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An association between lead (Pb) exposure and antisocial behaviors has been documented, but findings have been inconclusive. We aimed to estimate the association between prenatal, early childhood, and preadolescent/adolescent (periadolescent) Pb exposure and aggression and conduct problems in periadolescent residents of Mexico City.

•We examined prenatal metal mixture concentrations and reward motivation in children.•Metal mixture concentrations were associated with increased reward motivation.•Contributions of different metals differed by trimester and child sex.

•Mexican guidelines recommended a dietary reference intake for fluoride of 2.45 mg/d for adult and pregnant women.•Mexico has a salt fluoridation program.•High fluoride concentrations are neurotoxic.•Median fluoride intake through foods and beverages was estimated to be 1.01 mg/d (0.73, 1.32) in a Mexican pregnancy cohort.•Higher fluoride intake from foods and beverages during pregnancy is associated with lower cognitive neurodevelopment in male offspring.

Reducing the risk of respiratory disease during the plasticstages of lung development could have long-term health impacts. Psychosocial stress has been previously linked to adverse childhood respiratory outcomes, but the influence of child's anxiety and sex differences has not been completely elucidated.

It is believed that genetic factors play a large role in the development of many cognitive and neurological processes; however, epidemiological evidence for the genetic basis of childhood neurodevelopment is very limited. Identification of the genetic polymorphisms associated with early-stage neurodevelopment will help elucidate biological mechanisms involved in neuro-behavior and provide a better understanding of the developing brain. To search for such variants, we performed a genome-wide association study (GWAS) for infant mental and motor ability at two years of age with mothers and children recruited from cohorts in Bangladesh and Mexico. Infant ability was assessed using mental and motor composite scores calculated with country-specific versions of the Bayley Scales of Infant Development. A missense variant (rs1055153) located in the gene WWTR1reached genome-wide significance in association with mental composite score (meta-analysis effect size of minor allele βmeta= −6.04; 95% CI: −8.13 to −3.94; P= 1.56×10−8). Infants carrying the minor allele reported substantially lower cognitive scores in both cohorts, and this variant is predicted to be in the top 0.3% of most deleterious substitutions in the human genome. Fine mapping and region-based association testing provided additional suggestive evidence that both WWTR1and a second gene, LRP1B, were associated with infant cognitive ability. Comparisons with recently conducted GWAS in intelligence and educational attainment indicate that our phenotypes do not possess a high genetic correlation with either adolescent or adult cognitive traits, suggesting that infant neurological assessments should be treated as an independent outcome of interest. Additional functional studies and replication efforts in other cohorts may help uncover new biological pathways and genetic architectures that are crucial to the developing brain.

Maternal antenatal stress may influence offspring development and behavior, but any association with child sleep is unknown.

Background: The 2006 Mexican National Health and Nutrition Survey documented a prevalence of zinc deficiency of almost 30% in children under 2 years of age.Objective: We sought to validate a food frequency questionnaire (FFQ) for quantifying dietary bioavailable zinc intake in 2-year-old Mexican children accounting for phytic acid intake and using serum zinc as a reference.Methods: This cross-sectional study was nested within a longitudinal birth cohort of 333 young children in Mexico City. Nonfasting serum zinc concentration was measured and dietary zinc intake was calculated on the basis of a semiquantitative FFQ administered to their mothers. The relationship between dietary zinc intake and serum zinc was assessed using linear regression, adjusting for phytic acid intake, and analyzed according to two distinct international criteria to estimate bioavailable zinc. Models were stratified by zinc deficiency status.Results: Dietary zinc, adjusted for phytic acid intake, explained the greatest proportion of the variance of serum zinc. For each milligram of dietary zinc intake, serum zinc increased on average by 0.95 µg/dL (0.15 µmol/L) (p= .06). When stratified by zinc status, this increase was 0.74 µg/dL (p= .12) for each milligram of zinc consumed among children with adequate serum zinc (n = 276), whereas among those children with zinc deficiency (n = 57), serum zinc increased by only 0.11 µg/dL (p= .82).Conclusions: A semiquantitative FFQ can be used for predicting serum zinc in relation to dietary intake in young children, particularly among those who are zinc-replete, and when phytic acid or phytate intake is considered. Future studies should be conducted accounting for both zinc status and dietary zinc inhibitors to further elucidate and validate these findings.

Recent evidence suggests that low-level environmental exposure to manganese adversely affects child growth and neurodevelopment. Previous studies have addressed the effects of prenatal exposure, but little is known about developmental effects of early postnatal exposure.

