Effects of Styrene-metabolizing Enzyme Polymorphisms and Lifestyle Behaviors on Blood Styrene and Urinary Metabolite Levels in Workers Chronically Exposed to Styrene

Carcinogenic and health risk assessment of respiratory exposure to Acrylonitrile, 1,3-Butadiene and Styrene (ABS) in a Petrochemical Industry Using the United States Environmental Protection Agency (EPA) Method

PURPOSE

This study aimed to carcinogenic and health risk assessment of respiratory exposure to acrylonitrile, 1,3-butadiene, and styrene in the petrochemical industry.

MATERIALS AND METHODS

This cross-sectional study was conducted in a petrochemical plant producing acrylonitrile, butadiene, and styrene (ABS) copolymers. Respiratory exposure with acrylonitrile, 1,3-butadiene and styrene was measured using methods No. 1604, 1024, and 1501 of the National Institute of Occupational Safety and Health, respectively. The US Environmental Protection Agency method was used to assess carcinogenic and health risks.

RESULTS

The average occupational exposure to acrylonitrile, 1,3-butadiene, and styrene was 560.82 μg. m^-3 for 1,3-butadiene, 122.8 μg. m^-3 for acrylonitrile and 1.92 μg. m^-3 for styrene. The average lifetime cancer risk (LCR) in the present study was 2.71 ×10^-3 for 1,3-butadiene, 2.1 ×10^-3 for acrylonitrile, and 6.6 for styrene. Also, the mean non-cancer risk (HQ) among all participants for 1,3-butadiene, acrylonitrile, and styrene was 4.04 ± 6.93, 10.82 ± 14.76, and 0.19 ± 0.11, respectively.

CONCLUSION

The values of carcinogenic and health risks in the majority of the subjects were within the unacceptable risk levels due to exposure to 1,3-butadiene, acrylonitrile, and styrene vapors. Hence, corrective actions are required to protect the workers from non-cancer and cancer risks.

Quantitative and Semiquantitative Health Risk Assessment of Occupational Exposure to Styrene in a Petrochemical Industry

Background

Styrene is one of the aromatic compounds used in acetonitrile-butadiene-styrene (ABS) producing petrochemicals, which has an impact on health of workers. Therefore, this study aimed to investigate the health risks of styrene emitted from the petrochemical industry in Iran.

Methods

Air samples were collected based on NIOSH 1501 method. The samples were analyzed by the Varian-cp3800 gas chromatograph. Finally, risk levels of styrene's health effects on employees were assessed by the quantitative method of the U.S. Environmental Protection Agency (U.S. EPA) and the semiquantitative way by the Singapore Occupational Safety and Health Association.

Results

Based on the results, the employees had the highest average exposure to styrene vapors (4.06 × 10 - 1 m g . ( k g - d a y ) - 1 ) in the polybutadiene latex (PBL) unit. Therefore, the most top predictors of cancer and non-cancer risk were 2.3 × 10 - 4 and 7.26 × 10 - 1 , respectively. Given that the lowest average exposure (1.5 × 10 - 2 m g . ( k g - d a y ) - 1 ) was in the dryer unit, the prediction showed a moderate risk of cancer (0.8 × 10 - 6 ) and non-cancer (2.3 × 10 - 3 ) for the employees. The EPA method also predicted that there would be a definite cancer risk in 16% and a probable risk in 76% of exposures. However, according to the semiquantitative approach, the rate of risk was at the "low" level for all staff. The results showed that there was a significant difference (p < 0.05) between the units in exposure and health risk of styrene (p < 0.05).

Conclusion

Given the high risk of styrene's health effects, appropriate control measures are required to reduce the exposure level.

