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2025
J Occup Environ Med
A French case-control study of 1,230 breast cancer patients and 1,315 controls examined occupational exposure to 49 common workplace chemicals and found elevated breast cancer risk associated with 12 agents. Women with the highest cumulative exposure showed increased risk ranging from 33% to 139% for chemicals including synthetic and natural fibers, plastics, organic dyes, nitrogen oxides, anesthetic gases, and various industrial compounds. The associations were generally stronger in premenopausal women compared to postmenopausal women. These findings suggest certain occupational exposures may play a role in breast cancer development, though larger studies with more detailed exposure assessments are needed to confirm these results.
2025
Environ Health Perspect
This nested case-control study, part of the E3N-Generations cohort of France, used satellite data to estimate exposures to both outdoor light-at-night. They found a linear increase in breast cancer risk, based upon quartiles or outdoor light-at-night exposure, p<.01. When they controlled for nitrogen dioxide exposure, pm 2.5, and vegetation density, the trend was no longer significant, but breast cancer risk was still elevated in association with light-at-night exposure (OR=1.11, 95%CI=1.02-1.20).
2025
JAMA Netw Open
In a cross-sectional study involving Black and White women participating in the NCI Maryland Breast Cancer Study, the investigators examined associations between neighborhood-level deprivation, air pollution (PM₂.₅) and presence of breast tissue crown-like structures (CLS-B) plus DNA methylation patterns. Higher PM₂.₅ exposure and greater neighborhood deprivation were associated with increased odds of having CLS-B (OR for PM₂.₅ 2.32, 95% CI: 1.12–4.78). The findings point to how socio-environmental disadvantage and pollution may influence breast adipose inflammation and epigenetic changes linked to cancer risk.
2025
Environ Pollut
A study of 574 breast cancer cases and 2,295 controls from rural Arkansas found that moderate exposure to polycyclic aromatic hydrocarbons (PAHs) and high chromium exposure were associated with statistically significant 32% increased breast cancer risk, with the strongest effects observed among women with a family history of breast cancer. When examining 12 hazardous air pollutants as a mixture, there was a suggested but non-statistically significant 21% increased breast cancer risk, with chromium, propylene dichloride, and PCBs contributing most to the elevated risk. This study is important because it demonstrates that hazardous air pollutants pose breast cancer risks even in rural areas, which are often overlooked in environmental health research despite experiencing different pollution sources and healthcare disparities compared to urban populations.
2024
Environ Pollut
A French study of over 10,000 women found that combined exposure to a mixture of four hormone-disrupting air pollutants (benzo[a]pyrene, cadmium, dioxin, and PCB153) was associated with an approximately 10-11% increased risk of breast cancer. Using advanced statistical methods that account for simultaneous exposure to multiple pollutants rather than examining each separately, researchers found that benzo[a]pyrene, cadmium, and PCB153 showed the strongest individual contributions to increased breast cancer risk within the mixture. This research provides important evidence that the cumulative effect of multiple air pollutants acting together on hormone pathways may be a significant risk factor for breast cancer development.
2024
Environ Health Perspect
A nationwide study using CDC biomonitoring data found that California’s Proposition 65, which requires warnings about chemicals that cause cancer or reproductive harm, led to reduced exposures to listed chemicals across the entire United States, not just California. While blood and urine concentrations of 37 monitored chemicals generally declined over time, the researchers found evidence of problematic chemical substitution—for example, after bisphenol A (BPA) was listed, its concentrations dropped 15% but levels of the unlisted substitute bisphenol S (BPS) increased 20%. Californians generally had lower levels of harmful chemicals in their bodies compared to residents of other states, suggesting the law had additional protective effects. The findings indicate that transparency laws like Prop 65 can drive manufacturers to reformulate products nationwide, but regulations need to address entire chemical classes rather than individual substances to prevent companies from simply switching to similar but unlisted toxic chemicals.
2024
Environ Res
This large Danish study of over 5,500 breast cancer cases found that daughters whose mothers worked in horticulture (greenhouse and nursery work) before conception or during pregnancy had significantly increased breast cancer risk—79% higher for estrogen receptor-positive tumors and 148% higher for estrogen receptor-negative tumors. The associations were particularly strong for maternal horticulture work compared to paternal work, suggesting that pesticide and chemical exposures during critical windows of fetal development may affect daughters’ breast cancer risk decades later. These findings are concerning because horticultural workers have high exposure to pesticides and other agricultural chemicals, and the study suggests that even preconceptional maternal exposure—before pregnancy begins—may influence a daughter’s future cancer risk, highlighting the potential for intergenerational effects of occupational chemical exposures.
