National Industrial Chemicals Notification and Assessment Scheme

8.6Cold cleaning

The NICNAS industry survey identified 26 companies in Australia using trichloroethylene in various cold cleaning processes. This represented 29% of the total number of respondents who are end users of trichloroethylene. The most common type of cleaning described was immersion in tubs or tanks (15/26 companies). In most cases this was combined with manual scrubbing of the articles using paint brushes and/or some form of agitation of the liquid solvent such as swirling. One respondent used an ultrasonic system. Manual wipe cleaning was the second most common form of cold cleaning (7/26 companies), and spraying was mentioned by one company. One company uses trichloroethylene for regular daily flushing of polyurethane mixing chambers to prevent gelling of mixture in the machine.

Some companies use cold cleaning processes only occasionally, however others use cold cleaning processes on a regular or semi-regular basis, as part of a normal work routine. Details of the industry, type of activity, number of workers, duration and frequency of employment on cold cleaning tasks, and personal protective equipment, where provided by respondents, are given in Table 13. The survey results indicate that there is a great variability in cold cleaning processes.

8.6.1Potential exposure during cold cleaning

Exposure to trichloroethylene from immersion cleaning processes may occur from inhalation of vapour or skin contact with liquid solvent during the transfer of solvent from bulk storage tanks, drums or other containers into soak tanks, during immersion and washing of the articles, and handling of articles after washing. The use of open containers to transport solvent to soak tanks and agitation of the solvent in the soak tank, via brushing for instance, presents an increased potential for inhalational exposure and for dermal exposure from accidental splashes and spills. The design of immersion tanks will affect the potential for exposure, with open tanks presenting an increased potential for inhalational and dermal exposure compared with closed tanks or enclosed automated systems.

In the case of wipe cleaning, inhalational and dermal exposure may occur during the transfer of solvent from drums or containers onto the cloth and during surface cleaning using the cloth. The use of open containers for dipping cloths increases the potential for inhalational exposure and for dermal exposure from accidental splashes and spills.

Spray cleaning using trichloroethylene presents an increased potential for exposure from inhalation of spray mist or vapour and skin contact with spray mist.

Table 14 shows the work activity and control measures obtained from the workplaces as part of a project undertaken by WorkCover for NICNAS.

8.6.2Atmospheric monitoring

No monitoring data were provided by applicants for cold cleaning activities using trichloroethylene.

Atmospheric and biological monitoring was conducted by WorkCover, as part of a project commissioned by NICNAS, at workplaces using trichloroethylene for cold cleaning. The monitoring was carried out on a half shift basis as most of the jobs were continuous throughout the day. At two workplaces trichloroethylene use occurred for only half a day. In these cases the monitoring results were converted to give an eight hour TWA (by halving the results). The cold cleaning activities ranged from dip cleaning to combined dip cleaning and rag wiping to rag wiping alone and are described in Table 14. Atmospheric monitoring was carried out in accordance with Australian Standard AS 2986 “Workplace Atmospheres - Organic Vapour Sampling by Solid Adsorption Techniques”. Biological monitoring involved estimation of urinary trichloroacetic acid with urine samples being collected at the end of shift at the end of the work week. Table 15 shows the air monitoring results and the urinary trichloroacetic acid levels obtained during this study.

Overseas data

Some atmospheric monitoring of cold metal cleaning operations using trichloroethylene has been carried out in the United States as part of a larger long-term analysis of exposure profiles for chlorinated hydrocarbons conducted for the Dow Chemical Company Product Stewardship Program (Skory Consulting Inc. & Skory, 1995). Monitoring was carried out using organic vapour monitors attached to the collars of employees during their work day and during the time they are exposed to trichloroethylene. The overall average concentration of 9 samples was 68.4 ppm. Of these, 5/9 were less than 50 ppm, 1/9 was between 50 to 100 ppm and 3/9 were > 100 ppm.

8.6.3Summary of exposure during cold cleaning

Inhalation and dermal exposure can occur during cold cleaning. Situations in which dermal contact might occur include immersion and brushing of articles in soak tanks, handling of work pieces that are not thoroughly drained of trichloroethylene and handling of cloths and rags used in cold cleaning. There is a potential for accidental splashes during the work process involving trichloroethylene such as transfer of solvent from or to drums or other vessels. Monitoring data from the cold cleaning project was used to estimate exposure. Exposure was estimated for 120 days/yr and 200 days/yr as these were the common scenarios encountered in the workplaces monitored. Inhalation exposure was considered to be continuous and dermal exposure was assumed for 5% of the total time. At two of the workplaces the job was continuous throughout the day while at the other two places exposure was for half a day only. Information obtained from the NICNAS survey indicated that in 3 of 21 workplaces trichloroethylene was used for cold cleaning during the entire shift (8 h). Inhalation exposure was therefore estimated for 8 h/day, 200 days in a year and 120 days in a year. The estimated exposures may be an overestimation for those workplaces involved in this activity for only a few hours of the shift. The temperature during monitoring at the various sites varied from 11.4 C to 19.5C. It is expected that in summer with high temperatures exposures are likely to be high. Estimates for the total body burden (mg/kg/day) from inhalation and dermal exposures are provided in Table 16.

Table 16 - Total body burden from inhalation and dermal exposure

	Exposure estimate (mg/kg/day)
	200 days/yr	120 days/yr
Inhalation
0.4 ppm (2.18 mg/m3)	0.13	0.079
3.8 ppm (20.75 mg/m3)	1.27	0.76
68.3 ppm (372.92 mg/m3)	22.77	13.66
0.9 ppm (4.91 mg/m3)	0.29	0.179
7.5 ppm (40.95 mg/m3)	2.5	1.5
Dermal	1.0	0.60

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