Comment - 21816 - Breast Cancer Prevention Partners

Breast Cancer Prevention Partners (BCPP) 1288 Sutter Street #109 San Francisco, CA 94109 Feb 6, 2026 Office of Environmental Health Hazard Assessment (OEHHA) CalEnviroScreen 5.0 Public Comment 1515 Clay Street, 16th Floor Oakland, CA 94612 RE: Public Comment on CalEnviroScreen 5.0 – Inclusion of Breast Cancer as a Population Characteristic Indicator Dear OEHHA CalEnviroScreen Team, I am submitting public comment on the development of CalEnviroScreen 5.0, urging OEHHA to consider including breast cancer as a population characteristic indicator. Given the substantial and growing body of peer-reviewed scientific literature demonstrating clear associations between multiple environmental exposures and breast cancer incidence, the inclusion of this indicator would significantly enhance the tool's ability to identify vulnerable communities and inform environmental justice policies. RATIONALE FOR INCLUSION Breast cancer is the most commonly diagnosed cancer among women in California and the United States. While genetic and hormonal factors play important roles, accumulating evidence demonstrates that environmental exposures contribute significantly to breast cancer risk. These environmental links are particularly relevant to CalEnviroScreen's mission of identifying communities disproportionately burdened by pollution and adverse health outcomes. Unlike many other cancer types already considered in environmental health assessments, breast cancer has been directly linked to several of the environmental exposures that CalEnviroScreen already measures—including PM2.5, diesel particulate matter, air toxics, lead, drinking water contaminants, pesticides, and proximity to hazardous waste facilities. This makes breast cancer an ideal candidate for inclusion as a population characteristic that reflects cumulative environmental burdens. SCIENTIFIC EVIDENCE: AIR POLLUTION AND BREAST CANCER Fine Particulate Matter (PM2.5) and Diesel Exhaust A landmark study published in the Journal of the National Cancer Institute analyzed data from 196,905 women in the NIH-AARP Diet and Health Study. White et al. (2023) found that ambient PM2.5 exposure was associated with increased breast cancer risk, particularly for estrogen receptor-positive (ER+) tumors. Notably, the researchers evaluated historical PM2.5 concentrations 10-15 years prior to study enrollment, accounting for the long latency period of cancer development. This study represents one of the largest investigations to date on the relationship between outdoor air pollution and breast cancer incidence. Nitrogen Dioxide (NO2) as a Marker for Traffic-Related Air Pollution A systematic review and meta-analysis by Praud et al. (2023) examining traffic-related air pollution found a significant positive association between NO2 exposure—a marker for traffic-related air pollution and diesel exhaust—and breast cancer risk (pooled relative risk of 1.015 per 10 µg/m³ increase in NO2; 95% CI: 1.003-1.028). The study reviewed 21 epidemiological investigations and concluded that the findings provide additional support for air pollution carcinogenicity. A case-control study in Montreal found evidence of an association between exposure to outdoor NO2 concentrations and the incidence of postmenopausal breast cancer, with an increased risk of approximately 25% for every increase of 5 ppb in exposure (Goldberg et al., 2010). The authors noted that aromatic hydrocarbons in diesel exhaust are lipophilic and may reach elevated concentrations in breast tissue. SCIENTIFIC EVIDENCE: HAZARDOUS AIR TOXICS AND BREAST CANCER The California Teachers Study evaluated the 2002 EPA National Air Toxics Assessment database to examine associations between hazardous air pollutants and breast cancer risk (Garcia et al., 2015; Hurley et al., 2014). In a study of 24 air toxics selected based on their ability to induce mammary gland tumors, researchers reported associations for acrylamide, carbon tetrachloride, chloroprene, 4,4'-methylene bis(2-chloroaniline), propylene oxide, and vinyl chloride with breast cancer. A 2024 study in the Los Angeles area examined 16 hazardous air pollutants from the National-Scale Air Toxics Assessment among the Multiethnic Cohort and found that 14 of 16 chemicals significantly increased breast cancer risk (Heck et al., 2024). Notably, 8 of 11 chemicals that increased breast cancer risk came from manufacturing, landfill, and hazardous waste emissions, with vinyl acetate, vinyl chloride, ethylene dichloride, and 1,1,2,2-tetrachloroethane presenting the highest breast cancer risk. Increases in breast cancer risk from hazardous air pollutants were greatest for women of color, highlighting environmental justice concerns. The International Agency for Research on Cancer has classified diesel exhaust as carcinogenic to humans, and the EPA classifies it as "likely to be carcinogenic to humans." Communities near major roadways, diesel truck routes, ports, and distribution centers face disproportionate exposure to diesel particulate matter and associated air toxics. SCIENTIFIC EVIDENCE: LEAD EXPOSURE AND BREAST CANCER Lead has been reclassified by the International Agency for Research on Cancer from a "possible" to "probable" human carcinogen. Lead acts as an endocrine disruptor and interferes with enzymatic and hormonal processes relevant to breast cancer development. A 2024 prospective cohort study of women in Poland found that blood lead levels were significantly associated with breast cancer risk, particularly in women under 50 years of age (Jaworska et al., 2024). The study noted that young women with higher blood lead levels had significantly increased cancer risk, possibly through interactions with estrogen. A case-control study in Serbia found lead bioaccumulation in breast cancer tissues, with significant positive correlations between lead levels and both tumoral mutational burden and microsatellite instability, suggesting an association with genomic instability (Javorac et al., 2025). An analysis of 2003-2012 National Health and Nutrition Examination Survey data found that women in higher quartiles of blood lead levels had significantly increased odds of prevalent breast cancer compared with those in the lowest quartile (Liu et al., 2019). While some studies have shown inconsistent results, a 2024 systematic review noted that 16 of 27 studies examining lead in various biological matrices reported positive associations between lead exposure and breast cancer risk. SCIENTIFIC EVIDENCE: PESTICIDE EXPOSURE AND BREAST CANCER Women in agricultural regions face elevated exposure to pesticides through occupational activities, pesticide drift, contaminated drinking water, and residential proximity to treated fields. Multiple studies have documented associations between pesticide exposure and breast cancer risk. A 2024 case-control study in Brazil found that a region with intensive pesticide use had a 41% higher breast cancer diagnosis rate and 14% higher breast cancer mortality rate than the national average, with a pesticide trade volume about 6 times higher than the national average (da Silva et al., 2024). The study found that exposure to pesticides increased breast cancer risk and promoted more aggressive metastatic disease. Notably, women who did not work in fields but performed equipment decontamination and clothes washing of partners who worked with pesticides had urine samples positive for glyphosate, atrazine, and 2,4-D. Studies from the Agricultural Health Study found that chlorpyrifos and terbufos were significantly associated with increased breast cancer risk in premenopausal women (Engel et al., 2005), and a California study found that breast cancer was three times as likely to occur among women exposed to chlorpyrifos at residences or workplaces compared with those not exposed (Gunier et al., 2011). A 2025 study examining occupationally exposed rural women diagnosed with breast cancer found significant reductions in immune system cytokines (IL-1β, IL-12, IL-17A, TNF-α) in exposed patients, suggesting pesticides impair immune response crucial for cancer defense (Carneiro et al., 2025). Organophosphate pesticides, organochlorine compounds including DDT and PCBs, and triazine herbicides have all been implicated in breast cancer risk through mechanisms including endocrine disruption, genotoxicity, and epigenetic modifications. SCIENTIFIC EVIDENCE: DRINKING WATER CONTAMINATION AND BREAST CANCER Per- and Polyfluoroalkyl Substances (PFAS) PFAS are synthetic "forever chemicals" that persist in the environment and have been detected in approximately 45% of drinking water supplies across