Table 2.

Some epidemiological studies on breast cancer.

Exposure	Study population	Relative risk or odds ratio (95% confidence interval)	Main strengths	Main limitations	Reference
Ecological studies
2,3,7,8-tetrachlorodibenzo-p-dioxin	Inhabitants of Seveso region	Rate 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 operations	OR for highest quartile of county-level specific pesticide use: 118 (1.03–1.35)	Large number of cases	Poor 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 based	OR 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 based	OR 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 Spain	OR 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 trend = 0.03	Highly 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 tissue	Hospital based, Southern Spain	OR 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 confounding	Significant effect only in subgroup of leaner women	[90]
Aldrin		OR for detectable adipose tissue concentration: 1.55 (1.00–2.40)
Aldrin		OR among postmenopausal women for detectable adipose tissue concentration: 1.84 (1.06–3.18)		No effect observed for other organochlorine pesticides
Lindane		OR among postmenopausal women for detectable adipose tissue concentration: 1.76 (1.04–2.98)
Dioxin	Residents near municipal solid waste incinerator. Population based	OR 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 levels	Population based in Wisconsin, USA	Highest quartile of creatinine-adjusted cadmium level (≥0.58 μg/g) versus lowest quartile (<0.26 μg/g) OR: 2.29 (1.3–4.2); P trend = 0.01	Measurement of personal internal exposure. Adequate correction for confounding		[92]
Traffic emisions	Women residing in Erie and Niagara Counties, USA	Exposure at the time of menarche: OR for premenopausal breast cancer for highest quartile of exposure: 2.05 (0.92–4.54, P trend = 0.03)	Adequate correction for confounding	Limited characterization of exposure. Limited statistical power	[93]
Traffic emmisions		Exposure 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 trend = 0.19)
Exposure as motor vehicle mechanics	Multicentre case-control study on male breast cancer in 8 European countries, including 104 cases and 1901 controls	OR for ever employment: 2.1, (1.0–4.4).OR for employment ≥10 years: 5.9 (2.4–14.6)	Adequate correction for confounding	Limited characterization of exposure	[94]
Alkylphenolic compounds		OR for exposure above median: 3.8 (1.5 to 9.5)
Cohort studies
Dieldrin	Participants in the Copenhagen City Heart Study	OR for highest quartile of serum concentration 2.05 (1.17–3.57), P trend = 0.01	Prospective design. Long follow-up. Adequate correction for confounding Individual internal exposure measured long before diagnosis.	Limited statistical power. No effects of other organochlorines	[95]
Solvents	Retrospective cohort study on 63,982 female workers in an electronics factory in Taiwan	SIR for women first employed prior to 1974: 1.38 (1.11–1.70)	Large number of subjects	Poor characterization of exposure; no correction for confounders	[96]
Volatile organic chemicals	274,596 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 subjects	Poor 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, California	OR 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 confounding	No effect for other DDT-related compounds	[98]