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ABSTRACT: A range of studies has been conducted on the detrimental effects of lead in mining and smelting communities. The neurocognitive and behavioural health effects of lead on children are well known. This research characterized the conjoint influence of lead exposure and home enriched environment on neurocognitive function and behaviour for first grade children living in a Mexican lead smelter community. Structural equation models were used for this analysis with latent outcome variables, Cognition and Behaviour, constructed based on a battery of assessments administered to the first-grade children, their parents, and teachers. Structural equation modeling was used to describe complex relationships of exposure and health outcomes in a manner that permitted partition of both direct and indirect effects of the factors being measured. Home Environment (a latent variable constructed from information on mother's education and support of school work and extracurricular activities), and child blood lead concentration each had a main significant effect on cognition and behaviour. However, there were no statistically significant moderation relationships between lead and Home Environment on these latent outcomes. Home Environment had a significant indirect mediation effect between lead and both Cognition and Behaviour (p-value<0.001). The mediation model had a good fit with Root Mean Square Error of Approximation <0.0001 and a Weighted Root Mean Square Residual of 0.895. These results were highly significant and suggest that Home Environment has a moderate mediation effect with respect to lead effects on Behaviour (β= 0.305) and a lower mediation effect on Cognition (β= 0.184). The extent of home enrichment in this study was most highly related to the mother's support of schoolwork and slightly less by the mother's support of extracurricular activities or mother's education. Further research may be able to develop approaches to support families to make changes within their home and child rearing practices, or advocate for different approaches to support their child's behaviour to reduce the impact of lead exposure on children's cognitive and behavioural outcomes.
NeuroToxicology 10/2012; · 3.10 Impact Factor
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ABSTRACT: The prevalence of obesity among Mexican women is high and it could be related to micronutrient status. We evaluated in a cross-sectional study the associations of zinc and vitamins A, C and E concentrations with BMI, central adiposity, body fat and leptin concentration.
Women aged 37 ± 7.5 years (n = 580) from 6 rural communities in Mexico were evaluated. Anthropometric measurements included weight, height, waist and hip circumference. A fasting blood sample was taken for the analysis of glucose, lipid profile, leptin, zinc, and vitamins A, C and E. Body composition was determined by DEXA (Hologic Mod Explorer).
The prevalence of overweight and obesity was 36% (BMI > 25 Kg/m2) and 44% (BMI > 30 Kg/m2), respectively. Prevalence of zinc and vitamins C and E deficiencies were similar in obese, overweight and normal weight women. No vitamin A deficiency was found. Vitamin C was negatively associated with BMI, waist-to-height ratio, and leptin concentrations (p < 0.05). Vitamin A was positively associated with leptin (p < 0.05). When stratifying by BMI, % body fat and waist circumference, high leptin concentrations were associated with lower zinc and lower vitamin C concentrations in women with obesity (p < 0.05) and higher vitamin A concentrations in women without obesity (p < 0.01). Vitamin E status was not associated with any markers of obesity.
Zinc and vitamins A and C are associated with obesity, adiposity and leptin concentration in women from rural Mexico, and may play an important role in fat deposition. The causality of these associations needs to be confirmed.
Nutrition & Metabolism 06/2012; 9(1):59. · 2.88 Impact Factor
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ABSTRACT: Micronutrient deficiencies have been associated with an increase in fat deposition and body weight; thus, adding them to low-fat milk may facilitate weight loss when accompanied by an energy-restricted diet.
The objective was to evaluate the effect of the intake of low-fat milk and low-fat milk with added micronutrients on anthropometrics, body composition, blood glucose levels, lipids profile, C-reactive protein, and blood pressure of women following an energy-restricted diet.
A 16-week randomized, controlled intervention study. PARTICIPANTS/SETTINGS: One hundred thirty-nine obese women (aged 34±6 years) from five rural communities in Querétaro, Mexico.
