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. 2022 Sep 1;64(9):e550-e558.
doi: 10.1097/JOM.0000000000002610. Epub 2022 Jul 28.

Cross-sectional Study of Workers Employed at a Copper Smelter-Effects of Long-term Exposures to Copper on Lung Function and Chronic Inflammation

Lisa-Marie Haase  1 , Thomas Birk, Craig A Poland, Olaf Holz, Meike Müller, Annette M Bachand, Kenneth A Mundt
Affiliations

Cross-sectional Study of Workers Employed at a Copper Smelter-Effects of Long-term Exposures to Copper on Lung Function and Chronic Inflammation

Lisa-Marie Haase et al. J Occup Environ Med. .

Abstract

Objective: The aim of the study was to assess the effect of exposure to copper-containing dust on lung function and inflammatory endpoints among workers of a German copper plant, effects rarely studied before.

Methods: One hundred four copper-exposed smelter workers and 70 referent workers from the precious metal and lead facilities were included, with different metal exposures in both groups due to the different process materials. Body plethysmography, exhaled nitric oxide (FeNO) measurements, and blood sampling were conducted in all workers. Smoking status and the use of respiratory protective equipment were considered. In a subgroup of 40 nonsmoking volunteers (28 copper-exposed and 12 referents), sputum biomarkers were assessed.

Results: Median lung function values of both copper-exposed and the referent groups were within reference ranges of "healthy" individuals, and statistical differences between the groups were mostly not evident. Similarly, differences in blood and sputum biomarkers were too small to be biologically relevant.

Conclusion: The results suggest the absence of the detectable effects of copper-containing dust exposure on lung function or chronic inflammation within the investigated cohort.

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Conflict of interest statement

Conflict of interest: The published work was part of a research project commissioned to the consultancy Ramboll by the International Copper Association (ICA). Dr Mundt supported Ramboll as independent consultant. The affiliated institutions of Dr Poland (University of Edinburgh), Dr Holz, and Dr Müller (Fraunhofer Institute for Toxicology and Experimental Medicine) received funding for their scientific input and contributions to the study from ICA as well.

Figures

FIGURE 1
FIGURE 1
Box-and-whisker plots of the unstratified data of (A) FEV1/FVC; (B) Rtot; (C) DLCO or TLCO %pred and (D) PEF by exposure group. Box is reflecting the IQR with the median (line) and mean value (x) of the data. Upper and lower whiskers indicating the data variability: 25th percentile − 1.5 *IQR; 75th percentile + 1.5 *IQR. Empty circles represent outliers. %pred, percentage of the predicted value for healthy nonsmokers; DLCO or TLCO, transfer factor of the lung for carbon monoxide; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; IQR, interquartile range; PEF, peak expiratory flow; Rtot, airway resistance.
FIGURE 2
FIGURE 2
Box-and-whisker plots of the absolute number of blood leukocytes, blood neutrophils, and serum IL-6 levels in copper-exposed workers and referents, separately for smoking status. Box is reflecting the IQR with the median (line) and mean value (x) of the data. Upper and lower whiskers indicating the data variability: 25th percentile − 1.5 *IQR; 75th percentile + 1.5 *IQR. Empty circles represent outliers. IL, interleukin; IQR, interquartile range.
FIGURE 3
FIGURE 3
Box-and-whisker plots of the absolute number of blood leukocytes, blood neutrophils, and the percentage of blood neutrophils in copper-exposed workers with and without RPE, separately for smoking status. Box is reflecting the IQR with the median (line) and mean value (x) of the data. Upper and lower whiskers indicating the data variability: 25th percentile − 1.5 *IQR; 75th percentile + 1.5 *IQR. Empty circles represent outliers. IQR, interquartile range; RPE, respiratory protective equipment.
FIGURE 4
FIGURE 4
Median and IQR of the percentage of sputum neutrophils (left) and macrophages (right) in 25 nonsmoking copper-exposed workers and 11 nonsmoking referent workers. IQR, interquartile range.
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References

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