Table 2: Some epidemiological studies on breast cancer.

ExposureStudy populationRelative risk or odds ratio (95% confidence interval)Main strengthsMain limitationsReference

Ecological studies

2,3,7,8-tetrachlorodibenzo-p-dioxinInhabitants of Seveso regionRate ratio (heavily contaminated zone versus control zone): 2.57 (1.07–6.20)Environmental exposure and time since exposure well documented, Based on only five cases[87]

Organochlorine pesticide methoxychlor California Latinas commonly employed in agricultural operationsOR for highest quartile of county-level specific pesticide use: 118 (1.03–1.35)Large number of casesPoor evaluation of exposure. Incomplete correction for confounding[88]
Organochlorine pesticide toxaphene OR for highest quartile of county-level specific pesticide use: 116 (1.01–1.34)

Case-control studies

Polychlorinated biphenyls (20 congeners) Mexican Women, hospital basedOR for serum concentration above detection limit: 1.09 (1.01–1.14) Measurement of personal internal exposure. Adequate correction for confounders Limited number of subjects [50]
Polychlorinated biphenyl congeners 128, 138 and 170 OR for serum concentration above detection limit: 1.90 (1.25–2.88)
Polychlorinated biphenyl congeners 153,180 OR for serum concentration above detection limit: 1.81 (1.08–3.04)
Polychlorinated biphenyl congeners 8, 195, 206 and 209 OR for serum concentration above detection limit: 1.57 (1.20–2.07)

Monoethyl phthalate (main diethyl phthalate metabolite)Northern Mexico, population basedOR for highest versus lowest tertile of urinary concentration: 2.20 (1.33–3.63)Measurement of personal internal exposure. 233 cases and 221 controls. Adequate correction for confounders Metabolites of other phthalates were inversely associated[89]

Total effective organohalogen xenoestrogen burden in adipose tissue Hospital based, Southern SpainOR for women with BMI below the median, highest quartile versus lowest of adipose tissue concentration: (28.6 kg/m2): 2.44; (1.03–5.78); 𝑃 t r e n d  = 0.03Highly relevant parameter of personal internal exposure. Adequate correction for confounding.Significant effect only in subgroup of leaner women.[90]
Total effective organohalogen xenoestrogen burden in adipose tissueHospital based, Southern SpainOR for postmenopausal women with BMI below the median (28.6 kg/m2), highest terile versus lowest of adipose tissue concentration: 5.6 (1.59–20.21)Highly relevant parameter of personal internal exposure. Adequate correction for confoundingSignificant effect only in subgroup of leaner women[90]
AldrinOR for detectable adipose tissue concentration: 1.55 (1.00–2.40)
AldrinOR among postmenopausal women for detectable adipose tissue concentration: 1.84 (1.06–3.18)No effect observed for other organochlorine pesticides
LindaneOR among postmenopausal women for detectable adipose tissue concentration: 1.76 (1.04–2.98)
DioxinResidents near municipal solid waste incinerator. Population basedOR for women aged ≥ 60 in region with high exposure: 0.31 (0.08–0.89)High total number of cases (434) and controls (2170).Exposure defined by area of residence; only 4 cases in highly exposed area. No effect on younger women. Limited correction for confounding.[91]
Urinary cadmium levelsPopulation based in Wisconsin, USAHighest quartile of creatinine-adjusted cadmium level (≥0.58 μg/g) versus lowest quartile (<0.26  𝜇 g/g) OR: 2.29 (1.3–4.2); 𝑃 t r e n d  = 0.01Measurement of personal internal exposure. Adequate correction for confounding[92]
Traffic emisionsWomen residing in Erie and Niagara Counties, USAExposure at the time of menarche: OR for premenopausal breast cancer for highest quartile of exposure: 2.05 (0.92–4.54, 𝑃 t r e n d  = 0.03)Adequate correction for confoundingLimited characterization of exposure. Limited statistical power[93]
Traffic emmisionsExposure at the time of a woman's first birth: OR for postmenopausal breast cancer for highest quartile of exposure: 2.57 (1.16–5.69, 𝑃 t r e n d = 0.19)
Exposure as motor vehicle mechanicsMulticentre case-control study on male breast cancer in 8 European countries, including 104 cases and 1901 controlsOR for ever employment: 2.1, (1.0–4.4).OR for employment ≥10 years: 5.9 (2.4–14.6)Adequate correction for confoundingLimited characterization of exposure[94]
Alkylphenolic compoundsOR for exposure above median: 3.8 (1.5 to 9.5)

Cohort studies

Dieldrin Participants in the Copenhagen City Heart StudyOR for highest quartile of serum concentration 2.05 (1.17–3.57), 𝑃 t r e n d  = 0.01Prospective design. Long follow-up. Adequate correction for confounding Individual internal exposure measured long before diagnosis.Limited statistical power. No effects of other organochlorines[95]
SolventsRetrospective cohort study on 63,982 female workers in an electronics factory in TaiwanSIR for women first employed prior to 1974: 1.38 (1.11–1.70)Large number of subjectsPoor characterization of exposure; no correction for confounders[96]
Volatile organic chemicals274,596 women in active duty in the US army (1980–1996)Incidence rate ratio for medium or high potential solvent exposure: 1.48 (1.01–2.07)Large number of subjectsPoor characterization of exposure. Poor correction for confounders[97]

Prospective nested case control study

P,p-DDT Members of the Child Health and Development Cohort, Oakland, CaliforniaOR for highest tertile of serum concentration among women under age 14 in 1945: 5.4 (1.7–17.1)Measurement of personal internal exposure. at highly relevant age. Adequate control for confoundingNo effect for other DDT-related compounds[98]