the United States. These chemicals act as endocrine disruptors and have been linked to breast cancer. A 2023 nested case-control study in the PLCO Cancer Screening Trial with 621 postmenopausal breast cancer cases found that serum PFOS concentrations were positively associated with hormone receptor-positive breast cancer (Chang et al., 2023). A French study with 194 postmenopausal breast cancer cases also observed a positive association with pre-diagnostic serum PFOS concentrations, particularly for hormone receptor-positive tumor subtypes. A meta-analysis examining PFAS exposure and breast cancer found that PFOA and PFHxS were positively correlated with breast cancer risk, with pooled odds ratios of 1.32 (95% CI: 1.19-1.46) and 1.79 (95% CI: 1.51-2.11), respectively (Jiang et al., 2022). A 2025 nationwide ecological study found that counties with PFAS-contaminated drinking water had higher cancer incidence, and the authors estimated that PFAS contamination of drinking water contributes to more than 6,800 cancer cases annually in the United States (Li et al., 2025). Other Drinking Water Contaminants Drinking water can be contaminated by various chemicals that may increase breast cancer risk, including disinfection byproducts, nitrates from agricultural runoff, and arsenic. Communities relying on private wells or older water infrastructure may face particularly high exposures. Advanced water filtration that removes PFAS has been shown to simultaneously reduce levels of other harmful contaminants including disinfection byproducts, nitrates, and heavy metals. SCIENTIFIC EVIDENCE: PROXIMITY TO HAZARDOUS WASTE SITES Proximity to hazardous waste sites, landfills, and toxic release facilities represents another environmental exposure pathway. Waste sites contain a broad range of suspected or confirmed human carcinogens and can contaminate air, soil, and groundwater. A 2022 study examining historical redlining in Detroit found that historically redlined neighborhoods were situated near 1.7 times more hazardous waste sites and twice as many Risk Management Plan sites than non-redlined neighborhoods (Nardone et al., 2022). These communities also experienced 4.4% higher lifetime cancer risk from air toxics inhalation. Several studies have examined cancer incidence in communities near waste sites, landfills, and Superfund locations, though methodological limitations have prevented definitive conclusions. A review of 19 studies examining cancer near toxic waste sites noted that most studies were ecological and few included detailed exposure assessment or contaminant measurements. The California Teachers Study and other research have documented that hazardous air pollutants from manufacturing facilities, landfills, and waste sites are associated with increased breast cancer risk, with the strongest effects observed for vinyl chloride, vinyl acetate, ethylene dichloride, and tetrachloroethane—chemicals commonly released from waste management facilities and industrial operations. BIOLOGICAL PLAUSIBILITY The associations between these environmental exposures and breast cancer are supported by plausible biological mechanisms: • Particulate matter and diesel exhaust contain endocrine-disrupting chemicals, polycyclic aromatic hydrocarbons, and genotoxic compounds that may directly affect breast tissue • Air pollutants cause oxidative stress, inflammation, and DNA damage • Lead interferes with hormonal processes, mimics calcium in biological systems, and inhibits DNA repair mechanisms • Pesticides act as endocrine disruptors, cause genotoxic effects, and suppress immune function • PFAS interfere with normal hormonal function and have estrogenic properties • These exposures often co-occur in environmental justice communities, suggesting potential for cumulative or synergistic effects ENVIRONMENTAL JUSTICE CONSIDERATIONS The inclusion of breast cancer as a population characteristic indicator is particularly important from an environmental justice perspective: 1. Communities already identified by CalEnviroScreen as facing high pollution burdens are also likely experiencing higher environmental exposures linked to breast cancer. 2. Women of color experience disproportionate exposure to hazardous air pollutants, with studies showing the greatest increases in breast cancer risk among these populations. 