An excerpt from Chapter 11, Beyond Cancer

Cancer holds a special dread in our culture. If Rachel Carson helped publicize suspected links between rising cancer rates and increasing use of synthetic pesticides, other forces added momentum to the emerging cancer paradigm. In June 1969, the National Cancer Institute completed animal tests prompted by Silent Spring and did find a higher incidence of liver tumors in mice exposed over a long period to low levels of DDT. Within a week, President Richard Nixon received a petition from seventeen congressmen, who asked for a ban on DDT on the grounds that it caused cancer. In 1971,President Nixon declared an all-out War on Cancer. Given the temper of the time and new evidence that pesticides like DDT might cause cancer, environmentalists seeking to ban DDT began to frame the battle around human health risks rather than the wildlife and environmental concerns put forward in earlier phases of the long campaign. In his 1972 decision to restrict most uses of DDT, U.S. Environmental Protection Agency Administrator William Ruckelshaus gave equal prominence to possible human cancer risks and to the adverse impacts on fish and wildlife.

Just as cancer holds a special place in our fears, it also commands a special place in federal regulation. It has defined and driven the EPA's regulatory process for toxic chemicals for more than two decades, mainly because the agency uses different assumptions for assessing cancer risk than it does when considering other risks. For noncancer hazards such as reproductive and developmental damage, the agency assumes that a chemical may pose no hazard in low concentrations beneath some threshold level. But when it is a question of cancer, the EPA turns to a linear model, which assumes that no level is safe. Even the tiniest dose of a chemical is presumed capable of causing cancer.

The federal appeals court had reinforced such a regulatory bias by a series of rulings on pesticides in the early 1970s, beginning with a 1970 case concerning federal tolerance levels for DDT residues on food. The Environmental Defense Fund, which brought the action, based its case on the Delaney clause, a 1958 amendment to the Federal Food, Drug, and Cosmetic Act, which prohibits the use of any food additive that has been shown to cause cancer in laboratory animals. In its opinion, the court decided that this law applies to pesticide residues as well and that the carcinogenicity of these residues has to be considered in setting tolerance limits. The court also required the responsible cabinet secretary to explain the basis for deciding any level of DDT residues to be safe if he proposed continuing to allow residues in food commodities. The ruling in effect endorsed the strict attention to carcinogens that the Delaney clause mandates. By the mid-70s, "cancer-causing" had become inextricably wedded to the words "toxic chemical" in the popular culture.

With cancer as the ultimate measure of our fears, it was widely assumed that setting levels based on cancer risk would protect humans as well as fish and wildlife from all other hazards as well. So over the past two decades, pesticide manufacturers and federal regulators looked mainly for cancer and obvious hazards such as lethal toxicity and gross birth defects in screening chemicals for safety. Cancer has also dominated the scientific research program exploring possible human health effects from chemical contaminants in the environment. This preoccupation with cancer has blinded us to evidence signaling other dangers. It has thwarted investigation of other risks that may prove equally important not only to the health of individuals but also to the well-being of the society.

If this book contains a single prescriptive message, it is this: we must move beyond the cancer paradigm. Until we do, it will be impossible to grapple with the challenges of hormone disrupting chemicals and the threat they pose to the human prospect. This is not simply an argument for broadening our horizons to recognize additional risks. We need to bring new concepts to our consideration of toxic chemicals. The assumptions about toxicity and disease that have framed our thinking for the past three decades are inappropriate and act as obstacles to understanding a different kind of damage.

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