Skin and respiratory exposure to soluble lead, cobalt, nickel, copper, arsenic and silver at two South African precious metals refineries.

Abstract

Precious metals refinery workers are exposed to soluble platinum group metals (PGMs) during PGM-refining but may also be exposed to hazardous non-PGMs (Pb, Co, Ni, Cu, As and Ag) still present in the matte following base metals refining. The aim of this article was to report the skin and respiratory exposure of workers to soluble non-PGMs during PGM-refining. Skin and respiratory exposure (of 40 workers at two precious metals refineries) were measured simultaneously over two consecutive shifts. Skin exposure was measured on the palm, wrist, neck and forehead using Ghostwipes™ and respiratory exposure was measured using the MDHS method 46/2 during which soluble metals were extracted using 0.07M HCl and mechanical agitation, followed by ICP-MS analysis. The geometric means (GM) of average skin exposure to individual soluble metals on all anatomical areas was found in the order Cu (0.018µg/cm2) > Ni (0.016µg/cm2) > Pb (0.008µg/cm2) > Ag (0.006µg/cm2) > As (0.004µg/cm2) > Co (0.0008µg/cm2) with the palm being the highest exposed anatomical area. The order of the GM respiratory exposure was Pb (0.224µg/m3) > Ag (0.201µg/m3) > Cu (0.159µg/m3) > As (0.079µg/m3) > Ni (0.034µg/m3) > Co (0.016µg/m3) with exposure to As exceeding the South African occupational exposure limit (20µg/m3) during concentrate handling (max 66.174µg/m3). Workers were exposed to a mixture of toxic PGM and non-PGMs via the skin and inhalation. Exposure to these metals could lead to the development of diseases, such as contact dermatitis, occupational allergy, or occupational cancer. Non-PGMs must be included in hazardous chemical risk assessments and control strategies implemented at precious metals refineries.