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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
Iran J of Pub Health
This study of nearly 5,000 U.S. women found that exposure to triclosan—an antibacterial chemical once commonly found in soaps, toothpaste, and other personal care products—was associated with more than double the breast cancer risk at moderate exposure levels, while propylparaben (a preservative in cosmetics and foods) showed a protective association. However, when researchers examined the combined effect of multiple phenols and parabens together, they found no significant association with breast cancer, suggesting these chemicals may have complex and sometimes opposing effects. These mixed findings highlight the need for more research to understand how individual chemicals versus chemical mixtures affect breast cancer risk, especially since people are typically exposed to multiple chemicals simultaneously in everyday products.
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 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
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
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
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
Rev Environ Health
This comprehensive systematic review and meta-analysis examined the relationship between exposure to DDT (a banned pesticide that persists in the environment and human body) and breast cancer by analyzing studies published from 2000 to 2021. The analysis found positive associations between DDT exposure and breast cancer risk across multiple study types: in long-term prospective studies, women with higher p,p’-DDT levels had 41% increased odds of breast cancer, while retrospective studies showed 15% increased odds with p,p’-DDE exposure and 33% increased odds with high p,p’-DDT concentrations. The strongest association was observed with o,p’-DDT exposure, showing 2.24 times higher odds of breast cancer. These findings support a positive relationship between DDT exposure and breast cancer risk, reinforcing the importance of maintaining the worldwide ban on DDT use, as this pesticide remains in human bodies for decades and continues to spread geographically even where it’s no longer applied.
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.
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.
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
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
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.
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 Pollut
A French study of over 10,000 women found that combined exposure to a mixture of four hormone-disrupting air pollutants (benzo[a]pyrene, cadmium, dioxin, and PCB153) was associated with an approximately 10-11% increased risk of breast cancer. Using advanced statistical methods that account for simultaneous exposure to multiple pollutants rather than examining each separately, researchers found that benzo[a]pyrene, cadmium, and PCB153 showed the strongest individual contributions to increased breast cancer risk within the mixture. This research provides important evidence that the cumulative effect of multiple air pollutants acting together on hormone pathways may be a significant risk factor for breast cancer development.
2024
Environ 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
Cancer Causes Cont
This large Canadian population-based study examined whether long-term residential exposure to polycyclic aromatic hydrocarbons (PAHs)—widespread environmental pollutants from sources like vehicle exhaust and industrial emissions—increases breast cancer risk. Using 20 years of residential history data, researchers found that exposure to fluoranthene (a common PAH) was associated with significantly increased risk of premenopausal breast cancer, with women in moderately high exposure areas showing 59-148% higher risk compared to those in low-exposure areas. The associations with postmenopausal breast cancer were inconsistent, with only one analysis showing a modest increased risk. These findings support the hypothesis that ambient PAH exposure may increase the risk of breast cancer in premenopausal women, though the relationship appears complex and requires further investigation.
2024
Nutrients
This study of 989 women with BRCA1 mutations in Poland examined whether blood lead levels affect cancer risk in this high-risk population. Women with elevated blood lead levels (above 13.6 μg/L) showed 3.33 times higher risk of developing ovarian cancer (95% CI: 1.23-9.00, p=0.02) compared to those with lower levels, though this association lost significance after adjusting for other factors (HR=2.10, 95% CI: 0.73-6.01), while no significant association was found with breast cancer risk. These findings suggest that lead exposure may be an additional risk factor for ovarian cancer in BRCA1 mutation carriers and could inform the timing of preventive surgery (removal of ovaries and fallopian tubes) in this population. The authors recommend validation of these findings in other populations and investigation of whether reducing lead exposure through detoxification could lower ovarian cancer risk in BRCA1 carriers.
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
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
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
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
Am J Epidemiol
This systematic review of 18 epidemiological studies evaluated whether exposure to PFAS—measured in blood or plasma—is associated with breast cancer risk. Across 11 of the studies included in the meta-analysis, higher concentrations of common PFAS such as PFOA and PFOS were not associated with increased breast cancer risk (per-log-unit RR for PFOA = 0.95, 95% CI: 0.77–1.18; PFOS = 0.98, 95% CI: 0.87–1.11). When analyses were restricted to studies where PFAS levels were measured before diagnosis, risk estimates were slightly higher (for PFOA: RR = 1.16, 95% CI: 0.96–1.40), but still not statistically significant. Overall, the evidence suggests that current PFAS exposures measured do not show a consistent link to breast cancer, though the authors note substantial study variability and the need for better prospective data.
2024
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.
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
Environ Health Perspect
A nationwide study using CDC biomonitoring data found that California’s Proposition 65, which requires warnings about chemicals that cause cancer or reproductive harm, led to reduced exposures to listed chemicals across the entire United States, not just California. While blood and urine concentrations of 37 monitored chemicals generally declined over time, the researchers found evidence of problematic chemical substitution—for example, after bisphenol A (BPA) was listed, its concentrations dropped 15% but levels of the unlisted substitute bisphenol S (BPS) increased 20%. Californians generally had lower levels of harmful chemicals in their bodies compared to residents of other states, suggesting the law had additional protective effects. The findings indicate that transparency laws like Prop 65 can drive manufacturers to reformulate products nationwide, but regulations need to address entire chemical classes rather than individual substances to prevent companies from simply switching to similar but unlisted toxic chemicals.
