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Is DDT a Carcinogen?
Some say YES
DDT has been banned in the United States since 1972 because it is believed to be a human carcinogen. There has been no direct proof implicating DDT as a cancer-causing agent in humans, but experiments on mice and rats found that when administered orally in the diet or by stomach tube, DDT caused hepatomas, lymphomas, lung carcinomas, and adenomas. DDT was also found to cause liver tumors in mice when injected subcutaneously [1].
In addition, DDE and TDE, two metabolic products of DDT, were also found to be carcinogenic. TDE caused an increase in liver, lung, and thyroid tumors, and DDE induced liver tumors in mice and also increased the incidence of neoplastic liver nodules in hamsters [1].
Some say NO
Follow-up studies of the carcinogenic effects of DDT on rodents have not been as conclusive as the one cited above. The National Toxicology Program issued a report which found that there is no correlation between tumor incidence and DDT and TDE consumption in male and female mice and rats. DDE was found to have no effect on rats, but was tumerogenic in mice [2].
In addition, carcinogenicity has never been demonstrated in primates. In fact, a study found that consumption of DDT at levels 33,000 times the average human exposure for 25 years found no conclusive link between DDT and cancer in primates [3]. However, the study did indicate that DDT was toxic to the liver and the central nervous system.
The biochemical pathways of mice, rats, and hamsters differ from those of humans, which means that extrapolation of DDT carcinogenicity from rodents to humans is technically not correct. In fact, there are numerous long and short-term studies suggesting that DDT is NOT a carcinogen in humans [4,5,6].
There is a website dedicated to "debunking" DDT myths regarding its safety profile called JUNKSCIENCE. It's fascinating, go ahead and check it out!
[1]U.S. Department of Health and Human Services ,Public Health Service, National Toxicology Program. "Tenth Report on Carcinogens." http://ehp.niehs.nih.gov/roc/toc10.html#search.
[2]National Toxicology Program. "TR-131 Bioassays of DDT, TDE, and p,p'-DDE for Possible Carcinogenicity (CAS No. 50-29-3, CAS No. 72-54-8, CAS No. 72-55-9)." http://ntp.niehs.nih.gov.
[3] Takayama, S et al. "Effects of long-term oral administration of DDT on nonhuman primates." J Cancer Res Clin Oncol 1999;125(3-4):219-25.
[4] Helzlsouer, KJ et al. "Serum concentrations of organochlorine compounds and the subsequent development of breast cancer."Cancer Epidemiol Biomarkers Prev. 1999 Jun;8(6):525-32.
[5] Hunter, DJ et al. "Plasma organochlorine levels and the risk of breast cancer." Engl J Med 1997 Oct 30;337:1253–8.
[6] vant'Veer P et al. "DDT (dicophane) and postmenopausal breast cancer in Europe: case-control study." BMJ. 1997 Jul 12;315(7100):81-5.
