Welding Fumes Study Highlights the Value of Checking Multiple Variables in Multiple Ways
Data matters. Data can matter even more when its collected across more than one variable in a real time and real world context. Consider the following results from monitoring of workplace exposures to chromium and nickel during welding. Note the exponential difference between the fit for the reference data for air data and the fit for the reference data from urine. Note also that chromium and nickel are not the same in terms of collecting data from urine. The study might have been even better if blood were monitored for differential microRNA expression patterns.
The paper is: Bertram, et al, Human Biomonitoring of Chromium and Nickel from an Experimental Exposure to Manual Metal Arc Welding Fumes of Low and High Alloyed Steel, Ann Occup Hyg (2014)doi: 10.1093/annhyg/meu104, First published online: December 15, 2014. The abstract is online here, and pasted below.
“Objectives: The uptake and elimination of metals from welding fumes is currently not fully understood. In the Aachen Workplace Simulation Laboratory (AWSL) it is possible to investigate the impact of welding fumes on human subjects under controlled exposure conditions. In this study, the uptake and elimination of chromium or chromium (VI) respectively as well as nickel was studied in subjects after exposure to the emissions of a manual metal arc welding process using low or high alloyed steel.
Methods: In this present study 12 healthy male non-smokers, who never worked as welders before, were exposed for 6h to welding fumes of a manual metal arc welding process. In a three-fold crossover study design, subjects were exposed in randomized order to either clean air, emissions from welding low alloyed steel, and emissions from welding high alloyed steel. Particle mass concentration of the exposure aerosol was 2.5mg m−3. The content of chromium and nickel in the air was determined by analysing air filter samples on a high emission scenario. Urine analysis for chromium and nickel was performed before and after exposure using methods of human biomonitoring.
Results: There were significantly elevated chromium levels after exposure to welding fumes from high alloyed steel compared to urinary chromium levels before exposure to high alloyed welding fumes, as well as compared to the other exposure scenarios. The mean values increased from 0.27 µg l−1 to 18.62 µg l−1. The results were in good agreement with already existing correlations between external and internal exposure (German exposure equivalent for carcinogenic working materials EKA). The variability of urinary chromium levels was high. For urinary nickel no significant changes could be detected at all.
Conclusions: Six-hour exposure to 2.5mg m−3 high alloyed manual metal arc welding fumes lead to elevated urinary chromium levels far higher (7.11–34.16 µg l−1) than the German biological exposure reference value (BAR) of 0.6 µg l−1 directly after exposure. On the other hand mean urinary nickel concentrations slightly increased, but did not exceed background levels due to lower bioavailability. We could underline with our single exposure experiment that a welding work related chromium exposure can be measured immediately after the work shift, while the same is not possible for nickel exposure due to lower nickel bioavailability. The data provide useful information for real occupational welding work places.” (underlining added)