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A cross-sectional study of general cognitive abilities among Uruguayan school children with low-level arsenic exposure, potential effect modification by methylation capacity and dietary folate.

ABSTRACT: BACKGROUND:Few studies have evaluated the association between low-level arsenic (As) exposure and cognitive performance among children. OBJECTIVES:In this cross-sectional study, we assessed the association between low-level As exposure and cognitive performance among 5-8 year-old children in Montevideo, and tested effect modification by As methylation capacity and children's dietary folate intake. METHODS:We measured total urinary As (UAs) concentrations and the proportion of monomethylarsonic acid (MMA) in the urine of 328 children. Seven subtests of the standardized Woodcock-Muñoz cognitive battery were used to assess cognitive performance, from which, the general intellectual abilities (GIA) score was derived. Total folate intake was estimated from two 24-h dietary recalls. Linear regression analyses were performed. Effect modification was assessed by stratifying at the median %MMA value and tertiles of total folate intake calculated as micrograms (µg) of dietary folate equivalents (dfe). RESULTS:The median UAs was 11.9?µg/l (range?=?1.4-93.9), mean folate intake was 337.4 (SD?=?123.3) µg dfe, and median %MMA was 9.42 (range?=?2.6-24.8). There was no association between UAs and cognitive abilities, and no consistent effect modification by %MMA. UAs was associated inversely with concept formation, and positively with cognitive efficiency and numbers reversed subtest in the lowest folate intake tertile; UAs was also positively associated with sound integration in the second tertile and concept formation in the highest tertile of folate intake. There was no consistent pattern of effect modification by %MMA or folate intake. CONCLUSION:There was no association between low-level As exposure and general cognitive abilities.

SUBMITTER: Desai G

PROVIDER: S-EPMC5911190 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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A cross-sectional study of general cognitive abilities among Uruguayan school children with low-level arsenic exposure, potential effect modification by methylation capacity and dietary folate.

Desai Gauri G Barg Gabriel G Queirolo Elena I EI Vahter Marie M Peregalli Fabiana F Mañay Nelly N Kordas Katarzyna K

Environmental research 20180224

<h4>Background</h4>Few studies have evaluated the association between low-level arsenic (As) exposure and cognitive performance among children.<h4>Objectives</h4>In this cross-sectional study, we assessed the association between low-level As exposure and cognitive performance among 5-8 year-old children in Montevideo, and tested effect modification by As methylation capacity and children's dietary folate intake.<h4>Methods</h4>We measured total urinary As (UAs) concentrations and the proportion ...[more]

PMID: 29486343

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Project description:BackgroundIn the human body, inorganic arsenic (iAs) is methylated via the one-carbon cycle to form monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Lower proportions of iAs and MMA, and higher proportions of DMA in urine indicate efficient methylation; formation of DMA is thought to detoxify iAs and MMA. Studies on folate, vitamin B-12 and iAs methylation yield mixed findings, depending on whether folate and vitamin B-12 were assessed from diet, supplements, or using a blood biomarker.ObjectiveFirst, to compare the associations of serum concentrations and estimated intake of folate and vitamin B-12 with indicators of iAs methylation. Second, to highlight the implications of these different B-vitamin assessment techniques on the emerging evidence of the impact of dietary modifications on iAs methylation.MethodsThe study was conducted among ~7-year-old children from Montevideo, Uruguay. Serum folate and vitamin B-12 levels were measured on the Horiba ABX Pentra 400 analyzer; urinary arsenic was measured using High-Performance Liquid Chromatography on-line with Inductively Coupled Plasma Mass Spectrometry. Dietary intakes were assessed using the average of two 24-h dietary recalls. Linear regressions assessed the associations of serum levels, and dietary intakes of folate (n = 237) and vitamin B-12 (n = 217) with indicators of iAs methylation. Models were adjusted for age, sex, body mass index, total urinary arsenic, and rice intake.ResultsSerum folate and vitamin B-12 levels were above the adequacy threshold for 99% of the participants. No associations were observed between serum folate, serum vitamin B-12, or vitamin B-12 intake and iAs methylation. Folate intake was inversely associated with urinary %MMA [β (95% confidence interval): -1.04 (-1.89, -0.18)].ConclusionAdditional studies on the role of B-vitamins in iAs methylation are needed to develop a deeper understanding of the implications of assessing folate and vitamin B-12 intake compared to the use of biomarkers. Where possible, both methods should be employed because they reflect different exposure windows and inherent measurement error, and if used individually, will likely continue to contribute to lack of consensus.