2024
Environ Int
A comprehensive French study of over 10,000 women examined exposure to eight different air pollutants simultaneously and identified that women exposed to high levels of nitrogen dioxide (NO₂), particulate matter, and PCB153 had a 38-61% increased risk of breast cancer compared to women with low pollution exposure. Using advanced statistical modeling that groups women by their combined pollution exposure patterns rather than examining pollutants individually, researchers found that specific combinations of high pollutant exposures were strongly associated with elevated breast cancer risk. This study provides important evidence that the combined “cocktail effect” of multiple air pollutants, particularly traffic-related pollution (NO₂) and industrial chemicals (PCB153), may significantly increase breast cancer risk beyond what individual pollutants cause alone.
2024
Am J Epidemiol
This systematic review of 18 epidemiological studies evaluated whether exposure to PFAS—measured in blood or plasma—is associated with breast cancer risk. Across 11 of the studies included in the meta-analysis, higher concentrations of common PFAS such as PFOA and PFOS were not associated with increased breast cancer risk (per-log-unit RR for PFOA = 0.95, 95% CI: 0.77–1.18; PFOS = 0.98, 95% CI: 0.87–1.11). When analyses were restricted to studies where PFAS levels were measured before diagnosis, risk estimates were slightly higher (for PFOA: RR = 1.16, 95% CI: 0.96–1.40), but still not statistically significant. Overall, the evidence suggests that current PFAS exposures measured do not show a consistent link to breast cancer, though the authors note substantial study variability and the need for better prospective data.
2024
Environ Health
This large French cohort study analysed long-term residential exposure trajectories of PCB153 and benzo[a]pyrene (BaP) among more than 10,000 women and estimated associations with breast cancer risk. Women in the highest trajectory class for PCB153 had an OR of ~1.69 (95% CI: 1.08–2.64) compared to the lowest class; associations for BaP were weaker and not consistently statistically significant. The research highlights how evolving environmental exposures over decades may influence hormone-sensitive cancer risk.
2024
Cancer Causes Cont
This large Canadian population-based study examined whether long-term residential exposure to polycyclic aromatic hydrocarbons (PAHs)—widespread environmental pollutants from sources like vehicle exhaust and industrial emissions—increases breast cancer risk. Using 20 years of residential history data, researchers found that exposure to fluoranthene (a common PAH) was associated with significantly increased risk of premenopausal breast cancer, with women in moderately high exposure areas showing 59-148% higher risk compared to those in low-exposure areas. The associations with postmenopausal breast cancer were inconsistent, with only one analysis showing a modest increased risk. These findings support the hypothesis that ambient PAH exposure may increase the risk of breast cancer in premenopausal women, though the relationship appears complex and requires further investigation.
2024
Environ Res
A decade-long study of 135 breast cancer cases and 540 controls found that exposure to PFAS (perfluoroalkyl substances) was strongly associated with increased breast cancer risk, with mixed PFAS exposure showing more than double the odds of developing the disease. Several specific PFAS compounds—including PFBA, PFOS, PFHxS, and PFDA—were identified as particularly significant risk factors, with some associations appearing exclusively in premenopausal women. The findings suggest that premenopausal women should be especially cautious about PFAS exposure, as these persistent “forever chemicals” may pose a substantial breast cancer risk.
2023
Environ Int
This cohort study examined associations of metals to multiple cancer sites. Participants were from a cohort study of worker from the French national energy company who lived in semi-urban or rural locations. The researchers estimated metal exposures from moss biomonitoring (part of a larger effort to measure air pollution). Estimated exposures to metals were associated any cancer (bladder, lung, breast or prostate), but no estimated exposures were associated with breast cancer alone. Some estimates appraoched HR >1 for breast cancer.
2023
Environ Res
A nationwide U.S. study of nearly 45,000 women found clear geographic patterns in breast cancer rates, with lower risk in the South and Southeast and higher risk in the Northwest and parts of the Midwest and Northeast, even after accounting for personal risk factors like family history and reproductive factors. Environmental exposures—including air pollution (nitrogen dioxide and fine particles), light at night, greenspace, and neighborhood socioeconomic disadvantage—explained 21% of the geographic variation in overall breast cancer and 63% of the variation specifically for estrogen receptor-positive (ER+) breast cancer. These findings provide strong evidence that where you live matters for breast cancer risk, with environmental factors playing a substantial role, particularly for ER+ breast cancer, the most common subtype, suggesting that reducing environmental exposures like air pollution and light at night could be effective prevention strategies at the community level.
