Published By: Water Quality
What are Endocrine Disruptors?
Endocrine disruptors are substances that alter the function of the endocrine system. Endocrine disruptors may be naturally occurring or man-made; some PPCPs may act as endocrine disruptors. Endocrine disruptors may cause adverse health effects in one of three ways: (1) they may mimic the actions of naturally, self-produced hormones, (2) they may block receptors so that naturally occurring hormones cannot act appropriately, or (3) they may affect the synthesis, metabolism or excretion of naturally occurring hormones.
How May I be Exposed to Endocrine Disruptors?
Naturally occurring plant hormones, known collectively as phytoestrogens, are abundant in the human diet. Some common foods known to contain phytoestrogens are: legumes (especially soybeans), clover, citrus fruits, grapes and flax seeds. Heavy metals such as arsenic, lead, mercury or cadmium may have endocrine disruption properties. Man-made endocrine disruptors include synthetically produced hormones such as oral contraceptives, and man-made chemicals including polychlorinated biphenyls (PCBs), pesticides (e.g. atrazine, perchlorate, DDT), or plastics additives (e.g. phthalates, bisphenol A).
What Health Effects May Endocrine Disruptors Have?
Because of structural similarity to the human hormone estrogen, phytoestrogens may interact with estrogen receptors to produce estrogenic effects in humans. Although not conclusive, studies suggest that the consumption of phytoestrogens-containing foods may provide a protective effect against menopausal symptoms, and breast and prostate cancers. Adverse reproductive effects have been seen in animals that consume plants with large amounts of phytoestrogens, however; observations of humans have not confirmed these effects.
Besides the adverse effects of diethylstilbestrol, the effects of man-made endocrine disruptors on human health are not proven. However, data from animal studies and epidemiologic studies suggest a possible role of man-made endocrine disruptors in adverse human health outcomes including reproduction, neurobehavior, immune function, and cancer.
The biological importance of exposure to very low levels of endocrine disruptors is uncertain but a recent health risk assessment indicated no appreciable risks to human health by the trace amounts of pharmaceuticals in U.S. water (Schwab, 2005). Scientists continue to study endocrine disruptors to better understand how people are exposed and what effects endocrine disruptors may have.
Should I be worried about endocrine disruptors in my drinking water?
No. San Francisco has one of the most pristine water sources in the country. SFPUC participated in the American Water Works Research Foundation project “Toxicological Relevance of EDCs and Pharmaceuticals in Drinking Water”. As part of the project, water samples were collected in 2006 from source and treated water. Tests included 26 potential endocrine disruptors, 5 steroid hormones, and 11 phytoestrogens. An additional bioassay for estradiol equivalents – a test for proliferation of human breast cells in response to estrogenic compounds-- was also completed. Two steroid hormones, progesterone and estrone were detected in SFPUC source water at levels of 2.5 and 0.2 parts per trillion; however, none of the tested compounds were detected in SFPUC treated and distribution system waters. “We didn't detect anything whatsoever,” said Dr. Shane Snyder, Research Manager at the Southern Nevada Water Authority and Principal Investigator for the study by the research arm of the nation's water utilities. His interview with the San Francisco Chronicle was published on March 11, 2008 .
What is SFPUC doing to ensure safety of San Francisco’s drinking water?
SFPUC meets all state and federal drinking water regulations. It employs a multi-barrier approach to water quality protection, i.e., not relying on any single protective measure but rather utilizing several safeguards to ensure that high water quality is achieved. SFPUC has sought to protect this quality through an on-going strategy of watershed control, optimized water treatment, sound distribution system operations and focused management. Consequently, SFPUC has not been vulnerable to types of contaminants (e.g., MTBE, pharmaceuticals, pesticides, etc.) that concern many other water suppliers. This strategy has served the customers of the SFPUC well in the past and it serves as a foundation for the future.
SFPUC has recently completed a Water Quality Protection Plan to ensure that the safety and quality of drinking water is maintained and improved in the future. The SFPUC was tasked by the San Francisco Mayor Gavin Newsom to develop such a plan in conjunction with the World Water Day on March 20, 2008. SFPUC has engaged a Council of national experts to advise SFPUC on the direction to protect and improve water quality. The National Water Quality Advisory Council was “unanimous in affirming that the SFPUC has a superb source of supply and a well-operated system. It is amongst the best in the country. This cannot be emphasized highly enough.” The Council also noted new challenges occurring as a consequence of technological advances, health effects research and changing customer expectations. Eleven recommendations were formulated to further protect and improve San Francisco’s drinking water quality.
The recommendations from the Council most applicable to address emerging contaminants, such as PPCPs and EDCs, are to: (1) continue to protect quality of the source waters, (2) continue to evaluate advanced treatment options, (3) continue to monitor technology developments, (4) clarify the monitoring framework for emerging contaminants.
For Further Information:
WHO, International Programme on Chemical Safety, Global assessment of the state-of-the-science of endocrine disruptors (2002)
EPA "What are Endocrine Disruptors?" Fact Sheet
EPA Endocrine Disruptor Screening Program
European Union, Endocrine Disrupter Research
National Academy Press - Hormonally Active Agents in the Environment (2000)
CDC, Third National Report on Human Exposure to Environmental Chemicals (2005)
