Sunday, September 02, 2007

The Sad State of Environmental Health Policy Today

The other day, Revere was discussing John Edwards’s presidential platform on cancer, and expressing disappointment that Senator Edwards gives virtually no attention to prevention, including regulatory approaches for reducing carcinogenic exposures and incentives for promoting “green chemistry” in manufacturing. I checked over at Hillary Clinton’s web site, which has a bit more meat on this topic: smoking prevention in young people, getting junk food out of schools, and improving biomonitoring of exposure to toxic substances. However, it’s only a slight improvement over what John Edwards would provide for us. To the credit of both of them, they appeared at Lance Armstrong’s cancer forum earlier this week (most of the Republican candidates bailed on it).

It seems so hard for our politicians to inject the environmental health focus into the debate over health care. Perhaps it’s too difficult for them. Too much of our economic system would have to change. For example, in a paper published last month in Environmental Health Perspectives, the cancer risks from organic hazardous air pollutants were ranked for a non-occupational and non-smoking population. The chemicals providing the largest contribution to total estimated cancer risks in the U.S. were benzene, butadiene, formaldehyde, dioxins and chloroform.
Mobile sources (cars and trucks) are a large part of the emissions of benzene, butadiene and formaldehyde into the air. So, by inference, a key strategy for reducing exposure to these substances could be to reduce the amount that we drive, or ship stuff around by truck. The alterations to our daily lives could range from minor, such carpooling, greater proportion of working from home, or buying locally, to fairly life-changing stuff, including redesigning cities for walking and urban biking, substantially increasing the urban mass transit infrastructure, changing patterns of employment, old industries collapsing while new ones flourish. . . more examples are provided here. There would be collateral benefits, too: redesigning our built environment to be more friendly to pedestrians and bicyclists could create a health benefit, and possibly cut into health care costs, by increasing the amount of exercise people get (NIEHS had a conference on this topic in 2004); in addition, reducing vehicle-miles traveled also reduces our consumption of oil, which promotes energy independence and begin reducing greenhouse gas emissions, both of which pose a risk to national security. Oh, and all of the upgrading of our infrastructure that would be needed to accommodate fewer cars and trucks in our lives would create jobs. . . . Stop me if all of this is making too much sense.

Chloroform occurs in drinking water as a disinfection byproduct (most chloroform exposure occurs indoors when we use that water – either from drinking, or inhaling chloroform that volatilizes from hot water during showering or using a washer or dishwasher). While the disinfection of drinking water using chemicals such as chlorine has been a major public health success story by reducing the risk of disease, elevated levels of disinfection byproducts may be associated with an increased risk of bladder, rectal, and/or colon cancers and adverse pregnancy outcomes. Many water utilities use chlorine gas for disinfecting drinking water, and chlorine is transported around the country in rail cars. Derailments have created hazards and caused fatalities to communities in the past (I’ve blogged about one such story in Graniteville, SC in 2005; as discussed here, further work is needed to increase the safety of rail cars transporting hazardous materials). However, alternatives are available for disinfection of drinking water that can reduce the formation of disinfection byproducts and at the same time reduce accidental releases from derailments by limiting the amount of chlorine transported around the country. There would need to be an investment made to fund the retrofitting of water treatment plants – but again, you could look at this as an opportunity for job creation.

The story is bit different for dioxins. People are exposed to dioxins principally through the food supply, particularly by eating animal fat, dairy products and fish. In 2003, the Institute of Medicine published a report discussing strategies for reducing exposure to dioxins in foods. Overall, about 34 percent of the calories in American adults’ daily diet come from fat, and one-quarter to one-third of that is from saturated fat, which is largely animal fat. Recommendations for reducing dioxin exposure in the diet (which, by the way, would also reduce exposure to other lipophilic persistent organic pollutants) include changing agricultural production methods to interrupt the cycle of dioxins through forage, animal feed, and food-producing animals, particularly with regard to the use of animal fats as livestock feed. In addition, they recommend educating people about reducing the amount of fat consumed in their diets. In general, making people more aware of the consequences and benefits associated with what they eat can provide health benefits beyond reducing exposure to dioxins and persistent organic pollutants.

There are pollutants not covered in the EHP article, because they aren’t hazardous air pollutants, but that still are examples of how attention to environmental health can have collateral economic benefits. For example, nearly 2 billion pounds per year of bisphenol-A are used in the production of polycarbonate plastics. Polycarbonates are used to manufacture all types of plastic components, including food and drink containers. There potentially are problems with using polycarbonates in food and drink containers – bisphenol-A can leach from them and be ingested. This makes bisphenol-A a textbook example of an environmental toxicology and health policy problem. It's a commercially important chemical substance. Nearly all of us are constantly exposed to low levels of it. The mechanisms for potentially adverse health effects are subtle and occur at low levels of exposure. The most vulnerable populations for these effects are young children, both during pre-natal development and in infancy. The kinds of biological effects observed in laboratory animals with low levels of exposure include stimulating the growth of prostate (in males) and mammary tissues (in females), potentially increasing susceptibility to carcinogenicity later in life; alterations in hormonol with effects such as early onset of sexual maturation; and neurobehavioral effects. Recently, one study provided indications that BPA might promote insulin resistance, a risk factor for diabetes. These effects can be observed at levels around 10-fold greater than levels of exposure in humans, which is not a comfortable margin of safety. As yet, adverse effects have not been observed in humans, though there hasn't been a concerted effort made to examine human populations.

Bisphenol-A is not the only component in plastics manufacturing with health concerns. Health effects potentially associated with phthalates, used as plasticizers, and perfluorooctanoic acid (PFOA), the precursor used to make Teflon, are also under scrutiny. As with bisphenol-A, these substances are in widely used products, and we all carry around a small body burden of them. As can be imagined, there is a strenuous scientific debate about the presence and significance of adverse health effects from exposure to bisphenol-A, phthalates and PFOA, a debate which may never be satisfactorily resolved. However, there is an opportunity to promote the research, development and manufacturing of lower-toxicity materials for use in consumer products, which could help to reduce the uncertainty regarding health risks from plastics. There are many initiatives promoting “green chemistry” (the Lowell Center for Sustainable Production and the Clean Production Action project are resources for learning more about this topic). However, while the chemical manufacturing industry acknowledges the importance of green chemistry, redirecting it onto a more sustainable path will happen faster if political pressure is applied.

Which brings us around to what our presidential candidates have said about cancer prevention, and more importantly, what they haven’t said. Dealing with disease burdens such as cancer is more than just fixing health insurance and giving more money to NIH. It is taking a more holistic view of how physical and socioeconomic factors can affect human health. Environmental health is very much a democratic issue. The Democratic candidates for president should be able to say more about it than they currently are doing.

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