Risk assessment of chemical mixtures by benchmark dose-principle component analysis approach in occupational exposure

Mixtures of organic solvents are widely used in industrial processes. Risk assessment for chemical co-exposure has always been a challenge in past years. The present study aims to employ principle component analysis (PCA) to produce an entry for benchmark dose approximation in shoemakers based on the color vision effect. A total of 134 subjects consisting of 67 shoemakers and 67 staff workers were employed for Benchmark Dose (BMD) evaluation. Occupational exposure to benzene, toluene, xylene, and n-hexane was evaluated using NIOSH 1501 and OSHA ID-07 methods. The color vision effect was quantified using Lanthony D-15 desaturated test (D-15d). PCA was run for cumulative exposure dose (CED) of the solvents by MATLAB 2018. Finally, the lowest 95% confidence limit of the benchmark dose (BMDL) was determined using US EPA benchmark dose software (BMDS) version 3.2.1. The color confusion index (CCI) level in shoemakers increased from 1 to 1.15 by a median of 1.07. There was a significant difference in the CCI level (p value<0.0001) between exposed and control subjects. The first score of PCA was used as intake dose level (IDL) in solvents co-exposure. Using BMD analysis, the log-logistics model was fitted with a p-value> 0.1 and the lowest BMDL level. BMDL level was evaluated at 1.63, 10.25, 2.21, and 3.35 ppm for benzene, toluene, xylene, and n-hexane, respectively. The results showed a risk of color vision effect with co-exposure to solvents at different levels in the occupational exposure standards. In conclusion BMDL-PCA approach has been suggested for the risk assessment of chemical co-exposure.