Research Results
Beta Version
Use the search bar below to find studies, or apply one or more filters to narrow your results. See our list of keywords to guide your search.
Search by keyword
Select
Select
- All Risk Factors
- Air Pollution
- Alcohol
- Antimicrobials
- Artificial sweeteners
- Bisphenols
- Body Weight
- Breast Density
- Chemical Mixtures
- Chemicals in products
- Cleaning Products
- Diet
- Exercise
- Family History
- Furniture & Electronics
- Genetics
- Gut Health
- Hair Dye
- Hormones
- Inflammation
- Job
- Light at night
- Metals
- Neighborhood
- Night Shift Work
- Noise
- Non-stick Pans & Waterproof Gear
- Oral Contraceptives
- PAHs
- Parabens
- PCBs
- Personal Care Products
- Pesticides
- PFAS
- Pharmaceuticals
- Place-based
- Plastic
- Pregnancy & Breastfeeding
- Processed Food
- Puberty Age
- Race/Ethnicity
- Radiation
- Red meat
- Scented Products & Soft Plastic
- Sleeping Patterns
- Soda
- Stress
- Sugar
- Sunscreen
- Tobacco
- Vitamin D
Select
Select
Select
Select
Select the Chemical Agents
- All Chemical Agents
- 1,1,2,2-TCA
- 1,3-Butadiene
- Acrolein
- Aldrin
- Alkylphenols
- Antimicrobials
- Antimicrobials: QACs, Triclosan, Triclocarban
- Aromatic Amines
- Arsenic
- Artificial Sweeteners
- Atrazine
- Benzene
- Bisphenols
- Cadmium
- Chlordane
- Chlorpyrifos
- DDT
- Dibutyl Phthalate
- Dichlorvos
- Dieldrin
- Dioxins
- ell/
- Ethanol (alcohol)
- Ethyl Benzene
- Ethylene Oxide
- Flame Retardants
- Food
- Formaldehyde
- Glyphosate
- Heptachlor
- Hormones
- Insulin
- Lead
- Light at Night
- Mercury
- Metals
- Methoxyclor
- Naphthalene
- Night Shift Work
- Nitrogen Dioxide
- Noise
- Oral Contraceptives
- Organochlorine Pesticides
- Organophosphate Pesticides
- Ozone
- PAHs
- Parabens
- Particulate Matter
- PCBs
- Pesticides
- PFAS
- Phenols
- Phthalates
- Processed Food
- PVC
- Radiation: Ionizing
- Radiation: Non-Ionizing
- Soda
- Stress
- Sugar
- Tobacco
- Toluene
- Trichloroethylene
- Triclosan
- Ultraviolet Radiation
- UV Filters
- Vinyl Chloride
Select the Study Tags
Sort By
- Relevance
- Title (A to Z)
- Title (Z to A)
- Publication Year (Ascending)
- Publication Year (Descending)
- Authors (A to Z)
- Authors (Z to A)
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
Public Health
In this Mendelian-randomization study of European and East Asian populations, genetic variants linked to daytime/evening Noise and air pollutants (NO₂, NOₓ, PM₂.₅, PM₁₀) were used to assess breast cancer risk. In the European cohort, genetically predicted NO₂ exposure had an OR of 1.94 (95% CI: 1.29–2.92) and PM₁₀ had an OR of 1.42 (95% CI: 1.09–1.85) for breast cancer; in East Asian populations, NO₂ exposure showed OR = 1.14 (95% CI: 1.008–1.287). The findings suggest that both traffic-related air pollutants and Noise may causally contribute to breast 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.
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
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
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
Environ Health Perspect
An updated analysis of the largest cohort of ethylene oxide (EtO)-exposed workers—7,549 women employed ≥1 year at 13 U.S. facilities followed from 1960-2021 (181 breast cancer deaths)—found that cumulative EtO exposure was strongly associated with elevated breast cancer mortality, with workers accruing 3,650 ppm-days of exposure (equivalent to 10 years at 1 ppm) having over three times the breast cancer death rate compared to unexposed workers (RR = 3.15; 95% CI: 1.78-5.60) using a 20-year lag model. This association remained robust in a subcohort with interview data on breast cancer risk factors after matching on potential confounders (RR = 3.22; 95% CI: 1.52-7.13), with evidence of variation by time since exposure and exposure rate. These findings provide strong evidence that EtO is a human breast carcinogen and support recent emission reduction proposals, raising serious public health concerns given the high prevalence of breast cancer, large numbers of occupationally exposed workers, and potential for widespread environmental exposure from industrial facilities, with elevated risks observed even in low exposure ranges highlighting the need for stringent exposure controls and environmental monitoring.
