Last week I wrote about the President’s Cancer Panel Report which highlighted the “grievous harm” caused by environmental carcinogens and urged action that included removing the toxins from our food, water, and air that “devastate American lives.”

Achieving this is will be no easy task for a nation whose primary tool for regulating chemicals, the Toxic Substances Control Act (TSCA), was added last year to a list of government programs at “high risk” of failure by the Government Accounting Office. The Cancer Panel authors write that TSCA, passed in 1976, is a weak law that doesn’t provide the Environmental Protection Agency with enough authority and “may be the most egregious example of ineffective regulation of environmental contaminants.”

When the Act was passed, some 62,000 chemicals already on the market were declared “safe”, even though there was little or no data to support this policy. Every year another 1,000 chemicals are introduced onto the market—usually with little toxicity testing. The net result: Only 2% of the 80,000 to 100,000 chemicals currently in use have been tested for carcinogenicity and other toxicity.

In theory, companies are required to provide health and safety data for new chemical agents before they can be approved for sale, and in the case of pesticides they may have to provide updated safety data down the road. But according to the President’s Panel report, “historically, chemical manufacturers have successfully claimed that much of the requested submissions are confidential, proprietary information. As a result, it is almost impossible for scientists and environmentalists to challenge the release of new chemicals.”

Once chemicals are on the market, the onus is on the EPA to show “substantial evidence” that a chemical is harmful to human health before it can be removed from the market. This requires costly research, epidemiological studies and extra staff that the agency just can’t afford. Also, the agency is required to weigh the economic costs of removing a chemical against the benefit of keeping it on the market. In light of these hurdles—and intensive lobbying by industry—in the 33 years since TSCA was instituted, only five chemicals have been restricted. Meanwhile, such known carcinogens as asbestos, mercury and formaldehyde have been unable to be banned or have their uses seriously restricted.

By all accounts, reforming TSCA will require changing the way we think about risk and chemical toxins. Margaret Kripke, an emeritus professor at M.D. Anderson Cancer Center and member of the President’s Cancer Panel says that the contribution of environmental toxins to cancer incidence is greatly underestimated. The figure cited most frequently by industry supporters is that besides smoking, environmental factors cause just 6% of cancers.

The problem is that this 6% figure is based on largely discredited data that originated in a 1981 study by epidemiologists Sir Richard Doll and Richard Peto. Doll and Peto set out to answer the question of what percentage of cancer deaths can be attributed to various known causes. To find the answer, they looked at white persons under age 65 who had died of cancer from 1950 to 1977. Their results: Occupational exposure to harmful agents like asbestos accounted for only 4% of all cancers, while “pollution” (unspecified agents in air and water) was estimated to cause some 2% of the cancer burden. The total contribution of environmental toxins (outside of tobacco smoke) to the cancer burden was then 6%. The Doll and Peto findings were eventually published in a book called "The Causes of Cancer" which became “the bible of cancer epidemiology.”

Over the years, critics have found much to fault in the Doll and Peto findings. First of all, by looking at cancer deaths and not incidence of disease, they were unable to accurately determine the full effect of environmental exposure. By excluding the black population and people over 65, they missed vitally important data about cancer rates in two groups who were experiencing increasing rates of disease. At the time, according to Devra Davis, an epidemiologist and director of the Center for Environmental Oncology at the University of Pittsburgh, some 4 out of 5 deaths from cancer were occurring in people over 65.

The Doll and Peto findings also failed to consider that cancers caused by environmental toxins could show up some 30 or 40 years after exposure and that there was a huge growth in the use of synthetic chemicals after the 1960’s. “By ignoring everyone who had cancer over sixty-five and was still alive, and by excluding blacks altogether, Doll and Peto systematically underestimated the effects of recent chemicals,” writes Davis in her book, “The Secret History of the War on Cancer.” “[T]he full brunt of cancer from synthetic organic materials could not possibly have been detected.”

