Published: July 8th, 2009
Revised: February 25th, 2015
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. Recently released occupational exposure limits to MWFs are based on aerosol concentrations determine by gravimetric measurements that have failed to consider the relevance of bioaerosol exposure, including viable airborne microbes (bacteria and fungi) and microbe-derived chemicals, such as endotoxin (Gram-negative bacteria) and ergosterol (moulds and yeasts). One bacterium in particular, Mycobacterium immunogenum, was described recently from synthetic and semi-synthetic MWFs. Recent research suggests that this bacterium plays a major role in respiratory disease of workers exposed to microbially contaminanted MWFs.
This test detects members of the M. immunogenum complex using PCR. This method cannot distinguish between living and dead cellular material. A negative result does not necessarily refute the presence of potentially infectious material in the area tested, since only a small amount of material is subjected to the test. The testing of multiple replicate samples is helpful to establish confidence on the generalizability of results. A positive result, however, may provide information that is useful in public health interventions.
Bulk samples of MWF should be collected dry in a clean, new, food-grade, bottle. A minimum volume of 100 mL should be collected. Air samples may be collected on a 25 or 37 mm 0.4 um polycarbonate membrane filter. A minimum of 1 cubic metre of air should be collected. Both sample formats should be placed individually in a clean, new, food-grade, zippered freezer bag, and delivered to the laboratory within 24 hr of collection.