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
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
Int J Hyg Environ Health
A study of 48,665 California women in the Multiethnic Cohort found that exposure to specific ambient air toxics at residential addresses was associated with increased breast cancer risk over a 10-year follow-up period. Industrial chemicals showed the strongest associations, with 1,1,2,2-tetrachloroethane linked to a 322% increased risk, ethylene dichloride to a 181% increased risk, and vinyl chloride to a 127% increased risk. Gasoline-related pollutants also showed elevated risks, including benzene (32% increase), acrolein (126% increase), and toluene (29% increase), with generally stronger associations observed among African American and White women. These findings suggest that toxic air pollutants, particularly from industrial sources and vehicle emissions, may contribute to breast cancer development, which is especially concerning for populations living in high-pollution areas like Los Angeles.
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
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
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
Cancer Epidemiol
A Canadian case-control study of 465 young women (ages 18-45) with breast cancer and 242 controls found that residential exposure to air pollution was strongly associated with increased breast cancer risk. For each interquartile range increase in nitrogen dioxide (NO₂) exposure—a traffic-related pollutant—women had a 133% increased risk of breast cancer at their current residence and a 116% increased risk based on exposure five years earlier. The findings suggest that traffic-related air pollution may be a particularly important and underrecognized breast cancer risk factor in younger women.
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
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
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.
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 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
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.
2021
Environ Int
Long-term exposure to benzo[a]pyrene (BaP), a toxic air pollutant from gas and diesel vehicle exhaust, was associated with a 15% increased risk of breast cancer in a large French study of over 10,000 women. The risk was particularly elevated in women transitioning through menopause and for hormone receptor-positive breast cancers, with each increase in BaP exposure levels raising breast cancer odds by 15-20%. This study provides important real-world evidence that BaP air pollution may contribute to breast cancer development, especially affecting hormone-sensitive tumors.
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
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
Scand J Work Environ Health
This large Danish study of over 38,000 women with breast cancer found that occupational exposure to diesel exhaust was associated with a modestly increased risk of estrogen receptor-negative breast tumors in women under age 50, with the risk increasing with longer duration and higher levels of exposure. No significant associations were found for overall breast cancer risk or for exposure to polycyclic aromatic hydrocarbons (PAHs). These findings suggest that workplace diesel exhaust exposure may be particularly relevant for early-onset, harder-to-treat forms of breast cancer, highlighting the importance of protecting workers from diesel fumes.
Chronic long-term exposure to cadmium air pollution and breast cancer risk in the French E3N cohort.
2020
Cancer Epiemiol
A French study of over 8,000 women found no overall association between long-term airborne cadmium exposure and breast cancer risk, but unexpectedly discovered that higher cadmium exposure was associated with a 32-38% decreased risk of estrogen receptor-negative (ER-) breast cancers. This finding contradicts the hypothesis that cadmium increases breast cancer risk through its estrogen-like effects, and instead suggests cadmium may have different biological effects depending on the hormone receptor status of tumors. These surprising results indicate that cadmium’s relationship with breast cancer is more complex than previously thought and may involve mechanisms beyond its known estrogen-mimicking properties, requiring further research to understand why it might protect against hormone receptor-negative tumors.
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
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.
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
Discov Oncol
This systematic review examined the relation of 4 neighborhood factors on breast cancer incidence and prognosis among African-American women: neighborhood socioeconomic status (nSES), residential segregation, spatial access to mammography, and residential pollution. The authors found that nSES, residential segregation and access to mammography were all related to stage at diagnosis, and nSES and living in more segregated areas were both associated with mortality. Residential pollution was not associated with increased risk of breast cancer in the studies reviewed.
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
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.
2025
J Hazard Mater
This study used advanced computer modeling to assess the combined reproductive health risks of phthalates (PAEs) and organophosphates (OPEs) found in atmospheric particles, focusing on their ability to disrupt hormone receptors. The researchers found that the mixed toxicity of these compounds was lower than expected from individual effects, suggesting they may interfere with each other’s toxic actions through antagonistic effects. Using network analysis and molecular modeling, they identified 590 potential targets and 50 core targets (including hormone receptors) affected by these pollutants, with DEHP, TPHP, and MEHP being key disruptors of hormone signaling pathways. The study also identified two previously overlooked targets (AKT1 and HSP90AA1) that may be important for reproductive toxicity, providing new insights into how these atmospheric pollutants may affect human reproductive health.