2023
Environ Res
This case-control study of 5587 women with breast cancer and age-matched controls for which there was data on maternal employment. Maternal occupational exposure to diesel exhaust (OR=1.13, 95%CI,1.01-1.27) and bitumen fumes (OR=1.51., 95%CI,1.00-2.26) was associated with breast cancer. Further, exposures to diesel exhaust (OR=1.23, 95%CI, 1.01-1.50) were more strongly associated with ER- tumors than with ER+ tumors.
2023
Biol Trace Elem Res
This cross-sectional analysis from the 2007–2016 National Health and Nutrition Examination Survey (NHANES) explored the relationship of urinary concentrations of heavy metals and breast cancer. 3,352 U.S. women (aged 20 or older) in the were included in the analysis. 106 reported a history of breast cancer (weighted prevalence ~ 3.1%). Researchers measured urinary concentrations of heavy metals — cadmium, lead, and mercury — corrected for creatinine, then applied multivariate logistic regression to assess associations with prevalent breast cancer. They found that women in the highest quartile of urinary lead (≥ 0.71 µg/g creatinine) had significantly elevated odds of prior breast cancer (OR = 2.95, 95% CI: 1.13–7.70) compared with those in the lowest quartile; by contrast, urinary cadmium and mercury showed no statistically significant associations. The findings suggest that among common endocrine-disrupting metals, lead exposure — as measured by urinary biomarkers — may be linked with increased breast cancer prevalence in U.S. women.
2022
Chemosphere
Researchers measured 41 endocrine-disrupting chemicals (EDCs) in women living in the Greater Manila Area, Philippines, comparing those with and without breast cancer. They found that certain perfluoroalkyl substances (PFAS) were significantly associated with breast cancer, with some chemicals showing dramatically increased risk: PFDoA was associated with a 1,263% increased risk, PFDA with an 826% increased risk, and PFHxA with a 166% increased risk. Long-chain PFAS levels were higher in women from heavily industrialized areas compared to the National Capital Region. This study provides the first baseline data on EDC exposure levels in Filipino women, filling a critical gap in knowledge about chemical exposures in Southeast Asian populations and suggesting that industrial pollution may be contributing to elevated PFAS levels and breast cancer risk.
2022
Cancer Epiemiol
The first Indian case-control study examining phthalates (chemicals widely used in plastics, cosmetics, and food packaging) and breast cancer found that women with higher urinary levels of di-butyl phthalate (DBP) had 1.5 times increased breast cancer risk, while those with higher DEHP levels had nearly 3 times increased risk. Analysis of breast tumor tissue revealed mutations in several genes known to respond to phthalate exposure, affecting pathways involved in hormones, metabolism, and cancer development. These findings suggest that exposure to certain phthalates may increase breast cancer risk through genetic changes, though larger studies are needed to confirm these results and understand how early-life exposures might contribute to cancer development later in life.
2022
Environ Int
A large French study of nearly 68,000 women followed for over 21 years found that dietary exposure to PBDEs (flame retardant chemicals) was associated with increased breast cancer risk, but importantly, this association was modified by vegetable oil consumption. Women who consumed higher amounts of vegetable oil (≥4.6 g/day) and had the highest PBDE intake showed a 23% increased breast cancer risk, while those with low vegetable oil consumption showed no increased risk regardless of PBDE exposure. These findings suggest that the interaction between diet and chemical contaminants is important to consider when developing public health recommendations, as certain dietary patterns may amplify or mitigate the health risks associated with environmental chemical exposures.
2022
Toxics
A meta-analysis of eight studies examining the relationship between PFAS chemicals and breast cancer found that two specific PFAS compounds—PFOA and PFHxS—were associated with significantly increased breast cancer risk, showing 32% and 79% elevated risk respectively. Surprisingly, PFNA showed a protective association with 24% reduced risk, while PFOS showed no association with breast cancer risk, though all findings had substantial statistical heterogeneity between studies. The researchers concluded that certain PFAS compounds may be potential breast cancer risk factors, with concerning evidence that even low-level exposures could have harmful impacts on human health, highlighting the need for further research to clarify the varied effects of different PFAS chemicals on breast cancer development.
2022
Crit Rev Food Sci Nutr
A systematic review of 131 epidemiological studies examining endocrine-disrupting chemicals (EDCs) and breast cancer risk found evidence that exposure to various EDCs—including pesticides (DDT/DDE, atrazine, dioxin), synthetic chemicals (BPA, phthalates, PFAS, PCBs, PBDEs), and other compounds found in everyday products—may elevate breast cancer risk, particularly when exposure occurs during early life. The review identified food as a major route of EDC exposure and emphasized that because most EDCs persist in the environment and accumulate in the body over time, long-term multi-generational health impacts need to be assessed. The authors call for improved exposure assessments of EDCs in food and food packaging, along with careful evaluation of their links to breast cancer development to inform policy-making and regulations aimed at protecting public health.
