EBDCs: Becoming a Household Word

by Food and Drug Administration (FDA)

Say the secret word and you'll win a hundred dollars, Groucho Marx promised contestants on his 1950s television show You Bet Your Life. Wiggling his bushy eyebrows and puffing his cigar, Groucho explained that at the mention of a certain common household word, a toy duck would fall from the ceiling, signaling the win. The duck would not have appeared for a word like ethylenebisdithiocarbamates. EBDCs, as they are called, may never be a household word, but more American consumers are becoming aware of these chemicals as attention focuses on their possible carcinogenicity (cancer-causing potential) in humans.

EBDCs have been used in the United States since the mid-1940s to control mold, mildew, and other fungal diseases in crops. This class of chemicals, which includes mancozeb, maneb and metiram, has been under review by the Environmental Protection Agency because animal studies show that ethylenethiourea (ETU), a breakdown product of the chemicals, causes cancer of the liver and thyroid in laboratory animals.

Last Dec. 4, EPA proposed to cancel the use of EBDCs on 45 of the 55 crops for which they are now registered. (EPA approves, or registers, pesticides for use on raw agricultural products and sets tolerance levels for residues of each pesticide. A tolerance is the maximum amount of residue permitted on a product.)

Although other fungicides have been developed since EBDCs came on the market, the older products have remained in wide use because they work against a broad spectrum of organisms and are relatively inexpensive. Some 12 million to 18 million pounds of the chemicals are used annually in the United States, and about 150 million pounds worldwide, particularly in areas where humid conditions are more conducive to the growth of fungus. The principal uses of EBDCs in this country have been on apples, potatoes, tomatoes, melons, cabbage, and spinach.

EBDCs are relatively unstable compounds. They degrade during production, storage, application, cooking, and heat processing. EPA has classified ethylenethiourea?a breakdown product of EBDC?as a probable human carcinogen, and scientists are concerned that the chemical can cause birth defects and possible damage to the thyroid gland as well, particularly in those who mix, load and apply the fungicide.

FDA Monitoring

The Food and Drug Administration monitors pesticide residue levels in domestic and imported foods and enforces tolerances on food shipped in interstate commerce (except for meat, poultry, and egg products, which are the responsibility of the U.S. Department of Agriculture). FDA has monitored for EBDCs and ETU for more than 10 years.

Between Oct. 1, 1987, and Sept. 6, 1989, FDA analyzed more than 100 different food commodities for EBDC or ETU residues. Ninety percent of the 2,156 samples tested had no detectable residues, and only 1 percent contained residues exceeding EPA tolerances.

When FDA finds that a food shipment contains a residue that exceeds a tolerance or is otherwise illegal, we try to prevent that product from reaching the consumer, explains Pat Lombardo, associate director of FDA's division of contaminants chemistry. The initial sampling is done at the wholesale level. If violative residues are found, we go back to the source the grower or shipper inform them of the problem, put a hold on the product if it's still available, and collect and analyze follow-up samples. In that way, we can turn off the problem at the source.

If necessary, the agency will initiate legal action, such as seizure or injunction, to prevent the product from reaching consumer channels. For imports, the food shipments may be refused entry into the country.

Domestic products that are not shipped out of state do not fall within FDA's jurisdiction. In cases of violations not involving interstate commerce, the agency alerts the state to the problem so that it can take appropriate action.

Additional data on ETU residues are now being gathered from FDA's Total Diet Study, also referred to as the Market Basket Study, for which agency personnel purchase foods from local supermarkets and grocery stores throughout the country four or five times a year. Each of the market baskets comes from a different geographic region and is a composite of foods collected in three cities in that region. Different cities are selected each year. Each market basket contains 234 food items that have been chosen, based on nationwide dietary surveys, to represent the diet of eight different U.S. age-sex population groups. Agency personnel prepare the foods to be table-ready from peeling bananas to making beef and vegetable stew. They then analyze the foods for pesticide residues.

Under an interagency agreement with FDA, USDA's Gulfport, Miss., facility is also analyzing several commodities for ETU, primarily processed fruits and vegetables. In addition, USDA will determine ETU residue levels in 60 processed baby foods to enable scientists to better assess the exposure of children to the fungicide.

Regulatory History

EPA initiated a special review of EBDCs in 1977 to determine what action, if any, it needed to take to protect the public. The resulting decision document, issued in 1982, imposed protective clothing requirements for workers who apply the chemicals. The report concluded, however, that the scientific data then available were inadequate to evaluate the potential for EBDCs to cause cancer. EPA, therefore, postponed addressing this risk until the agency could acquire more complete information.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.