Small doses can have big health effects. That is a main finding of a new report, three years in the making, published Wednesday by a team of 12 scientists who study hormone-altering chemicals. Dozens of substances that can mimic or block hormones are found in the environment, the food supply and consumer products, including plastics, pesticides and cosmetics. One of the biggest controversies is whether the tiny doses that most people are exposed to are harmful. Researchers led by Tufts University’s Laura Vandenberg concluded after examining hundreds of studies that health effects “are remarkably common” when people or animals are exposed to low doses. "Fundamental changes in chemical testing are needed to protect human health," they wrote.