Carcinogenicity of pesticides provides information about the production of malig- nant tumors in animals and humans exposed to pesticides. The general terms tumor, cancer, and neoplasm are all used to describe the phenomenon of uncontrolled pro- gressive growth of cells eventually leading to serious health disorders. The global regulatory authorities have made it mandatory to evaluate the carcinogenic potential of all pesticides. Accordingly, FIFRA in the United States and the Insecticide Act in India require testing to determine the carcinogenic potential of pesticides. In fact, the evaluation of pesticides for carcinogenicity in animal bioassay studies began in the late 1960s.11–11b These tests are required to determine oncogenic potential, which
is the ability to cause benign and/or malignant tumors; a substance causing malig- nant tumors would be considered carcinogenic.
According to the regulations of the U.S. EPA, European Commission, and the IARC (WHO), any pesticide or any chemical substance is classified within one of six possible groups:
group A: human carcinogen;
groups B1 and B2: probable human carcinogen; group C: possible human carcinogen;
group D: not classifiable; and group E: noncarcinogenic.
The U.S. EPA considers that all pesticides fall into groups B2 and C.
Studies conducted by several workers and the epidemiologic findings with spe- cific pesticides have caused concern. For instance, lung cancer has been associated with blood levels of DDT among residents of South Carolina,7a and the pancreatic
cancer risk was excessive among workers employed in the manufacture of DDT12 in
the United States. Reports have indicated that breast cancer among humans has been associated with concentrations of DDT and its metabolites in blood and adipose tis- sue13–15 and ovarian cancer among Italian women engaged in agricultural activities.16
Breast cancer in rodents17 has been linked with the use of triazine herbicides.16–18 A
study of manufacturers and workers associated with phenoxyacetic acid herbicides and exposed to dioxin showed excesses of several cancers, including lung cancer and soft-tissue sarcoma19 (Appendices 6.8 and 6.9).
6.13 ConCluSion
A variety of pesticides have been in use for many decades for the control of insect pests of agricultural crops and storehouses and as vectors of communicable diseases. Human exposure to pesticides during mixing, spraying, transportation, and waste disposal has become common. Prevention of inhalation and dermal absorption of
Pesticides 123
pesticides requires proper training and education to achieve safety to the worker and to the environment. Also, studies have shown an association between occupational pesticide poisoning and incidence of prostate, kidney, brain, and lung cancers. All these observations suggest proper use and management of pesticides at workplaces, at home, or in the field are very necessary for human health, safety, and protection of the living environment.
referenCeS
1. Hayes, W. J., Jr., and Laws, E. R., Jr., eds. 1991. Handbook of pesticide toxicology. New York: Academic Press.
1a. Dikshith, T. S. S., ed. 1991. Toxicology of pesticides in animals. Boca Raton, FL: CRC Press.
2. Dikshith, T. S. S., and Diwan, P. V. 2003. Industrial guide to chemical and drug safety. Hoboken, NJ: John Wiley & Sons, Inc.
3. Meister, R. T. 2004. Crop protection handbook. Willoughby, OH: Meister Media Worldwide.
4. Thomson, W. T. 2001. Agricultural chemicals. Book I, Insecticides. Fresno, CA: Thom- son Publications.
5. Tomlin, C., ed. 2006. The pesticide manual, 14th ed. Cambridge, UK: British Crop Protection Council. Blackwell Scientific Publications.
5a. Ashton, F. M., and Crafts, A. S. 1973. Mode of action of herbicides. New York: John Wiley & Sons, Inc.
5b. World Health Organization (WHO). 2000–2002. Classification of pesticides by hazard and guidelines to classification. Geneva: WHO.
6. Ware, G. W., and Whitacre, D. M. 2004. The pesticide book, 6th ed. Willoughby, OH: Meister Media Worldwide.
7. Greene, S. A., and Pohanish, R. P., eds. 2005. Sittig’s handbook of pesticides and agri-
cultural chemicals. Norwich, NY: William Andrew Publishing.
7a. Austin, H., Keil, J. E., and Cole, P. 1989. A prospective follow-up study of cancer mor- tality in relation to serum DDT. American Journal of Public Health 79: 43–46. 8. Jeyaratnam, J. 1999. Acute pesticide poisoning: a major global health problem. World
Health Statistics Quarterly 43: 139–144.
