Endocrine disruptor include DDT, polychlorinated biphenyls (PCB's), bisphenol A (BPA), polybrominated diphenyl ethers (PBDE's), and a variety of phthalates. In fact, almost all plastic products, including those advertised as "BPA free", have been found to leach endocrine-disrupting chemicals. In a 2011, study it was found that some "BPA-free" products released more endocrine active chemicals than the BPA-containing products. Other forms of endocrine disruptors are phytoestrogens (plant hormones). Xenoestrogens are a type of xenohormone that imitates estrogen. Synthetic xenoestrogens include widely used industrial compounds, such as PCBs, BPA and phthalates, which have estrogenic effects on a living organism. Alkylphenols are xenoestrogens. The European
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