For these reasons, the Doll and Peto “attributable fractions” findings have been largely rejected by the scientific community. Yet they remain the basis of many existing chemical regulations and policies, according to the authors of the President’s Cancer Panel report. “As a result of regulatory weaknesses and a powerful lobby, the chemicals industry operates virtually unfettered by regulation or accountability for harm its products may cause.”

In the intervening years, scientific insight into how some chemical agents can cause cancer and other diseases has evolved dramatically. Older methods used to determine whether a particular chemical is harmful or not most often measure the immediate, direct effect one particular substance has on human health. The most common way of determining this was to expose mice to a particular toxin and see whether it caused tumor growth over the course of a few weeks. But it turns out that human environmental exposure is a far more complex issue. Most of the suspected environmental toxins on the market today—like BPA and phthalates—cause problems years after exposure and do so primarily by interacting with other environmental, genetic and even socio-economic factors. These factors are a diverse lot that include ionizing and non-ionizing radiation; biological organisms; genetic inheritance; endocrine disruptors and chemical carcinogens in water, air, sediment,  food and consumer products; and psychosocial factors like stress, socioeconomic status and income disparities.

Scientists studying the effects of environmental toxins are performing tests far more sophisticated than injecting mice with a suspected carcinogen. They are using human cell cultures and searching for mutations and structural changes occurring at the gene level. What they are finding is that exposure to small amounts of  multiple toxins can lead to these so-called epigenetic changes that can change the way certain genes are expressed—leading to over-expression of cancer related genes and under-expression of those that block tumor growth, for example.

The problem with these new findings is that they are equivocal. How much of a single toxin causes cancer? How many other environmental factors have to come into play before risk becomes too high? Does this chemical pose a greater risk to developing fetuses and small children? How long does it stay in groundwater, air, in the human body? Answering the growing list of questions about a potentially harmful agent can conceivably take many years and involve great expense. These are highly complex problems.

Take the case of bisphenol A (BPA), a ubiquitous chemical compound found in plastic water and baby bottles, can linings and in hundreds of other consumer products. I wrote about state efforts to ban BPA in this post. The scientific evidence supporting such BPA bans is still somewhat equivocal—some studies show no adverse affects on health, others show moderate effects and still others point to a significant threat—mainly to developing infants and children. In other words; more studies could be undertaken, more years could go by and perhaps, just perhaps; enough evidence would emerge to prompt regulatory action.

Alternatively, we could take “precautionary” action on BPA; a view recently championed (perhaps unintentionally)  by Senator Diane Feinstein (D-CA):

"Evidence is mounting that exposure to this chemical is dangerous for developing children. Americans should not be used as guinea pigs by chemical companies while we wait, potentially for several years, for more scientific evidence to show this chemical is harmful to our health. The time has come to take action."

Although it may not have been her intention, Senator Feinstein is advocating for one of the more promising ideas in environmental health policy: Adoption of the so-called “precautionary principle.” Her recommendation that we shift toward a “better safe than sorry” attitude toward regulating BPA and other potential environmental hazards is one that is gaining growing
support in this country and underpins the current chemical regulatory framework in the European Union.

The concept first gained traction in the 1970’s with environmentalists in Germany, and has been percolating around the environmental movement since then. A working definition of the precautionary principle emerged in the U.S. in 1998 at a meeting of environmentalists: "When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically."
 
Richard Clapp, a professor at Boston University’s School of Public Health who has done extensive research on worker’s exposure to industrial chemicals and cancer told me; “Right now we employ the ‘Reactionary Principle;’ we wait until we can count the bodies before removing a chemical like BPA from the environment. With precautionary action, we’re trying to anticipate problems before they happen.”

