No abstract available.
Toluene* ; Xylenes*

OBJECTIVES: This study was conducted to assess the concentration of xylene exposure and exposure variability of a similar exposure group(SEG) in accordance with job title and confined space. METHOD: The study subjects included 28 workers working in the painting process in the ship-building industry. Measurement of subjects were repeated three times. Within and between-worker exposure variance components were estimated from log-transformed exposure concentrations employing a one-way nested random effects analysis of variance model. A uniformly exposed group was defined as one where the between-worker variance(sigmaB2) was less than or equal to 0.031 or bwR95 or=0.031) and the ratios of the 97.5th and 2.5th percentile workers of the log normally distributed exposures of each group of workers was more than 2. However dividing job title into confined space(in-block, out-block, in/out-block) decreased the between-worker exposure variability. CONCLUSION: This study focused on the quantitative aspects of exposure in painters in the ship-building industry. We cannot accept the assumption that SEG are uniformly exposed, as a major component of variation in exposure relates to differences in tasks or other factors. Therefore, the observational schemes can be improved by investigating jobspecific task and practice.
Confined Spaces ; Paint ; Paintings ; Xylenes*

OBJECTIVES: This study evaluated the efficacy of Endosolv-R and Xylene in softening epoxy resin based sealer after 1 to 2 min exposure. MATERIALS AND METHODS: Sixty Teflon molds (6 mm x 1.5 mm in inner diameter and depth) were equally divided into 3 groups of 20 each. AH 26 (Dentsply/De Trey), AH Plus (Dentsply/De Trey), Adseal (Meta-Biomed) were manipulated and placed in the molds allotted to each group and allowed to set at 37degrees C in 100% humidity for 2 wk. Each group was further divided into 2 subgroups according to the solvents used, i.e. Xylene (Lobachemie) and Endosolv-R (Septodont). Specimens in each subgroup were exposed to respective solvents for 1 and 2 min and the corresponding Vicker's microhardness (HV) was assessed. Data was analysed by Mauchly's test and two-way analysis of variance (ANOVA) with repeated measures, and one-way ANOVA. RESULTS: Initial hardness was significantly different among the three sealers with AH Plus having the greatest and Adseal having the least. After 2 min, Xylene softened AH Plus and Adseal sealer to 11% and 25% of their initial microhardness, respectively (p < 0.001), whereas AH 26 was least affected, maintaining 89.4% of its initial microhardness. After 2 min, Endosolv-R softened AH 26, AH Plus and Adseal to 12.7, 5.6 and 8.1% of their initial microhardness, respectively (p < 0.001). CONCLUSIONS: Endosolv-R was a significantly more effective short term softener for all the tested sealers after 2 min whereas Xylene was an effective short term softener against AH plus and Adseal but less effective against AH 26.
Fungi ; Hardness ; Humidity ; Polytetrafluoroethylene ; Solvents ; Xylenes*

Humans ; Neurotoxicity Syndromes ; etiology ; Xylenes ; toxicity

This study utilized the Community Multiscale Air Quality model to simulate the spatial distribution of benzene, toluene, and xylene (BTX) concentrations from large national industrial complexes (IC) located in the Ulsan metropolitan region (UMR). Through controlling pollutant emissions from major IC, this study performed a quantitative analysis of the influence of pollutant emissions on BTX concentrations in surrounding urban areas. The results showed that approximately 40% of the annual average BTX concentrations in nearby urban grids were directly influenced by pollutant emissions from the IC. Seasonal modeling results indicated that average BTX concentrations were high around petrochemical complexes, with higher concentrations in the surrounding urban areas during the summer (July). All three of the BTX pollutants showed similar seasonal differences. Daily contributions differed significantly throughout the modeling period, with some values reaching a maximum of 80% during July. Overall, when urban areas were located downwind of the IC, contributions rose. Moreover, this study compared the differences in BTX contributions at each measurement point within the IC and urban areas, which showed that the influence of the IC emissions decreased significantly with distance. The spatial distribution and direct influence of the IC on BTX concentrations in the UMR identified through this study could be used to provide input data in environmental epidemiological studies.
Benzene ; Epidemiologic Studies ; Seasons ; Toluene ; Ulsan ; Xylenes

OBJECTIVES: The goal was to model and quantify the atmospheric concentrations of volatile organic compounds (VOCs) as the result of the Hebei Spirit oil spill, and to predict whether the exposure levels were abnormally high or not. METHODS: We developed a model for calculating the airborne concentration of VOCs that are produced in an oil spill accident. The model was applied to a practical situation, namely the Hebei Spirit oil spill. The accuracy of the model was verified by comparing the results with previous observation data. The concentrations were compared with the currently used air quality standards. RESULTS: Evaporation was found to be 10- to 1,000-fold higher than the emissions produced from a surrounding industrial complex. The modeled concentrations for benzene failed to meet current labor environmental standards, and the concentration of benzene, toluene, ortho- meta- para-xylene were higher than the values specified by air quality standards and guideline values on the ocean. The concentrations of total VOCs were much higher than indoor environmental criteria for the entire Taean area for a few days. CONCLUSIONS: The extent of airborne exposure was clearly not the same as that for normal conditions.
Benzene ; Humans ; Petroleum Pollution ; Toluene ; Volatile Organic Compounds ; Volatilization ; Xylenes