2024
Int J Environ Res Public Health
A systematic review of 25 epidemiological studies (2013-2022) found that seven out of eight investigated outdoor air pollutants showed significant associations with increased breast cancer risk, with benzo[a]pyrene showing the strongest relationship. The review found that 100% of studies examining nitrogen oxides (NOₓ), 83% of PM₂.₅ studies, 69% of nitrogen dioxide (NO₂) studies, and 43% of PM₁₀ studies demonstrated positive associations with breast cancer risk, with hazard ratios ranging from 1.05-1.56 and odds ratios from 1.03-1.86, while ozone and cadmium showed negative or no associations. These findings strengthen the evidence that outdoor air pollution—particularly traffic-related pollutants and fine particulate matter—contributes to breast cancer development, though the authors note that further research is needed to establish causal mechanisms, particularly through epigenetic pathways, and acknowledge that the review’s focus on English-language articles from developed countries may limit generalizability.
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.
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.
2023
Cancer Epidemiol Biomark Prev
A pooled analysis of six European cohorts including 199,719 women followed for 3.6 million person-years found that long-term exposure to fine particulate matter (PM₂.₅) was associated with a 6% increased breast cancer risk per 5 μg/m³ increase. The association was strongest among middle-aged women (ages 50-54) and never-smokers, and notably, the cohorts studied represented the lower range of air pollution concentrations in Europe, suggesting that even relatively low levels of air pollution may contribute to breast cancer risk. These findings add to mounting evidence that air pollution—particularly fine particulate matter from traffic, industry, and combustion sources—is an environmental breast cancer risk factor operating independently of established risk factors, with important implications for public health policy, urban planning, and air quality regulations aimed at reducing population-level cancer burden, especially given that air pollution exposure is largely involuntary and affects entire populations.
2023
Environ Res
A nationwide Danish study of 55,745 breast cancer cases matched with controls found that each 10 μg/m³ increase in fine particulate matter (PM₂.₅) air pollution exposure over 20 years was associated with a 21% increased breast cancer risk, with the association particularly strong (32% increased risk) among women diagnosed before age 55. While elemental carbon and nitrogen dioxide also showed modest associations initially, these disappeared in multi-pollutant models, suggesting PM₂.₅ is the primary air pollutant linked to breast cancer risk. These findings add breast cancer to the growing list of cancers associated with air pollution exposure and suggest that younger women may be especially vulnerable, though the authors caution that unmeasured confounding factors may influence the results.
2023
Environ Res
A meta-analysis of 17 epidemiological studies examining cadmium exposure and breast cancer risk found no statistically significant associations overall or when examining specific exposure routes separately (dietary cadmium or biomarker-based studies), with substantial heterogeneity between studies and no clear patterns by menopausal status. The inconclusive findings leave critical questions about whether specific exposure routes (occupational, air pollution, smoking) pose different risks than dietary intake or whether residual confounding by tobacco smoke constituents may influence observed associations. These results highlight the need for future research with better exposure assessment methods that can distinguish between different cadmium sources and routes of exposure, particularly occupational and environmental air pollution exposures that may be more relevant than diet for populations living near industrial areas where cadmium contamination is prevalent.
2023
Reprod Toxicol
A review of epidemiologic literature examining environmental chemical exposures during pregnancy and three maternal health outcomes (preeclampsia, gestational diabetes, and breast cancer) found that pregnancy represents a unique critical period when biological changes can heighten women’s susceptibility to chemicals from air, food, water, and consumer products—including flame retardants, plasticizers, pesticides, and lead—though research has disproportionately focused on fetal outcomes rather than maternal health risks, which remain poorly characterized for most chemicals. While evidence shows that lead exposure increases risk of pregnancy-induced hypertensive disorders and pregnancy can amplify women’s vulnerability to environmental chemicals, variations in study design, exposure assessment methods, and inconsistent adjustment for confounders limited comparability across studies. The authors emphasize that future research must recognize pregnancy as a critical window for women’s lifelong health, calling for incorporation of biomarkers of exposure and effect, deliberate timing and methods of measurement, and consistent confounder adjustment to strengthen understanding of the pregnancy exposome and its impacts on maternal health outcomes beyond the immediate postpartum period.
