ABSTRACT
I. INTRODUCTION In contrast to the drugs we have considered that are taken by humans by their own volition largely because they have medical value, there are a number of chemicals that are used on a strictly voluntary basis for purely personal or social reasons, without necessary therapeutic benefit. In other words, use of these chemicals is by choice, rather than need. These include use of cosmetics, use of tobacco through a smoking habit, ingestion of caffeine through beverage drinking, abuse of addictive and mind-altering or psychogenic drugs, and consumption of alcohol. Most or all of these habits entail some risk, whether to pregnancy or other aspects of health; thus, there is concern over their use. It is the opinion of many observers that it is these controllable factors in the environment that may account for a significant number of reproductive failures.
