Professor James Scott
Dalla Lana School of Public Health
University of Toronto
223 College St. Toronto ON M5T 1R4
Tel. 416-946-8778

Sporometrics Inc.

Workplace Safety and Insurance Board of Ontario (WSIB), Centre for Research Expertise in Occupational Disease (CREOD)

Exposure to semisynthetic and synthetic metalworking fluids (MWF) has been associated with work-related asthma, hypersensitivity pneumonitis and dermatitis. Exposure to microbial contaminants in MWFs appears to be a key factor in the etiology of these diseases in machinists. Although a number of epidemiological studies have examined the impact of exposure to various components of MWF on occupational disease, none have provided a thorough quantitative and qualitative characterization of microbial exposure. Furthermore, recent occupational exposure limits to MWF based on aerosol concentrations determine by simple gravimetric measurements have failed to consider the relevance of gravimetric sampling to worker protection against microbial contaminants. It remains unclear if gravimetric measurements of MWF mists correlate to predictor variables of bioaerosol exposure, including viable airborne microbes (bacteria and fungi) and microbe-derived chemicals, such as endotoxin (Gram-negative bacteria) and (1,3)-beta-D-glucan (moulds and yeasts). Equally, the relationship between microbial fluid condition and bioaerosol emission has not been systematically studied.

Modern molecular genetic techniques such as high through-put next generation DNA sequencing have revolutionized the characterization and comparison of complex polymicrobial communities in a wide range of biological systems from agricultural soils to deep sea thermal vents. We are using this method to the study MWF microbial contaminants from a range of industrial settings, including parts manufacturers, metal stamping and milling. In addition to bulk samples of fluids in service, we will collect air samples adjacent to equipment during operation. These samples will be analyzed for: a) viable bacteria and fungi; b) (1,3)-beta-D-glucan; c) endotoxin; and d) community profile by 16S sequencing and qPCR for selected organisms (e.g. Mycobacterium immunogenum complex). In addition, air samples will be collected and analyzed for total and thoracic particulate by standard gravimetric methods.

The objectives of this study are:

  • to document the composition of microbial communities in MWF under conditions of use, including both bacterial and fungal microbial constituents, and the extent to which the quantitatively dominant microflora of MWF becomes aerosolized during common usage conditions;
  • to investigate the correlation of gravimetric air sampling data with bioaerosol measures indicated by: a) viable sampling of airborne bacteria and fungi; b) endotoxin measurement; and c) (1,3)-beta-D-glucan measurement; and,
  • to determine the workplace factors and work practices that present the greatest risk for generating MWF-associated bioaerosols.

Click below to review the results summaries:

For more information on the study, contact Professor James Scott: +1 416 946-8778 |