Dermal and respiratory exposure to cobalt salts in a packaging area of a base metal refinery
Van der Westhuizen, Lélani
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Cobalt is a commonly known sensitiser in industrial settings and has been classified by the IARC as a possible group (2B) human carcinogen. Workers at a South African base metal refinery are potentially exposed to cobalt in the cobalt packaging area. The respiratory and dermal exposure to cobalt is a possible health risk. Quantifying the exposures levels assists in determining the degree of the risk as well as the management thereof. The objectives of this study were to assess dermal and respiratory exposure of workers at a cobalt packaging area and to assess their skin condition by measuring transepidermal water loss (TEWL) and skin hydration indices. The skin hydration index was measured on the back of the hand, forehead, wrist and palm at the start, during and end of the shift. The TEWL index was measured at the start and end of the shift on the same areas as the hydration index. Ghostwipes was chosen as preferred wipe sampling media to collect dermal and surface samples. Wipe samples were also taken on suspected contaminated workplace surfaces. Respiratory samples were taken by using the Institute of Occupational Medicine (IOM) inhalable aerosol sampler at a flow rate of 2 l/min. Wipes and respiratory samples were analysed for cobalt according to NIOSH method 9102 using inductively coupled plasma–atomic emission spectrometry (ICP–AES). The hydration indices indicated that worker’s skin are slightly dry to normal at the beginning of the shift. Hydration on the wrist increased significantly during the shift. TEWL indices increased significantly on the back of the hand, wrist and forehead during the shift. TEWL indices of the palm showed a low barrier function before the shift and deteriorated further to a very low barrier function at the end of the shift. Significant dermal cobalt loading occurred on the back of the hand, forehead, wrist and palm during the shift. The palm was the most exposed and the forehead least. The barrier function of the skin is most likely to be affected by exposure to cobalt. The skin condition of workers put them at greater risk to develop adverse health effects of cobalt. Workplace surfaces were contaminated with cobalt. Airborne cobalt was visible at different working stations. Cobalt exposure is due to numerous sources in the packaging area, thus contributing to the dermal exposure. Respiratory exposure exceeded the 8 hour occupational exposure limit for most of the workers. The guidance limit for short term exposure was exceeded by half of the workers. It is important to minimise the exposure to cobalt in packaging area. Manifestation of the adverse health effects are usually not visible in the short term, the necessary precautions have to be taken to protect the workers.
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