Major Limitations in Using Element Concentrations in Hair as Biomarkers of Exposure to Toxic and Essential Trace Elements in Children

Abstract

Background:Hair is a commonly used exposure biomarker for metals and other trace elements, but concern has been raised regarding its appropriateness for assessing the internal dose.Objectives:The aim of the present study was to evaluate children’s hair as biomarker of internal dose for toxic (As, Mn, Cd, Pb) and essential elements (Mg, Ca, Fe, Co, Cu, Zn, Se, Mo).Methods:In 207 children (9–10 years of age), originating from a population-based cohort in rural Bangladesh, we measured concentrations of the selected elements in hair (2cm closest to the scalp) using ICP-MS. We compared these with previously measured concentrations in erythrocytes, urine, and water. For a subset of children (n=19), we analyzed four consecutive 2cm pieces of hair.Results:There were strong associations between hair As and the other biomarkers (erythrocytes: rnormalS=0.73, p<0.001; urine: rnormalS=0.66, p<0.001); and water (rnormalS=0.60, p<0.001); and there were significant correlations between Se in hair and erythrocytes (overall rnormalS=0.38, p<0.001), and urine (rnormalS=0.29, p<0.001). Hair Co and Mo showed weak correlations with concentrations in erythrocytes. Hair Mn was not associated with Mn in erythrocytes, urine, or water, and the geometric mean concentration increased almost five times from the 2cm closest to the head to the 7th–8th cm (p<0.001). Also Mg, Ca, Co, Cd, and Pb increased from the scalp outward (>50% higher in 7th–8th cm compared with 1st–2nd cm, p<0.001).Conclusions:Hair was found to be a useful exposure biomarker of absorbed As and Se only. Of all measured elements, hair Mn seemed the least reflective of internal dose. https://doi.org/10.1289/EHP1239

Early-Life Selenium Status and Cognitive Function at 5 and 10 Years of Age in Bangladeshi Children

“…We recently reported that selenium concentrations in hair correlated positively with concentrations in erythrocytes (Spearman’s rank correlation coefficient of 0.54 for samples representing the time of blood collection) in children from the same study population ( Skröder et al 2017 ). Therefore, we also used hair selenium concentrations to assess selenium status at the 10-y follow-up.…”

“…Hair samples were cut from the occipital part of the children’s heads using 18/8 stainless steel scissors and were transported in high-quality paper envelopes to Karolinska Institutet (Stockholm, Sweden) for analyses ( Skröder et al 2017 ). A sample of of hair (closest to the scalp) was washed in 2% Triton X-100 solution for 1 h, rinsed 10 times with deionized water, and dried for 24 h at room temperature ( ).…”

Dietary Manganese Exposure in the Adult Population in Germany—What Does it Mean in Relation to Health Risks?

“…The relevance of hair manganese concentrations is not completely clear. In general, manganese levels in hair do not correlate with manganese blood concentrations . This may be due to the fact that hair levels likely reflect a cumulative exposure over a longer period of time, whereas blood levels might strongly depend on sampling time as they rather reflect recent exposure.…”

“…This may be due to the fact that hair levels likely reflect a cumulative exposure over a longer period of time, whereas blood levels might strongly depend on sampling time as they rather reflect recent exposure. It was further suggested that hair manganese levels might be influenced by hair color, and hair distance from skull . Even more important, hair manganese levels are prone to external contamination with manganese containing dust or water.…”

A new washing procedure for inorganic element analysis of hair

“…Regarding this last point, chemical speciation could be enlarged from As and Hg to other elements [33][34][35]. Finally, Skröder [36] proposed to limit the relevance of children's hair as exposure biomarkers to only As and Se among 12 elements studied. These elements were apparently not affected by external contamination after washing the samples using Triton X.…”