Assessment of dermal exposure and skin condition of refinery workers exposed to selected metals
Du Plessis, Johannes Lodewykus
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Aims and objectives: The research aims and objectives of this thesis were: (i) to review literature pertaining to different dermal exposure assessment methods; (ii) to assess dermal exposure of refinery workers to nickel and/or cobalt by making use of skin wipes as a removal method; (iii) to assess concurrently the skin condition of the above mentioned workers by measuring skin hydration, transepidermal water loss (TEWL) and skin surface pH, and (iv) to compare South African skin notations and sensitisation notations with those of other developed countries. Methods: Refinery workers from two base metal refineries participated in this study. Skin condition and dermal exposure was measured on different anatomical areas before, during and at the end of a work shift. Dermal exposure to nickel and/or cobalt was assessed with Ghostwipes TM as a removal method. Wipe samples of potentially contaminated surfaces in the workplace were also collected. Wipes were analysed for nickel and/or cobalt according to NIOSH method 9102, using Inductively Coupled Plasma-Atomic Emission Spectrometry. The assignment and use of skin notations and sensitisation notations in South African legislation and six other developed countries were compared. Results: To date, occupational dermal exposure has been reported for numerous substances by making use of surrogate skin methods (interception methods), removal methods and fluorescent tracer methods (in situ detection methods). From published literature it is evident that skin (dermal) wipes, as a removal method, are the most appropriate method to assess dermal exposure to metals. Varying degrees of skin dryness (low hydration indices) and impaired barrier function (high TEWL indices) are reported, with the hands being implicated the most. However, normal skin condition is also reported for some anatomical areas. Skin surface pH for all anatomical areas sampled decreased significantly during the shift, but remained in normal range. Dermal exposure to nickel occurred during the shift at the electro-winning plant of one refinery, while dermal co-exposure to cobalt and nickel occurred at the cobalt plant of the other refinery. At both of the refineries, cobalt and/or nickel was collected from the workers’ skin even before the shift. Also, dermal exposure to these metals was highly variable between individual workers. Skin notations in South African legislation had a mean agreement of between 42.9% and 45.8% with other countries, while agreement for sensitisation notations was only 3.6% between countries.
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