This supplement contains the papers submitted at EUROTOX 88, the joint Congress of the European Society of Toxicology and the Federation of the European Societies of Toxicology. The theme was one of monitoring and examining the effects of toxic substances in the biological response at the subcellular level. Mechanisms of metal carcinogenicity are discussed as well as the biomonitoring of chemical exposure. Reports are provided on the role of individual differences in man and the effect of risk assessment. Papers appear dealing with the genetic control of drug metabolizing enzymes. The role of metabolism in organic specific toxicity is discussed. Information is included on the toxicological impact of chemicals interfering with the endocrine system as well as on the effects of toxicants on the immune system. Presentations deal with the current status of risk assessment in environmental toxicology.