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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.
2025
Sci Total Environ
This review examines the relationship between DEHP (a common plastic additive) and cancer development, noting that while epidemiological studies suggest a link between DEHP exposure and increased cancer risk, the specific mechanisms need further clarification. The research shows that DEHP influences multiple aspects of cancer biology, including cell growth, spread, and drug resistance, through various molecular pathways involving hormone receptors, inflammation, and genetic modifications. DEHP’s carcinogenic effects operate through complex mechanisms including PI3K/AKT signaling, estrogen receptor activation, and oxidative stress. Understanding these molecular pathways could help develop targeted strategies to prevent and treat cancers associated with DEHP exposure.
2025
Ecotoxicol Environ Saf
This study analyzed six xenoestrogens (hormone-disrupting chemicals including phthalates, BPA, and alkylphenols) in atmospheric particles at a university campus in China from 2021 to 2023. BPA was the most prevalent xenoestrogen detected, with concentrations of these chemicals being significantly higher in winter than summer, and the overall cancer and non-cancer health risks were below threshold limits for the general population. However, infants and young children showed significantly higher risk values compared to other age groups, indicating they face greater health risks from atmospheric exposure to these endocrine disruptors. The research provides important data for developing policies to reduce health risks from airborne xenoestrogen exposure, particularly for vulnerable populations like children.
2025
J Clin Oncol
A large California study of over 58,000 racially and ethnically diverse women found that long-term exposure to fine particulate matter (PM2.5) air pollution was associated with a statistically significant 28% increased risk of breast cancer for each 10 μg/m³ increase in PM2.5 concentration, with the association consistent across African American, Latino, and other ethnic groups. When combined with data from 10 other studies in a meta-analysis, PM2.5 exposure showed a borderline significant 5% increased breast cancer risk, providing strong evidence that air pollution is an important breast cancer risk factor. These findings emphasize that breast cancer prevention strategies should extend beyond individual lifestyle changes to include population-level policies aimed at reducing air pollution, particularly as traditional risk factors explain only half of breast cancer cases and incidence continues to rise globally.
2025
Int J Environ Health Res
In this case-control study of African American women in Memphis, 355 participants aged 20–88 were enrolled, and the final analysis included 50 breast cancer cases and 157 controls whose home addresses were linked to detailed environmental and socioeconomic data. Using logistic regression, the researchers found that women living closer to heavy traffic had higher odds of breast cancer (OR 1.64, 95% CI: 1.05–2.56), and those living nearer to Superfund hazardous waste sites had markedly higher odds (OR 12.26, 95% CI: 1.81–82.86) compared with women living farther away. Spatial mapping showed that cases clustered in Southwest Memphis, an area with higher environmental burden and disadvantage. These findings suggest that environmental inequities in the built and industrial environment may substantially contribute to breast cancer disparities among African American women in this region.
2025
Environ Health
This case-control study of 942 Brazilian women (471 with breast cancer and 471 matched controls) found that higher blood levels of certain per- and polyfluoroalkyl substances (PFAS)—persistent environmental chemicals found in products like non-stick cookware and food packaging—were significantly associated with increased breast cancer risk. Specifically, elevated concentrations of n-perfluoroheptane sulfonate (n-PFHpS) doubled the breast cancer risk, and this association was particularly strong for hormone receptor-positive breast cancers and varied by ethnicity. The study emphasizes the importance of analyzing specific PFAS chemical variants (isomers) rather than treating all PFAS as identical, as different forms showed different associations with breast cancer risk across ethnic groups. These findings add to growing evidence that PFAS exposure may be a modifiable environmental risk factor for breast cancer, though the researchers note that previous studies have shown mixed results.
2025
Ecotoxicol Environ Saf
This study examined the link between cadmium (Cd) exposure and breast cancer risk using data from nearly 6,000 participants and a meta-analysis of 20 studies. The researchers found that higher cadmium levels significantly increased breast cancer risk, with the strongest association in estrogen receptor-positive (ER+) breast cancer subtypes, and identified glycated hemoglobin (HbA1c, a marker of blood sugar control) as a potential mechanism linking cadmium exposure to cancer development. The findings suggest that cadmium, an endocrine-disrupting metal found in the environment, may contribute to breast cancer through metabolic disruption. These results highlight the importance of reducing cadmium exposure and understanding how environmental toxins interact with metabolic health to influence cancer risk.
