Endocrine disruptor occur from low-dose exposure to exogenous hormones or hormonally active chemicals such as bisphenol A. These chemical can bind to receptors for other hormonally mediated processes. Furthermore, since endogenous hormones are already present in the body in biologically active concentrations, additional exposure to relatively small amounts of exogenous hormonally active substances can disrupt the proper functioning of the body's endocrine system. Thus, an endocrine disruptor can elicit adverse effects at much lower doses than a toxicity, acting through a different mechanism. The timing of exposure is also critical. Most critical stages of development occur in utero, where the fertilized egg
Toxic Substances Control Act of 1976 later explained during a 1975 Congressional Testimony, "While some authority exists to control the production of certain categories of toxic substances, such as pesticides, drugs, and food additives, most existing Federal authorities are designed to prevent harmful exposure only after the substances have been introduced into production." In Order to adequately regulate what chemicals should enter the environment, CEQ recommended that the government create a more comprehensive chemical policy to identify and control the chemicals that are manufactured, produced, and used in the U.S economy. Specifically, CEQ recommended that TSCA strengthen government oversight by requiring the following measures: First, manufacturers