Measurements of environmental and human sanples requires dataof known quality.The basis to obtain such measurements is in awell designed and executed quality assurance and quality controlprogram.In the measurement of mutagenesis and other genotoxicendpoints in environmental and human samples,QA/QC programs arestill in the stages of development,as evidenced by the lack ofagreement of resuits from laboratory to laboratory.The purposeof this is to elucidate the principles,requirements andstrategies for the development or improvement of a qualityassurance and quality control program in order to providecredible data and,second,to promote an understanding of thecomponents of the QA/QC program to evaluate the accuracy,biasand precision of environmental and human biological monitoringgenotoxic data forming the basis for estimates of environmentalexposures for human risk assessment.Such risk assessments canprovide the basis for critical decisions on vital matters rangingfrom the health of individuals to the prot Measurements of environmental and human sanples requires data of known quality. The basis to obtain such measurements is in awell designed and executed quality assurance and quality controlprogram. The measurement of mutagenesis and other genotoxicendpoints in environmental and human samples, QA / QC programs arestill in the stages of development, as evidenced by the lack of agreement of resuits from laboratory to laboratory. The purpose of this is to elucidate the principles, requirements and strategies for the development or improvement of a quality assurance and quality control program in order to provide credible data and, second, to promote an understanding of thecomponents of the QA / QC program to evaluate the accuracy, bias and precision of environmental and human biological monitoringgenotoxic dataform the basis for estimates of environmentalexposures for human risk assessment.Such risk assessments canprovide the basis for critical decisions on vital matters rangingfrom the health of indiv iduals to the prot