The Chemical Manufacturers Association Phthalate Esters Program Panel submitted a voluntary test program under Section 4 of the Toxic Substances Control Act to the Environmental Protection Agency on October 30, 1981. Volume II of that submission dealt with health effects of phthalate esters. Notification of the Program's acceptability was given by the Agency on January 5, 1982. The Health Effects Program is intended to give guidance regarding the level of concern over health effects due to phthalates, prioritize phthalates for further testing in terms of the effects of concern, and initiate such further testing as may be appropriate. Three types of testing were conducted: genotoxicity tests, biological studies focusing on liver structure and function, and metabolic studies. Testing is proceeding in two phases; Phase I consists of genotoxicity and biological studies with reference materials to provide validation and optimization of the proposed tests. Phase II would be performed on phthalate esters chosen to be representative of the major structural classes. Metabolic studies on di-2-ethylhexyl phthalate (DEHP) were also undertaken simultaneously with Phase I.