Session VIII: Monitoring of Human Populations at Risk
The identification of carcinogenic and/or mutagenic activity in chemicals and the extrapolation of the experimental data to the human situation is the primary approach to controlling possible adverse health effects in human populations. Another useful approach, and one negating the difficulties inherent in extrapolating cell and animal data to humans, is to actually monitor human populations for genotoxic damage, e.g cancer, heritable diseases, during and after their exposure to hazardous agents. Epidemiological studies, the classical approach to population surveillance, are limited in that the ill-health effect must be readily apparent before an adverse health effect situation can be inferred. For epidemiological studies directed at assessing cancer incidence, a 15 to 20 year delay between the exposure to the causitive agent and the appearance of the cancers is not uncommon. For heritable diseases the delay in appearance is at least one generation. Except for an unrelated decrease in agent usage dictated by economic or for more immediate health effects, the burden of ill-health will increase throughout this delayed expression time. To circumvent this lag time associated with cancer or heritable diseases, several approaches have been developed or are being developed to assess several “indicators” of potential genotoxic ill-health. These indicators include: cytogenetic and mutagenic end- points in human peripheral blood lymphocytes, mutagenic or clastogenic substances in body fluids (urine, seminal fluid), nondisjunctional events or abnormal morphology in sperm, and the alkylation of hemoglobin.