Advances in scientific understanding of endocrine disruption: Creating new opportunities for preventing human disease

Almost a dozen years have passed since Theo Colborn, Dianne Dumanoski and I published 'Our Stolen Future' and generated a public debate about hormone disruption.

The most important contribution of the book was to raise a series of scientific questions that needed answering, questions about the role of endocrine-disrupting compounds in causing human disease and disability.

Our book did not claim scientific certainty. But the scientific evidence by then, the late 1990's, was strong enough to warrant a significant investment in scientific research. The range of scientifically-plausible effects was too important to ignore.

The public interest we and others stimulated encouraged governments around the world, including Japan, to invest in much needed research. Over the past decade, several hundred million dollars have been applied to research on endocrine disruption and related issues.

With this investment, scientific evidence about potential impacts of endocrine disrupting compounds has strengthened significantly over the past decade. We know much more about how contaminants impair infertility, increase cancer risk, undermine the immune system and impair neurological function and cognitive development. In every one of these health endpoints, the case for endocrine disruption has become much stronger, not weaker.

Even more striking, we have learned that endocrine disruption is likely to be involved in health issues 'Our Stolen Future' did not examine. The most important of these is Type 2 diabetes, obesity and metabolic syndrome, including heart disease. The first major epidemiological study of bisphenol A (BPA), published just this year in one of the world's leading medical journals, the Journal of the American Medical Association (JAMA), strongly implicates BPA in heart disease, type 2 diabetes and liver abnormalities. These epidemiological results are consistent with experiments with human fat tissues and predicted by animal experiments.

A decade since Our Stolen Future, the world is now midstream in a revolution in the environmental health sciences. None of the science has been easy. None of it is complete?scientific research unerringly leads to more questions. Nor has any of it resolved all the remaining uncertainties. Science is never certain.

Two themes are emerging clearly from this revolution. First, the methods in toxicology and epidemiology that we have depended upon for decades to assess the safety of chemicals don't work for endocrine disrupting compounds, and indeed, they are likely to have underestimated risks for many types of chemicals. That means many of today's safety standards, including in Japan, are too weak to protect public health.

Second, this revolution is identifying many opportunities to prevent disease, and perhaps even reduce the cost of health care, by revising the safety standards to reflect current science. And the range of diseases now plausibly linked to exposure to contaminants includes some of the most burdensome in the world.

The example of BPA above is illustrative of the potential. Type 2 diabetes and heart disease have become epidemic in the developed world, and are increasingly common in developing countries. They impose an enormous economic burden. Type 2 diabetes is estimated to cost the U.S. over $218 billion each year. The JAMA results suggest that risk for Type 2 diabetes and heart disease may be lowered by reducing exposure to BPA. Given that virtually all medical interventions have failed to slow these epidemics, surely reducing BPA exposure should be considered.

Multiple studies show that BPA may also cause infertility, spontaneous miscarriage, impaired neurological development, as well as prostate and breast cancers. And medical studies using standard tools for developing cancer-fighting drugs indicate that BPA can interfere with standard treatments for these cancers. Hence reducing BPA exposure is likely to have multiple health and economic benefits.

Not only is the science growing stronger, it is helping to stimulate change in chemistry. It has never been the responsibility of chemists to ask questions about the toxicity of materials they invent. They synthesize a new compound, determine its material characteristics, and look for potential uses. Finding out it causes harm has been left to others. This process has led to many examples of dangerous materials entering common use, becoming widespread, and hurting people. Once a material is widespread it is very difficult to withdraw.

A new generation of 'green chemists' is beginning to work with environmental health scientists to examine the toxicity of materials during the chemical design process. Their goal is to avoid hazardous materials in the first place. Their effort is likely to lead to tremendous and widespread innovation in the chemical industry.

The revolution in environmental health sciences, together with green chemistry, holds exceptional promise for human health and economic innovation. While there is much more to be done, a decade after Our Stolen Future, that's real progress.

Japanese