NORTH CAROLINA COOPERATIVE EXTENSION SERVICE

North Carolina State University
College of Agriculture & Life Sciences

Department of Entomology, Box 7613, Raleigh, NC 27695
Telephone: (919)515-2703 -- FAX: (919) 515-7746

PESTICIDE BROADCAST

Volume 8, Number 6
October 9, 1995

IN THIS ISSUE

DUKE POISON CONTROL CENTER
Telephone 1-800-672-1697

NATIONAL PESTICIDE TELECOMMUNICATIONS NETWORK
Telephone 1-800-858-7378

SPECIAL TOPIC

The Current State of Groundwater in North Carolina

Groundwater provides drinking water for nearly all rural residents in the North Carolina; thus, there is a great deal of interest in protecting groundwater. The impacts of agricultural activities on groundwater quality is the subject of a number of studies within the state. Studies by North Carolina State University, the North Carolina Departments of Agriculture and Environment, Health and Natural Resources, the U. S. Environmental Protection Agency, the U. S. Geological Survey, and the University of North Carolina at Asheville are either completed or currently underway. The focus of this work has been in the state's Coastal Plain where there is a combination of high-production agriculture and shallow groundwater, two factors which add up to high risks of pesticide contamination of groundwater. Very recent data from a small area in the North Carolina mountains is also available.

Results to date, which come from areas with high risk factors for pesticide contamination (i.e., poor well construction, extensive agricultural production, shallow groundwater, sandy soils, and point source suspects), show that 25 to 50 percent of the wells in some areas have trace amounts of pesticides. The vast majority of these are occurring in very low concentrations (0.05 to 0.5 parts per billion) and are much lower than health guidelines. Of the approximately 200 wells tested, two were over the maximum contaminant level for alachlor (2 parts per billion) and one was over the maximum contaminant level for atrazine (3 parts per billion). All three wells have been or are being replaced.

The maximum contaminant level, or MCL, is a number calculated by the Environmental Protection Agency to be used by public water suppliers for legal limits of contamination. This calculation assumes a person drinks water contaminated at or above the health limit for 70 years, that this exposure accounts for 25 percent of the total exposure during over the period, and includes a 100 to 1,000 fold safety factor. It is a very conservative estimate which is highly protective of public water supplies.

The aforementioned results may not be too surprising considering the wells are generally very shallow and near agricultural fields, so trace levels of pesticides do not have far to travel to enter into the wells. If one percent of a one pound of active ingredient per acre application enters groundwater, the concentration could be one part per billion. Most laboratories involved in these studies can detect 0.1 part per billion or less. It is unfortunate that any pesticide enters wells and we all should continue every effort toward implementing Best Management Practices to further reduce contamination risks.

Spills and other mixing and loading accidents account for most of the higher levels of pesticides in groundwater. This is a source of contamination that can be nearly eliminated by following the mixing and loading guidelines widely available from your county Cooperative Extension Service office or pesticide dealer.

An added level of groundwater protection will be in place in a couple of years, when the State Management Plans for the Protection of Groundwater will be in place. Such plans are required by the Environmental Protection Agency to maintain registration of these specific pesticides in the state. The five pesticides listed for plans in North Carolina are atrazine, alachlor, metolachlor, simazine, and cyanazine. These are among the most widely used herbicides in the state, so the impact of reducing the areas to which they may be applied would be significant.

A series of triggers for restricting or eliminating the use of these herbicides when they are detected in monitoring wells is planned. If the level of herbicide exceeds one-half of the health limit, it's use will be restricted in the area. Clearly, it will be in everyone's interest to see that this does not happen through problems in mixing and loading pesticides, poorly calibrated sprayers, or other situations which can be controlled. It is equally clear that if the normal uses of a product results in significant groundwater contamination, those uses need to be restricted or eliminated.

Studies of groundwater contamination by pesticides (i.e., how much of a problem exists, what are the major causes, and how can the contamination be reduced to a minimum) will continue. These studies will rely on the collaboration of the county staff, government agencies, and growers in the study area to obtain the best information possible. If you are interested in this program and would like more information, please contact Rich McLaughlin by telephone at (919) 515-7306 or electronic mail at rmclaugh@wolf.ces.ncsu.edu.

The above article was provided by Dr. Richard A. McLaughlin, an extension specialist in the Soil Science Department at North Carolina State University. Rich specializes in issues related to pesticide fate and water quality.

Bald Eagle Reclassified As A "Threatened" Species

The U. S. Fish and Wildlife Service reclassified the bald eagle (Haliaeetus leucocephalus) from endangered to threatened in the lower 48 states under the Endangered Species Act of 1973, effective August 11, 1995. This action does not alter those conservation measures already in place to protect the bald eagle and its habitats. The bald eagle was previously listed as threatened only in Michigan, Minnesota, Wisconsin, Oregon and Washington. In Alaska and Canada, the bald eagle is not at risk and not protected under the Endangered Species Act.

