From The New Republicc:

What I’ve discovered will come as no surprise to anyone who has been paying serious attention to research on consumer products, but, since that description had not previously applied to me, or to most people I know, I’ll report my finding: The United States deals with potentially toxic household products in a manner that is so cavalier that it would, in a saner world, be called negligence. To my husband, I explain that the world has not grown qualitatively more toxic than in the bad old preenvironmentalist days. What has changed is that the scientific understanding of how these things are poisonous has undergone a conceptual revolution, with the result that we mothers who fail to throw out our no. 7 plastics risk looking as complacent as Betty Draper, if not quite as culpable as those 1950s doctors who let themselves appear in ads for cigarettes.

When I first began my crash course on this subject, I assumed the reason quasi-eco-moms like me have spent the last half-decade fretting neurotically about the stuff our bodies come into contact with, rather than about the environment writ large—about what’s in our homes rather than in rivers and lakes and soil and air—is that we’re typical selfabsorbed bourgeois parents. Now I know the real reason is that we can see inside our bodies better than ever before, and what we find there horrifies us. Toxicologists used to test the environment and conduct surveys to discover the degree to which people might have been exposed to poisonous stuff; their conclusions were largely guesswork. Now, an increasingly common technology called biomonitoring lets them measure the effects of toxic exposure in blood, urine, breast milk, semen, and all the other parts of us where chemicals tend not to flush out. Biomonitoring brings home the truth in the saying that we are what we eat—not to mention drink, breathe, wear, sit on, rub up against, and chew on distractedly.

Since 1999, the Centers for Disease Control (CDC) has tested Americans every two years in order to build a database of what are called “body burdens,” thereby helping toxicologists set new standards for exposure and definitively link chemicals to illness, or else decouple them. The CDC started with 27 worrisome chemicals and is now up to 219. This process has revealed a surprising new form of egalitarianism at work on our continent: No matter how puritanical or hedonistic your lifestyle, whether you’re rich or poor, elderly or fetal, a resident of Portland or New York City, you almost certainly have BPA in your bloodstream, along with other toxins that have entered the food chain and water system or have become ubiquitous in building materials and food-packaging. In its most recent report on these body burdens, in 2009, the CDC stated that nearly everyone it tested had detectable amounts of BPA; of polybrominated diphenylethers, flame retardants that can thwart a fetus’s neurological development; of perfluorooctanoic acid (PFOA), the really bad stuff in non-stick cookware that has also been shown to thwart the proper development of young animals; of perchlorate, a chemical used in making rockets and fireworks, which can keep the thyroid from making necessary hormones; of a gasoline additive now banned in most states, methyl tert-butyl ether.

But is all this actually dangerous? Well, the answer depends on how you define “dangerous,” and, to know how to do that, you have to know about a paradigm shift in our understanding of toxicity that cuts so deep, it should thoroughly undermine your sense of what is safe and what isn’t.

The transformation started with something called the “endocrine-disruption hypothesis.” Its discovery in the late ’80s involves one of those heroic scientific narratives that make people like me— people who instinctively discount their own opinions when faced with the gnomic wisdom of credentialed experts—feel both emboldened and depressed. Its heroine is Theo Colborn, a rancher and mother of four who went back to school at the age of 51, eventually getting a Ph.D. in zoology. Soon after graduating, she landed a job reviewing other scientists’ data at the Conservation Foundation in Washington. She noticed that biologists investigating the effects of presumably carcinogenic chemicals on predators in and around the Great Lakes (fish, birds, reptiles, and mammals) were reporting odd phenomena. Whole communities of minks were failing to reproduce; startling numbers of herring gulls were being born dead, their eyes missing, their bills misshapen; and the testicles of young male gulls were exhibiting female characteristics. Colborn correlated this data with the presence in the water of organochlorine compounds such as PCBs, DDT, and dieldrin, some of which have hormone-mimicking effects and build up in fatty tissue. Often, the offspring of creatures exposed to chemicals were worse off than the animals themselves. Colborn concluded that nearly all the symptoms could be traced to things going awry in the endocrine system, the network of glands that orchestrates development by secreting hormones such as testosterone, estrogen, and growth hormone into the body at set times.