2022
Am J Clin Nutr
A large French study following over 80,000 women for nearly 9 years found that higher dietary acrylamide intake—a probable carcinogen formed when starchy foods like coffee, French fries, chips, and baked goods are cooked at high temperatures—was associated with a 40% increased risk of premenopausal breast cancer. The association showed a nonlinear pattern, with elevated risk at both moderate and high exposure levels, and was specifically linked to estrogen receptor-positive breast cancer, while no association was found for postmenopausal breast cancer. These findings support the need for continued efforts to reduce acrylamide formation in foods through improved cooking and processing methods, as dietary acrylamide exposure—averaging about 30 micrograms per day in this population—may be a modifiable risk factor for breast cancer, particularly in younger women.
2022
Environ Res
A study of 6,247 greenspace workers (landscapers, gardeners, groundskeepers) from the French AGRICAN cohort found significantly elevated cancer risks compared to farmers and non-agricultural workers. Male greenspace workers showed 15% higher overall cancer incidence, with particularly elevated risks for prostate cancer (21% increase), thyroid cancer (184% increase), testicular cancer (298% increase), and skin melanoma (115% increase), while female greenspace workers had a 71% increased risk of breast cancer. The study also found that greenspace workers reported more allergic diseases and, among males, more depression compared to other occupational groups. These findings highlight that greenspace workers face distinct occupational health risks, likely related to pesticide exposure and other workplace hazards, and should be studied separately from agricultural workers rather than being grouped together in research.
2021
Cancer Epidemiol Biomarkers Prev
A Spanish case-control study of 1,738 breast cancer cases and 1,910 controls found that occupational heat exposure was associated with a 22% increased risk of breast cancer among women who had ever been exposed. The study found significant dose-response relationships, with risk increasing with both cumulative heat exposure and duration of exposure, and particularly strong associations for hormone receptor-positive breast cancer (38% increased risk). The associations were strongest when not adjusted for detergent exposure, suggesting potential confounding or interaction between these workplace exposures. These findings suggest that chronic workplace heat stress may be a previously underrecognized occupational risk factor for breast cancer, though further research is needed to confirm these results and understand potential interactions with other workplace exposures.
2021
Cancer Epi
This study of nearly 48,000 women found that frequent use of chemical hair straighteners and perms during adolescence (ages 10-13) was associated with more than double the risk of premenopausal breast cancer, though no increased risk was seen for postmenopausal breast cancer. Black women who used permanent hair dye during adolescence had a 77% increased breast cancer risk, though permanent dye use was uncommon overall in the study population. The findings are particularly concerning because adolescence is a critical developmental window when breast tissue may be more vulnerable to chemical exposures, and these hair products contain hormonally active and potentially carcinogenic compounds that may have long-lasting effects on breast cancer risk decades later.
2021
Environ Res
A nationwide Danish study of 1.8 million women followed from 2000-2017 found that each 10-decibel increase in 10-year average road traffic Noise exposure was associated with a 3.2% increased risk of breast cancer at the least exposed façade (typically bedrooms) and a very slight increased risk at the most exposed façade. Railway Noise showed similar patterns. The associations were strongest for HER2-negative breast cancer and suggest that nighttime Noise exposure during sleep may be particularly important, adding transportation Noise to the growing list of environmental breast cancer risk factors.
2021
Environ Res
This large U.S. study using NHANES data found that multiple PFAS chemicals were associated with increased odds of both breast and ovarian cancer, with dose-response relationships showing dramatically higher risks at the highest exposure levels—women in the highest quartile of exposure had 130% increased odds for breast cancer (up to 607% for PFHxS) and 77-125% increased odds for ovarian cancer compared to those in the lowest quartile. Different PFAS chemicals showed stronger correlations with different cancers: PFOA was most strongly correlated with breast cancer while PFHxS was most strongly correlated with ovarian cancer, suggesting these endocrine-disrupting chemicals may affect different hormone-sensitive tissues through distinct mechanisms. No associations were found with prostate or uterine cancers. These findings are particularly concerning because PFAS are ubiquitous environmental contaminants found in everyday products and the water supply, and the strong dose-response relationships suggest that reducing PFAS exposure could potentially lower the risk of these estrogen-related cancers in women.
