Metalworking Fluids

Health Effects

Metalworking fluids (MWFs) is the name given to a range of oils and other liquids that are used to cool and lubricate metalwork when being machined. MWFs are classified as either "straight” oils or "neat" oils (not meant to be diluted with water, and may contain highly refined petroleum, animal, marine, vegetable or synthetic oils); soluble oil (highly refined petroleum oils and emulsifiers); semi-synthetic fluids; and synthetic fluids (which may include detergent-like components). The last three classes are diluted with water before use. All MWF classes may contain additives such as stabilizers, biocides, dispersants, dyes, and odorants. When MWFs are used, a primary concern is the presence of contaminants that encourage the growth of bacteria and fungi. Also, there is a potential for oils to be heated high enough where the cutting tool works on metal workpiece to form polynuclear hydrocarbons (PAH's).

While MWFs are used by many workers safely, problems can develop when good hygiene practices are not followed or when fluids are not properly managed or maintained. Major health concerns of improperly managed fluids or when good hygiene practices are not followed include skin irritation, allergic contact dermatitis, irritation of the eyes, nose and throat, and, occasionally, breathing difficulties such as bronchitis and asthma. Although rare, some workers have contacted hypersensitivity pneumonitis (HP) from improperly managed fluids. HP is an allergic type reaction in the lungs that may be caused by exposure to certain microbial products. HP is marked by chills, fever, shortness of breath and a deep cough - similar to a cold that will not go away. Prior to 1985, the use of poorly refined mineral oils had been associated with an increase risk of cancers of the larynx, rectum, pancreas, skin, scrotum, and bladder. The following metalworking fluid references provide more hazard identification and health effects.