AbstractObjective:To evaluate the validity of a food-frequency questionnaire (FFQ) for assessment of the dietary intakes of polyunsaturated fatty acids (PUFAs) against a biochemical marker of fat intake, erythrocyte cell membrane phospholipid levels, during pregnancy.Design:Cross-sectional analysis.Setting:Developmental Neurobiology Department, National Institute of Perinatology, Mexico City.Subjects:One hundred forty-six healthy pregnant women during the last trimester of pregnancy. Among women enrolled, the first 35 pregnant women (24%) had their erythrocytes analysed for fatty acid status.Methods:We administered an FFQ and compared intakes of PUFAs against their erythrocyte cell membrane concentrations, processed by gas chromatography.Results:Pearson correlation coefficients among ?-linolenic acid (ALN), docosahexaenoic acid (DHA) and eicosapentaenoic acid in erythrocyte cell membranes against their crude dietary counterparts were 0.32, 0.35 and 0.36 (each P< 0.05). In a simple linear regression, erythrocyte DHA and arachidonic acid (AA) were significantly related to their respective dietary intakes (? = 0.30, 95% confidence interval (CI): 0.007?0.60, P= 0.045 for DHA; ? = 0.49, 95% CI: 0.010?0.98, P= 0.044 for AA). Erythrocyte cell membrane ALN concentration (%/total) was only marginally related to ALN dietary intake (mg day?1) (? = 0.52, 95% CI: ?0.020?1.10, P= 0.061). However, after adjustment for long-chain n?3 PUFA/AA, this association reached significance (? = 0.44, 95% CI: 0.026?0.825, P= 0.038). Main dietary sources for n?3 PUFAs were canned tuna fish and fresh catfish; for n?6 these were eggs and cow's milk. The use of this FFQ in these pregnant Mexican women provided estimates of average long-term intakes of PUFAs and correlated reasonably well with their erythrocyte cell membrane phospholipid status. However, we need to consider that, during pregnancy, there is a faster turnover of PUFAs from fat storage that may modify the profile of erythrocyte PUFAs and lower the correlation between dietary intake and erythrocyte PUFAs.

The authors evaluated the effects that maternal bone lead stores have in anthropometry at birth in 223 mother-infant pairs. The participants were recruited between April and November 1994. Anthropometric data were collected within the first 12 hr following delivery. Maternal information was obtained 1 mo after delivery occurred. Bone lead burden was determined with in-vivo K-x-ray fluorescence of the tibia (cortical bone) and the patella (trabecular bone). The authors transformed anthropometric measurements to an ordinal 5-category scale, and the association of measurements with other factors was evaluated with ordinal logistic-regression models. Mean bone lead levels were 9.8 μg/gm bone mineral and 14.4 μg/gm bone mineral for the tibia and patella, respectively. Birth length of newborns decreased as tibia lead levels increased. Compared with women in the lower quintiles of the distribution of tibia lead, those in the upper quintile had a 79% increase in risk of having a lower birth length newborn (odds ratio = 1.79; 95% confidence interval = 1.10, 3.22). The authors adjusted by birth weight, and the effect was attenuated—but nonetheless significant. Patella lead was positively and significantly related to the risk of a low head circumference score; this score remained unaffected by inclusion of birth weight. The authors estimated the increased risk to be 1.02 per μg lead/gm bone mineral (95% confidence interval = 1.01, 1.04 per μg lead/gm bone mineral). Odds ratios did not vary substantially after the authors adjusted for birth weight and other important determinants of head circumference.

The authors determined the secular trend in blood lead levels in a cohort of 91 children born in Mexico City between 1987 and the beginning of 1993. The authors grouped children by calendar year in which they reached 36 mo of age (i.e., 1990–1995), and their blood lead levels were measured every 6 mo during a 66-mo period. The overall geometric mean blood lead level was 8.6 μmlg/dl (range = 1.0–61.0 μmlg/dl). A repeated measures analysis of variance revealed a significant downward linear trend in blood lead levels by year (p < .001)—from an estimated marginal geometric mean of 14.2 μmlg/dl in 1990 to 6.3 μmlg/dl in 1995. There was also a significant linear age effect (p < .001); blood lead levels generally fell during the 36th-66th mo. Family use of lead-glazed pottery significantly elevated blood lead levels (p = .006), and the effect magnified as age increased (Age x Pottery Interaction [p = .014]). Although the overall downward trend in blood lead levels during the time period described corresponded to a reduction in various sources of lead exposure, there was no alteration in production, distribution, or use of leaded pottery. Currently, use of lead-glazed ceramic pottery is one of the most profound sources of lead exposure in the Mexican population.

