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OBJECTIVE: To study the biological exposure limit of 1,3-butadiene occupational exposure. METHODS: A total of 139 workers who exposed to 1,3-butadiene in a rubber plant was chosen as exposure group,and 45 workers without 1,3-butadiene exposure were chosen as control group by judgment sampling method. Gas chromatography-flame ionization detection method was used to detect the level of 1,3-butadiene in workplace air,and ultra-high performance liquid chromatography-tandem mass spectrometric was used to determine the level of urinary dihydroxybutyl mercapturic acid( DHBMA) in end-of-shift workers. The correlation between 1,3-butadiene level and urinary DHBMA level was analyzed.The biological limit of 1,3-butadiene occupational exposure was assessed. RESULTS: The range of concentration-time weighted average( C_(TWA)) of 1,3-butadiene was from 0. 004 to 7. 609 mg/m~3,the medium was 0. 253 mg/m~3 in the exposure group,while the level of urinary DHBMA was from 0. 171 to 4. 235 mg/g Cr,and the medium was 1. 220 mg/g Cr. The range of C_(TWA)of 1,3-butadiene was below detection limit in the control group. The level of urinary DHBMA was from 0. 157 to 1. 808 mg/g Cr,and the medium was 0. 627 mg/g Cr in the control group. The level of urinary DHBMA in the exposure group was higher than that of the control group( P < 0. 01). The level of urinary DHBMA( y) of workers was related to the level of 1,3-butadiene( x) of the workplace air in the exposure group( y = 0. 349 x + 1. 082,P < 0. 01).CONCLUSION: DHBMA in urine could be used as a biomarker for 1,3-butadiene exposure in workers. The recommended biological exposure limit of DHBMA is 2. 900 mg/g Cr.
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Objective@#To analyze the exposure level and the geographical distribution trend of toxicological indicators of rural drinking water in Shandong Province.@*Methods@#The drawing method was used to randomly select no less than 60% villages and towns from 137 counties (cities, districts) of 17 cities in Shandong Province in 2015, and then 1-3 rural centralized water supply units were selected according to the circumstance of rural centralized water supply units in each village and town. In total, 735 villages and towns, 1 473 rural centralized water supply units were selected, and 1 473 water samples were collected. The water treatment process, water supply population and other circumstances of the rural centralized water supply units were investigated, the water quality was monitored, the content of toxicological indicators of drinking water in different areas was compared, and the trend surface isogram of excessive toxicological indicators was drawn.@*Results@#The qualified rate of toxicological indicators in 1 473 water samples was 83.64% (n=1 232). The main toxicological indicators that affected the qualified rate of toxicological indicators of drinking water in rural areas in Shandong Province were nitrate and fluoride. The excessive rate of fluoride was 5.70% (n=84) and the exposed population was 1 736 709 (4.22%). The excessive rate of nitrate (as nitrogen) was 12.29% (n=181) and the exposed population was 1 393 612 (3.39%). The P50 content of fluoride in the eastern, middle and western regions was 0.24, 0.29 and 0.59 mg/L, respective;which was higher in the western region than in the east and the middle regions (P<0.05). There was no significant difference between the eastern and the middle regions (P>0.05). The P50 content of nitrate (as nitrogen) in the eastern, middle and western regions was 8.00, 7.48, and 2.00 mg/L, which was higher in the eastern and middle regions than in the west region (P<0.05), there was no significant difference between the eastern and the middle regions (P>0.05). The trend surface isogram of nitrate and fluoride content showed that the content of nitrate (as nitrogen) in rural drinking water in the eastern region was significantly higher than that in the western region, especially there was a high peak area in the northeastern region, and this high content distribution extended diagonally to the central region, while the other regions were in a relatively low range. The content of fluoride in rural drinking water in the western region was significantly higher than that in the eastern region, and there were high peaks in the southwest and northwest regions, and the other regions were in a relatively low range.@*Conclusion@#The high exposed toxicological indicators in rural drinking water in Shandong Province were nitrate (as nitrogen) and fluoride, and their distribution showed obvious geographical distribution trend.
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<p><b>OBJECTIVE</b>Risk assessment and risk control for occupational exposure to chemical toxicants were performed on an isophorone nitrile device with an annual production of 5,000 tons, based on improved Singaporean semi-quantitative risk assessment method, with consideration of actual situation in China and in the present project.</p><p><b>METHODS</b>With the use of engineering analysis and identification of occupational hazards in the improved Singaporean semi-quantitative risk assessment method, hazard rating (HR) and risk assessment were performed on chemical toxicants from an isophorone nitrile device with an annual production of 5,000 tons.</p><p><b>RESULTS</b>The chemical toxicants in the isophorone nitrile device were mainly isophorone, hydrocyanic acid, methanol, phosphoric acid, sodium hydroxide, and sodium cyanide; the HR values were mild hazard (2), extreme hazard (5), mild hazard (2), mild hazard (2), moderate hazard (3), and extreme hazard (5), respectively, and the corresponding exposure rating (ER) values were 2.09, 2.72, 2.76, 1.68, 2.0, and 1.59, respectively. The risk of chemical toxicants in this project was assessed according to the formula Risk = [HR×ER](1/2). Hydrocyanic acid was determined as high risk, sodium hydroxide and sodium cyanide as medium risk, and isophorone, methanol, and phosphoric acid as low risk. Priority in handling of risks was determined by risk rating. The table of risk control measure was established for pre-assessment of occupational hazards.</p><p><b>CONCLUSION</b>With risk assessment in this study, we concluded that the isophorone nitrile device with 5,000 ton annual production was a high-occupational hazard device. This device is a project of extreme occupational hazard. The improved Singaporean semi-quantitative risk assessment method is a scientific and applicable method, and is especially suitable for pre-evaluation of on-site project with no analogy.</p>
Subject(s)
Humans , Cyclohexanones , Nitriles , Occupational Exposure , Risk AssessmentABSTRACT
Cyanobacterial toxins may pose a threat to human health through drinking water and recreational water exposure. The official guideline limits of cyanobacterial toxins have not been established. The human health effects, exposure routes, possible guideline limits and calculation method were introduced in the present paper. The knowledge will provide a base to undertake risk management for the toxins and will also contribute to establishing official guideline limits of cyanobacterial toxins in water and will be benefit for ensuring the safety of drinking water.
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To provide the human being with safe drinking water is one of the most important issues in public health. In response to the more and more serious pollution of algal toxins, growing concern has been attached to the water bodies contaminated with algal toxins and the effects posed on human health. Drinking water suppliers are confronted with the important problem of how to remove the toxins to the acceptable levels. Conventional water treatment procedures are not efficient in removing toxins. Activated carbon adsorption, membrane filtration, photocatalic process, ozonation and chlorination are effective in removing cyanobacterial toxins, but each has its limitation.