NTP Multigenerational Study of Environmental Estrogens

Abstract

Nearly 10 years ago, researchers with the National Toxicology Program (NTP) and the National Center for Toxicological Research (NCTR) began a complex set of experiments in rats to determine whether exposure to estrogenic compounds throughout life and across generations could cause changes in development or patterns of endocrine-related cancers at doses that cause only subtle reproductive effects. Now, at last, specialists in the field of endocrine-active chemicals are close to getting a first look at the findings from these studies. The three compounds chosen for study—genistein, ethinyl estradiol, and p-nonylphenol—represent a natural estrogenic substance, a drug, and an industrial chemical, respectively. The first experiments for all three compounds focused on determining appropriate dose ranges for later multigenerational studies. Additionally, studies were conducted with genistein and ethinyl estradiol to determine whether and how the carcinogenic potential of these substances changed across generations following long-term chronic exposure. On 12 June 2006, the first reports based on these experiments will undergo peer review at a one-day meeting at the NIEHS, with final publication expected later this year and additional reports scheduled for review in 2007. The reports to be reviewed on June 12 center on genistein, an estrogen-like compound found in soy, and detail the results of dose range–finding studies and multigenerational reproductive and carcinogenesis experiments.