2025
Environ Int
A large French study following nearly 68,000 women for over 17 years found that dietary intake of polycyclic aromatic hydrocarbons (PAHs)—cancer-causing chemicals formed when meat, fish, and other foods are grilled, smoked, or cooked at high temperatures—was associated with increased breast cancer risk, particularly for hormone receptor-negative (ER-PR-) breast cancer which had a 34% higher risk at the highest exposure levels. The relationship showed a non-linear pattern, with elevated risk observed at moderate PAH intake levels, and similar trends for benzo[a]pyrene, a marker compound for total PAH exposure. These findings suggest that cooking methods that produce PAHs—such as grilling, barbecuing, and smoking foods—may increase breast cancer risk, supporting recommendations to limit charred or heavily grilled foods and use gentler cooking methods like baking, steaming, or stewing, particularly for women at higher risk.
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.
2024
Environ Int
This large prospective study of over 170,000 women in the NIH-AARP Diet and Health Study examined whether air emissions of 19 known or suspected carcinogenic chemicals from industrial facilities (1987-1995) were associated with postmenopausal breast cancer risk through 2018. Women living within 1 km of high benzene emissions had more than double the breast cancer risk compared to unexposed women (HR=2.06, 95% CI: 1.34-3.17, p-trend=0.001), with the association weakening at greater distances and appearing strongest for invasive rather than ductal carcinoma in situ. Elevated risk was also observed for vinyl chloride exposure at 5 km distance (HR=1.20, 95% CI: 1.01-1.43, p-trend=0.04), with suggestive but unclear associations for asbestos, trichloroethylene, and styrene. These findings indicate that residential proximity to industrial facilities emitting benzene and other carcinogens may increase breast cancer risk, warranting further investigation particularly in diverse populations living near high concentrations of industrial sources.
2024
J Natl Cancer Inst
A large US study of nearly 197,000 women found that exposure to fine particulate matter air pollution (PM2.5) during the 1980s—when pollution levels were higher—was associated with an 8% increased risk of breast cancer overall, with each 10 µg/m³ increase in PM2.5 concentration linked to the elevated risk. The association was particularly strong for estrogen receptor-positive breast cancers, showing a 10% increased risk, while no association was found for estrogen receptor-negative tumors. This study provides important evidence that historical air pollution exposure, even decades before diagnosis, may contribute to breast cancer development, particularly for hormone-sensitive tumors, emphasizing the long-term health consequences of air quality and the benefits of pollution reduction efforts.
2024
Br J Cancer
This comprehensive meta-analysis of 63 studies found that women who never smoked but were exposed to secondhand smoke had a 24% increased risk of breast cancer, with the risk rising to 45% in some exposure settings. The breast cancer risk increased with greater exposure duration, intensity, and cumulative exposure—women exposed to secondhand smoke for 40 years had a 29% increased risk, while those exposed to the equivalent of 20 cigarettes per day had a 38% increased risk. The analysis showed the strongest associations for home exposure (17% increased risk) and combined home or workplace exposure (24% increased risk), demonstrating clear dose-response relationships where more exposure meant higher breast cancer risk. These findings are particularly important for public health policy because they show that even non-smokers face significant breast cancer risk from breathing others’ tobacco smoke, supporting the need for comprehensive smoke-free laws in homes, workplaces, and public spaces.
2024
Eur J Cancer
A French study of over 5,400 women found a suggested 28% increased risk of breast cancer associated with long-term exposure to fine particulate matter (PM2.5) air pollution for each 10 µg/m³ increase in average concentration, though this association did not reach statistical significance, with weaker trends also observed for PM10 and nitrogen dioxide (NO2). This study uniquely examined air pollution exposure at both residential and workplace locations, finding that residential and workplace pollution levels were highly correlated, suggesting that residential exposure assessments can serve as a reasonable proxy for total pollution exposure. The findings contribute to growing evidence linking air pollution to breast cancer risk and suggest that future research should also consider exposure during commuting to capture complete pollution exposure patterns.
