Does maternal MDR1 C1236T polymorphism have an effect on placental arsenic levels?

Associations among prenatal and postnatal arsenic, lead, and cadmium exposures and motor development in 3-year-old children: a longitudinal birth cohort study in Taiwan

Prenatal and postnatal exposures to heavy metals have been suggested to interfere with neurodevelopment, but the neurotoxicity of lead (Pb), arsenic (As), and cadmium (Cd) is still unclear. In this study, we aimed to assess the associations between the levels of As, Cd, and Pb and children's neurodevelopment. A total of 299 mother-infant pairs were recruited in this study and their meconium were collected. After three years, 53 children underwent the Bayley Scales of Infant and Toddler Development (Bayley-III) examinations and provided hair and fingernail specimens. The levels of As, Cd, and Pb in the meconium, hair, and fingernail were measured by inductively coupled plasma mass spectrometry; the median levels were the following: meconium, 42.7, 5.57, and 25.6 ng/g, respectively; hair, 0.19, 0.05, and 3.61 μg/g, respectively; and fingernail, 0.29, 0.04, and 0.84 μg/g, respectively. After adjusting for potential confounding factors, we found that the log-transformed levels of As in the hair samples was negatively associated with gross motor development (β =  - 0.032; 95% confidence interval: - 0.061 to - 0.004). We conclude that postnatal exposure to As is a crucial period for gross motor development in children, while the effects of Cd and Pb on neurodevelopment are less clear.

Association of Arsenic Methylation Capacity with Developmental Delays and Health Status in Children: A Prospective Case-Control Trial

This case–control study identified the association between the arsenic methylation capacity and developmental delays and explored the association of this capacity with the health status of children. We recruited 120 children with developmental delays and 120 age- and sex-matched children without developmental delays. The health status of the children was assessed using the Pediatric Quality of Life Inventory (PedsQL) and Pediatric Outcomes Data Collection Instrument (PODCI). The arsenic methylation capacity was determined by the percentages of inorganic arsenic (InAs%), monomethylarsonic acid (MMA^V%), and dimethylarsinic acid (DMA^V%) through liquid chromatography and hydride generation atomic absorption spectrometry. Developmental delays were significantly positively associated with the total urinary arsenic concentration, InAs%, and MMA^V%, and was significantly negatively associated with DMA^V% in a dose-dependent manner. MMA^V% was negatively associated with the health-related quality of life (HRQOL; −1.19 to −1.46, P < 0.01) and functional performance (−0.82 to −1.14, P < 0.01), whereas DMA^V% was positively associated with HRQOL (0.33–0.35, P < 0.05) and functional performance (0.21–0.39, P < 0.01–0.05) in all children and in those with developmental delays. The arsenic methylation capacity is dose-dependently associated with developmental delays and with the health status of children, particularly those with developmental delays.

Cellular arsenic transport pathways in mammals

Natural contamination of drinking water with arsenic results in the exposure of millions of people world-wide to unacceptable levels of this metalloid. This is a serious global health problem because arsenic is a Group 1 (proven) human carcinogen and chronic exposure is known to cause skin, lung, and bladder tumors. Furthermore, arsenic exposure can result in a myriad of other adverse health effects including diseases of the cardiovascular, respiratory, neurological, reproductive, and endocrine systems. In addition to chronic environmental exposure to arsenic, arsenic trioxide is approved for the clinical treatment of acute promyelocytic leukemia, and is in clinical trials for other hematological malignancies as well as solid tumors. Considerable inter-individual variability in susceptibility to arsenic-induced disease and toxicity exists, and the reasons for such differences are incompletely understood. Transport pathways that influence the cellular uptake and export of arsenic contribute to regulating its cellular, tissue, and ultimately body levels. In the current review, membrane proteins (including phosphate transporters, aquaglyceroporin channels, solute carrier proteins, and ATP-binding cassette transporters) shown experimentally to contribute to the passage of inorganic, methylated, and/or glutathionylated arsenic species across cellular membranes are discussed. Furthermore, what is known about arsenic transporters in organs involved in absorption, distribution, and metabolism and how transport pathways contribute to arsenic elimination are described.