Women followed an energy-restricted diet (-500 kcal) and received in addition one of the following treatments: 250 mL of low-fat milk (LFM) three times/day, 250 mL of low-fat milk with micronutrients (LFM+M) three times/day, or a no milk control group (CON). Weight, height, and hip and waist circumferences were measured at baseline and every 4 weeks. Body composition measured by dual-energy x-ray absorptiometry, blood pressure, and blood analysis were done at baseline and at the end of the 16 weeks.
Changes in weight and body composition.
One-factor analysis of variance, adjusted by age, baseline values, and community random effects.
After the 16-week intervention, participants in the LFM+M group lost significantly more weight (-5.1 kg; 95% CI: -6.2 to -4.1) compared with LFM (-3.6 kg; 95% CI: -4.7 to -2.6) and CON (-3.2 kg; 95% CI: -4.3 to -2.2) group members (P=0.035). Body mass index change in the LFM+M group (-2.3; 95% CI: -2.7 to -1.8) was significantly greater than LFM group members (-1.5; 95% CI: -2.0 to -1.1) and CON group members (-1.4; 95% CI: -1.9 to -0.9) (P=0.022). Change in percent body fat among LFM+M group members (-2.7%; 95% CI: -3.2 to -2.1) was significantly higher than LFM group members (-1.8%; 95% CI: -2.3 to -1.3) and CON group members (-1.6%; 95% CI: -2.2 to -1.0) (P=0.019). Change in bone mineral content was significantly higher in LFM group members (29 mg; 95% CI: 15 to 44) and LFM+M group members (27 mg; 95% CI: 13 to 41) compared with CON group members (-2 mg; 95% CI: -17 to -14) (P=0.007). No differences were found between groups in glucose level, blood lipid profile, C-reactive protein level, or blood pressure.
Intake of LFM+M increases the effectiveness of an energy-restricted diet to treat obesity, but had no effect on blood lipid levels, glucose levels, C-reactive protein, or blood pressure.
Journal of the American Dietetic Association 10/2011; 111(10):1507-16. · 3.59 Impact Factor
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ABSTRACT: Previous studies suggest adverse effects of arsenic exposure on children's cognitive function. In this study, we examined the potential association between arsenic exposure and children's behavior. Five hundred and twenty-six children, 6-7 years old, living near a metal foundry in Torreón, Mexico, participated in the study. Arsenic exposure was measured as total urinary arsenic (UAs) and arsenic metabolites-monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) concentrations. Children's behavior was assessed by Conners Behavior Rating Scales for parents and teachers. The median (interquartile range) concentrations of UAs, MMA and DMA were 55.2 (39.7), 6.7 (5.9) and 39.3 (28.5) μg/L, respectively. The mean behavior scores from parent and teacher ratings were within the clinically normal range (T<65). The relationship between behavior and urinary arsenic was modeled in linear and logistic regression models, with UAs, MMA and DMA tested in separate models and entered as quartiles. No significant association was found between any measure of urinary arsenic and parent ratings of behavior. However, higher UAs was modestly associated with higher scores on the Oppositional, Cognitive Problems and ADHD sub-scales of the teacher ratings; a dose-response relationship was not established between UAs quartiles and behavior. Higher urinary DMA was associated with higher ratings on the Oppositional, Cognitive Problems and ADHD Index by teachers. The associations between UAs and behavior became statistically non-significant after adjustment for the Peabody Picture Vocabulary Test scores, suggesting that the harmful effects of arsenic on behavior may be secondary to arsenic-induced cognitive deficits. These data suggest a potential adverse association between arsenic and children's behavior and indicate a need to further study the effects of arsenic and arsenic metabolites on neurobehavioral outcomes in children.
Environmental Research 03/2011; 111(5):670-6. · 3.40 Impact Factor
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ABSTRACT: Previous studies have suggested an effect of high arsenic concentration on cognitive and neurobehavioral function in humans.
Our goal was to identify demographic and nutritional factors that are associated with As exposure and the influence of this exposure on cognitive function in school-age children.