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
Med Lav
A meta-analysis of 23 cohort and case-control studies found that occupational benzene exposure was associated with an 8% increased breast cancer risk overall, with high-level benzene exposure showing a stronger 35% increased risk. The association was consistent for cancer incidence (8% increased risk) though not statistically significant for cancer mortality, and significant heterogeneity was detected across studies based on sex, publication year, study design, quality, and industry of employment. These findings suggest that benzene—a recognized carcinogen primarily studied in relation to leukemia—may also increase breast cancer risk in occupationally exposed workers, though the authors acknowledge that bias, confounding factors, and publication bias limit the strength of causal inference, highlighting the need for high-quality prospective studies with detailed exposure assessment to confirm these associations and inform workplace safety standards for the millions of workers potentially exposed to benzene in petroleum, chemical manufacturing, automotive repair, and other industries.
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
Sci Total Environ
A Chinese study of 226 breast cancer cases and 990 controls found that exposure to certain perfluoroalkyl substances (PFAS), particularly perfluorononanoic acid (PFNA) and perfluoroheptanoic acid (PFHpA), was associated with increased mitochondrial DNA copy number (mtDNAcn) in blood, which in turn was linked to breast cancer risk. Women with the highest mtDNAcn levels had a 234% increased risk of breast cancer and a 271% increased risk of postmenopausal breast cancer compared to those with the lowest levels. The study found that mtDNAcn mediated about 15% of the relationship between PFHpA exposure and breast cancer, suggesting that PFAS may increase breast cancer risk partly by affecting mitochondrial function. These findings provide new insights into how PFAS chemicals may contribute to breast cancer development through effects on cellular energy production and mitochondrial health.
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.
2024
Sci Total Environ
This large prospective cohort study investigated the association between DEHP exposure and breast neoplasms in 273,295 women from the UK Biobank, using modeled DEHP levels from environmental data and Cox regression analysis. Results showed that higher baseline and long-term DEHP exposure was positively associated with increased risk of malignant neoplasm, carcinoma in situ, and benign breast neoplasms, with suggestive higher risk in younger women and oral contraceptive users.
2023
J Endocrinol Invest
A comprehensive literature review examining environmental endocrine-disrupting chemicals (EDCs) and hormone-related cancers concludes that several EDCs can be definitively classified as carcinogenic, including dioxin and cadmium for breast and thyroid cancer, arsenic and dioxin for prostate cancer, and organochlorines for testicular cancer. The review highlights that fetuses and newborns are most vulnerable to endocrine disruption, with adverse effects potentially manifesting at different ages throughout life, making it difficult to assess the full health impact of EDC exposure. The authors emphasize that EDCs represent a major environmental health issue requiring effective prevention policies, increased public awareness, and protective measures—particularly for pregnant women—along with standardized testing criteria to evaluate the carcinogenic potential of new chemicals before they enter widespread use.
2023
Asian Pac J Cancer Prev
A study of 360 participants found that agricultural workers exposed to pesticides who carry genetic variations that impair their body’s ability to detoxify chemicals (null mutations in GSTT1 and GSTM1 genes) had substantially increased cancer risk, with 4-7 times higher odds of developing lymphoma or breast cancer compared to those with normal detoxification genes. The study also found elevated markers of oxidative stress (cellular damage) in farm workers with these genetic variants who developed leukemia, suggesting that pesticide exposure combined with impaired detoxification capacity triggers cancer development. These findings indicate that certain genetic profiles make agricultural workers particularly vulnerable to pesticide-related cancers, highlighting the importance of protective measures for farm workers and potential genetic screening to identify high-risk individuals.
