Objectives The occupational exposure limit for trichloroethylene (TCE) in different countries varies from 1 to 100 ppm as an 8-hour time-weighted average (TWA). Many countries currently use 10 ppm as the regulatory standard for occupational exposures, but the biological effects in humans at this level of exposure remain unclear. The objective of our study was to evaluate alterations in immune and renal biomarkers among workers occupationally exposed to low levels of TCE below current regulatory standards.
Methods We conducted a cross-sectional molecular epidemiology study of 80 healthy workers exposed to a wide range of TCE (ie, 0.4–229 ppm) and 96 comparable unexposed controls in China, and previously reported that TCE exposure was associated with multiple candidate biological markers related to immune function and kidney toxicity. Here, we conducted further analyses of all of the 31 biomarkers that we have measured to determine the magnitude and statistical significance of changes in the subgroup of workers (n=35) exposed to <10 ppm TCE compared with controls.
Results Six immune biomarkers (ie, CD4+ effector memory T cells, sCD27, sCD30, interleukin-10, IgG and IgM) were significantly decreased (% difference ranged from −16.0% to −72.1%) and one kidney toxicity marker (kidney injury molecule-1, KIM-1) was significantly increased (% difference: +52.5%) among workers exposed to <10 ppm compared with the control group. These associations remained noteworthy after taking into account multiple comparisons using the false discovery rate (ie, <0.20).
Conclusion Our results suggest that occupational exposure to TCE below 10 ppm as an 8-hour TWA may alter levels of key markers of immune function and kidney toxicity.
- occupational exposure
- immune function
- kidney toxicity
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Contributors QL, MTS, NR, and LZ designed this study, managed data collection and participated in data processing. K-ML conducted the analyses and was primarily responsible for writing the paper under the supervision of QL. WH conducted the statistical analyses. All authors contributed to draft manuscripts and the final version. QL and NR are the guarantors.
Funding Intramural funds from National Institutes of Health and National Cancer Institute; National Institute of Environmental Health Sciences (P42ES04705 and P30ES01896 to MTS); Northern California Center for Occupational and Environmental Health and Department of Science and Technology of Guangdong Province, China (2007A050100004); International Research Fund (2018) from Korea National Open University
Competing interests None declared.
Ethics approval The study was approved by institutional review boards at the US National Cancer Institute and the Guangdong National Poison Control Center, China.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.
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