Lung function assessment and its association with blood chromium in a chromate exposed population

Hexavalent chromium [Cr(VI)] and its compounds have been associated with various respiratory diseases, while few studies have attempted to determine its adverse effect on lung function. To explore the potential early indicators of health surveillance for respiratory diseases induced by chromate exposure, a longitudinal cohort study including 515 workers with 918 measurements across 2010-2017 was conducted to investigate the impact of individual internal exposure on lung function. Inductively coupled plasma mass spectrometry (ICP-MS) and spirometry were used to measure whole blood chromium (blood Cr) and lung function respectively. In the linear mixed-effects analysis, each 1- unit increase in Ln- transformed blood Cr was significantly associated with estimated effect percentage decreases of 1.80 (0.35, 3.15) % in FEV1, 0.77 (0.10, 1.43) % in FEV1/FVC, 2.78 (0.55, 4.98) % in PEF, and 2.73 (0.59, 4.71) % in FEF25-75% after adjusting for related covariates. Exposure- response curve depicted the reduction of lung function with blood Cr increase, and the reference value of blood Cr was proposed as 6 μg/L considering the lung function as health outcome. Based on the repeated-measure analysis, compared with the low frequency group, subjects with high frequency of high exposure across 2010-2017 had an additional reduction of 5.65 (0, 11.3) % in FVC. Subjects with medium frequency showed more obvious declines of 9.48 (4.16, 14.87) % in FVC, 8.63 (3.49, 13.97) % in FEV1, 12.94 (3.34, 22.53) % in PEF and 10.97 (3.63, 18.30) % in MVV. These findings suggested that short- term high exposure to Cr associated with obstructive ventilatory impairment, and long- term exposure further led to restrictive ventilatory impairment.