Meteoric rise of endocrine disruptors

In Hormonal Chaos , science-policy pundit Sheldon Krimsky sets out to chart the meteoric rise of a new theory of environmental disease. Its advocates argue that a diverse group of industrial and agricultural chemicals can act as "endocrine disruptors", mimicking human hormones or blocking their action. They may distort processes normally under hormonal control, particularly early development in the womb, with consequences ranging from low sperm counts to low IQ. Krimsky, professor of urban and environmental policy at Tufts University, Massachusetts, wants to explain how, in the United States at least, this controversial idea became big news in the 1990s.

Krimsky begins with a lengthy account of the "scientific developments" that gradually lent credence to the revolutionary hypothesis. The bulk of the data to date centres on disturbing findings in wildlife, particularly abnormalities in the sexual organs of fish, alligators, marine mammals and polar bears exposed to certain pollutants. Laboratory studies on pregnant rats and the like proffer more support: give an expectant female rodent a meal of oestrogen-like dioxin, and her babies are "feminised" forever.

Could humans be at risk from insidious endocrine disruptors in water or food? Could falling sperm counts and a rise in testicular cancer be linked to a "sea" of artificial oestrogens that constitute an "assault on the male", as a 1994 BBC Horizon film argued? And might environmental chemicals also disrupt the action of thyroid hormone in the womb, damaging the developing brain? In one study, Michigan women who ate fish from the polluted Great Lakes were more likely to have children with learning difficulties and behavioural disorders.

But fool-proof evidence that hormone-like pollutants are to blame is elusive. Krimsky points out: "To date, despite the accumulating evidence, the environmental endocrine hypothesis cannot claim a single dramatic episode or discovery capable of turning public opinion into a potent force for political change, or, for that matter, capable of inspiring a broad scientific consensus on the risks to human health."

So why are American tax-

payers shelling out millions of dollars to fund a scheme to screen chemicals for their endocrine-disrupting capabilities? There is a mystery here: "The explosive growth of this issue within such a short time without a signature event or definitive evidence of human illness is quite unusual in modern environmental history." In Krimsky's account, most of the credit goes to Theo Colborn, a middle-aged pharmacist-turned-environmental scientist/activist, who drew together disparate evidence to come up with the global "environmental endocrine hypothesis". Crucially, a series of "public interest non governmental organisations" - the Conservation Foundation, the World Wildlife Fund and the W. Alton Jones Foundation - funded Colborn's work, enabling it to be brought "to the attention of a vast number of scientists and policy-makers".

The media reacted with the usual cynicism and sensationalism. But Colborn shines through as the hero: it was she who built a scientific constituency for the environmental endocrine hypothesis through strategic conferences and consensus statements, and she who used that constituency to alert policy makers and the public, crows Krimsky. She is portrayed as the admirable "advocacy scientist", who responsibly took it upon herself to push her scientific revelation into public policy.

Yet the book's tone sits awkwardly in today's science studies, where the empirical "truth" of the matter is not the point. Although purporting merely to explore "the role of contested knowledge in the choice of a policy path", Krimsky clearly takes sides. In the penultimate chapter, he proclaims, a mite blithely perhaps: "We will need to reach a consensus on effective and inexpensive assays for identifying endocrine disruptors and on methods of assessing the human health risk of cumulative doses." If only.

There is a fascinating cultural history of this debate still to be written. When I interviewed Colborn in the mid-1990s, she mentioned the difficulties environmental campaigners were having in generating public concern. When focus groups were told of the low sperm-count warning, Colborn recalled, the women just laughed while the men hastily added: "It's nothing to do with me."

There is more to hormonal chaos, I suspect, than Krimsky's carefully written, but strangely triumphal account, is able to convey.

Gail Vines is life sciences consultant to New Scientist and author of Raging Hormones.