Background: Cobalt (Co) is increasingly used in green technology development. Recently, our group detected Co in the scalp hair of 73 out of 97 monitored adolescents born and residing in Alcalá de Henares (Spain), suggesting some exposure. We studied Co presence in young children, owing to their greater susceptibility.
Methods: Co was analysed by ICP-MS, after the appropriate removal of exogenous contamination, in scalp hair from 120 children (6 to 9 years old; 70 females) who met strict inclusion criteria.
Results: Data were processed using the NADA statistical package owing to the level of censored values (26.05%; LoD=0.0034 µg/g), which was similar to the percentage observed in adolescents’ hair (24.73%). Co levels were slightly higher in children’s hair [data presented as medians and ranges, in µg/g: 0.0062 (0.0036-0.0437) vs. 0.0036 (0.0016-0.0817)], suggesting a minor dependency of detoxification on young age. This effect was also reported in an study carried out with individuals living in the city of Madrid and in a village in the NE; thus, significantly higher levels of Co were detected in children’s hair (aged 6-10 years) versus the hair of teenagers aged 11-15 years (0.0172 vs. 0.0141 µg/g). Similarly to what was observed in the adolescent cohort, Co presence in children’s hair was sex-dependent; it was significantly higher in female participants [p-value=0.00087; median and range, in µg/g: 0.0074 (0.0037-0.0437) vs. 0.0047 (0.0036-0.0157)], which is also in agreement with what was observed in individuals living in Madrid.
Conclusions: The results suggest some exposure to Co, which would be mostly from dietary sources, as little Co has been detected in the environment of Alcalá de Henares. Tentative reference values for Co, i.e., the 95% confidence interval of the 95th population percentile (CI-PP95), are proposed for girls (0.0199-0.0356) and boys (0.0083-0.0144), as age and sex have been shown to affect the levels of Co in human hair. These ranges could be used to detect exposure to Co in children living in the same city.
