An excerpt from Chapter 13, Loomings

Plummeting sperm counts loom ominously over this discussion, for these reports harbor implications that extend beyond the question of male fertility. Animal experiments indicate that contamination levels sufficient to impair sperm production may affect brain development and behavior as well. Thus, it is likely that sperm counts are just one concrete, measurable signal of much broader effects on aspects of human health and well-being that are not so easily quantified. What is at stake is not simply a matter of some individual destinies or impacts on the most sensitive among us but a widespread erosion of human potential over the past half century. The evidence taken as a whole makes it difficult to avoid questions about the significance of this chemical assault for society at large.

Wildlife data, laboratory experiments, the DES experience, and a handful of human studies support the possibility of physical, mental, and behavioral disruption in humans that could affect fertility, learning ability, aggression, and conceivably even parenting and mating behavior. To what extent have scrambled messages contributed to what we see happening around us-the reproductive problems seen among family and friends, the rash of learning problems showing up in our schools, the disintegration of the family and the neglect and abuse of children, and the increasing violence in our society? If hormone-disrupting chemicals undermine the immune system, could they be increasing our vulnerability to disease and thus, contributing to rising health care costs? Most fundamentally, what does this mean for the human prospect?

If these effects are occurring broadly, hormone disruption may well be contributing to aberrant and unhealthy tendencies in our society. On the other hand it is doubtful these chemicals are causing all the social dysfunction we see around us. Those seeking a single, simple explanation for such complicated phenomena are bound to be frustrated and disappointed.

Even in the case of relatively straightforward physical problems, such as sperm count declines, we understand far too little about the hormone-disrupting chemicals unleashed in the environment to assess the prospects with confidence. The four studies reported to date show a precipitous drop in human male sperm counts in recent decades-a loss on average of one million sperm per milliliter of semen a year. Such a sharp downward trend is truly alarming. Even more alarming is the fact that this decline continued for almost a half century before medical researchers recognized what was happening. Will this stunning rate of loss continue? Where will it end?

If currently regulated persistent chemicals are largely responsible for the decline, sperm counts could begin rebounding around 2030. As noted in Chapter 10, the studies find a correlation between the quantity and quality of sperm and the date of a man's birth with the youngest men showing the lowest sperm counts and the greatest number of malformed sperm- a pattern that strongly supports the theory that the decline is the result of damage before birth or early in life. There is inevitably a long delay, however, before damage becomes evident through a sperm count analysis. The youngest men in the recently reported sperm count studies were born in the early 1970s, just at the time that the United States and other industrialized countries began to restrict the use of highly persistent organochlorine chemicals such as DDT, dieldrin, lindane, and PCBs. So their low sperm counts could reflect the high exposure of their mothers to persistent chemicals in the 1960s and 1970s before governments imposed restrictions. Since then, the concentrations in human tissue of DDT, the DDT breakdown product DDE, and lindane, for example, have dropped considerably in countries where their use is restricted. So if prenatal exposure to endocrine-disrupting pesticides have played a major role in sperm count reductions, one would expect to see an upswing in sperm numbers over the next decade, at least in developed countries, as males born in the 1980s reach maturity. In countries such as India, however, just two persistent pesticides, DDT and lindane, make up 60 percent of the pesticides and their use is still increasing, according to pesticide experts. It is important to note, also, that human body burdens of PCBs, which were banned in industrial countries at about the same time as DDT, have not shown a significant decline even where the compounds were banned. Animal and human studies have both linked this family of chemicals to impaired male fertility.

Falling sperm counts could be an unfortunate historical episode-an unforeseen consequence of the midcentury experiment with persistent chemicals, which many countries have now wisely discontinued. The threat could now be essentially behind us, even though it may take decades to play out the effects. Unfortunately, the worrisome new discoveries described in previous chapters indicate the hazard from synthetic chemicals has probably not abated. As human exposure to DDT and other persistent compounds has diminished in countries like the United States, exposure to other hormone-disrupting chemicals has rapidly increased. Consider the extent to which plastic has replaced glass and paper in packaging over the past two decades. A series of accidental discoveries have demonstrated that plastics are not inert as was commonly assumed and that some of the chemicals leaching from plastics are hormonally active. Plastics have found their way into every corner of our lives, creating the potential for significant chronic exposure to hormone disruptors. They carry everything from soda to cooking oil; they line metal cans and are the preferred material for children's toys. It is unlikely that all plastics are hazardous, but because of manufacturers' claims of trade secrets, there is no way to know the chemical composition of any given plastic container or to judge how much of the plastic in use might be shedding hormone-disrupting chemicals. Scientists also warn that hormone-disrupting chemicals may lurk in ointments, cosmetics, shampoos, and other common products.

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