Overview and Expected Outcomes


Breast cancer rates vary widely across California. Differential exposures to environmental contaminants, e.g., via drinking water, is one possible contributor. California’s public water supplies come from diverse sources and are subject to varying degrees and types of treatment. Rapid advances in chemical detection technologies allow a much broader range of potential carcinogens to be sensitively detected in water supplies.

In this project, tap water will be collected twice from 120 California households receiving their water from one of 8 public suppliers. Bottled water (30 samples) will also be tested for comparison. Half of the household water systems tested will be located within areas of concern for elevated breast cancer rates. Water samples will also be tested for the presence of compounds that may interfere with the endocrine system, one potential pathway to breast cancer.

Research questions:

1. Which water sources are associated with the highest levels of endocrine disrupting compounds or known cancer causing agents? Are these water sources in communities with historically elevated breast cancer rates compared with areas with lower rates? How do these compounds vary across households within a particular water system?

2. How do water treatment processes, particularly disinfection and advanced treatment operations influence the levels and identities of estrogen active or carcinogenic compounds present in water supplies?

Expected Outcomes and Impact on Breast Cancer:

This study will be the largest and most comprehensive systematic investigation ever conducted of nontarget chemicals in diverse drinking water sources. Combined with measurement of estrogenic activity of the samples, it offers the opportunity to identify water sources and/or treatment operations that may elevate cancer risks.

Four of the eight public water systems to be studied (San Mateo, Oakland, Irvine, Los Angeles) are within areas of elevated breast cancer risk and will allow us to determine if there are statistically elevated levels of known mammary gland carcinogens, suspected carcinogens, or estrogenic endocrine disrupting activity in these communities.

Our partnerships with breast cancer research and advocacy organizations Breast Cancer Prevention Partners (BCPP) the Susan G. Komen Advocates in Science program (Komen), and Zero Breast Cancer (ZBC), as well as with organizations having extensive knowledge of drinking water systems, as represented by the Orange County Water District (OCWD) and the Yurok Tribal Environmental Program (YTEP) will ensure the research is conducted in a manner that will maximize benefits to these groups and that results are communicated in ways that are sensitive to the concerns of breast cancer patients, survivors and others concerned about the quality of California’s drinking water supply.