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CONTEXT: Several cross-sectional studies have assessed the association of lead exposure with type 2 diabetes and cardiometabolic risk factors in adults; however, studies of such associations in childhood are rare. OBJECTIVE: We assessed the prospective associations of prenatal exposure to lead with type 2 diabetes and cardiometabolic risk factors in children. DESIGN: The Early Life Exposure in Mexico to Environmental Toxicants is a birth cohort study of pregnant women and their offspring. SETTING: Public hospitals in Mexico City. PATIENTS OR OTHER PARTICIPANTS: Women were recruited during pregnancy; their offspring were recruited for a follow-up visit at age 10 to 18 years (n = 369). MAIN OUTCOME MEASURES: We measured fasting serum markers of type 2 diabetes and cardiometabolic risk factors in children, including fasting glucose, insulin, and lipids. The index of insulin resistance was calculated. RESULTS: The geometric mean of maternal blood lead levels (BLLs) during pregnancy was 4.3 µg/dL (95% confidence interval [CI]): 4.0-4.6 µg/dL) in the entire sample. In boys, those with maternal BLLs ≥ 5 µg/dL (compared with those with BLLs < 5 µg/dL) had significantly lower z scores for total cholesterol (ß = -0.41, 95% CI: -0.71, -0.12), high-density lipoprotein cholesterol (ß = -0.32, 95% CI: -0.59, -0.05), and low-density lipoprotein cholesterol (ß = -0.52, 95% CI: -0.81, -0.22), adjusting for covariates. No associations were detected in girls. CONCLUSIONS: In our study, we found that higher prenatal exposure to lead was associated with lower levels of cholesterol in children following a sex-specific pattern. Further studies with a larger sample size that examine whether sex is a potential modifier are needed to confirm our findings.

Asunto(s)

Enfermedades Cardiovasculares/etiología , Hijo de Padres Discapacitados , Diabetes Mellitus Tipo 2 , Intoxicación por Plomo , Enfermedades Metabólicas/etiología , Embarazo en Diabéticas , Efectos Tardíos de la Exposición Prenatal/epidemiología , Adolescente , Adulto , Enfermedades Cardiovasculares/epidemiología , Niño , Hijo de Padres Discapacitados/estadística & datos numéricos , Estudios de Cohortes , Estudios Transversales , Femenino , Estudios de Seguimiento , Humanos , Recién Nacido , Plomo/análisis , Plomo/sangre , Plomo/toxicidad , Masculino , Enfermedades Metabólicas/epidemiología , México/epidemiología , Embarazo , Efectos Tardíos de la Exposición Prenatal/sangre , Factores de Riesgo , Adulto Joven

RESUMEN

BACKGROUND: Prenatal and early childhood lead exposures have been associated with reduced weight in infants and young children, while studies that have examined such associations in children during peripubescence are rare. OBJECTIVES: We investigated the associations of prenatal and early-life exposure to lead with indices of adiposity in peripubertal children living in Mexico City. METHODS: Maternal bone lead (as a proxy for cumulative fetal exposure) was assessed at 1 month postpartum. Blood samples were obtained from children annually from 1 to 4 years. Multivariable linear regression models were used to examine the association between each lead biomarker and BMI z-score, waist circumference, sum of skinfolds and body fat percentage in 248 children aged 8-16 years. RESULTS: After adjusting for covariates, maternal patella lead was associated with lower child BMI z-score (ß = -0.02, 95% CI: 0.03, -0.01, p = 0.004), waist circumference (ß = -0.12 cm, 95% CI: 0.22, -0.03, p = 0.01), sum of skinfolds (ß = -0.29 mm, 95% CI: 0.50, -0.08, p = 0.007) and body fat percentage (ß = -0.09%, 95% CI: 0.17, -0.01, p = 0.03). No significant associations were detected from the postnatal exposure period. CONCLUSIONS: We observed a significant and inverse association of prenatal lead exposure with body composition in Mexican children, suggesting the potential role of early lead exposure in the fetal programming of child growth. Further research on the biological mechanisms underlying these associations is needed.

