Biological monitoring of dermal and air exposure to cobalt at a Swedish hard metal production plant: does dermal exposure contribute to uptake?

Abstract

SummaryBackgroundOccupational exposure to cobalt is well established in hard metal manufacture. Cobalt is known to cause contact allergy, asthma, hard metal lung disease, and lung cancer. The relationship between skin exposure and uptake determined in blood has not been extensively investigated.ObjectiveTo examine whether skin and inhalable air exposure to cobalt contributes to uptake, determined as cobalt in blood, in a hard metal manufacturing factory.MethodsThe amount of cobalt on the skin found with an acid wash technique, the air concentrations of inhalable cobalt and cobalt blood concentrations were determined and correlated in exposed workers.ResultsWe found a significant rank correlation for cobalt concentrations on the skin, in inhalable air, and in blood (0.376–0.498). Multiple linear regression showed significant regression coefficients for cobalt skin exposure and blood (B = 0.01, p < 0.05) and for inhalable cobalt in air and blood (B = 49.1, p < 0.001). According to our model based on data from the regression analyses, a twofold increase in skin exposure levels at different air concentrations caused a 3–14% increase in blood levels.ConclusionsOur data suggest that skin exposure to cobalt in the hard metal industry could affect the total uptake at the same order of magnitude as air exposure.

Contamination of skin and surfaces by cobalt in the hard metal industry

“…They reported a median skin dose of cobalt based on all areas on the hand of 4.0 μg/cm 2 /2 hours (range 0.09‐200 μg/cm 2 ) for 62 participants. The highest skin doses were found in powder and pressing departments, with median values of 3 and 46 μg/cm 2 /2 hours (range 1.8‐22 and 0.88‐200 μg/cm 2 ), respectively . These observations are in line with our study of 40 workers, in which raw material workers had the highest skin doses after 2 hours, with a median of 1.51 μg/cm 2 and a range 0.25 to 28 μg/cm 2 .…”

“…Already in the 1980s, it was evident that contact allergy to cobalt was common among workers in hard metal (cemented tungsten carbide) production . Wide ranges of cobalt skin doses are still found in the hard metal industry, depending on the work area . Assessment of surface contamination has been limited to work surfaces inside production areas of hard metal facilities .…”

“…Measurements of cobalt on skin, deposited by contact with metallic items and materials, have been performed in various occupational groups, [11][12][13][14] and have shown that skin doses frequently exceed the ED 10 value. In these studies, no information is available on how skin comes into contact with cobalt other than by direct handling of cobalt-containing items or materials.…”

“…1 Wide ranges of cobalt skin doses are still found in the hard metal industry, depending on the work area. 14,15 Assessment of surface contamination has been limited to work surfaces inside production areas of hard metal facilities. 15 Less evident, but potential, sources of skin exposure outside production areas have not been investigated.…”

How to prevent skin damage from air pollution. Part 1: Exposure assessment

“…Weschler et al (2015) performed a series of experiments with bare-skin participants who were exposed to diethyl phthalate, via inhalation and skin. In a Swedish study, blood has been used as a biomarker for skin exposure of cobalt; despite low measured air concentrations, monitoring of cobalt in blood shows relatively high concentrations, confirming the role of dermal absorption(Klasson et al, 2017). These results clearly indicate the importance of dermal absorption.In addition, several occupational studies have quantified heavy metals skin exposure.…”