Abstract

Water-based coolants are routinely colonized with microorganisms which form a part of the coolant mist. Dominant microbes in water-based coolants are usually Gram negative (GM-) bacilli, and reported health effects have been restricted to relatively small cross-shift changes in pulmonary function. After i0 workers exposed to coolant mist developed hypersensitivity pneumonitis (HP), we studied microbes in two coolant sumps (A associated with cases and B as a control). Fluids were cultured on R2A and malt extract agars for 5-7 days at 30°C & 25°C respectively,
colonies counted, fungi identified, and bacteria Gram stained, and acid-fast stained using the auramine fluorochrome procedure. Sump A contained 10(6)-10(7) Gram-positive, acidfast bacilli (AFB) per ml of fluid, and no
yeasts or fungi. Biocldes were added, the fluid removed, the system cleaned with dilute bleach, and a new brand of fluid introduced. Levels of
AFB rose to 5000 after 5 days, and to 7x10(5) after 2 weeks. A different fluid in Sump B co~tained 10(7)-10(9) GM- bacteria, 10(5) yeasts, and I0(4)Fusarium/ml. One of the workers with HP had strong precipitin hands against the sump A fluid, and an atypical "Mycobacterium" infection.
This is the first report of a possible connection between exposure to AFB bacilli and HP, and emphasizes the need to monitor the kinds of organisms in reservoirs that contribute to aerosols and human exposure.

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