An occupational hygiene assessment of dermal nickel exposures in primary production industries

Nickel is known to cause contact dermatitis in humans and it is possible that nickel may be absorbed through the skin and contribute to overall systemic dose. However, the permeation rate of metallic nickel is considered to be low, so the main concern is in relation to dermatitis. There is a lack of dermal exposure data for industrial workers and this information was required for a regulatory risk assessment purposes. The object of this study was therefore to measure the levels of nickel in the skin contaminant layer of nickel refinery workers and to facilitate a comparison with analogous data from the zinc industry and predicted exposure levels given by the EASE model. Workplace surveys were carried out in two different nickel refineries and a range of production tasks were studied. The subjects monitored were involved with processes such as leaching, electro-winning and packaging of the final products. Dermal exposure samples were collected using a removal method, using commercial moist wipes to recover nickel deposits from measured areas of skin. The test procedures were validated by measuring the recovery of known quantities of nickel contamination from surrogate skin media. In addition, background dermal nickel levels were established by studying a group of non-occupationally exposed subjects. The combined nickel recovery efficiency for the sample preparation and analysis procedure was approximately 95% for insoluble nickel and 87% for soluble nickel compounds.A total of 33 complete sets of dermal exposure measurements were collected from 22 different workers. Of the total 792 dermal exposure measurements, 60 were less than the LOD of 0.02 μg/cm2. The highest actual dermal exposures were recorded for nickel powder packing, where the hands, arms, face and neck all received more surface contamination compared with other tasks. In the case of the powder packers, the median and 95th percentile combined hand/arm dermal nickel exposures were 8.40 and 15.37 μg/cm2. The corresponding results for the electro-winning workers were 0.30 and 1.91 μg/cm2. Taking all tasks combined, the corresponding levels were 0.76 and 8.90 μg/cm2. Although the exposure levels for the electro-winning area were much less than in the nickel powder packing plant the solubility of the nickel was higher, thereby possibly increasing the potential health risks. Overall, the dermal exposures were low, and certainly much less than predicted values generated by the EASE model. In addition, the dermal nickel levels were much lower than levels measured in the zinc industry. It is concluded that this is largely due to the much higher levels of engineering controls applied to the nickel production processes generally, combined with specific hygiene measures such as the consistent use of personal protective equipment. “”