What should it take to describe a substance or product as sperm-safe

Male reproductive potential continues to be adversely affected by many environmental, industrial and pharmaceutical toxins. Pre-emptive testing for reproductive toxicological (side-)effects remains limited, or even non-existent. Many products that come into direct contact with spermatozoa lack adequate testing for the absence of adverse effects, and numerous products that are intended for exposure to spermatozoa have only a general assumption of safety based on the absence of evidence of actual harm. Such assumptions can have unfortunate adverse impacts on at-risk individuals (e.g. couples who are trying to conceive), illustrating a clear need for appropriate up-front testing to establish actual sperm safety. After compiling a list of general areas within the reviews scope, relevant literature and other information was obtained from the authors personal professional libraries and archives, and supplemented as necessary using PubMed and Google searches. Review by co-authors identified and eliminated errors of omission or bias. This review provides an overview of the broad range of substances, materials and products that can affect male fertility, especially through sperm fertilizing ability, along with a discussion of practical methods and bioassays for their evaluation. It is concluded that products can only be claimed to be sperm-safe after performing objective, properly designed experimental studies; extrapolation from supposed predicate products or other assumptions cannot be trusted. We call for adopting the precautionary principle, especially when exposure to a product might affect not only a couples fertility potential but also the health of resulting offspring and perhaps future generations.