3. Low-income communities and communities of color often face higher concentrations of traffic-related air pollution, diesel exhaust, pesticide drift, PFAS-contaminated drinking water, lead exposure, and proximity to hazardous waste sites due to residential segregation, proximity to industrial facilities and highways, and lack of political power. 4. Agricultural workers and their families, who are predominantly Latino, face elevated pesticide exposures through occupational contact, take-home contamination, residential proximity to treated fields, and contaminated drinking water. 5. Historically redlined communities continue to experience elevated exposures to diesel particulate matter, air toxics, hazardous waste sites, and associated cancer risks. 6. Including breast cancer would help identify communities where environmental interventions could reduce cancer burden, particularly for the most common cancer affecting women. CALENVIROSCREEN CONNECTIONS CalEnviroScreen currently measures several environmental exposures that have been directly linked to breast cancer in peer-reviewed research: • PM2.5 - Associated with breast cancer in large prospective cohort studies • Diesel Particulate Matter - Component of traffic pollution linked to breast cancer • Traffic Density - Proxy for NO2 and diesel exhaust exposure associated with breast cancer • Ozone - Component of air pollution mixture • Drinking Water Contaminants - CalEnviroScreen includes drinking water indicators; PFAS and other contaminants are associated with breast cancer • Pesticide Use - CalEnviroScreen includes pesticide use indicators; multiple pesticides are linked to breast cancer • Hazardous Waste Proximity - Communities near waste sites face elevated exposures to breast carcinogens • Toxic Release from Facilities - Air toxics from industrial facilities, including vinyl chloride and other chemicals, are associated with breast cancer The fact that CalEnviroScreen already measures these exposures makes breast cancer a particularly appropriate population characteristic to include, as it would directly reflect the health impacts of the environmental burdens the tool is designed to assess. PRECEDENT AND CONSISTENCY CalEnviroScreen already includes several health outcome indicators that reflect environmental impacts on population health. Breast cancer, with its documented environmental links and high prevalence, represents a logical addition: • CalEnviroScreen currently includes cardiovascular disease and asthma, both of which are linked to air pollution—the same exposures associated with breast cancer • The tool measures environmental exposures that research has specifically linked to breast cancer, creating a direct connection between exposure indicators and this health outcome • Including breast cancer would enhance the tool's ability to capture the full spectrum of health impacts from environmental pollution • Breast cancer incidence varies geographically in California, with some of this variation potentially attributable to differences in environmental exposures DATA AVAILABILITY Breast cancer incidence data are readily available through: • California Cancer Registry, which provides comprehensive, high-quality cancer surveillance data at various geographic levels • Age-adjusted incidence rates can be calculated for census tracts or other geographic units used in CalEnviroScreen • Data quality and completeness are comparable to or exceed other health indicators currently included in the tool • Hormone receptor status data are available for most cases, allowing for analysis by subtype if desired CONCLUSION The scientific evidence demonstrating associations between environmental exposures and breast cancer has grown substantially in recent years. Multiple large-scale epidemiological studies, meta-analyses, and pooled analyses now provide evidence linking air pollution (PM2.5, diesel exhaust, NO2, air toxics), lead, pesticides, PFAS and other drinking water contaminants, and proximity to hazardous waste facilities to increased breast cancer incidence. Given that: • Breast cancer is the most common cancer among women • Multiple environmental exposures measured by CalEnviroScreen are associated with breast cancer risk • Biological mechanisms support these associations • Environmental justice communities face disproportionate