2023
Breast Cancer Res
This large study of over 181,000 women from the UK Biobank examined whether allostatic load (AL)—a measure of cumulative physiological stress on the body over time—is associated with breast cancer risk. Women with higher AL scores had a significantly increased risk of developing breast cancer, with each one-unit increase in AL associated with a 5% higher risk, and women in the high AL group showing a 17% increased risk compared to those in the low AL group, even after accounting for known risk factors like family history, lifestyle, and genetic factors. The association was found across multiple subgroups and appeared independent of traditional breast cancer risk factors, suggesting that chronic physiological stress may contribute to breast cancer development. These findings indicate that AL could serve as a valuable biomarker for predicting and stratifying breast cancer risk in women.
Association between Urinary Lead and Female Breast Cancer: A Population-Based Cross-Sectional Study.
2023
Discov Med
This study analyzed data from nearly 2,800 women in the National Health and Nutrition Examination Survey (NHANES) to investigate whether urinary lead levels are associated with breast cancer risk. Researchers found that higher urinary lead levels were positively associated with breast cancer, with women having the highest lead levels showing 2.16 times the odds of breast cancer compared to those with the lowest levels, and this association persisted after adjusting for numerous factors including age, BMI, smoking, and socioeconomic status. The positive trend was consistent across different subgroups of women regardless of age, race, pregnancy history, or other health conditions. These findings suggest that lead exposure, as measured in urine, may be a risk factor for breast cancer in US women.
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.
2022
Environ Res
This case-only study included 2,998 women with breast cancer from the Women’s Circle of Health Study and examined how characteristics of hair dye and hair relaxer use were related to tumor features. Compared with women who only used salon-applied permanent hair dye, those using home dye kits or both salon and home dye had higher odds of having poorly differentiated (more aggressive) tumors, especially among Black women (for Black women: home kits OR 2.22, 95% CI: 1.21–5.00; combination use OR 2.46, 95% CI: 1.21–5.00) and among women with ER-positive tumors (combination use OR 2.98, 95% CI: 1.62–5.49). Combination use of hair relaxers was also associated with larger tumors (>2.0 cm vs <1.0 cm; OR 1.82, 95% CI: 1.23–2.69). Although some associations did not remain statistically significant after strict multiple-comparison correction, the overall pattern suggests that frequent, mixed use of hair dyes and relaxers may be linked to more aggressive breast tumor characteristics.
2022
Environ Sci Poll Res
This meta-analysis of 24 studies found that women occupationally exposed to organic solvents (chemicals used in manufacturing, cleaning, and industrial processes) had an 18% increased risk of breast cancer compared to unexposed workers, with the association being particularly strong in postmenopausal women (35% increased risk) and European workers. Organic solvents are commonly found in workplaces involving paint, adhesives, dry cleaning, and manufacturing, and the increased risk was consistent across both large cohort studies and case-control studies. These findings suggest that workplace exposure to organic solvents is an important and preventable occupational health hazard that contributes to breast cancer risk, especially for women working in industries that regularly use these chemicals.
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 French study of over 10,000 women found that long-term atmospheric exposure to PCB153, a widespread environmental pollutant with estrogen-like properties, was associated with a 19% increased risk of breast cancer for each standard deviation increase in cumulative exposure. The association was particularly strong for women who became postmenopausal during the study period (23% increased risk) and for estrogen receptor-positive breast cancers (18% increased risk), while no association was found for estrogen receptor-negative tumors. This is the first study to link airborne PCB exposure to breast cancer risk, providing evidence that these persistent environmental pollutants may contribute to hormone-sensitive breast cancer development even decades after their use was banned.
2021
Epidemiol
A study of 1,407 North Carolina women examined the relationship between blood levels of polychlorinated biphenyls (PCBs)—banned industrial chemicals that persist in the environment—and breast cancer risk. The researchers found that exposure to mixtures of PCBs was associated with increased breast cancer risk, with stronger associations observed among Black women (50% increased risk) compared to White women (10% increased risk) at higher exposure levels. Several individual PCB compounds showed elevated breast cancer risk when comparing highest to lowest exposure groups, with risk increases ranging from 20-40%. These findings support the hypothesis that PCB exposure may increase breast cancer risk, though additional studies in other populations are needed to confirm the results.
