Bayesian varying coefficient kernel machine regression to assess neurodevelopmental trajectories associated with exposure to complex mixtures.

Exposure to environmental mixtures can exert wide-ranging effects on child neurodevelopment. However, there is a lack of statistical methods that can accommodate the complex exposure-response relationship between mixtures and neurodevelopment while simultaneously estimating neurodevelopmental trajectories. We introduce Bayesian varying coefficient kernel machine regression (BVCKMR), a hierarchical model that estimates how mixture exposures at a given time point are associated with health outcome trajectories. The BVCKMR flexibly captures the exposure-response relationship, incorporates prior knowledge, and accounts for potentially nonlinear and nonadditive effects of individual exposures. This model assesses the directionality and relative importance of a mixture component on health outcome trajectories and predicts health effects for unobserved exposure profiles. Using contour plots and cross-sectional plots, BVCKMR also provides information about interactions between complex mixture components. The BVCKMR is applied to a subset of data from PROGRESS, a prospective birth cohort study in Mexico city on exposure to metal mixtures and temporal changes in neurodevelopment. The mixture include metals such as manganese, arsenic, cobalt, chromium, cesium, copper, lead, cadmium, and antimony. Results from a subset of Programming Research in Obesity, Growth, Environment and Social Stressors data provide evidence of significant positive associations between second trimester exposure to copper and Bayley Scales of Infant and Toddler Development cognition score at 24 months, and cognitive trajectories across 6-24 months. We also detect an interaction effect between second trimester copper and lead exposures for cognition at 24 months. In summary, BVCKMR provides a framework for estimating neurodevelopmental trajectories associated with exposure to complex mixtures.

Trace elements and toxic metals in intensively produced tomatoes (lycopersicon esculentum) / Metales traza y metales tóxicos en tomates producidos intensivamente (lycopersicon esculentum)

Introduction: Tomato is considered a healthy food due to its high content in lycopene and other health-promoting natural compounds. Tomatoes have, undoubtedly, assumed the status of a food with functional properties, considering the epidemiological evidence of reducing the risk of certain types of cancers. Objective: Samples of tomatoes from Morocco were analyzed for the mineral composition. Methods: 94 tomato samples from Morocco were analyzed. Flame Atomic Absorption Spectrophotometry (FAAS) was used to determine essential elements (Copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn)) and Atomic Absorption Spectrophotometry with Graphite Furnace (GAAS) was used to analyzed cadmium (Cd) and lead (Pb). Results: The mean concentrations were 0.17 mg/kg, 0.73 mg/kg, 0.20 mg/kg, 0.44 mg/kg, 7.58 μg/kg and 15.8 μg/kg for Cu, Fe, Mn, Zn, Cd and Pb, respectively. The highest contribution to the intakes was observed for Cu (0.67% for adults) while that Zn showed the lowest contribution (0.14% for adult males and 0.20% for adult females). Conclusions: Tomatoes are a good source of essential elements for the diet, mainly iron and zinc. Tomatoes consumption does not significantly affect the intake of heavy metals (AU)

Introducción: El tomate es considerado un alimento saludable debido a su alto contenido en licopeno y otros componentes naturales promotores de salud. Indudablemente, los tomates han asumido el estatus de un alimento con propiedades funcionales, considerando desde un punto de vista epidemiológico reducir ciertos tipos de cánceres Objetivo: Analizar la composición mineral de muestras de tomates de Marruecos. Métodos: 94 muestras de tomates de Marruecos fueron analizadas. Espectrofotometría de Absorción Atómica por llama (FAAS) se usó para determinar elementos esenciales (Cobre (Cu), hierro (Fe), manganeso (Mn) y zinc (Zn) y Espectrofotometría de Absorción Atómica con cámara de grafito (GAAS) se usó para analizar cadmio (Cd) y plomo (Pb). Resultados: Las concentraciones medias fueron 0,17 mg/kg, 0,73 mg/kg, 0,20 mg/kg, 0,44 mg/kg, 7,58 μg/kg and 15,8 μg/kg para Cu, Fe, Mn, Zn, Cd y Pb, respectivamente. La contribución a la ingesta más alta fue observada para el Cu (0,67% para adultos) mientras que el Zn presentó la contribución más baja (0,14% para hombres adultos y 0,20% para mujeres adultas). Conclusión: Los tomates son una buena fuente de elementos esenciales para la dieta, principalmente hierro y zinc. El consumo de tomates no afecta significativamente a la ingesta de metales pesados (AU)

Heavy metals exposure and hearing loss in US adolescents.

INTRODUCTION: Hearing loss is common and, in young persons, can compromise social development and educational achievement. Exposure to heavy metals has been proposed as an important risk factor for hearing loss. METHODS: We evaluated the cross-sectional associations between blood lead, blood mercury, and urinary cadmium and arsenic levels and audiometrically determined hearing loss in participants aged 12 to 19 years in the 2005-2008 National Health and Nutrition Examination Survey after accounting for the complex survey design. There were 2535 individuals available for analysis of blood lead and mercury levels, 878 for urinary cadmium levels, and 875 for urinary arsenic levels. Multivariate logistic regression was used to calculate adjusted odds ratios (ORs) and 95% CIs. RESULTS: A blood lead level greater than or equal to 2 µg/dL (to convert to micromoles per liter, multiply by 0.0483) compared with less than 1 µg/dL was associated with increased odds of high-frequency hearing loss (OR, 2.22; 95% CI, 1.39-3.56). Individuals in the highest quartile of urinary cadmium levels had significantly higher odds of low-frequency hearing loss than those in the lowest quartile (OR, 3.08; 95% CI, 1.02-9.25). There was no overall association between quartiles of blood mercury or urinary arsenic levels and hearing loss. CONCLUSION: Blood lead levels well below the current recommended action level are associated with substantially increased odds of high-frequency hearing loss.

Methodological problems in the neuropsychological assessment of effects of exposure to welding fumes and manganese.

Recently, Kaiser (2003) raised concerns over the increase in brain damage claims reportedly due to exposure to welding fumes. In the present article, we discuss methodological problems in conducting neuropsychological research on the effects of welding exposure, using a recent paper by Bowler et al. (2003) as an example to illustrate problems common in the neurotoxicity literature. Our analysis highlights difficulties in conducting such quasi-experimental investigations, including subject selection bias, litigation effects on symptom report and neuropsychological test performance, response bias, and scientifically inadequate casual reasoning.