exposures to these breast carcinogens • Data are readily available • CalEnviroScreen's mission is to identify communities experiencing cumulative environmental health burdens I strongly urge OEHHA to include breast cancer incidence as a population characteristic indicator in CalEnviroScreen 5.0. This addition would enhance the tool's ability to identify communities experiencing cumulative environmental health burdens and would support more comprehensive environmental justice policy and interventions to reduce cancer risk in California's most vulnerable communities. Thank you for considering this comment and for your continued work to advance environmental justice in California. Sincerely, Rainbow Rubin Breast Cancer Prevention Partners (BCPP) REFERENCES Carneiro L, Brito VS, da Costa JP, et al. Pesticide exposome reveals oxidative stress and immune response disruptions in occupationally exposed women with breast cancer. Sci Rep. 2025;15:2226. doi:10.1038/s41598-025-12870-2 Chang VC, Rhee J, Berndt SI, et al. Serum perfluorooctane sulfonate and perfluorooctanoate and risk of postmenopausal breast cancer according to hormone receptor status: An analysis in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Int J Cancer. 2023;152(6):1282-1296. doi:10.1002/ijc.34361 da Silva JPA, Panis C, de Brito VSS, et al. Exposure to Pesticides and Breast Cancer in an Agricultural Region in Brazil. Environ Sci Technol. 2024;58(15):6743-6753. doi:10.1021/acs.est.3c08695 Engel LS, Hill DA, Hoppin JA, et al. Pesticide use and breast cancer risk among farmers' wives in the Agricultural Health Study. Am J Epidemiol. 2005;161(2):121-135. Garcia E, Hurley S, Nelson DO, Hertz A, Reynolds P. Hazardous air pollutants and breast cancer risk in California teachers: a cohort study. Environ Health. 2015;14:14. doi:10.1186/1476-069x-14-14 Goldberg MS, Labrèche F, Weichenthal S, et al. The association between the incidence of postmenopausal breast cancer and concentrations at street-level of nitrogen dioxide and ultrafine particles. Environ Res. 2017;158:7-15. Gunier RB, Harnly ME, Reynolds P, Hertz A, Von Behren J. Agricultural pesticide use in California: pesticide prioritization, use densities, and population distributions for a childhood cancer study. Environ Health Perspect. 2001;109(10):1071-1078. Heck JE, He D, Wing SE, et al. Exposure to outdoor ambient air toxics and risk of breast cancer: The Multiethnic Cohort. J Int Environ Res Public Health. 2024;259:114362. doi:10.1016/j.ijheh.2024.114362 Javorac D, Anđelković M, Tatović S, et al. Lead bioaccumulation in human breast cancer tissue is associated with DNA instability and cell death resistance. Cell Death Discov. 2025;11:26. doi:10.1038/s41420-025-02676-6 Jaworska K, Durda K, Muszyńska-Rosłan K, et al. Blood Lead (Pb) Levels as a Possible Marker of Cancer Risk in a Prospective Cohort of Women with Non-Occupational Exposure. Cancers. 2024;16(15):2741. doi:10.3390/cancers16152741 Jiang H, Li H, Wang L, et al. Associations between Polyfluoroalkyl Substances Exposure and Breast Cancer: A Meta-Analysis. Int J Environ Res Public Health. 2022;19(13):7779. doi:10.3390/ijerph19137779 Li C, Sun L, Zhuang Y, et al. Associations between per-and polyfluoroalkyl substances (PFAS) and county-level cancer incidence between 2016 and 2021 and incident cancer burden attributable to PFAS in drinking water in the United States. J Expo Sci Environ Epidemiol. 2025. doi:10.1038/s41370-024-00742-2 Liu Y, Huang D, Wang Z, et al. Blood levels of endocrine-disrupting metals and prevalent breast cancer among US women. Environ Pollut. 2019;255:113239. doi:10.1016/j.envpol.2019.113239 Nardone A, Casey JA, Rudolph KE, Karasek D, Mujahid M, Morello-Frosch R. Associations between historical residential redlining and current age-adjusted rates of emergency department visits due to asthma across eight cities in California: an ecological study. Lancet Planet Health. 2020;4(1):e24-e31. Praud D, Deygas F, Amadou A, et al. Traffic-Related Air Pollution and Breast Cancer Risk: A Systematic Review and Meta-Analysis of Observational Studies. Cancers. 2023;15(3):927. doi:10.3390/cancers15030927 White AJ, Fisher JA, Sweeney MR, et al. Ambient fine particulate matter and breast cancer incidence in a large prospective US cohort. J Natl Cancer Inst. 2024;116(1):53-63. doi:10.1093/jnci/djad170