Environmental factors are key drivers in Alzheimer's and Parkinson's diseases.
When we take any prescribed or over-thecounter medication, we assume it has been tested not only for effectiveness, but also for safety. That is one of the primary roles of the U.S. Food and Drug Administration and reflects both foundational medical ethics- the Hippocratic dictum "First, do no harm"- and what most educated modern people would see as common sense, in the more colloquial slogan "better safe than sorry."
In another important arena, however, the reverse has been the common approach. With over 85,000 industrial chemicals registered for use in modern life and thousands more added yearly, very few have been tested before use to make sure they are not hazardous to human health (or the health of other species). The rise of the modern environmental movement, particularly as embodied by the late Rachel Carson and her landmark 1962 book Silent Spring, has led to increasing questioning of the wisdom ofthat de facto "innocent until proven guilty" approach. And in more recent years, many doctors and researchers on human health are joining the chorus of concern.
Indeed, chemical pollutants have become widespread in our air, water, soil, food, homes, schools, and workplaces, and thus also in our bodies. The sources are manifold. They include pesticides, industrial chemicals, chemicals found in the home and workplace, personal care products, and pharmaceuticals to which people are widely exposed.
"Environmentalism" has traditionally been most associated, at least in the public eye, with preservation of wilderness and wildlife. Carson's book reflected that focus, with an emphasis particularly on birds- and thus her title. But in more recent decades, concern about the welfare of humans with respect to environmental factors has grown, and the field of "environmental health" is now large, diverse, and still growing.
Recognizing the links between chemicals and human health, the Institute of Medicine- a part of the National Academy of Sciences- emphasizes the importance to health of minimizing environmental exposures to "chemical and physical hazards in homes, communities and workplaces through media such as contaminated water, soil and air."
It must be acknowledged that our understanding of risk among the links between individual toxicants and diseases varies widely. The well-known examples of the harms of lead, mercury, some pesticides, and environmental tobacco smoke, for example, are proven. Recent research on Bisphenol A (BPA), a widely used chemical in plastic, has reached the point where mainstream medical organizations now urge its removal from our environment and bodies. The first Gulf War, which lasted only a few days, has provided a sad example of impacts of exposure to chemicals in soldiers who are now experiencing lasting health problems. Hundreds of other substances are increasingly suspect, with varying degrees of evidence gleaned from animal studies and, increasingly, research on human impacts as well.
In general, the developing human fetus appears to be uniquely at risk of harm from environmental toxicants, and such damage can be profound and permanent. Scientists worldwide are studying interactions among chemicals and longitudinal studies examining links between early developmental exposures and health challenges much later in life, in order to determine what might be making us sick and how to prevent future illnesses. At any point along our lifespan, "from womb to tomb," chemical exposure, even at extremely low levels in some cases, can result in health problemssooner or later.
Diseases of Aging - and Pollution?
Chronic diseases and disabilities have reached epidemic proportions in the United States, affecting more than 100 million men, women, and children, which is more than one-third of our population. Asthma, autism, birth defects, cancers, developmental disabilities, diabetes, obesity, endometriosis, infertility, Parkinson's disease, learning disabilities, Alzheimer's disease, and other diseases and disabilities are causing increased suffering, costs, and concern. …