Asunto(s)

Adiposidad , Contaminantes Ambientales/análisis , Plomo/análisis , Exposición Materna , Efectos Tardíos de la Exposición Prenatal , Adolescente , Adulto , Monitoreo Biológico , Niño , Ciudades , Femenino , Humanos , Masculino , Intercambio Materno-Fetal , México , Rótula/química , Embarazo , Tibia/química , Adulto Joven

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BACKGROUND: Previous studies have examined the association between blood lead levels and pubertal timing in adolescent girls; however, the evidence is lacking on the role of lead exposure during sensitive developmental periods on sexual maturation. OBJECTIVES: To examine the association of prenatal and early childhood lead exposure with pubertal stages among 264 boys and 283 girls aged 9.8-18.0 years in Mexico City. METHODS: We measured maternal bone lead (a proxy for cumulative fetal exposure to lead from maternal bone stores mobilized during pregnancy) at 1 month postpartum. Blood lead was measured annually from 1 to 4 years. Pubertal stage was assessed by a pediatrician. We examined the association between lead and pubertal stages of breast, pubic hair and genitalia using ordinal regression. Age at menarche was evaluated using Cox proportional-hazard models. RESULTS: Multivariate models showed that maternal patella lead and early childhood blood lead were inversely associated with breast growth (patella OR = 0.72, 95% CI: 0.51-1.00; blood OR = 0.70, 95% CI: 0.53-0.93) in girls. Girls with maternal patella lead in the 3rd tertile and child blood lead in the 2nd tertile had a later age at menarche compared with girls in the 1st tertile (patella HR = 0.60, 95% CI: 0.41-0.88; blood HR = 0.65, 95% CI 0.46-0.91). Additionally, early childhood blood lead was negatively associated with pubic hair growth (OR = 0.68, 95% CI: 0.51-0.90) in girls. No associations were found in boys. CONCLUSIONS: These data suggest that higher prenatal and early childhood exposure to lead may be associated with delayed pubertal development in girls but not boys. Our findings are consistent with previous analyses and reinforce the reproductive effects of lead for girls.

Asunto(s)

Contaminantes Ambientales/metabolismo , Plomo/metabolismo , Exposición Materna , Pubertad/efectos de los fármacos , Maduración Sexual/efectos de los fármacos , Adolescente , Huesos/química , Niño , Exposición a Riesgos Ambientales , Contaminantes Ambientales/sangre , Femenino , Humanos , Plomo/sangre , Estudios Longitudinales , Masculino , Menarquia/efectos de los fármacos , México , Madres , Embarazo , Efectos Tardíos de la Exposición Prenatal

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Background: Studies in Western nations have shown associations of certain dietary patterns with obesity and metabolic risk in youth. Little is known about these relations in newly industrialized countries where obesity prevalence is surpassing those of developed countries.Objective: We sought to characterize dietary patterns in a cross-sectional study in 224 adolescents aged 8-14 y in Mexico and to investigate associations of the dietary patterns with adiposity and metabolic risk.Methods: We used principal components analysis to derive dietary patterns from food-frequency questionnaire data. By using linear regression models that accounted for mother's marital status, education, and smoking habits and child's age and physical activity, we examined associations of the dietary patterns with adiposity [body mass index z score, waist circumference, the sum and ratio of the subscapular and triceps skinfold thicknesses, blood pressure, serum fasting glucose and a C-peptide-based measure of insulin resistance (CP-IR), lipid profile, and a metabolic syndrome risk z score (MetS z score)].Results: We identified a "prudent" dietary pattern characterized by high intakes of vegetables, fruit, fish, chicken, and legumes and a "transitioning" dietary pattern, which comprises processed meats, Mexican foods, and sweetened beverages. Each unit increase in the prudent pattern factor score corresponded with 0.33 ng/mL (95% CI: 0.09, 0.57 ng/mL) lower C-peptide, 0.08 units (95% CI: 0.02, 0.13 units) lower CP-IR, and a 0.14 unit (0.00, 0.27 unit) lower MetS z score in boys. In girls, the transitioning pattern corresponded with higher subscapular + triceps skinfold thickness (per 1-unit increase in the factor score: 2.46 mm; 95% CI: 0.10, 4.81 mm). These results did not change after accounting for pubertal status.Conclusions: A prudent dietary pattern was protective against metabolic risk in adolescent boys, whereas a transitioning dietary pattern corresponded with higher adiposity among adolescent girls. Given that adolescence is a key developmental period for long-term health, efforts to elucidate dietary determinants of metabolic risk during this life stage may have long-term benefits.

