Problems or assessing the genetic impact of mutagens on man.

Available human data, of the kinds needed to assess the genetic harm to man from possible changes in his mutation rate, currently suffer from major limitations. In particular there is uncertainty about a) the total amount of hereditary disease, b) the fraction of this that is mutation-related and therefore likely to be increased in frequency as a result of exposures to elevated levels of environmental mutagens, and c) the severities of the mutation-related conditions and the collective public health importance of any anticipated increases in their frequencies. Standards of protection against environmental mutagens cannot be set on the basis of laboratory data alone, and more effort on the part of geneticists will need to be directed towards quantitative assessment of the impact of the mutagens in terms of human disease. The needs for relevant human data, and various deficiences in the statistical information that is currently available, are discussed.