2021
Int J Clin Pract
A case-control study of 250 breast cancer patients and 250 controls found that women consuming diets that trigger higher insulin responses after meals—measured by dietary insulin index (DII) and dietary insulin load (DIL)—had 46-87% increased odds of breast cancer compared to those with lower scores. These high insulin-stimulating diets were more common among overweight women and those with family histories of cancer, suggesting that dietary patterns affecting blood insulin levels may be a modifiable risk factor for breast cancer. The findings support reducing consumption of foods that spike insulin levels—typically refined carbohydrates and high-glycemic foods—as a potential dietary strategy for breast cancer prevention, particularly for women at higher risk.
2021
Environ Pollut
A pilot study of 250 predominantly postmenopausal women in Hawaii found that higher levels of AMPA (the primary breakdown product of the herbicide Glyphosate) in urine were associated with significantly increased breast cancer risk, with women in the highest exposure group having 4.5 times the risk compared to those with the lowest exposure. AMPA was detected in the urine of 90% of breast cancer cases and 84% of healthy controls, with cases showing 38% higher average AMPA levels. This is the first study to prospectively examine the link between AMPA exposure and breast cancer, and while the findings suggest a concerning association, the authors emphasize that larger studies are needed to confirm these preliminary results and explore potential differences across racial and ethnic groups.
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.
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.
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
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
Environ Res
A 24-year study of over 112,000 U.S. nurses found that women living within 10 kilometers (about 6 miles) of municipal solid waste incinerators had a 15% increased breast cancer risk compared to those not living near these facilities, with risk rising to 25% for women within 5 kilometers (3 miles). The association strengthened with longer duration of residence near incinerators and higher dioxin emission levels, and was consistent across hormone receptor subtypes and menopausal status. These findings provide evidence that residential exposure to dioxins—toxic chemicals released from waste incineration that persist in the environment and accumulate in the food chain—may increase breast cancer risk, highlighting the need for stricter emissions controls on incinerators and consideration of proximity to such facilities in community planning and cancer prevention strategies.
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
Int J Env Res Pub Health
This Brazilian case-control study of 351 women in an intensive agricultural region found that women living near cropland where pesticides are used had more than twice the risk of developing breast cancer compared to those who didn’t live near such areas. The study also found that women over 50 who experienced early menarche (first menstrual period at 9-12 years) had approximately double the breast cancer risk. These findings suggest that residential proximity to pesticide-treated agricultural land may be an important environmental risk factor for breast cancer, adding to concerns about pesticide exposure beyond just occupational settings or dietary intake.
2019
Epidemiol
A large US study of nearly 51,000 women found that exposure to airborne toxic metals, particularly mercury, cadmium, and lead, was associated with increased postmenopausal breast cancer risk, with mercury showing the strongest effect at 30% increased risk for the highest exposure levels. When examining the combined effect of 10 different airborne metals together, the mixture was associated with elevated postmenopausal breast cancer risk, with mercury, lead, and cadmium contributing most to this increased risk. These findings suggest that environmental exposure to toxic metals through air pollution may be an important and underrecognized risk factor specifically for breast cancer in postmenopausal women.
2019
Environ Int
This 20-year study of 748 women diagnosed with breast cancer in North Carolina found that those with the highest levels of DDE (a breakdown product of the banned pesticide DDT) in their blood had nearly twice the risk of death compared to those with the lowest levels. The association between DDE exposure and breast cancer death was particularly strong among Black women and women with estrogen receptor-negative tumors, with Black women showing more than double the mortality risk. Since DDT was banned in the U.S. in 1972 but DDE persists in the environment and body fat for decades, these findings suggest that legacy pesticide exposure may contribute to worse breast cancer outcomes and racial disparities in breast cancer survival.
2019
Occ Environ Med
This Canadian study of over 2,200 women found that occupational exposure to polycyclic aromatic hydrocarbons (PAHs)—chemicals released from burning materials like coal, oil, and gasoline—increased breast cancer risk by 32%, with higher risks seen in women exposed to high levels for more than 7 years. The association was particularly strong among women with a family history of breast cancer, where prolonged high exposure nearly tripled the risk. These findings suggest that workplace PAH exposure may be an important and preventable breast cancer risk factor, especially for women with genetic susceptibility to the disease.
