Hematological Effects and Benchmark Doses of Long-Term Co-Exposure to Benzene, Toluene, and Xylenes in a Follow-Up Study on Petrochemical Workers

Benzene, toluene, and xylenes (BTX) commonly co-exist. Exposure to individual components and BTX-rich mixtures can induce hematological effects. However, the hematological effects of long-term exposure to BTX are still unclear, and respective reference levels based on empirical evidence should be developed. We conducted a follow-up study in BTX-exposed petrochemical workers. Long-term exposure levels were quantified by measuring cumulative exposure (CE). Generalized weighted quantile sum (WQS) regression models and Benchmark Dose (BMD) Software were used to evaluate their combined effects and calculate their BMDs, respectively. Many hematologic parameters were significantly decreased at the four-year follow-up (p 0.010, Ptrend Pinteraction Ptrend for WQS indices 3 × year, respectively. Our study demonstrated the hematological effects of long-term BTX co-exposure and developed 8h-RELs of about 0.01 ppm based on their hematological effects

Pulmonary hypofunction due to calcium carbonate nanomaterial exposure in occupational workers: a cross-sectional study

<p>Calcium carbonate nanomaterials (nano-CaCO₃) are widely used in both manufacturing and consumer products, but their potential health hazards remain unclear. The objective of this study was to survey workplace exposure levels and health effects of workers exposed to nano-CaCO₃. Personal and area sampling, as well as real-time and dust monitoring, were performed to characterize mass exposure, particle size distribution, and particle number exposure. A total of 56 workers (28 exposed workers and 28 unexposed controls) were studied in a cross-sectional study. They completed physical examinations, spirometry, and digital radiography. The results showed that the gravimetric nano-CaCO₃ concentration was 5.264 ± 6.987 mg/m³ (0.037–22.192 mg/m³) at the workplace, and 3.577 ± 2.065 mg/m³ (2.042–8.161 mg/m³) in the breathing zone of the exposed workers. The particle number concentrations ranged from 8193 to 39 621 particles/cm³ with a size range of 30–150 nm. The process of packing had the highest gravimetric and particle number concentrations. The particle number concentration positively correlated with gravimetric concentrations of nano-CaCO₃. The levels of hemoglobin, creatine phosphokinase (CK), lactate dehydrogenase, and high-density lipoprotein cholesterol (HDL-C) in the nano-CaCO₃ exposure group increased significantly, but the white blood cell count (WBC), Complement 3 (C3), total protein (TP), uric acid, and creatinine (CREA) all decreased significantly. The prevalence rate of pulmonary hypofunction was significantly higher (<i>p</i> = 0.037), and the levels of vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow and forced expiratory flow 25% (FEF 25%), FEF 25–75% were negatively correlated with gravimetric concentrations of nano-CaCO₃ (<i>p</i> < 0.05). Logistic analysis showed that nano-CaCO₃ exposure level was associated with pulmonary hypofunction (<i>p</i> = 0.005). Meanwhile, a dose-effect relationship was found between the accumulated gravimetric concentrations of nano-CaCO₃ and the prevalence rate of pulmonary hypofunction (<i>p</i> = 0.048). In conclusion, long-term and high-level nano-CaCO₃ exposure can induce pulmonary hypofunction in workers. Thus, lung function examination is suggested for occupational populations with nano-CaCO₃ exposure. Furthermore, future health protection efforts should focus on senior workers with accumulation effects of nano-CaCO₃ exposure.</p