RESUMEN
The authors analyzed the relation between lactation history, organochlorine serum levels-in particular, 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE)-and the risk of breast cancer within a subsampe from a larger breast cancer case-control study conducted among women living in Mexico City, Mexico, between 1990 and 1995. From the original study, they selected a random sample of 260 subjects (1:1 case/control ratio). Analysis was restricted to 120 cases and 126 controls who had given birth to at least one child and had complete information on all key variables. Serum DDE levels were higher among cases (mean = 3.84 microg/g lipids, standard deviation = 5.98) than among controls (mean = 2.51 microg/g lipids, standard deviation = 1.97). After adjustment for age, age at menarche, duration of lactation, Quetelet index, and serum DDT levels, serum DDE levels were positively related to the risk of breast cancer (adjusted odds ratio (OR)Q1-Q2 = 1.24, 95% confidence interval (CI): 0.50, 3.06; ORQ1-Q3 = 2.31, 95% CI: 0.92, 5.86; ORQ1-Q4 = 3.81, 95% CI: 1.14, 12.80; test of trend, p = 0.02). The increased risk associated with higher serum DDE levels was more apparent among postmenopausal women (ORQ1-Q4 = 5.26, 95% CI: 0.80, 34.30; test of trend p = 0.03). A longer period of lactation was associated with a slightly decreased risk of breast cancer independently of serum DDE levels (OR = 0.91, 95% CI: 0.85, 0.99 change in risk per 10 months of lactation). Serum DDT level was not related to the risk of breast cancer. The data suggest that high levels of exposure to DDE may increase women's risk of breast cancer, particularly among postmenopausal women.
Asunto(s)
Neoplasias de la Mama/epidemiología , DDT/efectos adversos , Diclorodifenil Dicloroetileno/efectos adversos , Insecticidas/efectos adversos , Lactancia , Adulto , Anciano , Neoplasias de la Mama/etiología , Estudios de Casos y Controles , DDT/sangre , Diclorodifenil Dicloroetileno/sangre , Exposición a Riesgos Ambientales , Femenino , Humanos , Insecticidas/sangre , Persona de Mediana Edad , Posmenopausia , Factores de RiesgoRESUMEN
Mercury is used widely for gold extraction in French Guiana and throughout the entire Amazon basin. To evaluate contamination among the general population, the authors chose individuals who attended 13 health centers and maternity hospitals dispersed geographically across the territory and served Guiana's different populations. Five hundred individuals (109 pregnant women, 255 "other" adults, and 136 children) who received care at one of the centers were selected randomly for this study. Each individual answered a questionnaire and provided a hair sample. The authors determined mercury in hair with atomic absorption spectrometry. The following mean levels of mercury were observed: 1.6 microg/g (95% confidence interval [CI]=1.3, 1.9) among pregnant women; 3.4 microg/g (95% CI=3.0, 3.9) among other adults; and 2.5 microg/g (95% CI=2.1, 3.0) among children. Diet factors contributed the most to mercury levels, especially consumption of freshwater fish (mean=6.7 microg/g for individuals who ate fish more than 5 times/wk) and livers from game. Other factors, including age, dental amalgams, use of skin-lightening cosmetics, and residence near a gold-mining community, did not contribute significantly to mercury levels. Overall, 12% of the samples contained mercury levels in excess of 10 microg/g, but in some Amerindian communities up to 79% of the children had hair mercury levels that exceeded 10 microg/g. The results of this study indicated that (a) diet played a predominant role in total mercury burden, and (b) in some communities, mercury contamination exceeded safe levels.