The main objectives of the present study were to (i) investigate the effects of mineralogy and solid-phase distribution on element bioaccessibility and (ii) perform a risk assessment to calculate the ...risks to human health via the ingestion pathway. Multiple discriminant analysis showed that the dust chemistry discriminates between indoor and outdoor samples. The solid-phase distribution of the elements in indoor dust indicated that a large proportion of zinc, nickel, lead, copper, and cobalt is associated with an aluminum oxy-hydroxides component, formed by the weathering of aluminum silicates. This component, which seems to influence the mobility of many trace elements, was identified for a group of indoor dust samples that probably had a considerable contribution from outdoor dust. An iron oxide component consisted of the highest percentage of chromium, arsenic, antimony, and tin, indicating low mobility for these elements. The bioaccessible fraction in the stomach phase from the unified BARGE method was generally high in zinc, cadmium, and lead and low in nickel, cobalt, copper, chromium, and antimony. Unlike other potentially toxic elements, copper and nickel associated with aluminum oxy-hydroxides and calcium carbonates were not extracted by the stomach solutions. These trace elements possibly form stable complexes with gastric fluid constituents such as pepsin and amino acid. Lead had a hazard quotient >1, which indicates the risk of non-carcinogenic health effects, especially for children.
In March, 2022, a Working Group of 31 scientists from 13 countries met remotely at the invitation of the International Agency for Research on Cancer (IARC) to finalise their evaluation of the ...carcinogenicity of nine agents: cobalt metal (without tungsten carbide or other metal alloys), soluble cobalt(II) salts, cobalt(II) oxide, cobalt(II,III) oxide, cobalt(II) sulfide, other cobalt(II) compounds, trivalent antimony, pentavalent antimony, and weapons-grade tungsten (with nickel and cobalt) alloy. In two Good Laboratory Practice (GLP) studies2 in mice and rats, inhaled cobalt metal caused bronchioloalveolar carcinoma in male and female mice; bronchioloalveolar carcinoma, and malignant pheochromocytoma of the adrenal medulla in male and female rats; pancreatic islet carcinoma in male rats; and leukaemia in female rats. In two GLP studies in mice and rats, inhaled cobalt(II) sulfate caused bronchioloalveolar carcinoma in male and female mice; bronchioloalveolar tumours in male rats; and bronchioloalveolar carcinoma, and adrenal medulla tumours in female rats. In two GLP studies6 in rodents, inhalation exposure caused bronchioloalveolar carcinoma in male and female mice; fibrous histiocytoma and fibrosarcoma of the skin in male mice; lymphoma in female mice; and lung and adrenal medulla tumours in female rats.
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