The historic range of the bald eagle is throughout North America, except extreme northern Alaska and Canada, and central and southern Mexico. DDT and other organochlorine insecticides were widely used in the U. S. following World War II. DDT accumulated in bald eagles through ingestion contaminated food, resulting in a serious decline in their reproduction. It was determined that DDE, the principal breakdown product of DDT, accumulated in the fatty tissue of adult females and impaired calcium release necessary for egg shell formation. On March 11, 1967, the Secretary of the Interior listed bald eagles as endangered under the Endangered Species Preservation Act of 1966. DDT use in the U. S. was banned on December 31, 1972.

In 1973, the Endangered Species Act was passed which established the new category of "threatened." The 1973 act defined an endangered species as a species that is in danger of extinction throughout all or a significant portion of its range. A threatened species is a species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

As a result of the cancellation of DDT and other persistant organochlorine pesticides, habitat protection, and other recovery efforts, the bald eagle population in the U. S. has increased in number and range. A National Audubon Society survey in 1963 reported only 417 active bald eagle nests in the lower 48 states, while 4,452 occupied breeding areas were reported in 1994 (Fig. 1). Compared to 1974, the number of occupied breeding areas in the lower 48 states has increased by 462 percent. There has been a 47 percent increase since 1990. The bald eagle is doubling its breeding population every 6 to 7 years since the late 1970's.

Fig. 1. The number of bald eagle pairs counted in the lower 48 U. S. states from 1963 to 1994.

The Endangered Species Act requires a periodic review of the status of listed species. The reclassification of the bald eagle as a threatened species is a result of this review. Federal Register Volume 60, Number 133, July 12, 1995

EPA Proposes to Cancel Most Uses of Pesticide Dichlorvos

To eliminate unacceptable health risks to the public and workers, the U.S. Environmental Protection Agency is proposing to cancel most uses of the pesticide dichlorvos including all home uses, such as hanging pest strips, room foggers and pet flea collars. The Agency is also proposing that most retained uses be restricted to specially trained certified applicators.

Lynn Goldman, M.D., EPA Assistant Administrator for Pesticides said, "During EPA's review, there is no need for public concern as long as label directions are carefully followed. If consumers so choose, they always can use alternative methods of pest control in lieu of products containing dichlorvos."

EPA's action is based on evidence that risks to public health outweigh the benefits of most uses of this chemical. Dichlorvos (DDVP) poses a risk of cancer to the general population from dietary exposure and a risk of harmful effects on the central nervous system (cholinesterase inhibition) of persons living in homes where the product has been applied as well as to those mixing, loading, and applying this chemical or entering enclosed areas treated with dichlorvos.

Because of dietary cancer risk, EPA is proposing to cancel the uses of dichlorvos on non-perishable raw or processed agricultural commodities which are stored in bulk, packages or bags. The following uses are being proposed for cancellation because of unacceptable risks to persons applying dichlorvos or persons who live in or work in areas where the chemical is applied: all warehouses, including tobacco warehouses; commercial, institutional and industrial areas including food service, food manufacturing and food processing facilities; dichlorvos applied by hand to farm livestock, except poultry; all home uses (including uses by residents and commercial applicators); ornamental lawns, turf and plants; and in airplanes.

EPA is proposing to retain the following uses: mushroom houses and greenhouses (only automatic foggers or fogging through a port), kennels, feedlots, insect traps, garbage dumps, direct application to poultry, automated application to livestock, animal premises, manure and buses. The uses in mushroom houses, greenhouses and passenger buses will be canceled unless specified re-entry period statements (no re-entry within 48 hours after application except in emergency) are added to the labels.

However, because of the potential adverse effects of dichlorvos on the nervous system, EPA also is proposing to restrict all registered products to use by certified applicators, except for impregnated strips used in enclosed spaces within museums and insect traps. The Agency is also proposing to require a person applying this pesticide to wear a long sleeved shirt, long pants, gloves, socks and shoes.

Dichlorvos, registered since 1948, kills insects on contact. It is used to control flies, mosquitos, gnats, cockroaches, fleas, and other insect pests. Most of the dichlorvos products are used for animal, livestock and premise treatments; and on bulk, packaged and bagged raw or processed commodities. The remainder is used in greenhouses, homes and mushroom houses. Amvac Chemical Corp. of Los Angeles, California, is the sole producer of the technical grade dichlorvos in the United States. Amvac has already voluntarily agreed to cancel some uses of dichlorvos.

When EPA began a Special Review of dichlorvos, it was based on evidence that exposure to the registered uses of dichlorvos could pose unreasonable risks of cancer as well as adverse effects on the central nervous system (cholinesterase inhibition). Based on new studies and extensive examination of new data, EPA has determined that the cancer risk is limited to dietary exposure.

When a pesticide inhibits cholinesterase in humans, excess acetylcholine (a chemical which helps to transmit signals through the nervous system) accumulates and impairs the proper functioning of the nervous system. Symptoms of poisoning because of cholinesterase inhibition include headache, nausea, tremors, vomiting, hypersecretion, psychosis, respiratory failure, and death in extreme cases.

Consumers concerned about the use of dichlorvos pesticide products may call the National Pesticide Telecommunications Network at 800-858-7378.

