... we find ourselves facing a rising tide of biologically active, synthetic organic chemicals. Some tinker with our hormones. Some attach themselves to our chromosomes and trigger mutations. Some cripple the immune system. Some light up our genes and so enhance the production of certain enzymes. If we could metabolize these chemicals into completely benign breakdown products and excrete them, they would pose less of a hazard. Instead, a good many of them accumulate.

We can decide that the presence of cancer-causing substances in our air, water, and food is too expensive. A 2009 study, for example, has found that coal miners in Appalachia costs the region five times more in premature deaths, including from cancer, than it provides to the region in jobs, taxes, and economic benefits. In California, the production and use of hazardous chemicals cost the state $2.6 billion in 2004 alone in lost wages and health-care expenses to treat workers and children with pollution-linked diseases.

We can change our thinking. Rather than viewing the chemical adulteration of our environment and our bodies as the inevitable practice of convenience and progress, we can decide that cancer is inconvenient and toxic pollution archaic and primitive. We can start seeing the creation of carcinogens as the result of outmoded technologies. We can demand green engineering and green chemistry. We can let our systems of industry and agriculture know that they are suffering from a design flaw.

The study of how substances alter gene expression is part of the field of epigenetics. Some chemical exposures appear to turn on and turn off genes in ways that disregulate cell growth and predispose for cancer. From this perspective, our genes are less the command-and-control masters of our cells and more like the keys of piano, with the environment as the hands of the pianist.

As currently written, the laws require certain manufacturers and users of such chemicals to report any and all environmental releases-either accidental or routine-to air, water, or soil. The Toxics Release Inventory is the main registry of such events, and it is available to the public through the Environmental Protection Agency. It is hardly comprehensive. Toxic emissions reported to the federal government are thought to account for only 5 percent of all chemical releases.

Between the late 1950s and the late 1980s, more than 750 million tons of chemical wastes were discarded.

Besides, the sense of safety offered by bottled water is a mirage. It turns out that breathing, not drinking, constitutes our main route of exposure to volatile pollutants in tap water, such as solvents, pesticides, and byproducts of water chlorination. As soon as the toilet is flushed or the faucet turned on-or the bathtub, the shower, the humidifier, the washing machine-these contaminants leave the water and enter the air. A recent study shows that the most efficient way of exposing yourself to chemical contaminants in tap water is to turn on a dishwasher.