OBJECTIVES: This study was performed to investigate the effect of drink containing sodium benzoate on the change of urinary hippuric acid (UHA) and methyl hippuric acid (UMHA) excretion among workers coexposed to low toluene and xylene. METHODS: Study subjects were 55 male shipbuilders who were divided into 3 groups; nonexposed group (n=10, who were not exposed to organic solvent and had drunk sodium benzoate), exposed A group (n=24, who were coexposed to toluene and xylene, and had drunk sodium benzoate), and exposed B group (n=21, who were coexposed to toluene and xylene, and had not drunk sodium benzoate). The study methodology consisted of questionnaire survey, urinary analysis for metabolites of toluene and xylene before and after drinking with or without sodium benzoate, and personal air sampling of toluene and xylene. RESULTS: Before drinking, there was no significant difference in UHA or UMHA between the exposed A and B groups. After 1.5 hour of drinking, UHA of the exposed A group was significantly higher than that of the exposed B group. After 3 hours, however, UHA of the exposed A group was decreased to the level of the exposed B group, regardless of the ambient toluene level. UMHA exhibited no significant difference between the exposed A and B groups regardless of time and ambient toluene level. The regression model showed that drinking of sodium benzoate was positively correlated with UHA after 1.5 hours of drinking, but not after 3 hours. In addition, sodium benzoate didn't affect UMHA. CONCLUSIONS: This study showed that sodium benzoate initially increased UHA temporally but that its effect disappeared after 3 hours. In the medical examination of toluene exposure workers, the ingestion of drink containing sodium benzoate should be forbidden during the 3 hours prior to urinary sampling.
Drinking ; Eating ; Humans ; Male ; Questionnaires ; Sodium Benzoate* ; Sodium* ; Toluene* ; Xylenes*

Epilepsy ; chemically induced ; Humans ; Poisoning ; physiopathology ; Xylenes ; poisoning

In order to study the correlation of ambient toluene and xylene exposure with their biological monitoring indices, we measured the concentration of toluene and xylene in the workplace. We also measured their biological monitoring indices of workers from August to November in 1994. The exposed group consisted of 103 male workers and the non-exposed group consisted of 34 male workers. The ambient concentration of toluene was 44.7 +/-55.4 ppm and that of xylene was 2.35+/-2.15 ppm. The urinary concentration of hippuric acid in exposed group was 1.72+/-1.53 g/g creatinine and that of non-exposed group was 0.34+/-0.28 g/g creatinine. The difference was statistically significant between two groups (p<.0.001). The urinary concentration of o-cresol in exposed group was 692.9+/-710.8 ug/g creatinine and that of non-exposed group was 184.7+/-167.6 microgram/g creatinine. The difference was also statistically significant between two groups (p<0.001). The urinary concentration of methylhippuric acid which was compensated with urinary creatinine in I exposed group was 62. 7+/-104.6 mg/g creatinine and that of non-exposed group was 64.0+91.5 mg/g creatinine. However the difference was not statistically significant between two groups (p>0.05). When compensated with urinary creatinine, the correlation coefficient of ambient toluene with urinary hippuric acid and ocresol were 0.63(p=0.0001) and 0.65(p=0.0001), respectively. When compensated with urinary specific gravity, the correlation coefficient of ambient toluene with hippuric acid and ocresol were 0.525 (p=0.0001) and 0.547 (p=0. 0001), respectively. The compensation method using urinary creatinine provided a higher correlation coefficient. We could not find any statistically significant differences between the duration of work and other variables (urinary hippuric acid, o-cresol and methylhippuric acid). In order to monitor biological indices of toluene-exposed workers, we suggest the measurement of urinary hippuric acid rather than o-cresol. As the compensation method, we suggest to use urinary creatinine rather than urinary specific gravity.
Compensation and Redress ; Creatinine ; Environmental Monitoring* ; Humans ; Male ; Specific Gravity ; Toluene* ; Xylenes*

This study was conducted to evaluate the ability of plants to purify indoor air by observing the effective reduction rate among pollutant types of particulate matter (PM) and volatile organic compounds (VOCs). PM and four types of VOCs were measured in a new building that is less than three years old and under three different conditions: before applying the plant, after applying the plant, and a room without a plant. The removal rate of each pollutant type due to the plant was also compared and analyzed. In the case of indoor PM, the removal effect was negligible because of outdoor influence. However, 9% of benzene, 75% of ethylbenzene, 72% of xylene, 75% of styrene, 50% of formaldehyde, 36% of acetaldehyde, 35% of acrolein with acetone, and 85% of toluene were reduced. The purification of indoor air by natural ventilation is meaningless because the ambient PM concentration has recently been high. However, contamination by gaseous materials such as VOCs can effectively be removed through the application of plants.
Acetaldehyde ; Acetone ; Acrolein ; Benzene ; Formaldehyde ; Particulate Matter* ; Plants ; Styrene ; Toluene ; Ventilation ; Volatile Organic Compounds* ; Xylenes