSCPR request for proposals, contact Catherine Daniels at 509-372-7492.

The Washington State Commission on Pesticide Registration (WSCPR), in its January 18 meeting, authorized release of a request for proposals for projects leading to pesticide registrations and maintenance of pesticide registrations in the state of Washington.

Proposals are due by March 7, 1996. The WSCPR will decide in its next meeting which proposals to fund. That meeting is scheduled for March 20 at the WSU Tri-Cities branch campus. For more information on how to submit a proposal, contact Catherine Daniels at 509-372-7492.

Synopsis of the Request for Proposals: Proposals must originate from the affected pesticide user community. The requests may come from an individual, company or organization on behalf of a particular user community. Project requests should be limited to five single-spaced pages, not including budgets and attachments, and should state who will conduct the work, their qualifications and the time frame for project completion. Names, addresses and phone numbers of individuals involved in submitting and conducting the work should be included. Any project that involves generation of pesticide residue data in support of a registration must include provisions for use of Good Laboratory Practices (GLP), if appropriate. Although multi-year proposals will be accepted, funding will be provided for no more than one year at a time. Projects should address crop protection needs of importance to Washington and the Pacific Northwest.

Although proposals are not required to include matching support, applicants are encouraged to provide matching funds, in-kind services or materials for laboratory studies and investigations.

Description of Problem: Each proposal should contain a brief description of the affected industry and a detailed description of the pest problem. This should be done using any of the following appropriate criteria: per acre/unit impact, including potential monetary losses if appropriate; acres impacted; aggregate impact to the industry; effect of the pest problem on the industry; effect of the pest problem on consumers, society, environment, non-target species or human health; and description of why alternative control measures are not effective, or any additional information on the specific need.

Criteria: Proposals will be judged by the following criteria: relevance to stated WSCPR areas of emphasis; overall merit and quality of proposal: feasibility of completing project objectives within stated time frames; appropriateness of requested budget and adherence to WSCPR guidelines.

Areas of Emphasis: The WSCPR will consider proposals dealing with pest control problems that 1) have an adverse economic impact to a user community or local economy; 2) pose some risk to human health or 3) pose adverse risks to the environment.

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USGS releases results of agrichemical studies

The United States Geological Survey recently released three fact sheets on the occurrence of agricultural chemicals in the waters of the Columbia Basin. One fact sheet deals with pesticides in ground water, a second with pesticides in surface water and the third with nitrates in ground water.

There is much information in the three fact sheets. Space remaining in this edition of the AENews does not permit a thorough review of the studies; one may expect such a review in the next edition. Following is a basic overview of the studies.

USGS sampled several wells in the Quincy and Pasco subbasins for pesticides; it checked 573 wells throughout the basin for nitrates and then checked two dryland streams (Palouse River and Upper Crab Creek) and two irrigated waterways (Crab Creek Lateral and EL68D Wasteway). The USGS invested a considerable amount of resources into the study, screening a large number of samples for a wide array of pesticides.

There is some good news and some not so good news. First, the good news: although many different kinds of pesticides were found in the surface water, none were at a level EPA considers unsafe. Forty-five pesticides or degradation products were found, with the most commonly detected products being atrazine (AAtrex), DCPA (Dacthal), simazine (Princep), EPTC (Eptam), metolachlor (Dual), terbacil (Sinbar), alachlor (Lasso), metribuzin (Sencor), 2,4-D, triallate (Far-Go), chlorpyrifos (Lorsban), trifluralin (Treflan) and pendimethalin (Prowl). As one might expect, the greater amounts of pesticides were found in the more intensively farmed, irrigated agricultural areas.

No registered pesticides were found in ground water at levels EPA considers unsafe. Twenty-three pesticides or degradation products were found, with the most commonly detected products being atrazine (AAtrex), an atrazine breakdown product, 1,2-dichloropropane, metribuzin (Sencor), and metolachlor (Dual).

Now, the bad news. EDB (ethylene dibromide) was detected in three wells at concentrations ranging from just below the maximum contamination level to over 20 times the MCL. EDB is a discontinued soil fumigant that was once used widely in the Basin. While the presence of the compound at 20 times the MCL may not pose a risk to human health, this is a pretty high level from the point of view of a concerned public.

Nineteen percent of the 573 wells tested for nitrates were above EPA's MCL for the chemical. Although consumption of water containing nitrates may not pose a risk to humans, the occurrence of nitrates at such high levels points to a need to refine crop production and protection practices.