We recruited 602 children 6-8 years of age living within 3.5 km of a metallurgic smelter complex in the city of Torreón, Mexico, to participate in a cross-sectional evaluation. Of these, 591 had complete anthropometry, iron, and zinc status by biochemical measurements in serum, blood lead concentration (PbB), and arsenic in urine (UAs), and 557 completed several cognitive performance tests.
The mean for UAs was 58.1 +/- 33.2 microg/L; 52% of the children had UAs concentrations > 50 microg/L, and 50.7% of children had PbB > or = 10 microg/dL. UAs concentration was associated with low socioeconomic status. Nutritional status indicators were not related to UAs concentrations. Linear and logistic regressions adjusted for hemoglobin concentration, PbB, and sociodemographic confounders showed a significant inverse association between UAs and Visual-Spatial Abilities with Figure Design, the Peabody Picture Vocabulary Test, the WISC-RM Digit Span subscale, Visual Search, and Letter Sequencing Tests (p < 0.05). Boys excreted significantly more UAs (p < 0.05) and were affected on different cognitive areas than girls.
Children living in an area contaminated with both As and lead showed that As contamination can affect children's cognitive development, independent of any effect of lead.
Environmental Health Perspectives 09/2007; 115(9):1371-5. · 7.04 Impact Factor
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ABSTRACT: The role of lead exposure or micronutrient deficiencies in children's sleep problems is unknown. Although elevated blood lead concentrations (BPb) are clearly related to behavior problems in children, few researchers have used objective observations. The authors investigated relationships between lead, micronutrient status, sleep, classroom behavior, and activity in Mexican children aged 6-8 years living close to a metal foundry. Mean BPb was 11.5 +/- 6.1 microg/dL; 50% had levels >or= 10 microg/dL. Ten percent of children had hemoglobin < 12.4 g/dL. Parents reported on children's sleep and fatigue (n 550). The authors also observed classroom behavior (n = 157) and measured physical activity (n = 168). BPb >or= 10 microg/dL was associated with later waking time and shorter duration of sleep. Anemia was linked to more off-task behaviors, lower physical activity, earlier bedtime, and shorter sleep onset. Researchers should investigate these relationships further, using more sensitive measures.
Archives of Environmental and Occupational Health 02/2007; 62(2):105-12. · 0.85 Impact Factor
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ABSTRACT: There is increasing interest in the interaction of nutritional deficiencies with toxic metals. Iron deficiency and elevated blood lead concentrations (PbB) reportedly occur together, and zinc also plays an important role in lead metabolism. The objective was to evaluate the effect of zinc and/or iron supplementation on PbB of children attending schools in the neighborhood of a smelter complex for 6 mo. We conducted a double-blind, placebo-controlled field trial in 9 elementary schools located within a 3.5-km radius of a metal foundry in Torreón, Mexico. Of the 602 first-graders enrolled, 517 completed supplementation and had initial and final PbBs. Children were given either 30 mg of iron, 30 mg of zinc, both, or a placebo daily for 6 mo. Baseline and final measures included nutritional status and PbB. The overall prevalence of iron and zinc deficiencies was 12.1 and 30.3%, respectively, and 10.3% were anemic. The PbB concentration decreased in all experimental groups (P < 0.05). After controlling for initial PbB, groups administered zinc and/or iron did not have lower PbB concentrations than the placebo group (P < 0.05). In conclusion, iron supplementation of lead-exposed children significantly improved iron status but did not reduce PbBs. Zinc supplementation did not reduce PbBs independently of zinc nutritional status. Neither iron nor zinc can be recommended as the sole treatment for lead-exposed school children.
Journal of Nutrition 10/2006; 136(9):2378-83. · 3.92 Impact Factor
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ABSTRACT: Lead exposure in children has been associated with both global and specific cognitive deficits. Although chelation therapy is advised for children with blood lead concentrations of >44 microg/dL, treatment options for children with lower blood lead values are limited. Because lead absorption is related to children's nutritional status, micronutrient supplements may be 1 strategy for combating low-level, chronic lead exposure. This study was designed to test the efficacy of iron and zinc supplementation for lowering blood lead concentrations and improving cognitive performance in schoolchildren who live in a lead-contaminated city.