Asunto(s)

Adiposidad , Dieta , Conducta Alimentaria , Síndrome Metabólico/etiología , Obesidad/etiología , Adolescente , Índice de Masa Corporal , Proteína C-Reactiva/metabolismo , Niño , Estudios Transversales , Países en Desarrollo , Dieta/tendencias , Desarrollo Económico , Femenino , Humanos , Masculino , México , Pubertad , Factores de Riesgo , Factores Sexuales , Grosor de los Pliegues Cutáneos , Población Urbana/tendencias , Circunferencia de la Cintura

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BACKGROUND: Some evidence suggests that fluoride may be neurotoxic to children. Few of the epidemiologic studies have been longitudinal, had individual measures of fluoride exposure, addressed the impact of prenatal exposures or involved more than 100 participants. OBJECTIVE: Our aim was to estimate the association of prenatal exposure to fluoride with offspring neurocognitive development. METHODS: We studied participants from the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) project. An ion-selective electrode technique was used to measure fluoride in archived urine samples taken from mothers during pregnancy and from their children when 6-12 y old, adjusted for urinary creatinine and specific gravity, respectively. Child intelligence was measured by the General Cognitive Index (GCI) of the McCarthy Scales of Children's Abilities at age 4 and full scale intelligence quotient (IQ) from the Wechsler Abbreviated Scale of Intelligence (WASI) at age 6-12. RESULTS: We had complete data on 299 mother-child pairs, of whom 287 and 211 had data for the GCI and IQ analyses, respectively. Mean (SD) values for urinary fluoride in all of the mothers (n=299) and children with available urine samples (n=211) were 0.90 (0.35) mg/L and 0.82 (0.38) mg/L, respectively. In multivariate models we found that an increase in maternal urine fluoride of 0.5mg/L (approximately the IQR) predicted 3.15 (95% CI: -5.42, -0.87) and 2.50 (95% CI -4.12, -0.59) lower offspring GCI and IQ scores, respectively. CONCLUSIONS: In this study, higher prenatal fluoride exposure, in the general range of exposures reported for other general population samples of pregnant women and nonpregnant adults, was associated with lower scores on tests of cognitive function in the offspring at age 4 and 6-12 y. https://doi.org/10.1289/EHP655.

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Contaminantes Ambientales/toxicidad , Fluoruros/toxicidad , Inteligencia , Exposición Materna/estadística & datos numéricos , Efectos Tardíos de la Exposición Prenatal/epidemiología , Adulto , Niño , Desarrollo Infantil , Preescolar , Cognición , Contaminantes Ambientales/orina , Femenino , Fluoruros/orina , Humanos , Pruebas de Inteligencia , Masculino , México , Embarazo

RESUMEN

OBJECTIVE: To compare self-report and physician assessments of sexual maturation against serum hormone markers to evaluate the hypothesis that the validity of self-assessed sexual maturation is underestimated in traditional validation studies. STUDY DESIGN: We adapted a self-assessment instrument that 248 Mexican children and adolescents, aged 8-13 years, completed. The participants were examined by a trained pediatrician and provided fasting blood samples for measurement of reproductive hormones (eg, testosterone, estradiol, sex hormone-binding globulin, inhibin B) and other hormones (eg, C-peptide, insulin-like growth factor 1, leptin, dehydroepiandrosterone sulfate) known to change during adolescence. Spearman correlations (r) were calculated among the average rank of all hormones and self-assessed and physician-assessed Tanner stage. The method of triads was used to assess the validity of self-reports by estimating correlations between self-assessments and true but unobservable sexual maturation based on all available data. Bootstrap sampling was used to construct 95% CIs. RESULTS: The validity of self-reported genitalia staging for boys was modest (r = 0.50; 95% CI, 0.31-0.65) and inferior to physician assessment (r = 0.75; 95% CI, 0.56-0.93). Breast stage was well reported (r = 0.89; 95% CI, 0.79-0.97) and superior to physician assessment (r = 0.80; 95% CI, 0.70-0.89). Pubic hair stage reported by boys (r = 0.91; 95% CI, 0.79-0.99) and girls (r = 0.99; 95% CI, 0.96-1.00) was superior to physician assessment (r = 0.79; 95% CI, 0.57-0.97 and r = 0.91; 95% CI, 0.83-0.97, respectively). CONCLUSION: Self-assessment can be validly used in epidemiologic studies for evaluating sexual maturation in children; however, physician assessment may be necessary for accurate assessment of genitalia development in boys.

