- "the Secretary of the Food and Drug Administration shall not approve for use in food any chemical additive found to induce cancer in man, or, after tests, found to induce cancer in animals."
The Delaney Clause applied to pesticides in processed foods, but only when the concentration of a residue of a cancer causing pesticide increased during processing; for example when more of a pesticide was present in ketchup than in the raw tomatoes used to make it. (It never applied to pesticides in raw foods.) When the law was passed, "neither advocates nor opponents of the policy, including FDA ofﬁcials, believed it would have broad application, for only a handful of chemicals had then been shown to be animal carcinogens."
The Delaney Clause was invoked in 1959 when Arthur Sherwood Flemming, the Secretary of the Department of Health, Education and Welfare issued a statement advising the public about the possible contamination of substantial quantities of cranberries in Oregon and Washington with the herbicide aminotriazole, which the FDA had recently determined was a carcinogen (see Cranberry scare of 1959). Taking place the week of Thanksgiving, the announcement was referred to by many in the cranberry industry as "Black Monday" − sales plummeted, even though many government officials attempted to defuse the scare by declaring their intention to eat cranberries anyway. This episode is regarded as one of the first modern food scares based on a chemical additive.
As analytical chemistry became more powerful and able to detect smaller and quantities of chemicals, and as chemicals became more widely used, regulatory agencies had an increasingly difficult time administering the Delaney Clause as it "recognizes no distinctions based on carcinogenic potency and, at least in theory, it applies equally to additives used in large amounts and to those present at barely detectable levels. It thus takes no account of the actual risk a carcinogenic additive might pose."
The FDA was the first agency to have to confront this problem, with respect to the use of diethylstilbestrol to promote the growth of livestock used in meat production, which remained present in the meat. It addressed the issue by using quantitative risk assessment, declaring that if a carcinogenic food additive was present at a concentration of less than 1 part in 1,000,000, the risk was negligible. This standard became known as the "de minimis" exception to the Delaney Rule and was used throughout the FDA and other agencies.
In 1988 the United States Environmental Protection Agency eased restrictions on several pesticides which posed a "de minimis" risk to humans. This change was challenged by the Natural Resources Defense Council, and overturned in 1992 by the Ninth Circuit Court of Appeals.
Pesticide use was removed from the Delaney Clause in 1996 by an amendment to Title IV of the Food Quality Protection Act of 1996 (P.L. 104-170, Sec. 404).
The Delaney prohibition appears in three separate parts of the FDCA: Section 409 on food additives; Section 512, relating to animal drugs in meat and poultry; and Section 721 on color additives. The Section 409 prohibition applied to many pesticide residues until enactment of the Food Quality Protection Act of 1996. This legislation removed pesticide residue tolerances from Delaney Clause constraints.
Many foods contain natural substances which are carcinogenic, for example safrole, which occurs in sassafras and sweet basil. Even these substances are covered by the Delaney clause, so that, for example, safrole may not be added to root beer in the USA.
- Merrill, Richard A. "Food Safety Regulation: Reforming the Delaney Clause" in Annual Review of Public Health, 1997, 18:313-40. This source includes a useful historical survey of prior food safety regulation.
- Fennema, Owen R. (1996). Food chemistry. New York, N.Y: Marcel Dekker. p. 827. ISBN 0-8247-9691-8.