 The number of new chemicals is increasing exponentially. We're talking 12,000 new substances a day. Yet data aren't available on the hazards of even some of the high-volume chemicals. BPA is one of the highest-volume chemicals, with billions of pounds produced each year. And studies have raised concerns about its possible implication in the cause of certain chronic diseases, such as diabetes, obesity, reproductive disorders, cardiovascular diseases, birth defects, chronic respiratory and kidney diseases, and breast cancer. A new study in health implications of BPA comes out nearly every week. BPA was first developed over 100 years ago as a synthetic estrogen, but it wasn't until the 50s that industry realized it could be used to make polycarbonate plastic, and it rapidly became one of the most used chemicals worldwide, even though it was recognized to have hormonal effects. About a billion pounds are also used to line food and beverage cans, especially, it seems, in tuna and condensed soups. And now we basically all have BPA in our bodies and our children's bodies. But not to worry, the government says up to 50 a day is safe, 50 micrograms per kilogram. And even those working in Chinese BPA factories don't get exposed to more than like 70 times lower than that safety limit. OK, then why did exposure seem to affect the male worker sperm counts? In the US, the general population only gets less than like a thousand times lower than the safety limit, yet still, we seem to be seeing adverse effects on thyroid function, weight control, blood sugar control, cardiovascular disease, liver function, and immune function, even at those incredibly low doses. So the fact that there are significant adverse effects in populations exposed to BPA at concentrations thousands of times lower than the official tolerable daily limit indicates that the safe exposure to BPA may be much lower than previously thought in humans, yet the limit hasn't been changed. It's been banned from baby bottles and sippy cups, but nearly unlimited doses are still apparently OK for everyone else. What's the disconnect here? It has to do with the fascinating world of low dose effects of hormone-disrupting chemicals. For decades, these chemicals have challenged traditional concepts in toxicology, particularly the old adage that it's the dose that makes the poison. The concept that lower exposures to a hazardous compound will therefore always generate lower risks. That's the core assumption underlying our system of chemical safety testing. They start dosing lab animals with super high amounts and then keep lowering the dose until whatever adverse effects disappear, then add a safety buffer and assume everything below that dose should be OK, assuming the curve looks like this, you know, the higher the dose, the higher the effect. But hormone-disrupting chemicals can have all sorts of curious curves. Wait a second, how could something have more of an effect at a lower dose? Think about a hormone and its receptors in the body. At low levels of the hormone, like going from 0 to 1, the receptors can fill up quickly, but once they're almost all filled up going from 4 to 5, adding really high doses may not change things much. Let's use an actual BPA example. This was a study to see if BPA suppressed an obesity protective hormone in fat samples taken from breast reduction in tummy-tuck patients. As you can see, at a hundred nanomoles of BPA, feel like a weatherman here, but at a hundred nanomoles of BPA, you can see hormone levels are no lower than they are at zero BPA. And since most people have levels between like 1 and 20, then BPA must be safe. But here's the actual graph. So no suppression at zero, no suppression at a hundred, but right where levels are in people's bodies, BPA appears to cut hormone release nearly in half. As the world's oldest, largest and most active organization devoted to research on hormones concluded, even infinitesimally low doses of exposure. Indeed, any level of exposure at all may cause problems. Nearly $3 billion worth of problems every year, just counting the estimated effects of BPA and childhood obesity and heart disease alone. Now there are alternatives that the industry could use. The problem, though, is that they may cost two cents more.