ASSESSMENT OF REPRODUCTIVE DISORDERS AND BIRTH-DEFECTS IN COMMUNITIESNEAR HAZARDOUS CHEMICAL SITES .3. GUIDELINES FOR FIELD STUDIES OF MALE REPRODUCTIVE DISORDERS

Exposures to environmental toxicants can have detrimental effects on s everal aspects of human male reproduction: fertility, sexual function, hormone status, and pregnancy/birth outcomes. However, no simple pres creening methods are available for reliably identifying potential haza rds; questionnaires alone are relatively imprecise and inefficient in the absence of field data. Multidisciplinary field studies are require d that include detailed exposure information, health and reproductive histories, physical examinations, semen analyses, and possibly, hormon e analyses. Semen analysis is a critical component of field studies fo r evaluating two aspects of male reproduction: 1) changes in sperm or seminal content, which may be indicative of adverse effects on the mal e reproductive system with possible implications for fertility potenti al; and 2) defects in sperm DNA or chromosomes, which may be associate d with subsequent changes in viability during embryonic development an d health risks to the offspring. Semen analyses may be tiered: 1) init ially, each semen study may include conventional semen assays (concent ration, motility, and morphology) as well as specific biomarkers indic ated by the health effect of concern in the study cohort; and 2) archi ved samples (i.e., frozen, videotaped, or smeared) mag be utilized in later second-tier analyses to further characterize specific findings. Before initiating any field study, it is cost effective to critically evaluate the suitability of the cohort by confirming exposure and dete rmining that there are adequate numbers of male participants in each e xposure category. Such evaluations must be based on the statistical se nsitivities of the specific tissue biomarkers and health endpoints for detecting changes. This article summarizes the components of the idea l field study and identifies research needs for improving field studie s of mate effects and for understanding the mechanisms of male reprodu ctive toxicity. Several promising semen methods currently under develo pment are also discussed. (C) 1997 Elsevier Science Inc.