Asunto(s)

Hormonas Esteroides Gonadales/sangre , Autoevaluación (Psicología) , Maduración Sexual , Adolescente , Desarrollo del Adolescente , Niño , Estudios de Cohortes , Femenino , Humanos , Masculino , Valor Predictivo de las Pruebas , Pubertad , Reproducibilidad de los Resultados

RESUMEN

OBJECTIVE: To assess the relationship between in utero and concurrent child urinary exposures to bisphenol A (BPA) and phthalates with BMI z-score, waist circumference, and sum of triceps and subscapular skinfold thickness in Mexican children. METHODS: Among participants (N=249) from the Early Life Exposure in Mexico to ENvironmental Toxicants study, we evaluated associations between maternal third trimester and concurrent urinary BPA and individual and summed phthalates metabolites (∑Di(2-ethylhexyl phthalate), ∑high molecular weight, ∑low molecular weight) with measures of weight status and adiposity in children aged 8-14 years. Linear regressions with specific-gravity corrected and natural log-transformed urinary concentrations were estimated, adjusting for covariates. Effect modification by sex was explored. RESULTS: Prenatal urinary exposure to monobenzyl phthalate (MBzP) was inversely associated with child's BMI z-score (ß=-0.21, 95%CI: -0.41, -0.02) and child urinary exposure to mono(2-ethylhexyl)phthalate (MEHP) was inversely associated with waist circumference (ß=-1.85, 95%CI: -3.36, -0.35) and sum of skinfold thicknesses (ß=-2.08, 95%CI: -3.80, -0.37) after adjusting for confounders. In the childhood exposure period, sex modified the relationships with BPA, MEHP, MBzP, monoethyl phthalate (MEP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP). In girls, increased BPA exposure was positively associated with sum of skinfold thickness (ß=3.47, 95%CI: 0.05, 6.40) while increased MEHP was inversely associated with sum of skinfold thicknesses in boys (ß=-2.95, 95%CI: -5.08, -0.82); these results remained in sensitivity analyses after excluding children who had initiated pubertal development (Tanner stage >1 for pubic hair). We did not observe relationships between summed phthalates metabolites at any exposure period with outcome measures. CONCLUSION: Our results identified associations between urinary BPA and phthalates metabolites with measures of weight status and adiposity that differed by timing of exposure, sex, and pubertal status. Additional studies are needed to explore how associations may differ between those who are pre- and post-pubertal.

Asunto(s)

Adiposidad/efectos de los fármacos , Compuestos de Bencidrilo/toxicidad , Índice de Masa Corporal , Exposición a Riesgos Ambientales , Contaminantes Ambientales/toxicidad , Fenoles/toxicidad , Ácidos Ftálicos/toxicidad , Grosor de los Pliegues Cutáneos , Adolescente , Compuestos de Bencidrilo/análisis , Compuestos de Bencidrilo/metabolismo , Niño , Estudios Transversales , Contaminantes Ambientales/análisis , Contaminantes Ambientales/metabolismo , Femenino , Humanos , Modelos Lineales , Masculino , Exposición Materna , México , Fenoles/análisis , Fenoles/metabolismo , Ácidos Ftálicos/análisis , Ácidos Ftálicos/metabolismo , Estudios Prospectivos , Circunferencia de la Cintura/efectos de los fármacos

