As usual, your coverage provided a thorough and illuminating look at a very important subject. First, the authors state that most people simply will not choose celibacy, yet later they say that sex education caused teens to be less likely to engage in sex. Finally, the graph on page 97, showing trends in the occurrence of unprotected intercourse, stops with data taken from 10 years ago. There is no such research that abstinence-only programs have positive and sustained effects on the behavior of young people. Unfortunately, there has been an upward trend in the occurrence of unprotected intercourse during the past two years, probably in part because of the dangerously incorrect thinking that prevention is not necessary once treatments become available.
Current medications are far from perfect prevention is still the order of the day.
In fact, environmental factors are an unlikely cause. By all measures, the environment is cleaner now than in 1970. To suggest that environmental factors are the cause of changes in the sex ratio would require suppositions about racial differences in the effects of these factors and that surely runs into Occam's razor. Although a sudden increase in price or tax on a given item has been shown to reduce its consumption in the short term, it is not at all evident that it does so over the long term. What Glantz ignores is the well-known phenomenon that expensive items are perceived as prestigious luxury items.