International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC working paper 5/5. Perspectives in mutation epidemiology. 5. Modern medical practice versus environmental mutagens: their possible dysgenic impact.

We do not know how many mutations are being produced in human populations by exposure to environmental mutagens. If these mutagens caused a persistent rise in mutation rates, then ultimately there would be a proportional increase in the frequency of a variety of genetic diseases, including those that are difficult to treat and that require life-long care of affected individuals. In contrast, modern medical practices are relaxing selection pressure selectively with respect to disease, leading to a gradual increase in the frequency of certain genetic and partly genetic diseases that can be effectively treated. The pattern of this increase would differ from condition to condition, depending upon the mode of inheritance and the extent to which selection is relaxed; except for some special cases, the anticipated increase would generally be slow. Additional economic burdens on future society and families imposed by relaxed selection would mainly involve expenditures for relatively inexpensive treatments, and not those for expensive life-long care. Moreover, individuals treated successfully can be expected to contribute productively to society. With education and counseling for those who survive serious dominant and X-linked disorders, and with the development of accurate, inexpensive prenatal diagnosis, the presumed dysgenic effects of relaxed selection could be balanced.