RESUMEN

BACKGROUND: There is need to assess the developmental neurotoxicity of fluoride. Our knowledge of prenatal fluoride exposure is challenged as few population-based studies have been conducted and these generally date back several decades, provide incomplete data on sociodemographic variables, and have methodological limitations. OBJECTIVE: To measure urinary and plasma fluoride levels across three time points in pregnant mothers who were enrolled in the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) birth cohort study. METHODS: Fluoride levels were characterized in archived urine and plasma from 872 pregnant mothers sampled from the ELEMENT cohort. Various statistical methods were used to analyze the fluoride data with particular consideration for changes across three stages of pregnancy and against sociodemographic variables. RESULTS: All samples had detectable levels of fluoride. The mean urinary and plasma fluoride levels were 0.91 and 0.0221mg/L respectively, and these were not statistically different across three stages of pregnancy. Fluoride levels correlated across the stages of pregnancy studied, with stronger correlations between neighboring stages. Urinary fluoride changed as pregnancy progressed with levels increasing until ~23 weeks and then decreasing until the end of pregnancy. For plasma fluoride, there was a decreasing trend but this was not of statistical significance. Creatinine-adjusted urinary fluoride levels did not associate consistently with any of the sociodemographic variables studied. CONCLUSIONS: This study provides the most extensive characterization to date of fluoride exposure throughout pregnancy. These results provide the foundation to explore exposure-related health outcomes in the ELEMENT cohort and other studies.

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Fluoruros/sangre , Fluoruros/orina , Embarazo/sangre , Embarazo/orina , Adulto , Estudios de Cohortes , Monitoreo del Ambiente , Femenino , Humanos , Recién Nacido , Masculino , Exposición Materna , Intercambio Materno-Fetal , México , Adulto Joven

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Introduction Estrogen inhibits lactation and bisphenol A (BPA) is a high production environmental estrogen. We hypothesize an inhibitory effect of BPA on lactation and aim to analyze the association between third trimester pregnancy urinary BPA and breastfeeding rates 1 month postpartum. Methods Odds ratios (OR) and 95 % confidence intervals (95 % CI) of breastfeeding and perceived insufficient milk supply (PIM) in relation to maternal peripartum urinary BPA concentrations were calculated in 216 mothers. Results 97.2 % of mothers in the lowest BPA tertile were breastfeeding at 1 month postpartum, compared to 89.9 % in highest (p = 0.01). Adjusted ORs (95 % CI) for not breastfeeding at 1 month were 1.9 (0.3, 10.7) and 4.3 (0.8, 21.6) for second and third BPA tertiles, respectively, compared to the lowest (p = 0.06, trend). 4.2 % reported PIM in the lowest BPA tertile, compared to 8.7 % in the highest (p = 0.03). Adjusted ORs (95 % CI) for PIM were 1.8 (0.4, 7.7) and 2.2 (0.5, 9.5), for the second and third BPA tertiles, respectively, compared to the lowest (p = 0.29, trend). Discussion These results suggest an association between maternal BPA exposure and decreased breastfeeding.

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Compuestos de Bencidrilo/efectos adversos , Lactancia Materna/estadística & datos numéricos , Exposición a Riesgos Ambientales/efectos adversos , Estrógenos no Esteroides/efectos adversos , Lactancia/efectos de los fármacos , Exposición Materna/efectos adversos , Fenoles/efectos adversos , Tercer Trimestre del Embarazo , Adulto , Animales , Compuestos de Bencidrilo/orina , Exposición a Riesgos Ambientales/análisis , Contaminantes Ambientales , Estrógenos no Esteroides/orina , Femenino , Humanos , México , Leche Humana , Madres , Oportunidad Relativa , Fenoles/orina , Embarazo , Adulto Joven

