Endocrine disruptor own hormones. These regulation effects are intertwined so that a hormone that is level affected by another hormone in turn affects the levels of multiple other hormones produced by the body itself, leaving no endogenous hormones or traits affected by them unaffected by endocrine disruptors. Most toxicants, including endocrine disruptors, have been claimed to follow a U-shaped dose response curve. This means that very low and very high levels have more effects than mid-level exposure to a toxicant. Endocrine disrupting effects have been noted in animals exposed to environmentally relevant levels of some chemicals. For example, a common flame retardant,
Obesity and the environment trigger." The theory of environmental obesogens proposes a different causal facet to obesity – that lifetime exposure to xenobiotic chemicals may change the body's metabolic system. Chemical obesogens are molecules that do not properly regulate lipid metabolism in the body and could therefore promote obesity. Data is scarce, but some in-vitro studies have found this model could be an accurate predictor of future obesity. A study suggested that smoking before and during pregnancy, for example, increases the risk of obesity twofold in children of school age. Many chemicals that are known or suspected to be obesogens are endocrine disruptors. These