Use of Methanol as a Coolant During Machining of Aluminum in a Shipbuilding Environment: A Failure to Assess and Manage Risk

Abstract

Minimization of harm during the conduct of work is one of the most important tenets of industrial hygiene. Organizations make changes to solve perceived problems. What appears to be expedient for solving a problem can create serious risks totally unrecognized by the proponent. This investigation reports on such a situation involving the use of methanol as a lubricant during machining of aluminium panels using a router. Spot samples for methanol were measured using colorimetric detector tubes and samples of long duration by colorimetric diffusion tubes utilizing similar chemistry. Both were positioned in the breathing zone. Most of the spot samples exceeded the 8-hour TLV-TWA (Threshold Limit Value-Time-Weighted Average) of 200 ppm and the TLV-STEL (Short-Term Exposure Limit) of 250 ppm. The two long duration samples also exceeded the TLV-TWA. A change in the operation prevented collection of additional long duration samples. By these measures, workers were overexposed to methanol during this activity. An additional serious consequence from use of methanol in this manner was risk of fire. This situation illustrates the complexity of decisions affecting workplace operations. What appears to be expedient for solving a problem may be totally inappropriate.