2021
Int J Epidemiol
This French study of over 13,000 postmenopausal women found that those with low dietary exposure to synthetic pesticides (primarily from eating organic foods) had a 43% lower breast cancer risk, while overweight and obese women with high exposure to certain pesticides (including chlorpyrifos and malathion) had over four times the breast cancer risk. The researchers estimated pesticide exposure by tracking whether participants ate conventional or organic versions of various foods and using a database of pesticide residues found on different crops. These findings suggest that dietary pesticide exposure from conventional foods may increase breast cancer risk, particularly in women who are overweight or obese, though more research is needed to confirm these results and understand the underlying mechanisms.
2021
Int J Cancer
In a nested case-control study of over 1,000 breast cancer cases and matched controls from the Multiethnic Cohort, pre-diagnostic urinary concentrations of bisphenol A (BPA), triclosan, and parabens were evaluated in relation to breast cancer risk. BPA was not significantly associated with risk; the highest tertile of total parabens had OR ≈ 0.77 (95% CI: 0.62–0.97) relative to the lowest tertile, indicating a modest inverse association. These results suggest that the relationships between common endocrine-disrupting chemicals and breast cancer may be more complex than anticipated and vary by exposure type.
2020
Int Arch Occup Environ Health
This Swedish study of 2,400 postmenopausal women found that those exposed to chemicals in the workplace had a 59% increased risk of breast cancer, with the risk increasing with longer duration of exposure. Women exposed to chlorinated hydrocarbon solvents or oil mist for more than 10 years had approximately triple the breast cancer risk compared to unexposed women. The study used individualized exposure assessments based on specific work tasks rather than just job titles, providing stronger evidence that workplace chemical exposures—particularly to organic solvents and oil mist commonly found in manufacturing and industrial settings—may be important contributors to breast cancer risk.
2020
Int J Epidemiol
This Russian study of 468 breast cancer cases found that women exposed to prolonged low-level radiation from the Chernobyl nuclear accident had approximately three times higher breast cancer risk in the highest exposure groups compared to those with the lowest exposure, even though radiation doses were relatively low (averaging just 1.3 centigray). The study tracked women for about 25 years after the 1986 Chernobyl accident and estimated their radiation exposure based on where they lived and what they ate during that time. The findings suggest that even prolonged exposure to low levels of radiation—not just high-dose exposures—can increase breast cancer risk, particularly among women who were younger at the time of exposure.
2020
Environ Toxicol Pharmacol
This analysis of US health data from 2003-2012 found that women with higher long-term exposure to organophosphorus insecticides (common pesticides measured through urine samples) faced significantly elevated health risks, including three times higher risk of cardiovascular disease and 2.7 times higher overall cancer risk among women aged 60-85. Women with higher pesticide exposure also showed increased risks of asthma in younger age groups and chronic bronchitis in older age, with breast cancer risk elevated among female smokers and prostate cancer risk elevated among male smokers. These findings suggest that chronic exposure to these widely-used agricultural pesticides may pose greater health threats to women than men, particularly for cardiovascular disease and cancer.
2019
J Clin Oncl
This large-scale Danish nationwide study followed 1.12 million women over nearly 10 million woman-years to examine the relationship between phthalate exposure from prescription medications and breast cancer risk. The researchers tracked phthalate exposure by linking a database of drug ingredients with prescription records, finding that most phthalate exposures were not associated with increased breast cancer risk. However, high-level cumulative exposure to dibutyl phthalate (≥10,000 mg) was associated with approximately double the risk of estrogen receptor-positive breast cancer, consistent with laboratory evidence showing this compound has estrogenic effects. The study concludes that women should avoid high-level dibutyl phthalate exposure, particularly through long-term use of pharmaceuticals containing this compound, though lower exposure levels did not increase breast cancer risk.
2019
J Natl Cancer Inst
This study of over 700 women found that DDT exposure was associated with increased breast cancer risk through age 54, but the timing of first exposure mattered critically: women first exposed to DDT after infancy had nearly triple the risk of early postmenopausal breast cancer (ages 50-54), while women first exposed during infancy through puberty had nearly four times the risk of premenopausal breast cancer (before age 50). These findings suggest there are specific windows of vulnerability when DDT exposure has the strongest impact on future breast cancer risk, with effects that can persist for decades. The results support the idea that DDT acts as an endocrine disruptor affecting breast tissue throughout a woman’s life—from before birth through menopause—even though DDT was banned in the U.S. in 1972, highlighting the long-term health consequences of early-life chemical exposures.
2019
J Work Environ Health
A prospective study of 16,084 Swedish women found that occupational exposure to chemicals was associated with a 26% increased risk of postmenopausal breast cancer, with risk increasing based on duration of exposure. Women exposed to diesel exhaust for more than 10 years showed a 69% increased risk, while exposure to organic solvents showed a non-significant elevated risk. The researchers estimated that occupational chemical exposures accounted for 2% of all breast cancer cases in this population, highlighting workplace chemical exposure as a potentially important but often overlooked risk factor for breast cancer.