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UNLABELLED: Geostatistical interpolation methods to estimate individual exposure to outdoor air pollutants can be used in pregnancy cohorts where personal exposure data are not collected. Our objectives were to a) develop four assessment methods (citywide average (CWA); nearest monitor (NM); inverse distance weighting (IDW); and ordinary Kriging (OK)), and b) compare daily metrics and cross-validations of interpolation models. We obtained 2008 hourly data from Mexico City's outdoor air monitoring network for PM10, PM2.5, O3, CO, NO2, and SO2 and constructed daily exposure metrics for 1,000 simulated individual locations across five populated geographic zones. Descriptive statistics from all methods were calculated for dry and wet seasons, and by zone. We also evaluated IDW and OK methods' ability to predict measured concentrations at monitors using cross validation and a coefficient of variation (COV). All methods were performed using SAS 9.3, except ordinary Kriging which was modeled using R's gstat package. Overall, mean concentrations and standard deviations were similar among the different methods for each pollutant. Correlations between methods were generally high (r=0.77 to 0.99). However, ranges of estimated concentrations determined by NM, IDW, and OK were wider than the ranges for CWA. Root mean square errors for OK were consistently equal to or lower than for the IDW method. OK standard errors varied considerably between pollutants and the computed COVs ranged from 0.46 (least error) for SO2 and PM10 to 3.91 (most error) for PM2.5. OK predicted concentrations measured at the monitors better than IDW and NM. Given the similarity in results for the exposure methods, OK is preferred because this method alone provides predicted standard errors which can be incorporated in statistical models. The daily estimated exposures calculated using these different exposure methods provide flexibility to evaluate multiple windows of exposure during pregnancy, not just trimester or pregnancy-long exposures. IMPLICATIONS: Many studies evaluating associations between outdoor air pollution and adverse pregnancy outcomes rely on outdoor air pollution monitoring data linked to information gathered from large birth registries, and often lack residence location information needed to estimate individual exposure. This study simulated 1,000 residential locations to evaluate four air pollution exposure assessment methods, and describes possible exposure misclassification from using spatial averaging versus geostatistical interpolation models. An implication of this work is that policies to reduce air pollution and exposure among pregnant women based on epidemiologic literature should take into account possible error in estimates of effect when spatial averages alone are evaluated.

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Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , Exposición a Riesgos Ambientales , Monitoreo del Ambiente/métodos , Modelos Estadísticos , Femenino , Humanos , México , Embarazo , Estaciones del Año

RESUMEN

BACKGROUND: Mercury is a global contaminant of concern though little is known about exposures in México. OBJECTIVES: To characterize mercury levels in pregnant women, children, and commonly consumed seafood samples. METHODS: Use resources of the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) birth cohorts to measure total mercury levels in archived samples from 348 pregnant women (blood from three trimesters and cord blood), 825 offspring (blood, hair, and urine) and their mothers (hair), and 91 seafood and canned tuna samples from Mexico City. RESULTS: Maternal blood mercury levels correlated across three trimesters and averaged 3.4 µg/L. Cord blood mercury averaged 4.7 µg/L and correlated with maternal blood from trimester 3 (but not trimesters 1 and 2). In children, blood, hair and urine mercury levels correlated and averaged 1.8 µg/L, 0.6 µg/g, and 0.9 µg/L, respectively. Hair mercury was 0.5 µg/g in mothers and correlated with child's hair. Mean consumption of canned tuna, fresh fish, canned sardine, and shellfish was 3.1, 2.2, 0.5, and 1.0 times per month respectively in pregnant women. Mean mercury content in 7 of 23 seafood species and 5 of 9 canned tuna brands purchased exceeded the U.S. EPA guidance value of 0.3 µg/g. CONCLUSIONS: Mercury exposures in pregnant women and children from Mexico City, via biomarker studies, are generally 3-5 times greater than values reported in population surveys from the U.S., Canada, and elsewhere. In particular, mercury levels in 29-39% of the maternal participants exceeded the biomonitoring guideline associated with the U.S. EPA reference dose for mercury.

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Ciudades , Exposición a Riesgos Ambientales/análisis , Contaminantes Ambientales/análisis , Contaminación de Alimentos/análisis , Mercurio/análisis , Alimentos Marinos/análisis , Animales , Niño , Estudios de Cohortes , Monitoreo del Ambiente/estadística & datos numéricos , Femenino , Sangre Fetal/química , Cabello/química , Humanos , Mercurio/sangre , Mercurio/orina , México/epidemiología , Embarazo , Refractometría , Atún/metabolismo