Chemical Exposure Web Tool Defines Risks Faced by Millions of California Women

Tool Depicts Workplace Chemical Hazards that May Put Women at Risk for Breast Cancer

By Elizabeth Fernandez

A new web tool spells out for the first time the exposures that more than 6.5 million working women in California face that could increase their risk for breast cancer, including industrial solvents, antimicrobials and phthalates.

The tool, which was developed by researchers at UC San Francisco and the California Department of Public Health’s Occupational Health Branch, is part of an ongoing study focused on understanding potential breast cancer risks related to workplace chemical exposures.

Users can search the database by ethnicity/race, age, and occupation to see risk information on more than a thousand chemicals, sorted into 24 chemical groups, as well as which chemicals are likely to be present in various occupations. The tool can be found here.

“This is the first time that data of this magnitude have been made visible in one place,” said Robert Harrison, MD, MPH, co-principal investigator on the website project and founder of UCSF Occupational Health Services. He has diagnosed and treated more than 10,000 patients with work- and environmental-induced diseases and injuries. He also directs the worker tracking investigation program for the California Department of Public Health.

“With the site, researchers and advocates can see which chemical exposures may be putting working women in particular jobs at risk for breast cancer,” Harrison said.

still image showing chemical exposure risk for 243,053 formal registered nurses. The 24 chemicals are divided into probable, possible, and unlikely cause for concern.

Still image showing chemical exposure for registered nurses. View the interactive version here. Credit:

Site visitors also can see why certain chemical groups may be of concern for breast cancer, and find information on the likelihood that women in certain occupations, such as cashiers, housekeepers and nurses, are facing increased risk from workplace exposures.  

While only a fraction of the estimated 80,000 chemicals used in workplaces have been tested to see if they cause cancer, at least 200 have been shown to cause mammary tumors in animals.

The interactive tool also enables viewers to map out what women’s employment looks like in California, and what chemical exposures are likely to occur in the jobs where substantial numbers of women work. The tool shows known and suspected mammary gland carcinogens, mammary gland toxicants, and endocrine disrupting chemicals.

Such explorations will provide important preliminary data to guide future research aimed at understanding breast cancer risks associated with occupational chemical exposures.

“There are currently gaps in our understanding about the risks of cancer faced by working women, particularly women of color,” said Peggy Reynolds, PhD, MPH, co-principal investigator and epidemiologist at UCSF. Her research focuses on environmental risk factors for cancer. 

The data presented on the web site are meant to present simple snapshots of potential chemical exposures faced by working California women and enumerate the number and characteristics of the workforce who may be potentially exposed. Exposure probabilities are presented as “probable,” “possible,” or “unlikely” based on a job exposure matrix (JEM) created by the research team. 

The matrix is a qualitative assessment of the potential for exposure due to job task or location. The creation of such an assessment was necessitated by the lack of existing occupation-specific quantitative chemical exposure data. 

The list of occupations was constructed from the American Community Survey, administered by the U.S. Census. 

The data visualization tool also indicates which occupational groups are likely to contain an informal workforce that does not show up in formal data sources and often operates outside of established labor laws, and shows the exposure probabilities for women working informally.

Principal investigators: Robert Harrison and Peggy Reynolds of UCSF. They report no conflict of interest.

Funding: The research is funded by the California Breast Cancer Research Program at the University of California, and supported by occupational health experts at the Public Health Institute, the California Department of Public Health, and UCSF.

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