2018
Scand J Work Environ Health
A European multicenter case-control study of 104 male breast cancer cases and 1,901 controls found that high cumulative lifetime exposure to trichloroethylene (>23.9 ppm-years) was associated with a 110% increased male breast cancer risk compared to non-exposure, with the association persisting when only exposures occurring 10 or more years before diagnosis were considered, indicating a true latency effect. The study also suggested possible roles for benzene and ethylene glycol in male breast cancer risk, though no clear dose-response relationships were observed for these chemicals. These findings are particularly important given that male breast cancer is rare, often diagnosed at later stages, and has worse prognosis than female breast cancer, and they add to evidence that occupational solvent exposures—particularly trichloroethylene used in metal degreasing, dry cleaning, and industrial cleaning—may be underrecognized risk factors for breast cancer in both men and women, warranting stricter workplace exposure limits and enhanced surveillance of workers in high-exposure industries.
2018
Cancer Epidemiol Biomarkers Prev
This study examined how exposure to endocrine-disrupting chemicals (EDCs) during puberty affects breast tissue development in 200 Chilean girls by measuring urinary concentrations of phenols and phthalates at two stages of breast development and assessing breast density. The researchers found that certain phthalate metabolites were associated with increased breast density measures – specifically, higher levels of monocarboxyisooctyl phthalate were linked to 7% higher percent dense breast tissue, and monoethyl phthalate was associated with increased fibroglandular volume. Bisphenol A showed a U-shaped relationship with fibroglandular volume, where girls with middle-level exposures had at least 10% lower fibroglandular volume compared to those with low or high exposures. The findings suggest that developing breast tissue is vulnerable to certain EDCs during childhood and adolescence, which may have implications for future breast cancer risk since breast density is a known risk factor.
2018
Environ Res
A Chinese case-control study of 209 breast cancer patients and 165 controls found that women with the highest levels of PBDE flame retardants in their adipose tissue had dramatically elevated breast cancer risk, with some congeners showing 447% to 545% increased risk in the highest exposure groups compared to the lowest. Most individual PBDE congeners—including BDE-47, BDE-99, BDE-100, BDE-209, and total PBDEs—were significantly higher in breast cancer cases than controls (median 95.0 vs 73.7 ng/g lipid) and showed strong dose-response relationships with increasing exposure levels. The associations remained robust for estrogen receptor-positive breast cancers and in multivariate models adjusting for age and reproductive factors, providing compelling evidence that PBDE exposure may play an important role in breast cancer development, particularly in populations with high environmental exposures to these persistent flame retardant chemicals.
2018
Am J Epidemiol
A cohort study of 4,503 female autoworkers in Michigan exposed to metalworking fluids (MWFs)—oil and chemical mixtures used in metal manufacturing—found that increased exposure to straight mineral oil MWFs was associated with a 13% increased breast cancer risk per interquartile range increase in cumulative exposure. Among younger women who developed premenopausal breast cancer, exposure to synthetic MWFs (chemical lubricants without oil) showed elevated risk, suggesting potentially different carcinogenic mechanisms in younger versus older women. This occupational study addresses a critical gap in breast cancer research by providing quantitative exposure-response data for a specific chemical mixture affecting a large workforce, offering one of the few leads on modifiable environmental risk factors for breast cancer.
2025
Sci Totl Environ
This study investigated the effects of three common plastic additives (DEHP, BPA, and benzotriazoles) on Atlantic cod liver tissue using precision-cut liver slices exposed to various concentrations of these chemicals individually and in mixtures. The researchers found that BPA and chemical mixtures caused estrogenic effects, significantly increasing vitellogenin (a female egg protein) production and related gene expression in male juvenile cod. The study also observed changes in liver metabolism genes, with mixture exposures showing potentially different effects than individual chemical exposures. The results suggest these plastic additives can disrupt hormone systems in fish, with BPA being the primary driver of estrogenic effects, though the interaction effects between chemicals require further investigation.