2023
Endocrinol Metab Clin North Am
Multiple social and structural determinants of health undoubtedly contribute to the marked racial/ethnic-, gender-, and socioeconomic-based disparities in endocrine health; however, the contribution of environmental injustice is vastly underappreciated. Indeed, those groups disproportionately burdened by endocrine disorders are often exposed to higher levels of various EDCs, including PCBs, phthalates, bisphenols, OC pesticides, air pollutants, PFASs, toxic metals/metalloids, and BFRs. These chemicals threaten our reproductive and metabolic health, contributing to diabetes prevalences, obesity, and disorders related to hormonal regulation. This review increases awareness of these disparities and encouraged equitable healthcare for those who are disadvantaged.
2023
J Natl Cancer Inst
A large cohort study of 451,945 National Institutes of Health-AARP Diet and Health Study participants used EPA Toxics Release Inventory data to estimate historical environmental ethylene oxide (EtO) exposures based on proximity to EtO-emitting facilities, wind patterns, and emission levels from enrollment in 1995-1996. Among 173,670 postmenopausal women, living within 10 km of EtO facilities was associated with statistically significant breast cancer risk for invasive disease (HR = 1.03; 95% CI: 0.97-1.09); women in the highest quartile of the airborne emissions index showed elevated risk of in situ breast cancer at 10 km (HR = 1.25; 95% CI: 1.02-1.53), with no clear patterns for non-Hodgkin lymphoma risk. These findings reveal a novel potential association between environmental EtO exposure and in situ breast cancer—but not invasive breast cancer or lymphohematopoietic cancers—contrasting with occupational studies that found associations with invasive disease. The differential association with in situ versus invasive disease suggests EtO may influence early-stage breast carcinogenesis, though the mechanism remains unclear and warrants further investigation to understand why environmental exposures show different patterns than occupational exposures and why the effect appears limited to pre-invasive lesions.
2023
Environ Sci Technol
The following study discusses a strategic framework to improve how chemicals are managed in North America. The Essential-Use Approach is a policy that prioritizes restricting the use of chemicals based on necessity and safety. It proposes three guiding questions: Is the chemical essential to the product’s function? Is it the safest option? Is it necessary for health and safety? They also prioritize speed of assesments so that chemicals can be quickly phased out if evidence suggests danger to human health. This study is a call for change and aims to become a tool to simplify decision-making for regulating organizations, help businesses avoid liability related to harmful chemicals, and ultimately improve public health by ensuring only the safest substances are used in consumer products.
2022
Int Arch Occup Environ Health
A nationwide retrospective cohort study of over 4.7 million Taiwanese workers found that occupational exposure to specific hazardous chemicals was associated with significantly elevated breast cancer risk among female workers, with asbestos showing the highest increase (107% increased incidence, 80% increased risk after adjusting for age and exposure duration). Other notable associations included 1,1,2,2-tetrachloroethane (74% increased incidence, 52% adjusted risk increase), trichloroethylene/tetrachloroethylene (47% increased incidence, 42% adjusted risk increase), benzene (40% increased incidence, 38% adjusted risk increase), and lead (27% increased incidence, 31% adjusted risk increase), with associations remaining robust even after accounting for 2- or 5-year latency periods. These findings from 3,248 breast cancer cases among exposed workers provide compelling evidence that occupational chemical exposures substantially increase breast cancer risk, highlighting the urgent need for enhanced workplace protections, regular breast cancer screening programs for exposed workers, substitution of safer alternatives where possible, and recognition of breast cancer as an occupational disease for workers with documented exposure to these carcinogens.
2022
Environ Sci Pollut Res
The following study explores the presence of endocrine disruptors such as phthalates (specifically mono-2-ethyl phthalate and mono-n-butyl phthalate), bisphenol A (BPA), and 1-hydroxypyrene in the urine samples of marginalized Indigenous populations. The study found that 100% of the women sampled showed exposure to these harmful chemicals, with higher concentrations than observed in similar studies from other communities. This increased exposure is linked to environmental and cultural factors, such as the common use of plastic containers and practices such as burning garbage. The women sampled were found to have especially high levels of mono-2-ethyl phthalate, which suggests significant exposure to di(2-ethylhexyl) phthalate. These findings highlight the vulnerability of indigenous communities to pollution due to a lack of awareness, limited healthcare access, and inadequate regulatory measures.
