Persistent organic pollutants (POPs) and metals in primiparous women: a comparison from Canada and Mexico.

Under the North American Commission for Environmental Cooperation (CEC) and its Sound Management of Chemicals (SMOC) program, a tri-national human contaminant monitoring initiative was completed to provide baseline exposure information for several environmental contaminants in Canada, Mexico and the United States (U.S). Blood samples were collected from primiparous women in Canada and Mexico, and were analysed for a suite of environmental contaminants including polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene(p,p'-DDE),beta-hexachlorocyclohexane (ß-HCH), mercury and lead. A multiple stepwise linear regression analysis was conducted using data from Canadian and Mexican primiparous mothers, adjusting for ethnicity group, age, pre-pregnancy BMI, years at current city and ever-smoking status. Concentrations of p,p'-DDE, ß-HCH, and lead were found to be higher among Mexican participants; however, concentrations of most PCBs among Mexican participants were similar to Canadian primiparous women after adjusting for covariates. Concentrations of total mercury were generally higher among Mexican primiparous women although this difference was smaller as age increased. This initial dataset can be used to determine priorities for future activities and to track progress in the management of the selected chemicals, both domestically and on a broader cooperative basis within North America.

Persistent organic pollutant concentrations in first birth mothers across Mexico.

This project was initiated by the North America Commission for Environmental Cooperation (CEC). Its main purpose was to obtain an initial profile on pregnant woman's exposure to persistent organic pollutants (POPs) in North America (Canada, the United States and Mexico). Persistent organic pollutants are transferred to the fetus via the placenta during the pregnancy or to the infant via maternal milk; therefore, the pregnant woman's body burden is important because of the higher exposures and potential health effects in the fetus and infant. This paper presents the results from 240 pregnant women in 10 Mexican cities, and includes the concentrations of various POPs such as polychlorinated biphenyls (PCBs), organochlorine pesticides and polychlorinated dibenzo dioxins and furans (PCDDs and PCDFs) in maternal plasma. We found concentrations of p,p'-DDE in maternal samples from Coatzacoalcos to be ∼60% higher than those found in Ciudad Obregon, which had the second highest concentration. Pregnant women from Merida had higher mean concentrations of PCBs than all women in other regions. Results for PCDDs and PCDFs plus dioxin-like PCBs data were only available on the basis of composite samples, and their concentrations are similar in most cities except for Coatzacoalcos, which had more than double the concentration found in other cities. Although this study provides useful information on the variability of POPs in specific populations and possible regional/local differences, these results cannot be generalized to the entire Mexican population because of differences in age, gender, sources of exposure and nonrandom nature of the sample.

DDE, a degradation product of DDT, and duration of lactation in a highly exposed area of Mexico.

BACKGROUND: Higher levels of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), the major degradation product of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), have been related to shorter duration of breast-feeding in previous studies. If DDE truly shortens lactation, this has public health importance regarding infant mortality and the use of DDT for malaria control. OBJECTIVE: Our aim was to assess the relationship of maternal DDE concentrations with length of subsequent lactation. METHODS: We conducted a relatively large study in a highly exposed area of Mexico. We followed 784 mother-son pairs to determine length of lactation. DDE and DDT were measured in maternal serum obtained within a day of delivery. We fit proportional hazard models with and without stratifying by previous breast-feeding, because an association of DDE with duration of lactation among those who breast-fed previously could be attributed to a noncausal mechanism. RESULTS: Compared with those with DDE concentrations < or = 3.00 microg/g, the adjusted hazard ratios of weaning according to DDE category were, for concentrations 3.01-6.00 microg/g, 1.27 [95% confidence interval (CI), 1.04-1.55]; for concentrations 6.01-9.00 microg/g, 1.23 (95% CI, 0.92-1.63); and for concentrations > 9.00 microg/g, 1.17 (95% CI, 0.92-1.49). The corresponding ratios for women who previously breast-fed were 1.40 (95% CI, 1.06-1.87); 1.91 (95% CI, 1.24-2.93); and 1.76 (95% CI, 1.22-2.53). Those for women who had not breast-fed previously were 1.14 (95% CI, 0.86-1.52); 0.90 (95% CI, 0.61-1.31); and 0.91 (95% CI, 0.66-1.26). CONCLUSIONS: Data from our relatively large study in a highly exposed area of Mexico did not support the hypothesis that exposure to DDE shortens length of lactation. The association seen in women who previously breast-fed was likely attributed to a noncausal mechanism. Nonetheless, whether DDT has other important adverse effects on humans is still an open question.

