Dermal and respiratory exposure to nickel in a packaging section of a base metal refinery

Abstract

Nickel is one of the most commonly known sensitisers and has been classified by the International Agency for Research on Cancer (IARC) as a possible carcinogen to humans (group 2B). Workers at a South African base metal refinery packaging area are potentially exposed to many hazardous chemicals that include nickel. Aims and Objectives: The aim and objectives of this study were to assess dermal and respiratory exposure of workers exposed to nickel in a packaging section at a South African base metal refinery and to assess the change in skin barrier function during a work shift by measuring percentage change in trans epidermal water loss (TEWL), skin hydration and skin surface pH. Skin health was established with a skin questionnaire. Surfaces that workers may come into contact with were also assessed. Method: Respiratory and dermal exposure assessment was done concurrently. Respiratory exposure was assessed and analysed by using the National Institute for Occupational Safety and Health (NIOSH) method 7300. The Institute of Occupational Medicine (IOM) inhalable aerosol sampler was used for personal air sampling. The TEWL index, skin hydration and skin surface pH of the index finger, palm, forearm and forehead were measured before and at the end of the shift with a Derma Measurement Unit, EDS 12 and Skin-pH-Meter® pH 905. These measurements were reported as percentage change in skin barrier function during the shift. Dermal exposure samples were collected with Ghostwipes™ from the index finger and palm of the dominant hand before, during and at the end of the shift, while samples from the forearm and forehead were only collected before and after the shift. Surface sampling was collected and all wipes were analysed for nickel according the NIOSH method 9102, using inductively coupled plasma-atomic emission spectrometry. Results: Respiratory exposure for the whole group of workers in a packaging section was well below the eight hour Time Weighted Average (TWA) respiratory Occupational Exposure Limit (OEL) of 0.5 mg m-3 for nickel. Dermal nickel loading was detected for all the job categories on all the anatomical areas even before the shift had commenced. During the shift more nickel was detected on the index finger and palm of the hand. Levels on the forearm and forehead were much lower in comparison with the index finger and the palm of the hand. Workplace surfaces, which workers may come into contact with on a daily basis, were also contaminated with nickel. Forklift drivers showed high exposure on the index finger and palm of their hands, and this can be attributed to them not wearing any gloves for hand protection. An increase in percentage change for TEWL was seen for most of the job categories on all anatomical areas measured during the shift. Percentage change in skin surface pH and skin hydration varied among job categories. Conclusion: The research addressed the problem statement, with the stated objectives. It was hypothesised that workers at a packaging section of a base metal refinery are exposed to quantifiable levels of nickel through the dermal exposure route. The hypothesis was accepted and control measures together with future studies were recommended. The results confirmed that all workers at a base metal refinery are exposed to quantifiable levels of nickel through the dermal exposure route. Dermal exposure was evident on all anatomical areas for all job categories before the shift had commenced. Personal protective equipment was provided to all employees, but forklift drivers did not wear gloves when operating the forklift. Respirable exposure to nickel was below the OEL. Changes in TEWL and to a lesser extent skin hydration, suggest a deterioration in skin barrier function during the shift. Forklift drivers as well as plate washers may be the highest risk job categories in developing allergic contact dermatitis. Several measures to lower respiratory and dermal exposure to nickel are also recommended.