9. Gunnell, D., and Eddleston, M. 2003. Suicide by intentional ingestion of pesticides—A continuing tragedy in developing countries. International Journal of Epidemiology 32: 902–909.
10. Phillips, M. R., Yang, G., Ahang, Y., Wang, L., et al. 2002. Risk factors for suicide in China: A national case-control psychological autopsy study. Lancet 360: 1728–1736. 11. Innes, J. R. M., Ulland, B. M., Valeria, M. G., et al. 1969. Bioassay of pesticides and
industrial chemicals for tumorigenicity in mice: A preliminary note. Journal of the
National Cancer Institute 42: 1101–1114.
11a. U.S. Environmental Protection Agency. 2005. Guidelines for carcinogen risk assessment, risk assessment forum EPA/630/P-03/001B. Washington, D.C.: U.S. EPA.
11b. U.S. Environmental Protection Agency. 2007. Pesticides: Health and safety evaluation of pesticides for carcinogenic potential. Washington, D.C.: U.S. EPA.
12. Garabrant, D. H., Held, B., Langholz, et al. 1992. DDT and related compounds and risk of pancreatic cancer. Journal of the National Cancer Institute 84: 764–771.
13. Falck, F., Ricci, A., Wolff, M. S., et al. 1992. Pesticides and polychlorinated biphenyl residues in human breast lipids and their relation to breast cancer. Archives of Environ-
mental Health 47: 143–146.
14. Wolff, M. S., Toniolo, P. G., Lee, E., et al. 1993. Blood levels of organochlorine residues and risk of breast cancer. Journal of the National Cancer Institute 85: 648–652. 15. Krieger, N., Wolff, M. S., Hiatt, R. A., et al. 1994. Breast cancer and serum organo-
chlorines: A prospective study among white, black, and Asian women. Journal of the
National Cancer Institute 86: 589–599.
16. Donna, A., Crosignani, P., Robutti, F., et al. 1989. Triazine herbicides and ovarian neo- plasms. Scandinavian Journal of Work and Environmental Health 15: 47–53.
17. International Agency for Research on Cancer (IARC). 1987. IARC monographs on the evaluation of carcinogenic risks to humans. Occupational exposures in insecticide application and some pesticides, vol. 53. Lyon, France.
18. International Agency for Research in Cancer (IARC). 1999. Monographs on the evalu- ation of carcinogenic risks to humans, vol. 53. Lyon, France.
19. Fingerhut, M. A., Halperin, W. E., Marlow, D. A., et al. 1991. Cancer mortality in work- ers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin. New England Journal of Medicine 324: 212–218.
aPPendix 6.1
Global developMentoF pestICIdes
Period/
era Chemicals and location
era of natural Products (900–1690) 900 Arsenites (China)
1690 Tobacco (Europe)
era of modern Synthetic insecticides (1800–1920) 1800 Pyrethroids (Caucasus)
1848 Derris root (Malaya)
era of fumigants, inorganics, Petroleum Products 1854 Carbon disulfide (France)
1867 Paris green (United States) 1892 Lead arsenate (United States) 1918 Chloropicrin (France) 1932 Methyl bromide (France) 1939 DDT (Germany) 1941 BHC (France)
Chlorinated Cyclodienes (1945–1955) 1945 Aldrin (United States)
1947 Dimetan (Switzerland)
Cholinesterase inhibitors, organophosphate Compounds, Carbamates (1945–1970) 1944 Parathion (Germany)
Pesticides 125
aPPendix 6.1 (continued) Global developMentoF pestICIdes
Period/
era Chemicals and location
era of hormone mimics and Pheromones; rebirth of botanical insecticide 1967 First juvenile hormone analog (United States)
1970–1985 Synthetic pyrethroids, avermectins, juvenile hormone mimics, biological pesticides 1985– Genetically engineered organisms
Source: Stephenson, G. A., and Solomon, K. R. 1993. Pesticides and the Environment. Guelph, Ontario, Canada: Department of Environmental Biology.