Solvent levels were about five times higher in small enterprises as compared with the levels in large enterprises. There was a gradual shift in solvent use from aromatics to other solvents, typically alcohols. The use of hexane in adhesives was reduced. Solvent levels were relatively high in solvent-drying and printing workplaces and low in degreasing/cleaning/wiping workplaces and testing/research laboratories.
This study was initiated to elucidate possible changes in types of organic solvents (to be called solvents in short) used in enterprises in Japan through comparison of current solvent types with historical data since 1983. To investigate current situation in solvent use in enterprises, surveys were conducted during one year of 2009 to 2010. In total, workroom air samples in 1,497 unit workplaces with solvent use were analyzed in accordance with regulatory requirements. Typical use pattern of solvents was as mixtures, accounting for >70% of cases. Adhesives spreading (followed by adhesion) was relatively common in small-scale enterprises, whereas printing and painting work was more common in middle-scale ones, and solvent use for testing and research purpose was basically in large-scaled enterprises. Through-out printing, painting, surface coating and adhesive application, toluene was most common (being detected in 49 to 82% of workplaces depending on work types), whereas isopropyl alcohol was most common (49%) in degreasing, cleaning and wiping workplaces. Other commonly used solvents were methyl alcohol, ethyl acetate and acetone (33 to 37%). Comparison with historical data in Japan and literature-retrieved data outside of Japan all agreed with the observation that toluene is the most commonly used solvent. Application of trichloroethylene and 1,1,1-trichloroethane, once common in 1980s, has ceased to exist in recent years.
In 2008-2009, types of organic solvents used and air-borne vapor concentrationswere surveyed in 1909 laboratories in four large research institutions in accordance with current regulations. The results were classified into 5 groups in terms of research fields (agriculture, biology, medicine, natural science, and technology and engineering) and evaluated after the regulatory rules. Laboratory air analyses by gas chromatography identified 5 and 20 solvents out of 7 Group 1 solvents and 40 Group 2 solvents, respectively; 10 solvents were used in more than 10% of the laboratories in each of the 5 research fields. The use of unmixed single solvent appeared to be unique in research laboratories in contrast to use of solvent mixtures in industrial facilities for production. Laboratories of technology and engineering fields used more various organic solvents more frequently, whereas use of xylenes appeared to be more specific to laboratories of bio-medical fields. Among the commonly used solvents, chloroform was the leading solvent to induce poorer results in regulatory classification (i.e., Class 3 in Administrative Control Classes) typically when applied in high pressure liquid chromatography which was too voluminous to be accommodated in a local exhaustion chamber.
Objectives Laboratories in research institutions use organic solvents in research and development. Nevertheless, the types of solvents in use have been seldom reported. This study was initiated to elucidate types of organic solvents used in large research institutions in Japan, with a focus on possible different use among research fields. Methods In 2010-2011, 4517 laboratories in seven large research institutions were visited. In accordance with legal stipulations, air in each laboratory was collected in polyvinyl fluoride bags and analyzed by direct injection into a gas-chromatograph for 47 types of organic solvents. In evaluation, the laboratories were grouped by 5 research fields, i.e., agriculture, biology, medicine, natural science, and technology and engineering. Results Types of organic solvents commonly used in research activities were not diverse. Those commonly used were chloroform and 1,2-dichloroethane out of 7 Group 1 organic solvents (with high toxicities); 6 organic solvents, i.e., acetone and methyl alcohol in general, ethyl acetate, hexane and toluene in technology and engineering laboratories; and xylenes in medical fields out of 40 Group 2 organic solvents (with relatively low toxicities). Judging from solvent vapor concentrations, work environments in more than 99 % of laboratories were considered adequate. Nevertheless, use of chloroform in high-performance liquid chromatography (HPLC) resulted in inadequate environments in 30 laboratories (0.7 %). Conclusions Organic solvents commonly used were not very diverse. Work environments in research laboratories were generally good, but the environment with use of chloroform in HPLC analysis remained yet to be improved.
The regulation in Japan takes two types of strategy in evaluating solvent vapor concentrations in solvent workplaces (SWPs); one follows the grid sampling trategy to take samples at 5 crosses in the SWP, and a geometric mean and a geometric standard deviation of the concentrations were figured out as representative parameters of solvent concentrations in the workplace. The other approach is to take one grab air sample at the site where the worker's vapor exposure concentration is empirically estimated to be the highest (the estimated highest concentration or EHC) in the SWP 1, 2) .Both of the two approaches, the grid sampling for a geometric mean and a geometric standard deviation and the grab sampling for EHC, are important because the geometric mean and the geometric standard deviation indicate the representative workplace vapor concentration (RWC) for the SWP and the sampling site-dependent variation in the concentrations (VWC) within the SWP, respectively, whereas EHC suggests the possible highest exposure condition for a worker, e.g., a foreman in the Abstract: The present study was initiated to examine the relationship between the workplace concentrations and the estimated highest concentrations in solvent workplaces (SWPs), with special references to enterprise size and types of solvent work. Results of survey conducted in 1010 SWPs in 156 enterprises were taken as a database. Workplace air was sampled at 5 crosses in each SWP following a grid sampling strategy. An additional air was grab-sampled at the site where the worker's exposure was estimated to be highest (estimated highest concentration or EHC). The samples were analyzed for 47 solvents designated by regulation, and solvent concentrations in each sample were summed up by use of additiveness formula. From the workplace concentrations at 5 points, geometric mean and geometric standard deviations were calculated as the representative workplace concentration (RWC) and the indicator of variation in workplace concentration (VWC). Comparison between RWC and EHC in the total of 1010 SWPs showed that EHC was 1.2 (in large enterprises with>300 employees) to 1.7 times [in small to medium (SM) enterprises with 300 employees] greater than RWC. When SWPs were classified into SM enterprises and large enterprises, both RWC and EHC were significantly higher in SM enterprises than in large enterprises. Further comparison by types of solvent work showed that the difference was more marked in printing, surface coating and degreasing/cleaning/wiping SWPs, whereas it was less remarkable in painting SWPs and essentially nil in testing/research laboratories. In conclusion, the present observation as discussed in reference to previous publications suggests that RWC, EHC and the ratio of EHC/WRC varies substantially among different types of solvent work as well as enterprise size, and are typically higher in printing SWPs in SM enterprises.
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