National Industrial Chemicals Notification and Assessment Scheme
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- 8.Occupational Exposure
- 8.2Methodology for estimating exposure
- 8.3Importation and repacking
- 8.3.2Repacking
- 8.3.3Importation of products
- 8.3.5Summary of exposure during importation and repacking
7.3Other information on usesTrichloroethylene is used overseas as a precursor in the manufacture of CFC alternatives such as HFC-134a or HCFC-123. However, trichloroethylene is not used as a feed stock for other chemicals in Australia. In the past, trichloroethylene has been used in Australia as an anaesthetic agent, in dry cleaning, in correction fluids and as a solvent in pesticide formulations. These uses apparently no longer occur. It has come to the attention of NICNAS that trichloroethylene is being considered for use in scouring wool.
8.Occupational Exposure8.1Routes of exposureOccupational exposure to trichloroethylene may occur during transport, storage, formulation or use of the chemical, during the solvent re-cycling process or during disposal (ie of contaminated solvent). Workers may be exposed to trichloroethylene by the inhalation and dermal routes. Trichloroethylene is a volatile liquid at room temperature. Inhalation of trichloroethylene may occur through exposure to vapour emitted by liquid or mixtures containing trichloroethylene, or by exposure to aerosols. Activities such as heating or agitation of the liquid will increase the emission of vapours and the likelihood of exposure. Dermal absorption of trichloroethylene may occur through contact with the liquid form. Contact with vapour condensate, or with aerosols from sprayed products or mixtures containing trichloroethylene, are also potential sources of dermal exposure.
The exposure estimates in this assessment are considered to be “feasible” worst case estimates, as they describe high-end or maximum exposures in feasible, not unrealistic situations. The estimates are not intended to be representative of extreme or unusual use scenarios which are unlikely to occur in the workplace. However, it is likely that the majority of occupational exposures will be below these estimates. The formulae used to calculate exposures are detailed in Appendix 1. The constants in the formulae such as body weight and inhalation rate were those used in international assessments. Estimates for exposure to vapour did not include dermal uptake of vapour as dermal absorption of vapour is considered to be negligible (see section 9). 8.3Importation and repacking8.3.1Importation of trichloroethyleneDrums Trichloroethylene is imported in 205 L sealed steel drums and is generally transported to distributors or direct to end-users without being opened. Exposure during transportation and storage of drums is unlikely except in case of accidents such as leakage from damaged drums. Bulk storage facilities Trichloroethylene is also imported in bulk containers to Port Botany in NSW and to Coode Island in Victoria. Bulk trichloroethylene is pumped by shoreline from tanks on board ships to on-shore bulk tanks. From here it is transferred to road tankers and drums (205L) and transported to a warehouse site, where it is stored prior to distribution. Occasionally trichloroethylene is transported directly to the end-user from the bulk storage facility. Worker activities include connection and disconnection of shore and wharf lines, and a process called ‘pigging’ in which a polyurethane foam sponge is placed at one end of a line and propelled by nitrogen through the line (for up to one kilometre) in order to clean and dry it. The sponge is collected from the other end of the line by an operator who places it in a bucket of water. Other activities include filling of road tankers and drums, cleaning of bulk storage tanks, and maintenance work on pumps and piping. A continuously operating automatic carbon absorption vapour extraction system draws air from around hose connections at tanker and drum filling stations, and openings on bulk storage tanks, through piping to a central carbon bed adsorption unit. The air is drawn through the carbon and out an emission stack. The carbon is regularly desorbed of trapped chemical by high pressure steam. Vapour condensate is collected and disposed of through waste collection agencies. Filling of tankers is controlled by a mass flow meter. Tanker filling station areas have an underground collection area in case of accidental spillage. Drums are filled using a specially designed device that uses a mass flow meter to pre-set the volume. This system involves a moveable filling handle that minimises manual handling of drums. More traditional filling stations employing scales are also used for drum filling. Drums are double capped. Drum filling station areas are bunded. Cloth gloves are supplied for use during filling. A full face organic canister mask or breathing apparatus is worn in situations where it is believed a potential for high exposure exists, such as during ‘pigging’ and dipping bulk storage tanks to measure levels. Special work permits issued by management are required before cleaning of bulk storage tanks, and confined space work procedures are followed. A total of 39 workers are employed at the two sites. Filling and monitoring of bulk tanks typically engages workers for 4-5 hours, 4-6 times a year. Similarly, filling of drums occurs for about 4 hours, 6 times a year. Filling of road tankers is typically undertaken 150 times a year, with filling taking approximately 10-20 minutes. Due to enclosure of the transfer process and other control measures in place, the potential for inhalation exposure is considered low. The potential for dermal exposure during tanker and drum filling is low due to the use of mass flow meters. Handling of shorelines and the sponges used for cleaning them may pose a potential for dermal exposure through splashes. In the exceptional circumstance of imported trichloroethylene being contaminated, it is sent to a recycling plant. Information provided suggests this happens rarely.
The repacking process presents a potential for both inhalational and dermal exposure through vapour emitted during the transfer process and accidental spills and splashes. The extent of exposure will depend on factors such as the method of transfer, amount of time spent on the task, and type of controls in place. Little information was available to determine whether distributors also repack and if they do, the methods used for repacking. Limited data indicates that repacking generally involves one to two workers, on an intermittent basis.
8.3.4Monitoring data for bulk storage, transfer and repackingAtmospheric monitoring results from the Port Botany (3 samples during ship to shore transfer) and Coode Island (60 samples during various activities) bulk storage sites were made available. The results are shown in Table 6. Both area and personal breathing zone sampling were conducted using passive dosimeters over full shift periods. All exposure levels were below 1 ppm with the exception of one sample taken during ‘pigging’ and connection and disconnection of wharf lines (3.2 ppm) and 3 samples taken during drum filling (2.0 - 2.4 ppm) No monitoring data were available for worksites engaged in repacking trichloroethylene or handling trichloroethylene products. Table 6 - Atmospheric monitoring results (TWA) at bulk storage facilities
TCE = trichloroethylene A = area monitoring P = personal monitoring
Very little information was provided on repacking. No monitoring appears to have been carried out. However, the limited data indicates that repacking is an infrequent process. Exposure during handling of trichloroethylene products is expected to be very low. Directory: data -> assets -> word doc -> 0017 word doc -> Rail safety news issue 6 – October 2011 word doc -> Review of Multiple Chemical Sensitivity: Identifying word doc -> Board Endorsed October 2009 amended 13-09-11 with extra units 0017 -> Rail Safety News Edition 8, December 2012 0017 -> Commonwealth of Australia 2010 0017 -> Real-Time License Plate Localisation on fpga 0017 -> Careers network bulletin issue 6 July 16 2012 0017 -> Wiser science: Finding References inspec for Physics and Engineering 0017 -> Part A: Depth Study: The globalising world Popular culture and public policy Download 1.35 Mb. Share with your friends:
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