Fertility as a measurement in reproductive toxicology

Abstract

The use of fertility as an endpoint in toxicologic research is hampered by the large number of variables that influence human reproductive potential. The effect of environmental and occupational chemicals on fertility can be measured in 2 ways: 1) comparison of fertility rates between a group exposed to an agent and a control population or 2) examination of exposed groups for specific parameters (e.g. decreased sperm density) known to be involved in infertility. Comparison studies require careful selection of control groups or knowledge of the baseline fecundability of the study group. The national fertility rate may serve as a poor control for a regional or local study and fertility rates in small groups may be greatly affected by unmeasured variables. Individual parameters believed to be important in fertility may be more readily measured; however except when a fertility factor is severely compromised data on individual parameters must be interpreted with caution. Subtle alterations of a single factor in the complex mechanism of fertility may not be significant against the high background rate of human reproductive failure.