2025
Ecotoxicol Env Saf
A Mendelian randomization study using genetic data from European populations found that specific endocrine-disrupting chemicals (EDCs) were causally associated with different breast cancer subtypes: n-butyl paraben (n-BuP) increased Luminal A risk, mono-methyl phthalate decreased Luminal B risk, and mono-iso-butyl phthalate (MiBP) increased triple-negative breast cancer risk. Mediation analysis revealed that blood metabolites—including caffeic acid sulfate and caffeine metabolism ratios—partially explained the n-BuP effect on Luminal A, while methylsuccinate mediated the MiBP effect on triple-negative cancer, and epigenetic analysis identified specific DNA methylation sites associated with EDC exposure and breast cancer risk. These findings provide the first genetic evidence suggesting causal relationships between specific EDC exposures and breast cancer subtypes through distinct metabolic and epigenetic pathways, identifying potential biomarkers for early detection and highlighting the heterogeneous effects of different EDCs on breast cancer biology—underscoring the need for chemical-specific and subtype-specific prevention strategies rather than treating all EDCs or breast cancers as uniform entities.
2025
JAMA Netw Open
A cross-sectional study of 121 Black and White women with breast cancer found that chronic stressors—including perceived stress, inadequate social support, discrimination, and neighborhood deprivation—were associated with harmful immune and tumor changes, with particularly pronounced effects in Black women who also lived in significantly more socioeconomically deprived neighborhoods. Higher stress, discrimination, and neighborhood deprivation were linked to increased systemic inflammation, immune-suppressive tumor environments (including tumor-promoting M2 macrophages), and elevated tumor mutational burden, while greater social support was associated with beneficial immune-stimulatory changes including increased natural killer cells in breast tissue. Black women showed distinct stress-related immunologic signatures including enhanced chemotaxis, immune suppression at the systemic level, and increased tumor-associated myeloid cells, suggesting that chronic psychosocial and environmental stressors may biologically contribute to breast cancer disparities by creating a pro-tumorigenic immune environment—findings that underscore the urgent need for interventions addressing social determinants of health as cancer prevention strategies.
2025
Sci Rep
A secondary analysis of 15,536 post-menopausal women from the Alberta Tomorrow Project cohort examined whether exposure to traffic-related air pollution (TRAP), measured using nitrogen dioxide (NO₂) levels, was associated with breast cancer risk over 12.6 years of follow-up during which 523 breast cancer cases were diagnosed. After adjusting for confounders including age, education, births, diet, income, physical activity, BMI, and smoking, the study found no significant association between NO₂ exposure and post-menopausal breast cancer risk (HR = 1.10 per 10-ppb increase in NO₂; 95% CI = 0.90, 1.34). The authors suggest that while the magnitude of risk observed was similar to other studies, the lack of statistical significance may be due to the study’s sample size limitations and the fact that NO₂ levels in Alberta are lower than in many other regions globally where associations have been found. These findings indicate that traffic-related air pollution may not significantly impact post-menopausal breast cancer risk in regions with relatively low pollution levels, though larger studies in more polluted areas may be needed to fully assess this relationship.
2024
Environ Health Perspect
A mouse study examining DNA methylation changes from lead and DEHP (phthalate) exposure during pregnancy and early development found that the brain (cerebral cortex) showed the most epigenetic changes (66% for lead, 57% for DEHP), with alterations concentrated in gene regulatory regions that control gene expression. The research identified imprinted genes—particularly Gnas and Grb10—as targets of both chemical exposures across multiple tissues, with some DNA methylation signatures in blood matching those in target organs like liver and brain, suggesting blood tests could potentially detect toxic exposures affecting other organs. Notably, lead exposure caused consistent hypermethylation of the Grb10 gene’s control region in both blood and liver of male offspring, providing preliminary evidence that epigenetic changes in easily accessible blood samples might serve as biomarkers for chemical exposures affecting critical organs like the brain. These findings are significant for breast cancer prevention because early-life exposures to lead and phthalates can alter epigenetic programming in ways that may increase disease risk decades later, and identifying blood-based biomarkers could enable early detection of harmful exposures during vulnerable developmental windows.
2024
Environ Int
A study of 1,031 pregnant women from the socioeconomically diverse CANDLE cohort in the urban South found that ultra-processed foods constituted 38.6% of participants’ diets on average, with each 10% higher dietary proportion of ultra-processed foods associated with 13.1% higher urinary concentrations of DEHP phthalate metabolites, while specific foods like hamburgers, French fries, soda, and cake showed 6-10.5% higher DEHP per standard deviation increase in consumption. Causal mediation analyses revealed that lower income and education levels were associated with 1.9% and 1.4% higher DEHP exposure respectively, mediated through increased ultra-processed food consumption, indicating that ultra-processed foods contribute to socioeconomic disparities in phthalate exposure during pregnancy. The findings demonstrate that consuming ultra-processed foods increases exposure to endocrine-disrupting phthalates from food contact materials, and because socioeconomic barriers can prevent dietary modifications, policies to reduce phthalates in food packaging and processing are needed rather than relying solely on individual dietary recommendations to reduce prenatal phthalate exposures.
