Carcinogenicity of pesticides

Not only do we seldom if ever obtain direct experimental data on the carcinogenicity of pesticide metabolites, it is likewise impractical to routinely subject most or all pesticide metabolites to a battery of vivo or vitro mutagenicity tests. How then can pesticide metabolites be properly evaluated for mutagenic or carcinogenic hazard In most cases there would appear to be... 

DHEW, The carcinogenicity of pesticides, in Report of the Secretary s Commission on Pesticides and Their Relationship to Environmental Health, pp. 459-506, GPO, Washington, D.C. (1969). 

Pesticides include the broad categories of insecticides, fungicides, rodenticides, and herbicides. Insecticides in common use fall into three categories. The chloroinsec-ticides have chlorine in their structure. They are less soluble than the other insecticide forms and much less biodegradable (i.e., more persistent). While they are less acutely toxic, several have been identified as potential carcinogens. Carbamatea are a relatively new form of pesticide. They are less persistent and less... 

Many very hazardous solvents, such as benzene and carbon tetrachloride, were widely used until the 1970s. The situation was very similar for the use of pesticides. Among the toxic pesticides that were still in wide use 20 years ago were chlorophenols, DDT, lindane, and arsenic salts, all of which are classified as human carcinogens as well as being acutely toxic. Fortunately, use of these kinds of very toxic chemicals is now limited in the industrialized world. However, because the number of chemicals used in various industries continues to increase, the risks of long-term health hazards due to long-term exposure to low concentrations of chemicals continues to be a problem in the workplace. 

Hurley, P. M., Hill, R, N., and W hiting, R. ]. (1998). Mode of carcinogenic action of pesticides inducing thyroid follicular cell tumors in rodents. Environ. Health Terspect. 106(8), 437-445. 

Saleh MA. 1980. Mutagenic and carcinogenic effects of pesticides. J Environ Sci Health B15 907-927. 

When EPA became aware almost five years ago that N-nitroso contaminants occurred in a number of pesticide products, the Agency immediately acted on the authority of Section 3 of FIFRA to place a moratorium on new registrations of pesticides suspected to contain N-nitroso contaminants at detectable levels (this term is defined and explained later in the text). As has been discussed in other papers of the Symposium, many N-nitroso compounds are animal carcinogens and, consequently, suspected human carcinogens. 

Technical chlordane is an organochlorine compound first introduced into the United States in 1947 in a variety of formulations for use as a broad-spectrum pesticide. By 1974, about 9.5 million kg of chlordane were being produced annually. Concern over the potential carcinogenicity of chlordane has led to sharply curtailed production. Since 1983, chlordane use in the United States has been prohibited, except for control of underground termites. 

Episodic pollution events can adequately be addressed by acute toxicity bioassays, however these are not sufficient to investigate the water quality for delayed toxicity effects of chemicals present. Chronic effects of pesticides can include carcinogenicity, teratogenicity, mutagenicity, neurotoxicity, and reproductive effects (endocrine disruption). 

Jin T, Lin H, Xin P, et al. 1982. [Preliminary screening of mutagenic and carcinogenic effect of pesticides by inhibition test of DNA synthesis.] Zhonghua Yufangyixue Zazhi 16(3) 174-176. (Chinese)... 

Ulland BM, Weisburger EK, Weisburger JH. 1973. Chronic toxicity and carcinogenicity of industrial chemicals and pesticides. Toxicol Appl Pharmacol 25 446. 

A list of pesticides considered to be probable carcinogens by the U.S. Environmental Protection Agency (EPA) is provided in Table 11.1. 

Most of the data located concerning the health effects of heptachlor and heptachlor epoxide in humans come from case reports and occupational epidemiology studies of workers engaged either in the manufacture or application of pesticides. There is some information on people who have consumed heptachlor-contaminated food or dairy products, but no adverse health effects have been related to these exposures. The occupational studies involve exposures that are predominantly inhalation with contributions from dermal exposure, whereas all the animal studies were conducted using oral or intraperitoneal exposures. The occupational and case reports provide no quantitation of dose or duration of exposure, which makes it impossible to determine with any precision the effect levels for humans. There are no data that indicate that heptachlor or heptachlor epoxide are carcinogenic to humans. However, human studies are limited by the long latency period of carcinogenesis and by ascertainment and follow-up biases. 

Brown, R. and A. Mitteknan. 1993. Evaluation of existing methods to rank the relative carcinogenicity of polycyclic aromatic compounds PAH). Draft. Technical Resources, Inc., Contract No. 68-01-0022, for Office of Emergency and Remedial Response, Office of Sohd Waste and Emergency Response, U.S. Environmental Protection Agency, Office of Pesticides, Pollution Prevention and Toxic Substances (OPPTS). 

In contrast to animal studies, epidemiological studies of workers employed in the manufacture of aldrin provide no conclusive evidence of carcinogenicity in humans. " One study of a cohort having mixed exposure to aldrin, dieldrin, and endrin found 9 deaths from cancer versus 12 expected. The workers had been exposed to the pesticides for a mean of 11 years and followed a mean of 24 years. A more recent examination of 2384 manufacturing workers, employed between 1952 and 1982, with exposure to a number of pesticides including aldrin found no excess mortality rates attributable to occupational exposures. Similarly, a 2 3-year follow-up of 570 aldrin- and dieldrin-exposed workers found no increase in overall mortality rates or mortality from liver cancer."... 

We conclude by illustrating how our understanding of these chemical processes in our clean and polluted troposphere and stratosphere plays a crucial role in generating the exposure portions of scientific health risk assessments. Such assessments provide the foundation for sound, health-protective and cost-effective strategies for the control of tropospheric ozone, particles, acids, and a spectrum of hazardous air pollutants (including carcinogens and pesticides)—as well as for the mitigation of stratospheric ozone depletion. 

Role of structure-activity relationship analysis in evaluation of pesticides for potential carcinogenicity, in Carcinogenicity and Pesticides, ACS Symposium Series, No. 414... 

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