Note: For more information on the USGS studies of agricultural chemicals in the ground and surface waters of the Columbia Basin, contact Sandy Williamson at USGS at 206-593-6530, ext 235 or by E-mail at
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The status of 2,4-D

The U.S. Department of Agriculture registered 2,4-D in 1947 as the first selective agricultural herbicide to control weeds without damaging crops. Its use in agriculture continues to expand, as reduced tillage gains popularity. Due to 2,4-D's low cost and its efficacy against many weed species, it's a 'perfect' herbicide and has found its way into weed management programs involving rights-of-way, turf, aquatics and forestry.

Congress amended FIFRA in 1988, mandating that all pesticides registered before November 1984 be subject to reregistration. The intent was to ensure that 'old' products like 2,4-D meet current regulatory standards...that their potential benefits outweigh potential risks, based on current criteria.

DowElanco, AGRO-GOR, Nufarm USA, and Rhone-Poulenc formed a task force in 1988 to coordinate and share the costs associated with developing the data required by the reregistration process. The task force identified 270 new studies that would be required to reregister 2,4-D. These included 54 studies on environmental toxicity, 60 on toxicology, 78 on environmental fate, 68 on residue, and 10 on chemistry. Thus far, the task force has submitted 174 studies to EPA; the remaining studies _ on chronic toxicity, field dissipation, and crop residue _ were due to be submitted to the agency by the end of 1995.

A summary of the task force work completed during the initial eight years of testing was presented recently at a one-day seminar in Chicago. It was stated that the studies to date haven't raised any major red flags relative to human health and wildlife. Results show that 2,4-D is not linked to genetic damage or tumor induction, or to reproductive or developmental problems. The task force believes that 2,4-D, with its low toxicity and low dietary exposure, will meet the "no unreasonable adverse effects" criterion written into FIFRA. The cost for these studies: $25 million.

But there is still a fly in the ointment that EPA and the task force will have to address during the decision making process. During this eight-year period, the National Cancer Institute and others have raised a number of epidemiological questions on the possible link between 2,4-D and non-Hodgkin's lymphoma among farm workers. Non-Hodgkin's lymphoma (NHL) is not a single disease but a group of diseases that are considered disorders of the immune system. NHL occurs infrequently (15 cases per 100,000).

Epidemiological evidence from National Cancer Institute (NCI) studies in Kansas, Nebraska, and Iowa/ Minnesota has been analyzed in detail. While the Kansas study (1986) is often cited as showing a relationship between frequency of 2,4-D use and non-Hodgkin's lymphoma, the actual question asked in the study pertained to the frequency of herbicide use _ not 2,4-D use _ among farmers who indicated they had used 2,4-D. In other words, the use frequency of 2,4-D, specifically, was neither asked nor determined.

In the Nebraska study (1990), data gathered by proxy (others answering on behalf of farmers) indicated greater risks than did data derived from farmers themselves.

In the third NCI study, Iowa/Minnesota (1993), no increased risks were observed between frequency of 2,4-D use and non-Hodgkin's lymphoma. Furthermore, under the Freedom of Information Act, the task force was able to show that when the data were separated by source of information _proxy respondents versus farmers _ proxy responses once again indicated higher risks associated with 2,4-D use than did those of farmers. In another study conducted by investigators at the University of Minnesota, similar findings were observed: indications of risk were seen to increase only when proxy respondents were used. This epidemiological phenomenon is called recall bias and, by virtue of such bias, risks indicated in proxy interviews should be considered invalid. When farmers themselves are asked specifically about 2,4-D use, there appear to be no recall differences, regardless of whether these farmers have non-Hodgkin's lymphoma.

Finally, the epidemiologists and toxicologists indicated that six different expert panels have reviewed the association between 2,4-D and non-Hodgkin's lymphoma. All have arrived at essentially the same conclusion: 2,4-D does not cause NHL. The most recent EPA-appointed panel, the Science Advisory Board, wrote in March 1994, "...our conclusion at this time is that, while there is some evidence that NHL may occur in excess in to 2,4-D, the data are not sufficient to conclude that there is a cause and effect relationship between...exposure to 2,4-D and NHL. The data are, however, sufficient to require continued examination of the issue through further studies."

The stage is set for 2,4-D to enter the decision phase of the reregistration process. EPA should render its reregistration decision on 2,4-D by 1997, in a document called the Reregistration Eligibility Document (RED). The RED will contain EPA's answer regarding the eligibility of reregistration, the rationale for their decision, and the need for additional data.

It is believed that the data package for 2,4-D will be as complete as for any pesticide product, old or new. One thing for sure is that the 4,000 peer-reviewed toxicology studies in a collection of 40,000 should provide sufficient evidence on which to base benefit-to-risk assessment. EPA's decisions will be scrutinized by all parties interested in seeing 2,4-D reregistered for use, as well as by those who believe this old herbicide should be removed from the marketplace.

Source: Reprinted from the Label, Purdue Pesticide Programs newsletter, January 1996

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