Endocrine disruptors (EDs) are chemicals that may act on the endocrine, or hormone, system. They often are similar in structure to natural hormones, so they may mimic or block the actions of the body’s hormones. They may also be called environmental estrogens (although other hormones may be involved) or “hormonally-active agents” (HAAs). The endocrine system regulates numerous functions in our bodies, with hormones acting as messengers between brain and other organs. The endocrine system of primary concern in relation to these chemicals is the one that controls reproduction, including menstrual cycling, sperm production, and normal pregnancy, involving hormones from the brain, pituitary and reproductive organs. Other systems include the thyroid system, which is critical to brain development during pregnancy, and the system that controls glucose (or sugar) levels in our bodies. More and more chemicals that are commonly used have been identified as potentially having these hormonal properties, primarily from animal studies and observations in exposed wildlife. The exposures may be linked to impaired reproduction or infertility, feminization of certain male species, lower sperm counts, delayed or early puberty, and certain cancers, including breast or other reproductive tract cancers. Some of the classes of chemical shown or suspected to have these effects include chemicals found in plastics or household products like phthlates or phenols, fire retardants called poly-brominated biphenyls (PBDEs) or poly-chlorinated biphenyls (PCBs, now banned), pesticides like DDT and others, and heavy metals, like mercury. Some of these chemicals persist in the environment a long time and get into the diet. EHIB staff are conducting a number of projects on these chemicals examining associations with breast cancer, autism, and puberty. In addition, work has been conducted to determine how we are exposed to these chemicals, including measuring levels in the body, also called biomonitoring.
Exposure to Organochlorine Compounds and Effects on Ovarian Function
Background: Some chemicals appear to have hormonally active properties in animals, but data in humans are sparse....
High body burdens of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in California women
Following our first report on elevated polybrominated diphenyl ether (PBDE) concentrations in California women, we expanded our investigation to include diverse groups of local women....
Cohort Study of Girls Nutrition, Environment and Tanner stage
-- This project is a renewal of the prior 7-year longitudinal study of factors that affect age at pubertal development in girls and is part of the Breast Cancer & the Environment Research Program (BCERP),....
Dioxins in adipose tissue and risk of breast cancer
-- Objective: To evaluate the breast cancer risk associated with body burden levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)....
Environmental and Genetic Determinants of Puberty
-- This project is part of the larger Bay Area Breast Cancer & the Environment Research Center (BCERC) at UCSF, which includes animal and epidemiological studies....
Organochlorine Body Burden in Women With and Without Breast Cancer
-- Recently considerable concern has focused on the relationship between environmental contaminants and the incidence of breast cancer....
Pesticide Use in the U.S.-Mexico Border Region
-- EHIB analyzed pesticide use data from 1991 to 1995 in Imperial and San Diego Counties, to investigate areas where potential pesticide exposures could occur in children living along the US-Mexico border....
Sex Ratio Among California Births, 1960-1996
-- The male sex ratio at birth (or the proportion of births in a population that is male) has been suggested as a sentinel environmental health indicator....
Testicular Cancer: Etiologic Factors
-- Although testicular cancer is the most common cancer in young males in the United States, and its incidence is increasing worldwide, not much is known about the etiology of this illness....