This article is about the fungicide captan. Captan is also the common name for ethanethiol or ethyl mercaptan, used as an odorant for natural gas and liquid propane delivery to help identify leaks.
Captan is the name of a general use pesticide (GUP) that belongs to the phthalimide class of fungicides. Though it can be applied on its own, Captan is often added as a component of other pesticide mixtures. It is used to control diseases on a number of fruits and vegetables as well as ornamental plants. It also improves the outward appearance of many fruits, making them brighter and healthier-looking. Captan is utilized by both home and agricultural growers and is often applied during apple production. Captan was previously cited as Group B2, a probable human carcinogen by the EPA., but was reclassified in 2004. Since the mode of action has been established as a proliferative response (in mice only) after intestinal villi are disrupted, captan is not likely to cause tumors at doses that do not irritate the intestine. The EPA now states, "The new cancer classification considers captan to be a potential carcinogen at prolonged high doses that cause cytotoxicity and regenerative cell hyperplasia. These high doses of captan are many orders of magnitude above those likely to be consumed in the diet, or encountered by individuals in occupational or residential settings. Therefore, captan is not likely to be a human carcinogen nor pose cancer risks of concern when used in accordance with approved product labels. A similar reclassification has been made for folpet, captan's sister fungicide, which shares a common mechanism of toxicity. A key finding for captan (and folpet) is these fungicides are not mutagenic in vivo; that is, they are not mutagenic in the intact animal.
^US EPA. 2004. Captan: Cancer Reclassification; Amendment of Reregistration Eligibility Decision; Notice of Availability. Federal Register 69: 68357-68360
^Bernard, B. K., and Gordon, E. B. 2000. An evaluation of the common mechanism approach to the Food Quality Protection Act: Captan and four related fungicides, a practical example. Int J Toxicol 19: (1): 43-61.
^Kidwell, J. (2010). Cancer Assessment Document. Second Evaluation of the Carcinogenic Potential of Folpet. PC Code 081601. Cancer Assessment Review Committee, Health Effects Division, Office of Pesticide Programs, U.S. Environmental Protection Agency, USA. Folpet Cancer Assessment Document Final. Memorandum to Abdallah Khasawinah, RAB IV, Health Effect Division (7505P) and Tony Kish, Product Manager, Team 22, Fungicide Branch, Registration Division (7505P), through Mary Manibusan and Jess Rowland, Co-Chairs Cancer Assessment Review Committee, Health Effects Division (7509P), 53 Pages, October 13, 2010.
^Cohen, S. M., Gordon, E. B., Singh, P., Arce, G. T., and Nyska, A. 2010. Carcinogenic Mode of Action of Folpet in Mice and Evaluation of Its Relevance to Humans. Critical Reviews in Toxicology 40: (6): 531-545.
^Arce, G. T., Gordon, E. B., Cohen, S. M., and Singh, P. 2010. Genetic Toxicology of Folpet and Captan. Critical Reviews in Toxicology 40: (6): 546-574.
^Gordon, E. B. 2010b. Captan and Folpet. In: R. Krieger, ed. Hayes Handbook of Pesticide Toxicology pp. 1915-1949. Elsevier, New York