Phthalates are a class of compounds used to hold color and scent in many cosmetics and personal care items such as soaps, detergents, skin preparations and aftershave lotions, and they also find their way into food through packaging materials. Di-ethylhexyl phthalate, one form of phthalate, is used to soften a wide range of plastic goods, which includes medical devices. Phthalates are also present in drinking water and air. Studies conducted by the Centers for Disease Control and Prevention found MEP in more than 75 percent of U.S. subjects sampled. Measurements were made of five different urinary phthalate metabolites, but only one yielded a significant association with sperm DNA damage, and that was MEP, which was found in all of the urine samples and at higher levels than the other metabolized phthalates. Researchers, led by Susan M. Duty and Russ Hauser of the Harvard School of Public Health, have termed the study preliminary, as it evaluated semen and a single urine sample from a limited number of subjects, just 168 men at an infertility clinic associated with the Vincent Memorial Obstetrics and Gynecology Service, Massachusetts General Hospital. The researchers plan follow-up studies with larger groups of men to confirm the results.