Ethylbenzene and styrene exposure in the United States based on urinary mandelic acid and phenylglyoxylic acid: NHANES 2005-2006 and 2011-2012

Ethylbenzene and styrene are air toxicants with widespread nonoccupational exposure sources, including tobacco smoke and diet. Ethylbenzene and styrene (EB/S) exposure was quantified from their common metabolites measured in spot urine samples obtained from participants (≥6 years old) in the 2005-2006 and 2011-2012 cycles of the National Health and Nutrition Examination Survey (NHANES; N = 4690). EB/S metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA) were measured using ultra-high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). MA and PGA were detected in 98.9% and 90.6% of tested urine specimens, respectively. Exclusive smokers had 2-fold and 1.6-fold higher median urinary MA and PGA, respectively, compared with non-users. Sampleweighted regression analysis among exclusive smokers showed that smoking 0.5 pack cigarettes per day significantly increased MA (+97.9 μg/L) and PGA (+69.3 μg/L), controlling for potential confounders. In comparison, exposure from the median daily dietary intake of grain products increased MA by 1.95 μg/L and was not associated with statistically significant changes in urinary PGA levels. Conversely, consuming vegetables and fruit was associated with decreased MA and PGA. These results confirm tobacco smoke as a major source of ethylbenzene and styrene exposure for the general U.S. population.

Subchronic Oral Dose Toxicity Study of Enterococcus Faecalis 2001 (EF 2001) in Mice

As a part of general toxicity studies of Enterococcus Faecalis 2001 (EF 2001) prepared using heat-treatment bacillus mort body EF 2001 in mice, this study examined the toxicity of EF 2001 in single and repeated administrations following the previous report in order to apply this product to preventive medicine. The safety of oral ingestion of EF 2001 was examined in 6-week-old male and female ICR mice with 1,000 mg/kg, 3,000 mg/kg and 5,000 mg/kg body weight/day administrated by gavage of the maximum acceptable dose of EF 2001. The study was conducted using distilled water as a control following the methods for general toxicity studies described in the “Guidelines for Non-clinical Studies of Pharmaceutical Products 2002”. As a control, 1) observation of general conditions, 2) measurement of body weight, 3) determination of food consumption, 4) determination of water consumption, 5) blood test and urinalysis and 6) pathological examination were performed for the administration of EF 2001. Mice received EF 2001 for 13 weeks and results were compared with those of the control group that received distilled water. The results of the above examinations revealed no significant differences between control and EF 2001 groups for both males and females. Thus, no notable toxicity was confirmed with single and repeated oral administrations of EF 2001. Oral administration in the above doses did not result in abnormal symptoms or death during the observation period. No abnormalities in blood cell count or organ weights were seen. Without any evidence of toxicity to cells and organs, EF 2001 is speculated to not adversely affect living organisms. The 50% lethal dose of EF 2001 with oral administration in mice is estimated to be greater than 5,000 mg/kg body weight/day for both male and female mice. Therefore, LD₅₀ value for animals was 5,000 mg/kg or more.

Combined Toxic Effects of Polar and Nonpolar Chemicals on Human Hepatocytes (HepG2) Cells by Quantitative Property-Activity Relationship Modeling

We determined the toxicity of mixtures of ethyl acetate (EA), isopropyl alcohol (IPA), methyl ethyl ketone (MEK), toluene (TOL) and xylene (XYL) with half-maximal effective concentration (EC₅₀) values obtained using human hepatocytes cells. According to these data, quantitative property-activity relationships (QPAR) models were successfully proposed to predict the toxicity of mixtures by multiple linear regressions (MLR). The leave-one-out cross validation method was used to find the best subsets of descriptors in the learning methods. Significant differences in physico-chemical properties such as boiling point (BP), specific gravity (SG), Reid vapor pressure (rVP) and flash point (FP) were observed between the single substances and the mixtures. The EC₅₀ of the mixture of EA and IPA was significantly lower than that of contained TOL and XYL. The mixture toxicity was related to the mixing ratio of MEK, TOL and XYL (MLR equation EC₅₀ = 3.3081 − 2.5018 × TOL − 3.2595 × XYL − 12.6596 × MEK × XYL), as well as to BP, SG, VP and FP (MLR equation EC₅₀ = 1.3424 + 6.2250 × FP − 7.1198 × SG × FP − 0.03013 × rVP × FP). These results suggest that QPAR-based models could accurately predict the toxicity of polar and nonpolar mixtures used in rotogravure printing industries.