Then, as now, the news arrived at a very tender moment for the human penis. In the early 1990s, a brand-new line of environmental research had begun to shift the focus of concern toward the groin: Whereas in the 1970s and ’80s, environmentalists had mostly worried over cancer-causing chemicals and nuclear waste, they’d lately started looking into hormones. A set of studies pioneered by zoologist Theo Colborn suggested that pesticides and other runoff were soaking wild animals with estrogenic chemicals. Intersex fish were turning up in the vicinity of paper mills; alligators from a polluted lake in Florida had shrunken penises; fertility was dropping among populations of birds, fish, shellfish, and mammals. Colborn and her peers began to ask, What if man-made toxins worked like gender-bending drugs during gestation? What if humankind had launched its own castration?

A few months before Skakkebaek went public with his sperm-count data at a World Health Organization workshop, Colborn and 20 other scientists had gathered to discuss their work at Wingspread — a Frank Lloyd Wright house near the shores of Lake Michigan. There, the scholars coined a phrase for what they deemed to be a novel and pervasive threat to pubic public health: endocrine disruption.

It seemed the major culprit — the No. 1 disrupter — was estrogen. In the “Hypothesis” section of The Lancet, Skakkebaek would lay out the theory with the help of Richard Sharpe, a longtime researcher on male infertility from the University of Edinburgh. For half a century, unborn baby boys and wild animals alike had been exposed to growing concentrations of the hormone from a host of different sources, including synthetic estrogens from the livestock industry, phytoestrogens in foods (especially soy), estrogenlike chemicals from pesticides and plastics, and even contamination of the nation’s drinking water with residue from oral contraceptives. Humans now live in what had been called a “sea of estrogens,” they warned, one that could well be causing genital malformations in the womb and lifelong decrements in semen quality.