Exposure to pesticides is very common world-wide. Currently, only two pesticides, arsenical insecticides and TCOD (a dioxin) have been designated by IARC as known human carcinogens, but many others with world-wide use are suspected human carcinogens.
Few pesticides on the market today are directly genotoxic and their role in human carcinogenesis will be questioned as long as the epidemiologic data are limited and alternative non-genotoxic mechanisms are not established.
Rapid progress in our understanding of non-genotoxic carcinogenic mechanisms is being made in the biomedical research arena. While no one study can provide all the evidence needed to evaluate the carcinogenicity of pesticides as human carcinogens, prospective cohort studies with comprehensive exposure assessment are likely to greatly increase our understanding. A prospective cohort study also allows for pertinent biological specimens to be collected at appropriate periods of time to examine the biological plausibility of the epidemiological observations.
The design strengths of prospective studies should help increase our scientific understanding of the links between pesticide exposure and cancer and other diseases. Better scientific understanding coupled with effective public health programs should greatly reduce the human disease burden currently caused by pesticide exposures.