The other major goal of the precautionary approach is to shift the burden of “proving” that a chemical agent is safe away from regulators and back onto the manufacturer prior to marketing. This acknowledges that there is a serious lack of up-to-date toxicology data available for thousands of chemicals currently on the market today; making it nearly impossible for regulators to remove potentially dangerous agents. The concept also requires that those interested in using certain chemical agents explore a range of alternatives that could limit harm to drinking water, air, and human health. 

For example, in the case of phthalates—plasticizers found in children’s toys and many other consumer products—there is moderate but not overwhelming evidence that the chemicals are endocrine disrupters that can harm the reproductive system. “Under the current regulatory model, phthalates will remain in products until scientists prove they cause harm,” says David Kriebel, Co-Director of the Lowell Center for Sustainability, a program at the University of Massachusetts, Lowell that helps industry and other groups work on environmental solutions. “Under a precautionary model, phthalates, with moderate evidence of harm, might not be used in products used by children and, as a result, safer alternatives would be explored.”

So far, precautionary action in this country occurs only on a case-by-case basis—and usually only after large-scale pushes by health advocates and consumer outcry. Linking adverse health affects with infants and children has been a particularly effective strategy. In July 2008, as a result of pressure from the Environmental Working Group and other advocacy groups, the U.S. Congress passed legislation banning six phthalates from children's toys and all cosmetics. Legislators in Washington State, Vermont and California have restricted phthalate use in children’s goods, and several major retailers, including Wal-Mart, Toys-R-Us, Lego, Evenflo and Gerber say they will voluntarily phase-out toys containing the plasticizers. This same kind of response is happening now with BPA and water bottles.

The European Union, meanwhile, has banned or restricted thousands of industrial chemicals used in consumer products like cosmetics and toys, agriculture and elsewhere. Many, like the herbicide atrazine—a chemical that is believed to have endocrine-disrupting and carcinogenic properties—are banned in Europe but are still widely used in the U.S. The EU has already taken a major step toward embracing the precautionary principle. In 2007, the EU began using a new approach called REACH  (Registration,  Evaluation and Authorization of Chemicals) for regulating chemicals that requires companies to provide extensive safety and use information about their agents before they can be marketed. American companies consider these regulations to be a burden; requiring them to provide extensive toxicity information and to reformulate some products that they sell in Europe to avoid bans and restrictions.

According to its website, the National Petrochemical and Refiners Association “considers REACH an unnecessary regulatory and social experiment during these uncertain economic times and, quite possibly, a detriment to European competitiveness in the global marketplace.” And when the chemical industry talks about reforming TSCA, they call for continuing to use a “risk-based, science-based” approach to regulating chemicals; i.e. the status quo. They support industry fees that will provide the EPA with a larger staff and pay lip service to giving the agency more authority for banning chemicals that pose a demonstrated risk to human health or the environment—but industry strongly opposes any regulations like REACH that include the precautionary principle.

Meanwhile, last month Senator Frank Lautenberg (D-NJ) introduced a bill in the Senate called the “Safe Chemicals Act of 2010” that would substantially amend TSCA and bring it closer to REACH in the European Union. A similar bill, the “Toxic Chemical Safety Act of 2010,” was introduced in the House. These bills would require manufacturers to submit safety data on each chemical produced and its use, the EPA will be required to prioritize chemicals based on their level of risk and act quickly on those considered high risk. The scope of what can be considered proprietary and therefore confidential information will be significantly narrowed and the focus will be shifted to finding safer alternatives to potentially toxic chemicals.

The battle that lies ahead in reforming TSCA could be epic—pitting environmentalists and health advocates against a formidable industry lobby and the Congressmen they heartily support. It's a battle the current administration should enter on the side of precaution. The science of toxicology is still evolving, yet it has advanced enough to point to the need for action on reducing our exposure to environmental carcinogens and other harmful agents. The President’s Cancer Panel Report provides 200-plus pages of compelling evidence; it’s time to call for TSCA reform and demand that companies provide evidence that their products are safe before we set them lose into our fragile and complex environment.