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
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
Biol Trace Elem Res
This cross-sectional analysis from the 2007–2016 National Health and Nutrition Examination Survey (NHANES) explored the relationship of urinary concentrations of heavy metals and breast cancer. 3,352 U.S. women (aged 20 or older) in the were included in the analysis. 106 reported a history of breast cancer (weighted prevalence ~ 3.1%). Researchers measured urinary concentrations of heavy metals — cadmium, lead, and mercury — corrected for creatinine, then applied multivariate logistic regression to assess associations with prevalent breast cancer. They found that women in the highest quartile of urinary lead (≥ 0.71 µg/g creatinine) had significantly elevated odds of prior breast cancer (OR = 2.95, 95% CI: 1.13–7.70) compared with those in the lowest quartile; by contrast, urinary cadmium and mercury showed no statistically significant associations. The findings suggest that among common endocrine-disrupting metals, lead exposure — as measured by urinary biomarkers — may be linked with increased breast cancer prevalence in U.S. women.
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
PLOS Med
A large UK study of nearly 10,000 breast cancer cases found that current or recent use of progestagen-only contraceptives (including pills, injections, implants, and IUDs) was associated with a 21-32% increased breast cancer risk, similar to the risk from combined oral contraceptives containing both estrogen and progestagen. The absolute risk increase is small and age-dependent: for women using hormonal contraceptives for 5 years, the excess risk translates to 8 additional breast cancer cases per 100,000 users among women aged 16-20, but rises to 265 additional cases per 100,000 users among women aged 35-39. While these findings add important evidence about hormonal contraceptive risks, the small increased risk must be weighed against the significant benefits of contraception during childbearing years, and women should discuss their individual risk-benefit profile with their healthcare providers when choosing contraceptive methods.
2023
Cancer Prev Res
A large prospective study of 76,951 postmenopausal women followed for nearly 17 years found that women reporting the highest levels of stressful life events had a 30% increased risk of developing ER-negative breast cancer compared to those with the lowest stress levels, with no association found for ER-positive breast cancer. The risk was particularly pronounced among widowed women, who showed a 139% increased risk when experiencing high levels of stressful life events. These findings suggest that chronic psychosocial stress may specifically increase risk for ER-negative breast cancer—a more aggressive subtype—and that the impact of stress may be amplified by loss of a spouse, highlighting the potential importance of stress management and social support in breast cancer prevention.
2023
Int J Cancer
This study of over 1,200 postmenopausal women found that higher blood levels of PFOS (a common “forever chemical” found in items like stain-resistant fabrics and food packaging) were associated with 59-134% increased risk of hormone receptor-positive breast cancers, while PFOA (another widespread PFAS chemical) showed modest associations with hormone receptor-negative tumors. PFAS are called “forever chemicals” because they persist indefinitely in the environment and human body, and these findings suggest they may contribute to breast cancer through hormone disruption. These results add to growing concerns about PFAS exposure from contaminated water, food packaging, and consumer products, though the different associations for PFOS and PFOA by tumor subtype require further investigation to fully understand how these chemicals affect breast cancer development.
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 Sci Poll Res
This meta-analysis pooled data from 17 epidemiological studies to examine whether exposure to the dioxin compound 2,3,7,8-TCDD or to per- and polyfluoroalkyl substances (PFAS) is associated with breast cancer risk. The authors found evidence of a modest but statistically significant increased breast cancer risk associated with TCDD levels in the body,
2023
Environ Res
This case-control study of 5587 women with breast cancer and age-matched controls for which there was data on maternal employment. Maternal occupational exposure to diesel exhaust (OR=1.13, 95%CI,1.01-1.27) and bitumen fumes (OR=1.51., 95%CI,1.00-2.26) was associated with breast cancer. Further, exposures to diesel exhaust (OR=1.23, 95%CI, 1.01-1.50) were more strongly associated with ER- tumors than with ER+ tumors.
2023
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
Environ Pollut
A case-control study in China found that tetrabromobisphenol A (TBBPA)—a flame retardant chemical—in breast adipose tissue was significantly associated with a 15% increased breast cancer risk per unit increase in exposure. Using advanced metabolomics analysis, researchers discovered that TBBPA disrupts linoleic acid metabolism in adipose tissue, with a specific phospholipid molecule (PC 16:0/16:0) mediating approximately 57% of the association between TBBPA exposure and breast cancer risk. These findings suggest that TBBPA may contribute to breast cancer development through metabolic disruption of fatty acid pathways in breast tissue, providing new mechanistic insight into how flame retardant chemicals may increase cancer risk and identifying potential biomarkers for early detection or intervention.
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
BMC Med
A large European study measuring inflammatory markers in the blood of over 3,000 women found that inflammation’s relationship with breast cancer risk differs dramatically by menopausal status, with higher levels of leptin and C-reactive protein (CRP) appearing protective in premenopausal women but associated with increased risk in postmenopausal women. The opposing effects were particularly evident for leptin and CRP, which showed 11-17% lower breast cancer risk in premenopausal women but 10-16% higher risk in postmenopausal women, and these associations were influenced by body weight. These findings suggest that inflammation and obesity may affect breast cancer development through different biological mechanisms before and after menopause, highlighting the importance of considering menopausal status when assessing breast cancer risk factors.
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.
2022
Cancers
This meta-analysis of nine studies involving over 33,000 women with BRCA1 or BRCA2 gene mutations. One significant finding was that women who first started using oral contraceptives at age 20 or older had a 21% increased risk of breast cancer compared to those who never used them. These findings suggest that the timing of oral contraceptive use may be important for women with BRCA mutations, though more research is needed to fully understand the relationship between hormonal contraception and cancer risk in genetic mutation carriers.