Although Mexico substantially reduced use of leaded gasoline during the 1990s, lead-glazed pottery remains a significant source of population exposure. Most previous studies of lead in nonoccupationally exposed groups in Mexico have been conducted in the Mexico City metropolitan area. Oaxaca, a poor southern state of Mexico, has a centuries-old tradition of use of low temperature lead-glazed ceramic ware manufactured mainly by small family businesses. We measured blood lead levels in 220 8–10-y-old children (i.e., not from pottery-making families) who were students in the innercity of Oaxaca and in the mothers of all children. The geometric mean blood lead level of the children was 10.5 μmlg/dl (+7.0/–4.3 μmlg/dl standard deviation; range = 1.3–35.5 μmlg/dl). The corresponding mean value for the mothers was 13.4 (+9.0/–5.4 μmlg/dl standard deviation; range = 2.8–45.3 μmlg/dl). We used cutoffs that were greater than or equal to 10 μmlg/dl, 20 μmlg/dl, and 30 μmlg/dl, and we determined that 54.9%, 10.3%, and 3.0% of the children were at or above the respective criteria. We accounted for 25.2% of the variance in blood lead levels of the children, using maternal responses to a questionnaire that assessed possible lead sources in a linear multiple-regression model. The most important factors related to lead levels were family use of lead-glazed pottery, use of animal fat in cooking, and family income. The addition of maternal blood lead level to the model increased accounted variance in blood lead to 48.0%. In logistic-regression modeling of children's blood lead levels, we used a cutoff of greater than or equal to 10 μmlg/dl, and we found that use of lead-glazed pottery was the most important of all questionnaire items that were predictive of blood lead levels (odds ratio = 2.98). In Oaxaca, as is the case elsewhere in Mexico, lead-glazed ceramic ware remains a significant risk factor for elevated blood lead levels in children.

We determined the secular trend in blood lead levels in a cohort of 104 children born in Mexico City between 1987 and 1993. We grouped children by the calendar year in which they reached 6 mo of age and measured blood lead levels every 6 mo until they attained 36 mo of age. The overall geometric mean blood lead level was 9.6 μg/dl (range = 1.5–59.5 μg/dl). A repeated measures analysis of variance revealed a highly significant linear trend in blood lead level with year (p < .001); there was a maximum decrease of 7.6 μg/dl between 1989 and 1993. There was a highly significant quadratic age effect (p < .001); blood lead levels rose between 6 and 18 mo of age and decreased thereafter. There was a marginally significant interaction between age of the child and year. Family use of lead-glazed pottery significantly elevated blood lead levels (p = .028). The downward trend in blood lead levels during the time period of study corresponded to the reduction in various sources of lead exposure.

Air pollution exposure in childhood is associated with greater incidence and exacerbation of asthma, particularly in children whose parents report high levels of psychological stress. However, this interaction has not been completely elucidated in pregnancy.

Increasing evidence links early-life exposure to psychosocial stress with adverse childhood respiratory outcomes. The influence of exposure timing has not been completely elucidated.

Apheresis is an efficient method to collect specific blood components such as platelets, leukocytes, plasma and stem cells. Its advantages include: the collection of standardized and high-quality blood products and a higher collection frequency. However, apheresis is usually accompanied by acute metabolic changes (specially in serum calcium and magnesium concentrations) due to citrate infusion during the whole procedure.To compare pre and post-plateletpheresis serum level concentrations of calcium, magnesium, zinc, copper and parathyroid hormone among donors and correlate these levels with symptoms that donors may experience during the procedure performance.This is a prospective study including 105 healthy plateletpheresis donors who attended the National Cancer Institute. Basal and post-procedure serum levels of parathyroid hormone (PTH), calcium (Ca), magnesium (Mg), zinc (Zn) and copper (Cu) were measured by ion selective potentiometry (Ca), final dot (Mg), atomic absorption (Cu, Zn) and solid phase two site chemoluminiscence (PTH) methods. In case of adverse reactions, a blood sample was drawn immediately in order to analyze concentrations of such hormone and minerals. We intended to correlate both, diet and adverse reactions with serum levels of aforementioned elements. Statistical analysis was performed by chi-square and ANOVA. Protocol was approved by the institutional ethical and research committee.One hundred and five consecutive donors were included in the study conducted from June 28th through July 27th, 2012. There were 68 males and 37 females. Median age was 31 years (range 18–56). Pre and post-apheresis PTH, Ca, Mg, Zn and Cu serum levels are shown in table 1. Furthermore we found significant differences in women older than 30 years but did not find any relationship between donors' symptoms and diet.Plateletpheresis induced a secondary hyperparathyroidism state resulting from chelation of calcium and magnesium. We demonstrated that Cu was also chelated by citrate. These results urges us to assess the kinetics of these metabolic changes as well as to follow a cohort of donors with bone densitometry in order to assure that frequent and chronic infusion of citrate during plateletpheresis donations does not become a long-term risk for osteopenia and osteoporosis as already suggested by some authors1,2. If such a risk is demonstrated other preventive measures must be implemented like: 1.- To restrict the number of apheresis donations per person and 2.- To develop new and safer anticoagulants to be used during the apheresis procedures.No relevant conflicts of interest to declare.

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