Comments on this proposal are due within 90 days and should be sent to: Public Response Section, Field Operations Division (7506C), Office of Pesticide Programs, U.S. EPA, 401 M St. SW, Washington, D.C. 20460. U. S. Environmental Protection Agency September 28, 1995

EPA Proposes Revocation of 36 Pesticide Tolerances in Animal Feed

In accord with a court-approved agreement, EPA is proposing to revoke 36 tolerances for 16 pesticides in animal feeds. EPA has found that two of these tolerances violate the Delaney Clause of the Federal Food, Drug and Cosmetic Act (FFDCA). The Agency is proposing to revoke the remaining 34 tolerances, or feed additive regulations, because they are not needed to permit marketing of animal feeds. These 34 revocations will not affect the uses of pesticides associated with the tolerances.

This action is another in a series of actions resulting from the 1992 U. S. Ninth Circuit Court of Appeals decision which requires a strict, literal interpretation of the Delaney Clause. This action also fulfills EPA's commitment in a February 9, 1995, settlement agreement to reach decisions on these tolerances by September 15, 1995. In the near future, EPA will also be making decisions regarding the status of a number of tolerances for human food.

The Delaney Clause prohibits the establishment of tolerances for food or animal feed for pesticides that have been found to induce cancer in man or animals. Such tolerances are necessary if pesticide residues concentrate (increase) in ready-to-eat processed foods above the approved raw food tolerances, or if residues are the result of pesticide application during food processing.

EPA is proposing to revoke the processed feed tolerance for simazine on sugarcane molasses and for tetrachlorvinphos in animal feed because they violate the Delaney Clause. Tolerances in processed commodities are required when the concentration of the pesticide residue in the processed animal feed is greater than the tolerance for the raw commodity, or if the processed feed is treated or comes into contact with a pesticide. In the case of simazine, the processed food concentration level exceeds the raw commodity tolerance; tetrachlorvinphos is a direct additive to processed animal feed. Both pesticides have been found to induce cancer.

The Agency is proposing to revoke 16 of the remaining 34 feed tolerances because the animal feeds are no longer considered to be a significant part of livestock diets. Under EPA's updated Pesticide Assessment Guidelines, Residue Chemistry (Table II), EPA generally requires animal feed tolerances only for feeds constituting at least 0.04 percent of weight of the U. S. total of livestock feed. The following 16 tolerances do not meet these criteria: benomyl on dried apple pomace, dried grape pomace and raisin waste; diflubenzuron on soybean soapstock; iprodione on dried grape pomace, raisin waste, and peanut soapstock; mancozeb on milled fractions of barley, oats, and rye; norflurazon on citrus molasses; propargite on dried apple pomace and dried grape pomace; thiophanate-methyl on dried apple pomace; and triadimefon on wet or dry grape pomace and raisin waste.

Revocation action for 10 tolerances is based on processing studies that show no concentration above the raw or precursor crop tolerance. These are: acephate on cotton seed meal and soybean meal; carbaryl on pineapple bran; diflubenzuron on soybean hulls; dimethipin on cottonseed hulls; dimethoate on dried citrus pulp; norflurazon on dried citrus pulp; propargite on dried citrus pulp; thiodicarb on cottonseed hulls; and tridimefon on wet or dry apple pomace. Tolerances for processed food or animal feeds are not required if the pesticide residue in the processed product, when ready to eat, is equal to or below the tolerance for that pesticide in the raw commodity from which it was derived.

Finally, EPA is proposing to revoke eight animal feed tolerances because they are for feeds that are "not ready to eat"; such feeds are mixed or blended with other feed before being consumed by livestock. As a consequence of mixing or blending, the level of residues in the ready-to-eat processed feed does not exceed the raw commodity tolerance. These are: acephate on cottonseed hulls; benomyl on dried citrus pulp and rice hulls; imazalil on dried citrus pulp; iprodione on rice bran and hulls; mancozeb on milled fractions of wheat; and thiodicarb on soybean hulls.

Public comments are due within 90 days and should be sent to: Public Response Section and Program Resources Branch, Field Operations Division (7506C), Office of Pesticide Programs, U. S. EPA, 401 M St. SW, Washington, D.C. 20460. U. S. Environmental Protection Agency September 15, 1995

Consumers Willing to Pay More to Reduce Pesticide Use

According to a national opinion poll sponsored by the Center for Science in the Public Interest (CSPI), 84 percent of consumers would be willing to pay as much as $2 per year per family member in additional food costs if pesticide use were reduced. Other findings of the poll, conducted by the Bruskin Goldring research firm on January 27-29, include: The CSPI released the results of the poll in a report Funding Safer Farming: Taxing Pesticides and Fertilizers. In the report, CSPI recommended that states raise taxes on pesticides by as much as 5 percent and taxes on fertilizers by as much as 1.5 percent to fund educational and technical efforts aimed at getting farmers to reduce pesticide use. These increases would add slightly less than $2.15 per person to the nation's food bill, according to the report. Food Chemical News 37(14), May 29, 1995

Reregistration Update