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Release Date: 11/10/94
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To ensure the protection of public health from potential risks posed by pesticide residues frequently found in food and drinking water, the U.S. Environmental Protection Agency has begun a Special Review of three chemically similar pesticides: atrazine, cyanazine and simazine (known collectively as the triazines). EPA initiated this Special Review because it has determined that the use of each of these pesticides may pose a significant risk to public health. The triazine pesticides are used to control broad leaf weeds and some grasses and are among the most widely used agricultural pesticides. The review could result in use restrictions or even cancellation of the pesticides if health data warrant such action.
Studies in animals indicate that all three of the triazines included in the Special Review, as well as some others in the same chemical class, produce mammary tumors in some strains of rats. Recently-published human epidemiologic studies offer conflicting but, in some cases, suggestive evidence that exposure to environmental toxins such as pesticides may contribute to the still-increasing rates of breast cancer in American women. While EPA does not have information which supports a link between exposure to the triazine herbicides and human breast cancer, the Agency cannot dismiss the possibility that such an association could exist. The Special Review will continue to examine the potential for these pesticides to cause cancer in humans.

"I am concerned that these triazine pesticide residues are frequently found in drinking water and food," said Carol M. Browner, EPA Administrator. "EPA will conduct a thorough review to determine what steps are necessary to reduce the potential adverse effects of these compounds to human health and the environment."

EPA is concerned that long-term exposure to these pesticides in food and in drinking water may pose a risk of cancer to the general U.S. population. Numerous ground water and surface water studies indicate the presence of the triazines in water used as drinking water sources, especially during the spring and summer in Midwest agricultural areas.

Also of concern is the potential cancer risk to persons mixing, loading and applying one or more of these compounds in agricultural areas as well as to persons applying atrazine to home lawns. In addition, the triazines may pose adverse effects to aquatic organisms, particularly algae, and, because of their persistence in water and soil, to non-target terrestrial plants and their ecosystems.

A Special Review is a structured procedure that encourages public involvement and is initiated whenever data on a pesticide leads the Agency to believe that a significant risk to public health or the environment may exist. The review weighs the risks and benefits of a pesticide use, analyzes the effects of a shift to alternative pesticide control strategies, and ultimately determines whether the pesticide(s) should be canceled, further restricted or continued to be used without further amendments.

The triazines are among the most used pesticides in the United States on a volume basis. EPA estimates that about 90-l20 million pounds of the triazines are used annually in the United States (atrazine, 64 to 80 million pounds; cyanazine, 21 to 34 million pounds; and simazine, five to seven million pounds). Field corn accounts for about 80 percent of the use of these pesticides with sorghum accounting for another nine percent. The triazine products are used primarily as pre-emergent pesticides. Other uses of atrazine include sugarcane, sweet corn, macadamia nuts, guava, and warm season turf grass. Cyanazine's primary use is on corn; it is also registered for use on cotton. Simazine is registered for use on corn (field and sweet), turf grass including lawns, avocados, bananas, olives, plums, cherries, peaches, citrus, caneberries, blueberries, cranberries, currants, strawberries, grapes, apples, pears, certain nuts, and other non-agricultural sites.

EPA already has taken other actions to reduce the potential risks of the triazine products. In l990, use of atrazine was restricted to certified applicators (except for certain home turf products), application rates were reduced, protective clothing for agricultural workers was added as a label requirement, and application near wells was prohibited to further protect ground water. In l992, additional label changes were approved including a further reduction in application rates, the requirement of buffer zones near surface waters, and deletion of non-crop uses. Similar label changes have also been approved for cyanazine, including restricted use. Most uses of simazine are restricted to certified applicators.

Earlier this year, all registered uses of simazine in swimming pools to control algae were cancelled because of potential cancer and non-cancer health risks to swimmers. There are no remaining registered aquatic uses of simazine.

Ciba-Geigy of Greensboro, N.C., is the principal registrant and manufacturer of atrazine (first registered in l959) and simazine (initially registered in l957). Currently 34 companies hold registrations for atrazine products. Du Pont Agricultural Products of Wilmington, Del., and Ciba-Geigy are the only registrants of Cyanazine (registered in l971 under the trade name Bladex). Other atrazine and simazine technical registrants are Oxon Italia of Valdosta, Ga., and Drexel Chemical Co. of Memphis, Tenn. These two companies have registered non-crop uses for simazine, some of which have use rates of up to 40 pounds an acre. All uses will be assessed during the Special Review.

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