2021
Sci Rep
A nested case-control study of 4,401 breast cancer cases and 4,401 matched controls from the French E3N cohort found no overall association between long-term airborne cadmium exposure and breast cancer stage or tumor grade, but identified a striking 240% increased risk of invasive tubular carcinoma (ITC)—a specific breast cancer subtype—among women in the highest versus lowest quintile of cadmium exposure. The dose-response analysis suggested a linear relationship between cadmium exposure and ITC risk specifically, though no associations were found for other histological subtypes or more advanced disease. These findings suggest that cadmium’s estrogenic properties may selectively promote certain breast cancer subtypes rather than broadly increasing all breast cancer risk, highlighting the importance of examining cancer heterogeneity in environmental exposure studies and raising concerns about air pollution from industrial sources, waste incineration, and fossil fuel combustion that release cadmium into the environment.
2021
Environ Res
A prospective cohort study of 16,941 Danish nurses followed from 1993/1999 through 2012 (745 breast cancer cases during 320,289 person-years) examined residential outdoor light at night (LAN) exposure using satellite data and found no overall association between LAN and breast cancer risk in fully adjusted models accounting for individual characteristics, traffic noise, and air pollution, with hazard ratios of 0.97 (95% CI: 0.77-1.23) for highest LAN exposure and 1.09 (95% CI: 0.90-1.31) for medium exposure compared to lowest tertile. A suggestive association was observed between LAN and estrogen receptor-negative (ER-) breast cancer, though this was not statistically significant. Despite mechanistic evidence from melatonin research and xenograft experiments suggesting that light at night exposure may disrupt circadian rhythms and increase breast cancer risk, this large prospective study found only weak evidence for such an association using objective outdoor LAN measurements, though the study was limited to outdoor residential exposure and may not capture indoor lighting exposure or occupational night work that could be more relevant to circadian disruption and breast cancer development.
2020
Environ Res
A systematic review of 100 publications across 56 epidemiologic studies found that research enriched with women at higher baseline breast cancer risk—through family history, early-onset disease, or genetic susceptibility—consistently showed stronger and more frequent associations between environmental chemical exposures and breast cancer compared to average-risk populations. Specifically, 80% of studies enriched with family history or early-onset cases showed significant associations with exposures including PAHs, air pollution, DDT, PCBs, PFAS, metals, personal care products, and occupational chemicals, while 74% of studies examining genetic susceptibility found significant gene-environment interactions for various pollutants in women with variants affecting carcinogen metabolism, DNA repair, and oxidative stress. These findings suggest that the inconsistent evidence for environmental chemicals and breast cancer in the literature may partly stem from studying predominantly average-risk populations who may be less susceptible to environmental carcinogens, highlighting the critical need for future research to focus on high-risk populations and measure exposures during key windows of susceptibility (puberty, pregnancy, menopause) to more accurately capture the role of environmental chemicals in breast cancer development.
2020
Food Chem Tox
This article discusses the harmful impacts of polycyclic aromatic hydrocarbons (PAHs) found in deep-fried foods. It highlights their endocrine-disrupting, genotoxic, and carcinogenic abilities when oils used for deep frying are heated repeatedly or at high temperatures. PAHs disrupt steroidogenic pathways which can lead to hormonal imbalances of estrogen and testosterone causing lower sperm quality, estrogenic effects, and endocrine related disorders. Furthermore, PAHs are linked to increased cancer risks through genotoxicity which can cause mutations in the cell. Organ sites that can be affected by this cancer risk are the breast, prostate, colorectal, renal, and pancreas.
2019
Int Arch Occup Environ Health
A systematic review and meta-analysis of 30 studies (with meta-analyses conducted on 13 studies) examined the association between occupational ethylene oxide (EO) exposure and risk of lympho-hematopoietic cancers (LHC) and breast cancer. The overall pooled meta-relative risk was 1.48 (95% CI: 1.07-2.05) for LHC and 0.97 (95% CI: 0.80-1.18) for breast cancer, with meta-RRs for LHC among EO production workers at 1.46 and sterilization workers at 1.07, neither reaching statistical significance. Notably, a clear temporal trend emerged showing substantially higher LHC risk estimates in earlier studies from the 1980s (meta-RR = 3.87) that progressively declined in more recent decades, with studies from the 2000s and 2010s showing meta-RRs of 1.05 and 1.19 respectively, neither statistically significant. The authors conclude that the most informative and methodologically rigorous epidemiological studies published in recent decades do not support an association between occupational ethylene oxide exposure and increased risk of either lympho-hematopoietic cancers or breast cancer, suggesting that earlier positive findings may have been influenced by methodological limitations, exposure misclassification, or confounding factors that have been better controlled in more recent research.