This collection of papers arose out of a meeting on the same topic held during the 48th session of the International Statistical Institute in Cairo, 9-17 September 1991. Interest in the topic has grown in recent years, with increasing awareness of the need to understand the impact of industrial processes on the health of the workforce or on the population at large. At the Cairo meeting papers by M.J. Gardner, by P.S.S. Sundar Rao and by C.R. Redmond and S. Mazumdar addressed different aspects of this question. For the present publication the authors have revised their papers and we have added this general introduction.