Concentraciones de DDT/DDE y riesgo de hipospadias: un estudio piloto de casos y controles / DDT/DDE concentrations and risk of hypospadias: a case-control pilot study

OBJETIVO: Evaluar la asociación entre los niveles séricos maternos de DDT/DDE y el riesgo de hipospadias. MATERIAL Y MÉTODOS: Estudio de casos y controles, efectuado en la Ciudad de México durante el periodo 1997-1999, con 41 casos de hipospadias y 28 controles. La informacion obtenida por cuestionario y las muestras sanguíneas fueron evaluadas mediante modelos multivariados de regresión logística. RESULTADOS: Las concentraciones materna de DDT y DDE no mostraron asociación con el riesgo de hipospadias (RM 1.13; IC 95 por ciento 0.24-5.29 y RM 0.48; IC 95 por ciento 0.15-1.60, respectivamente). Los predictores encontrados fueron hijos de madres con mayor edad (RM 8.69; IC 95 por ciento 1.69-44.9), y la actividad laboral durante el embarazo (RM, 4.68; IC 95 por ciento 1.15-18.9). CONCLUSIONES: Dado que se cuenta con escasa información sobre los efectos endocrinos a diferentes concentraciones de DDT/DDE en humanos, la dosis pudiera ser un factor determinante sobre el tipo de efecto.

OBJECTIVE: To evaluate the association between maternal serum DDT/DDE levels and risk of hypospadias. MATERIAL AND METHODS: A case-control study in Mexico City was conducted during 1997-1999 among 41 subjects with hypospadias and 28 controls. Blood samples were obtained from study subjects. Information was obtained using a standardized questionnaire. Data were analyzed using multivariate logistic regression models. RESULTS: Maternal DDT and DDE levels showed no association with hypospadias (OR 1.13; 95 percent CI 0.24-5.29 and OR=0.48; 95 percent CI 0.15-1.60, respectively). Associated factors were older age of mothers (OR 8.69; 95 percent CI 1.69-44.9), and working during pregnancy (OR 4.68; 95 percent CI 1.15-18.9). CONCLUSIONS: Information about the endocrine effects of different levels of DDT/DDE in human subjects is scarce; dosage may be a determinant factor of the type of effect.

[DDT/DDE concentrations and risk of hypospadias. Pilot case-control study]. / Concentraciones de DDT/DDE y riesgo de hipospadias. Un estudio piloto de casos y controles.

OBJECTIVE: To evaluate the association between maternal serum DDT/DDE levels and risk of hypospadias. MATERIAL AND METHODS: A case-control study in Mexico City was conducted during 1997-1999 among 41 subjects with hypospadias and 28 controls. Blood samples were obtained from study subjects. Information was obtained using a standardized questionnaire. Data were analyzed using multivariate logistic regression models. RESULTS: Maternal DDT and DDE levels showed no association with hypospadias (OR 1.13; 95% CI 0.24-5.29 and OR = 0.48; 95% CI 0.15-1.60, respectively). Associated factors were older age of mothers (OR 8.69; 95% CI 1.69-44.9), and working during pregnancy (OR 4.68; 95% CI 1.15-18.9). CONCLUSIONS: Information about the endocrine effects of different levels of DDT/DDE in human subjects is scarce; dosage may be a determinant factor of the type of effect. The English version of this paper is available at:http://www.insp.mx/salud/index.html.