2019
Environ Int
This population-based case-control study investigated whether occupational exposure to alkylphenolic compounds—endocrine-disrupting chemicals widely used in industry—is associated with breast and prostate cancer. The study included over 5,600 participants and found that occupational exposure to alkylphenolic compounds was modestly associated with increased breast cancer risk (23% increase), particularly from exposure to domestic cleaning products and nonylphenol ethoxylates. No significant associations were found between alkylphenolic compound exposure and prostate cancer overall, except among men exposed through cosmetics and personal hygiene products. The authors conclude these findings suggest a modest link between occupational alkylphenolic compound exposure and breast cancer that requires further confirmation in additional studies.
2019
Cancer Epidemiol
A 22-year Italian study following nearly 9,000 women found that those with the highest dietary cadmium intake (a toxic metal found in foods like grains, vegetables, and shellfish) had a 54% increased breast cancer risk compared to those with the lowest intake, with even stronger associations in premenopausal women (73% increased risk). Cadmium—classified as a proven human carcinogen—enters the food supply primarily through contaminated soil and water, with diet being the main exposure source for non-smokers at an average intake of about 8 micrograms per day in this population. The increased risk was consistent across all breast cancer subtypes regardless of hormone receptor status, supporting cadmium as a dietary risk factor for breast cancer and highlighting the need for strategies to reduce cadmium levels in the food supply through soil remediation and crop selection.
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.
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.
2000
Am J Indust Med
This Danish nationwide study of 230 male breast cancer cases found that men occupationally exposed to gasoline and its combustion products had a 2.5 times higher risk of breast cancer, with the risk rising to 5.4 times higher among men first exposed before age 40. Gasoline contains several known carcinogens including benzene and produces cancer-causing combustion products, which may explain this elevated risk. Since male breast cancer is rare but shares similar biology with female breast cancer, these findings suggest that gasoline exposure may also increase breast cancer risk in women and warrant further investigation in female workers.
2025
Epidemiol
A prospective study of 46,150 Sister Study participants followed for a median 13.4 years (4,155 breast cancer cases) used EPA Toxics Release Inventory data to quantify residential air emissions of 28 industrial compounds—many carcinogenic or endocrine-disrupting—during the 10 years before enrollment (2003-2006). Emissions within 3 km of residences showed non-significant associations with breast cancer for nickel compounds (HR = 1.3; 95% CI: 1.0-1.6 for highest vs. no exposure) and trichloroethylene (HR = 1.3; 95% CI: 1.0-1.6), while exposure continuum mapping identified 25 mixture profiles explaining 72% of emissions variance, with the joint-exposure response function suggesting higher breast cancer incidence among individuals with rare, high-emission profiles, though the overall mixture trend was not statistically significant (p = 0.09). These findings indicate that residential proximity to industrial air emissions of certain carcinogens—particularly nickel compounds and trichloroethylene—may be associated with increased breast cancer risk, though the lack of overall mixture association may reflect that individual compounds or specific emission sources are more important than cumulative exposure profiles, or that most participants experienced relatively low emissions with elevated risks concentrated among small subgroups with high exposure to specific pollutants.
2025
Global Health Res Pol
A meta-analysis of 17 observational studies found that the highest consumption of fast foods and ultra-processed foods (FFs/UPFs) was associated with a 25% increased breast cancer risk compared to the lowest consumption levels. The association was particularly strong in case-control studies and in Latin American populations, and remained significant regardless of sample size or BMI adjustment, though no association was found in cohort studies or when stratified by menopausal status. These findings suggest that diets high in ultra-processed foods—which often contain carcinogenic compounds formed during processing, additives, packaging contaminants, and unhealthy nutrient profiles—may contribute to breast cancer development, highlighting the urgent need for public health strategies and regulatory policies targeting food processing standards, marketing restrictions, improved labeling, and reduced accessibility of ultra-processed foods to reduce cancer risk, particularly as global consumption of these products continues to rise.
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.
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.