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.

Vulnerability to substance abuse and the risk of suicide in students of region 12 of islamic azad university.

BACKGROUND: Substance abuse prevalence and the number of suicides among university students is less than public population; however the sensitivity of society regarding the occurrence of such damages among students puts special emphasis on appraising these variables. More than 30% of Iranian students study in Islamic Azad University. OBJECTIVES: The current research aimed to appraise the vulnerability of substance abuse and the risk of suicide in students of region 12 of Islamic Azad University. PATIENTS AND METHODS: In the current study, 1053 students (606 boys and 447 girls) with the average age of 22.55 years were selected through stratified sampling from Karaj, Takestan, Qazvin and Qom branches of Islamic Azad University. In order to assess the variables, Mental Health Worksheet of Central Counseling Office of the Ministry Science, Research and Technology was utilized. RESULTS: Average, standard deviation, minimum and maximum scores in substance abuse vulnerability of the students in region 12 were measured as 36.28, 14.68, 11.22 and 92.87; and the same for risk of suicide were 31.29, 15.61, 7.93 and 96.30, respectively. Students in Qom branch were significantly less vulnerable to substance abuse and less exposed to the risk of suicide than their peers in Karaj, Qazvin and Takestan branches. CONCLUSIONS: Less significant possibility of substance abuse and risk of suicide in students of Qom branch in comparison with other branches could be due to numerous variables particularly their religious attitudes. Nevertheless the average of these variables among the students of region 12 were higher than the reported scores of their peers in the state universities which reflects the serious need for precise assessments and providing preventive services and mental health interventions.