Clinical, genetic and regulatory consequences of exposure to mutagens.

Not a single agent is known to cause an increase of genetic disorders in humans. Even studies on large numbers of children born to parents after exposure to ionizing radiation or DNA alkylating agents failed to detect significant genetic consequences. This is in contrast to effects observed in human somatic cells or germ cells, and to various investigations with laboratory animals. A definite explanation of these discrepancies does not exist. Nevertheless, on the basis of the currently available human data it cannot be justified to advise a previously exposed person against having children, if this individual is otherwise healthy. There are obvious incongruencies between the potency of an agent to cause mutations at all, and to induce genetic effects in the offspring. It should therefore be emphasized that a regulatory classification of agents according to a potential genetic hazard in man must not solely be based on in vitro mutagenicity data.