2024
Int J Env Res Pub Health
This study surveyed 746 Kenyan women about their hair product use and found that nearly 60% had used chemical relaxers and one-third had used hair dyes, despite many expressing concerns about health risks including breast cancer. Older women and those working in sales and service industries were more likely to use these products, which may contain endocrine-disrupting chemicals linked to breast cancer. Surprisingly, women’s awareness of potential health risks did not consistently lead to reduced use of these products, suggesting that concern alone may not be enough to change behavior. These findings are particularly important for Kenya, where breast cancer rates are rising, and highlight the need for better education about chemical exposures in hair products and strategies to reduce potentially harmful exposures.
2024
Environ Sci Technol
A study of 751 reproductive-aged Black women found that the relationship between personal care product (PCP) use and exposure to endocrine-disrupting chemicals (EDCs) varied significantly by socioeconomic status (SES), with different patterns of chemical exposure from the same products depending on women’s education, income, and employment. For example, vaginal powder use was associated with higher phenol exposure (a class of EDCs) among lower SES women but showed no such association in higher SES women, suggesting that product formulations, brands, or usage patterns may differ across SES groups. These findings highlight that Black women face inequitable EDC exposures that are influenced by both race and socioeconomic factors, underscoring the need for targeted public health interventions that address these intersecting disparities in chemical exposures from everyday products
2024
Cancer Causes Control
A population-based study using Kentucky cancer registry data (77,637 breast cancer and 56,598 colorectal cancer cases) found that higher ambient air concentrations of carcinogenic metals—cadmium, arsenic, nickel, and chromium(VI)—were associated with increased odds of residing in breast and colorectal cancer hotspots, independent of individual risk factors including age, race, smoking, and neighborhood socioeconomic characteristics. Cancer hotspot populations were disproportionately Black and exhibited markers of lower socioeconomic status, and importantly, the metal-cancer associations persisted even after adjusting for these factors, suggesting environmental metal exposure is an independent contributor to geographic cancer clustering. These findings provide evidence that historically marginalized communities face disproportionate exposure to carcinogenic metals through environmental pollution, likely contributing to cancer disparities, and underscore the urgent need for environmental justice interventions including stricter air quality regulations, cleanup of contaminated sites, and individual-level exposure assessments to fully understand how metal exposures drive cancer inequities in vulnerable populations.
2024
Environ Res
Endocrine Disrupting Chemicals (EDCs)—including bisphenol A, phthalates, parabens, pesticides, and heavy metals commonly found in pharmaceuticals, cosmetics, and packaging—are widespread environmental pollutants that interfere with the body’s hormone system. Research shows EDCs have harmful effects on women’s reproductive health, contributing to conditions such as endometriosis, polycystic ovary syndrome, uterine fibroids, premature ovarian failure, menstrual irregularities, and infertility. This review emphasizes the need for healthcare professionals to consider environmental exposures when evaluating patients, highlights potential mechanisms by which EDCs affect female reproduction, and discusses how nutritional interventions and stricter environmental regulations could help reduce EDC-related health risks. Understanding the link between EDCs and women’s health is crucial for developing protective strategies, informing treatment approaches, and shaping public policies to safeguard reproductive and overall well-being. The study seeks to advise that couples attempting to conceive should avoid endocrine disrupting chemicals (EDCs) such as BPA, pesticides, and phthalates. Following this advice is found to be crucial during the prenatal and periconceptional periods, where fetal development and growth are critical in this window.
2024
Breast Cancer Res
A nested case-control study within the French E3N-Generations cohort examined 523 breast cancer cases and 523 matched controls to investigate whether thirteen metabolic health biomarkers mediate the relationship between exposure to three air pollutants (nitrogen dioxide, PCB153, and benzo[a]pyrene) and breast cancer risk. The study found that benzo[a]pyrene exposure was associated with a significant 2.32-fold increased breast cancer risk (highest vs. lowest quartile), PCB153 showed inconsistent positive associations, and nitrogen dioxide showed no association; among biomarkers, estradiol was associated with increased breast cancer risk (OR = 1.22 per SD). Four-way decomposition mediation analysis revealed suggestive evidence that albumin, HDL and LDL cholesterol, parathormone, and estradiol may partially mediate the associations between all three pollutants and breast cancer risk, though findings were limited by statistical power. These results provide preliminary mechanistic insights suggesting that air pollutants may influence breast cancer risk through alterations in metabolic biomarkers—particularly lipid metabolism and hormone regulation—though larger studies are needed to confirm these pathways and establish the clinical significance of these mediating effects in the relationship between environmental exposures and breast cancer development.