INMA: “Is maternal nutrient status influencing the effects of arsenic on the child cognition?”
An INMA study investigated the relation between prenatal exposure to arsenic and cognitive and motor function in preschool children. Researchers also studied whether this relation may differ according to the maternal nutrient status.
The inorganic form of arsenic is mainly found in soil and water. In regions with low levels of arsenic in water, as is the case in Spain, the consumption of certain foods, especially rice but also mollusks or legumes, is the main route of exposure to arsenic. The route of exposure to the organic forms is mainly through seafood and fish consumption. After ingestion, inorganic arsenic is transformed through reduction and methylation processes. Several factors seem to affect methylation efficiency, such as the intake of some nutrients and elements (e.g., vitamins B6 and B12, manganese, selenium, and zinc levels), and pregnancy status.
Exposure to arsenic during fetal life has been linked to increased risk of neonatal mortality, decreased birth size, increased risk of respiratory symptoms and infections during childhood. A few studies have evaluated the relationship between prenatal exposure to arsenic and neuropsychological function in childhood, and reported heterogeneous results.
In the INMA study, a total of 1493 children from the Gipuzkoa and Valencia areas were included. Levels of total arsenic and its metabolites were measured in maternal urine samples collected during pregnancy. Serum manganese and selenium, urinary cadmium, and zinc, and plasma ferritin concentrations were also determined from the first trimester of pregnancy.
When children were around 5 years of age, cognitive and motor function were assessed using the McCarthy Scales of Children’s Abilities. Several scales were measured, related to processing of verbal information (verbal score); numerical abilities (quantitative score); perceptual information processing (perceptive-performance score); short-term retention of verbal, visual, or numerical information (memory score); and fine (e.g. drawing) and gross (e.g. balance or accuracy) abilities (motor score). Scales were used to create additional scores of general cognition, executive function score, working memory, and gross motor and fine motor skills.
The results suggest that prenatal exposure to arsenic was associated lower general cognition, executive function and working memory at 5 years of age. Additionally, lower methylation efficiency was associated with lower memory scores, and this association was influenced by the maternal concentrations of manganese, zinc, and ferritin. In other words, children whose mothers had lower levels of manganese, zinc, and ferritin during pregnancy obtained worse memory scores with lower methylation efficiency.
This is the first study showing that maternal nutrient status may influence the association between prenatal exposure to arsenic and cognitive function in childhood. Authors say that “similar epidemiological studies are necessary in order to improve knowledge about exposure to arsenic, as well as its different species, during critical periods such as prenatal development and its effects on children’s health”, adding that “there is a need for studies that can provide mechanistic data of arsenic neurotoxicity”.
Reference: Soler-Blasco R, Murcia M, Lozano M, Sarzo B, Esplugues A, Riutort-Mayol G, Vioque J, Lertxundi N, Santa Marina L, Lertxundi A, Irizar A, Braeuer S, Ballester F, Llop S. Prenatal arsenic exposure, arsenic methylation efficiency, and neuropsychological development among preschool children in a Spanish birth cohort. Environ Res. 2022 May 1;207:112208.
Link to the scientific article: https://pubmed.ncbi.nlm.nih.gov/34662579/