This randomized, double-blind, placebo-controlled field trial was conducted in public elementary schools in Torreón, an industrialized city in northern Mexico. A metal foundry, located close to the city center and within 3.5 km of 9 schools, was the main source of lead exposure. A total of 602 children who were aged 6 to 8 years and regularly attending first grade in the study schools were enrolled. Children were given 30 mg of iron, 30 mg of zinc, both, or a placebo daily for 6 months. A total of 527 completed the treatment, and 515 were available for long-term follow-up, after another 6 months without supplementation. Eleven cognitive tests of memory, attention, visual-spatial abilities, and learning were administered at baseline and each follow-up.
There were no consistent or lasting differences in cognitive performance among treatment groups.
Daily supplementation with iron and/or zinc may be of limited usefulness for improving cognition in lead-exposed schoolchildren. However, these treatments may be effective in settings with higher prevalence of nutritional deficiencies or in younger children.
PEDIATRICS 04/2006; 117(3):e518-27. · 4.47 Impact Factor
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ABSTRACT: Elevated blood lead levels in children are associated with lower scores on tests of cognitive functioning. Recent studies have reported inverse relations between lifetime exposure and intellectual functioning at blood lead concentrations below 10 microg/dL, the Centers for Disease Control and Prevention's (CDC) level of concern. We report associations between blood lead and cognitive performance for first-grade Mexican children living near a metal foundry. Using a cross-sectional design, we examined the relation between children's concurrent blood lead concentrations (mean (SD) 11.4 microg/dL (6.1)) and their performance on 14 tests of global or specific cognitive functions. The blood lead-cognition relations were modeled using both linear and nonlinear methods. After adjustment for covariates, a higher blood lead level was associated with poorer cognitive performance on several cognitive tests. Segmented linear regressions revealed significant effects of lead but only for the segments defined by a concurrent blood lead concentration below 10-14 microg/dL. One implication of these findings is that at the age of 7 years, even in the absence of information on lead exposure in infancy and early childhood, a test result with blood lead < 10 microg/dL should not be considered safe. Together with other recent findings, these results add to the empirical base of support available for evaluating the adequacy of current screening guidelines and for motivating efforts at primary prevention of childhood lead exposure.
Environmental Research 03/2006; 100(3):371-86. · 3.40 Impact Factor
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ABSTRACT: Lead exposure and nutritional factors are both associated with cognitive performance. Lead toxicity and nutritional status are also associated with each other. We examined whether nutritional status variables account for part or all of the association between cognitive performance and lead exposure. First-grade children (n = 724) ages 6-8 y, attending Mexican public schools located in the vicinity of a metal foundry were asked to participate and 602 enrolled in the study. Blood lead, iron status, anemia, anthropometry, and cognitive function were assessed. Results from 7 standardized tests are presented here. The mean blood lead concentration was 11.5 +/- 6.1 micro g/dL (0.56 +/- 0.30 micro mol/L) and 50% of the children had concentrations >10 micro g/dL (0.48 micro mol/L). The prevalence of mild anemia (<124 g/L) was low (10%) and stunting (<2 SD) was nonexistent (2.3%). In bivariate analyses, lead was negatively associated with 4 cognitive tests and was also inversely correlated with iron status, height-for-age Z scores, and head circumference. In multivariate models, the association between lead and cognitive performance was not strongly affected by nutritional variables, suggesting that the relation of lead to cognition is not explained by lead's relation to iron deficiency anemia or growth retardation. In multivariate models, hemoglobin concentration was also positively associated with Peabody Picture Vocabulary Test and Number Sequencing performance, whereas serum ferritin was negatively related to the Coding subscale of the Wechsler Intelligence Scales for Children-Revised Mexican Version (WISC-RM).
Journal of Nutrition 02/2004; 134(2):363-71. · 3.92 Impact Factor
