Laboratory methods for assessing human semen in epidemiologic studies: A consensus report

MICHAEL ZINAMAN H ANational Institute for Occupational Safety and Health, and National Toxicology Program, Cincinnati, Ohio; BNational Institute of Environmental Health Science and National Toxicology Program, Research Triangle Park, North Carolina; cUS Environmental Protection Agency, Washington, D.C.; DDepartment of Obstetrics and Gynecology, University of California, Davis; EFood and Drug Administration, Rockville, Maryland; FAndrology Laboratory and Sperm Bank, Cleveland Clinic Foundation, Cleveland, Ohio; °US Environmental Protection Agency, Cincinnati, Ohio; MDepartment of Obstetrics and Gynecology, Georgetown University, Washington, D.C. INTRODUCTION The report by Percival Pott in 1775 on the incidence of scrotal cancer in chimney sweeps (1) was not only the first description of environmentally related can- cer, but was also the seminal paper in the field of oc- cupational reproductive medicine. More recently, the effects of kepone (2), dibromochloropropane (3), and ethylene dibromide (4) on male reproductive capac- ity have focused our collective attention on the prob- lem of occupational exposures to reproductive toxi- cants. The depth of feeling is mirrored in California's Proposition 65, which exemplifies the concern sur- rounding not only carcinogens, but also chemicals producing terata or sterility. With this increased concern has come the need for more information, and in reproductive toxicol- ogy, additional human semen studies are necessary to generate those data. The latter frequently include the state-of-the-art computer-assisted semen analysis (CASA) techniques and endpoints. These systems were designed to digitize the microscopic image of each sperm cell, determine sperm concentrations, and analyze numerous parameters of sperm move- ment (5). The reports of significant correlations of sperm motion endpoints with fertility (6-8) expand our evaluation of CASA systems from validation (ac- curacy and precision) to interpretive usefulness. While the ability to detect structural and/or meta- bolic lesions in sperm is enhanced with these systems,