Occupational Exposure to Metalworking Fluids: An Assessment of Analytical Methods and Size Selective Air Sampling Techniques
| Principal investigator(s): | Dave K. Verma (McMaster University) |
| Co-investigator(s): | Don Shaw, Lorraine Shaw (McMaster University) |
| Institution: | McMaster University |
Purpose and Objectives
- Assess and validate analytical methods for Metalworking Fluids (MWFs) which are being used in North America and in the U.K.
- Assess various methods of sampling airborne MWFs, including size selective sampling techniques
- Collect prevailing airborne occupational MWFs exposure data in Ontario workplaces for comparison with an appropriate occupational exposure standard
- Compare and contrast Ontario exposure data to those reported elsewhere.
Methods
The analytical methods routinely used in North America (NIOSH 0500 and ASTM method PS 42-97) and the Health and Safety Executive (HSE) UK MDHS 95 method were evaluated in the laboratory. Laboratory validation included evaluation of sample recovery, determination of detection limits and determination of sample stability during storage.
For the assessment of size selective air sampling methods and prevailing occupational exposure to MWFs in Ontario, large, medium and small-sized companies using MWFs were canvassed for participation in the study. Two large and two medium to small-sized companies and their Joint Occupational Health and Safety Committees (JOHSC) agreed to participate in the study. The majority of MWFs being used at these plants were semi-synthetic and synthetic MWFs with a small amount of straight mineral oil and soluble oil MWFs.
Several hundred personal and area air samples were collected using total aerosol, thoracic and inhalable samplers. A Dust-Trak (TSI Inc., MN, USA) direct reading device was used to collect real-time aerosol concentrations. A Respicon Sampler (TSI Inc., MN, USA) which simultaneously collects respirable, thoracic and inhalable fractions of airborne MWFs was also used.
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Results
- Sample analysis using HSE method MDHS 95 proved to be very problematic. No accredited laboratory in North America could be found who routinely performed this analysis. Two laboratories who agreed to try the method failed to meet the required quality control on the blind samples.
- Results of MWF sample recovery by NIOSH and ASTM Methods showed good recovery. The detection limit determined was also acceptable. The sample storage study showed that the MWFs lost the most amount of weight in the first few days. MWFs samples should be analyzed as soon as possible, they should not be stored at room temperature. If samples are stored in the freezer, they should be analyzed within a week and if stored in a refrigerator, analysis should be done within two days.
- The result of field sampling showed the exposure to range between 0.04 to 3.84 mg/m3 for total and thoracic aerosols.
- Airborne exposure measured in Ontario plants were similar to those reported in North America.
Conclusions
- Both the NIOSH 0500 and ASTM PS 42-97methods can be used for analysis and to evaluate exposure in both oil and water-based MWFs. The HSE method MDHS 95 would require extensive validation work.
- Size selective sampling using thoracic samplers is most appropriate for assessing both oil and water-based MWFs.
- Airborne exposure to MWFs in Ontario is expected to exceed the NIOSH recommended exposure limit of 0.4 mg/m3 as thoracic aerosol approximately 38% of the time which is similar to what has been observed in the USA.
- It appears that full worker protection would require, in addition to controlling their airborne MWFs exposure, institution of programs for fluid management and dermal exposure prevention.
For more information: vermadk@mcmaster.ca
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