National Industrial Chemicals Notification and Assessment Scheme
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- 8.5.7Summary of exposure during vapour degreasing
United StatesAir monitoring data for trichloroethylene from sampling conducted at four worksites using vapour degreasers are available from reports of investigations carried out by the Hazard Evaluation and Technical Assistance Branch of NIOSH. This Branch is responsible for investigating possible health hazards in the workplace and investigations are carried out following a request from employers or employees. Exposure data taken at the four manufacturing sites between 1989 -1991 is presented in Table 11. In three cases, health effects were reported in the request to investigate. Effects reported in two cases were headache, dizziness, nausea, sleepiness/fatigue, upper respiratory tract irritation, and skin rash (one site). Effects reported in the third case were cancers, breathing problems, kidney problems and watery eyes. The sites investigated included a large industrial complex with 4 conveyor fed degreasers; a manufacturer operating a conveyor fed liquid-vapour immersion degreaser; a manufacturer operating an open-topped degreaser; and a company operating an open-topped degreaser and an ultrasonic degreaser. At the latter site, a further source of potential trichloroethylene exposure was the use of a spray lacquer containing trichloroethylene. Sampling was done over 8 h obtaining a TWA for the entire shift. (National Institute for Occupational Safety and Health (NIOSH), 1989a; 1989b; 1990; 1991). The highest readings were three short-term (10-24 minutes) personal samples taken at one worksite while the worker was engaged in servicing a liquid-vapour conveyor-fed degreaser.
A project, tracking exposure profiles of chlorinated solvents in various industries was conducted as part of the Dow Chemical Company’s Product Stewardship Program during 1994 - 1995 in the United States. Personal sampling (61 samples) was carried out using organic vapour monitoring badges. The average concentration of trichloroethylene for all vapour degreasing measurements was 28.4 ppm. The results are shown in Table 12, grouped and analysed according to the different ventilation conditions of the worksites sampled (Skory Consulting Inc. & Skory, 1995) Table 12 - Trichloroethylene vapour degreasing exposures - Dow Chemical Company (USA)
8.5.7Summary of exposure during vapour degreasingInhalation and dermal exposures to trichloroethylene are likely during use of the chemical in vapour degreasing. Emission of vapours from open-topped tanks may lead to inhalation exposure. Inhalation exposure may also occur during manual loading of metal parts to be degreased. Dermal exposure to liquid trichloroethylene may occur during filling of tanks with trichloroethylene or during handling of hollow degreased parts that may contain trapped liquid trichloroethylene or during spills. A variety of control measures may be incorporated in degreasing tanks to reduce emissions. A survey of degreasing operations carried out by the Health and Safety Executive in U.K.(1996) has shown that emission is likely to be < 30 ppm in tanks fitted with the appropriate control measures such as rim ventilation, adequate freeboard zone, condensing coils etc and where good work practices are followed. Some older tanks do not have all the appropriate controls resulting in high short-term emissions (Robinson, Updated January 1996). According to information obtained from the NICNAS survey most workplaces have open-topped tanks and those equipped with lids are generally only covered at night. At least 1000 people, excluding aerospace workers, are involved in vapour degreasing in Australia either on a regular or intermittent basis. The most common exposure scenario was 4-8 h a day for more than 200 days a year. Atmospheric monitoring is not conducted on a regular basis by most users during vapour degreasing in Australia. Very limited atmospheric monitoring data was provided by users with the data relating to grab samples and no time weighted average results being provided. Short-term measurements have been high in some cases especially during manual loading and unloading of parts. The monitoring data provided by WorkCover did not state the time period over which the monitoring was done making it difficult to determine if they were time weighted average or grab samples. Based on the the U.K. data of Shipman and Whim (1980) exposure during vapour degreasing in this assessment were estimated for three scenarios at 10, 30 (results recorded at most workplaces) and 50 ppm. Dermal exposure to liquid trichloroethylene was assumed to be incidental. The estimates for total body burden (mg/kg/day) from inhalation and dermal exposure were 3.5 mg/kg/day for 10 ppm, 10.2 mg/kg/day for 30 ppm and 16.9 mg/kg/day for 50 ppm. Details of the exposure estimates for vapour degreasing are given in Appendix 1.
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