Project description:BackgroundDetoxification of inorganic arsenic (iAs) occurs when it methylates to form monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Lower proportions of urinary iAs and MMA, and higher proportions of DMA indicate efficient methylation. The role of B-vitamins in iAs methylation in children with low-level arsenic exposure is understudied.ObjectivesOur study objective was to assess the association between B-vitamin intake and iAs methylation in children with low-level arsenic exposure (<50 µg/L in water; urinary arsenic 5-50 µg/L).MethodsWe conducted a cross-sectional study in 290 ∼7-y-old children in Montevideo. Intake of thiamin, riboflavin, niacin, vitamin B-6, and vitamin B-12 was calculated by averaging 2 nonconsecutive 24-h recalls. Total urinary arsenic concentration was measured as the sum of urinary iAs, MMA, and DMA, and adjusted for urinary specific gravity; iAs methylation was measured as urinary percentage As, percentage MMA, and percentage DMA. Arsenic concentrations from household water sources were assessed. Linear regressions tested the relationships between individual energy-adjusted B-vitamins and iAs methylation.ResultsMedian (range) arsenic concentrations in urine and water were 9.9 (2.2-48.7) and 0.45 (0.1-18.9) µg/L, respectively. The median (range) of urinary percentage iAs, percentage MMA, and percentage DMA was 10.6% (0.0-33.8), 9.7% (2.6-24.8), and 79.1% (58.5-95.4), respectively. The median (range) intake levels of thiamin, riboflavin, niacin, and vitamin B-6 were 0.81 (0.19-2.56), 1.0 (0.30-2.24), 8.6 (3.5-23.3), and 0.67 (0.25-1.73) mg/1000 kcal, respectively, whereas those of folate and vitamin B-12 were 216 (75-466) and 1.7 (0.34-8.3) µg/1000 kcal, respectively. Vitamin B-6 intake was inversely associated with urinary percentage MMA (β = -1.60; 95% CI: -3.07, -0.15). No other statistically significant associations were observed.ConclusionsAlthough vitamin B-6 intake was inversely associated with urinary percentage MMA, our findings suggest limited support for a relation between B-vitamin intake and iAs methylation in children exposed to low-level arsenic.

Project description:BackgroundCadmium (Cd) exposure has adverse health effects in children. Diet contributes to Cd exposure, but dietary components could affect body Cd levels.ObjectiveTo examine associations between diet and urinary Cd (U-Cd) in children.MethodsIn this cross-sectional study conducted in Montevideo, Uruguay, Cd exposure of 5-8 year old children (n = 279 with complete data) was assessed in first morning urine (U-Cd), a marker of long-term exposure, measured by ICP-MS and adjusted for specific gravity. Distribution of U-Cd was (median [5%, 95%]: 0.06 [0.02, 0.17] μg/L); data were natural-log-transformed (ln) for statistical analyses. Serum ferritin (SF), an indicator of iron stores, was measured in fasting samples. Trained nutritionists completed two non-consecutive 24-h dietary recalls with both child and caregiver present. Measures of iron, zinc, calcium and fiber intake, and the consumption of grains, root vegetables, milk, and foods rich in heme iron (white and read meats) and non-heme iron (legumes, spinach, broccoli, tomatoes, dried fruit) were derived. Multivariable ordinary least squares (OLS) and ordinal regressions were used to examine associations among tertiles of water Cd, SF, diet, and U-Cd. OLS models were further stratified by sex.ResultsIn covariate-adjusted models, SF was not related to ln-U-Cd. Children in highest tertile of iron and zinc intake had lower ln-U-Cd: (-0.23 [-0.42, -0.03]) and (-0.25 [-0.44, -0.05]), respectively, compared to the reference group. Children consuming higher amounts of foods rich in heme iron had slightly lower ln-U-Cd (-0.17 [-0.36, 0.03]). High grain consumption was related to higher ln-U-Cd (0.25 [0.06, 0.45]).ConclusionsDiets rich in grains were related to higher urinary Cd levels among children living in the context of low Cd pollution. Higher intake of iron and zinc was related to lower Cd levels. Given that urinary Cd is mainly a marker of long-term exposure, these findings should be further corroborated.

Project description:BackgroundDietary antioxidant intake has been hypothesized to influence the development of allergic diseases; however, few prospective studies have investigated this association.ObjectiveOur aim was to study the association between total antioxidant capacity (TAC) of the diet at age 8 years and the subsequent development of asthma, rhinitis and sensitization to inhalant allergens between 8 and 16 years, and to assess potential effect modification by known risk factors.MethodsA total of 2359 children from the Swedish birth cohort BAMSE were included. Dietary TAC at age 8 years was estimated by combining information on the child's diet the past 12 months from a food frequency questionnaire with a database of common foods analysed with the oxygen radical absorbance capacity method. Classification of asthma and rhinitis was based on questionnaires, and serum IgE antibodies were measured at 8 and 16 years.ResultsA statistically significant inverse association was observed between TAC of the diet and incident sensitization to inhalant allergens (adjusted odds ratio: 0.73, 95% confidence interval: 0.55-0.97 for the third compared to the first tertile, P-value for trend = 0.031). Effect modification by traffic-related air pollution exposure was observed, with a stronger association between dietary TAC and sensitization among children with low traffic-related air pollution exposure (P-value for interaction = 0.029). There was no evidence for effect modification by GSTP1 or TNF genotypes, although these results should be interpreted with caution. No clear associations were observed between TAC and development of rhinitis or asthma, although a significant inverse association was observed for allergic asthma (ORadj 0.57, 95% CI 0.34-0.94).Conclusions and clinical relevanceHigher TAC of the diet in early school age may decrease the risk of developing sensitization to inhalant allergens from childhood to adolescence. These findings indicate that implementing an antioxidant-rich diet in childhood may contribute to the prevention of allergic disease.

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A cross-sectional study of general cognitive abilities among Uruguayan school children with low-level arsenic exposure, potential effect modification by methylation capacity and dietary folate.

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A cross-sectional study of general cognitive abilities among Uruguayan school children with low-level arsenic exposure, potential effect modification by methylation capacity and dietary folate.

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