Factors influencing lead contents in human toenails utilised as biomarkers of exposure to this potentially toxic element in house dust: a Portuguese case study

A pilot survey focusing on potentially toxic elements (PTE) in house dust and toenails of residents from the industrial city of Estarreja was carried out for purposes of environmental exposure assessment studies. A total of 21... [ view full abstract ]

A pilot survey focusing on potentially toxic elements (PTE) in house dust and toenails of residents from the industrial city of Estarreja was carried out for purposes of environmental exposure assessment studies. A total of 21 households and 30 individuals were recruited for the pilot study. Whereas the exposure–biomarker association is subject to variation due to receptor-related and environmental factors, investigation on such factors was carried out via questionnaire data. Ethics approval was obtained from the National Committee for Data Protection (Proc. nº 1241/2013). This study aims at investigating relevant ambient factors influencing exposure to environmental Pb, as determined by its levels in human toenails. Total Pb concentrations in the indoor dust (mean: 174 mg kg-1) are higher than in outdoor dust (mean: 121 mg kg-1) although the differences are not statistically significant. Furthermore, average indoor dust Pb concentration for Estarreja is above the one of the control sites. Whilst levels of Pb are higher in toenail clippings from the exposed group, the differences are not statistically significant (p> 0.01). A random forest machine learning algorithm was used as a screening tool to check which of the possible 53 elements determined in the house dust and 19 household related environmental factors from the questionnaire could account for the elemental compositions of the toenail samples. Preliminary evaluations suggest that in addition to Pb, other PTEs such as Ag and Cu in toenails may relate to the household environment.