Exposure to metalworking fluids

By Vicki Bell

September 10, 2003

In 1993, the International Union, United Automobile, Aerospace & Agricultural Implement Workers of America (UAW) petitioned the Occupational Safety and Health Administration (OSHA) to take emergency regulatory action to protect workers from the risks of occupational cancers and respiratory illnesses due to exposure to metalworking fluids (MWFs). Bureaucratic wheels turn slowly.

To make a very long story short, the Secretary of Labor signed a charter establishing a Standards Advisory Committee (SAC) to address the issues on August 28, 1997, four years after the UAW petition. The SAC submitted its final report in 1999. Currently, there are no OSHA standards specific to MWFs. They are regulated under the following:

1910.1000 Table Z-1-

• Oil Mist, mineral: 5 mg/m.
• Particulates not otherwise regulated, total: 15 mg/m.
• Particulates not otherwise regulated, respirable: 5 mg/m.

1915.1000 Table Z-Shipyards-

• Oil Mist, mineral: 5 mg/m.
• Particulates not otherwise regulated, total: 15 mg/m.

1926.55 App A-

• Oil Mist, mineral: 5 mg/m.
• Particulates not otherwise regulated, total: 15 mg/m.

The National Institute for Occupational Safety and Health (NIOSH) recommended actions to reduce workplace exposures to MWFs in 1998. The recommended measures are intended to lower substantially the risks of serious respiratory disorders, including occupational asthma, associated with job-related exposure to widely used MWFs. In 1998, NIOSH recommended a limit of 0.5 mg/m3, as a time-weighted average up to 10 hrs. per day during a 40-hr. work week, for exposures to MWF aerosols. The current NIOSH Web page on MWFs recommends that the exposure be limited to 0.4 mg/m3 under the same conditions.

NIOSH also recommends that exposures be controlled through comprehensive workplace programs of safety and health training, worksite analysis, hazard prevention and control, and medical monitoring of exposed workers. The recommendations are documented in "Criteria for a Recommended Standard: Occupational Exposure to Metalworking Fluids."

The Risks

Metalworking fluids include a wide variety of petroleum oils and synthetic materials, sometimes combined with additives or diluted with water. Workers can be exposed to fluids by breathing aerosols or through skin contact. More than 1.2 million workers in machine finishing, machine tooling, and other metalworking and metal forming potentially are exposed. Among the conditions caused by exposure are hypersensitivity pneumonitis (lung tissue inflammation), chronic bronchitis, impaired lung function, asthma, allergic and irritant dermatitis, and increased risk of some types of cancer.

The Washington State Department of Labor released a brochure in 2001, Prevention of Skin Problems when Working with Metal Working Fluids, that goes into detail about possible skin problems, including how to recognize, treat, and prevent the various conditions. Among the skin problems included are mechanical trauma, infections, oil acne, folliculitis, and irritant and allergic dermatitis.

Small cuts to the skin from metal shavings are common and can become infected through contact with MWFs contaminated with microbial organisms.

Exposure to insoluble fluids can result in folliculitis (inflammation of the hair follicles) through direct contact of oil with the skin. Exposed skin or skin under clothing heavily contaminated with oil results in blocked follicles, which range in appearance from red irritation around the follicles, small black plugged pores, to large pustules. This problem usually appears on the neck, hands, arms, and thighs. Workers prone to acne may find that the condition worsens when working with MWFs.

Irritant dermatitis is the most common type of skin problem associated with MWF exposure. Soluble and synthetic MWFs are strong alkaline solutions containing many additives and solvents. They remove protective oils in the skin and damage proteins in the outer layer. The damage to the natural skin barrier causes a decrease in the skin's water content, leading to dry, thickened, fissured, and inflamed skin, especially on the hands.

The hands and forearms can develop dry, scaly, and inflamed patches. Infrequently, very small fluid-filled blisters can also develop on the hands and fingers. The type and concentration of the MWF used, the duration of exposure, and the presence of pre-existing skin diseases all contribute to the development of irritant dermatitis.

Less common than irritant dermatitis is allergic dermatitis. Additives in MWFs, such as biocides, preservatives, corrosion inhibitors, amines, and impurities from metal (chrome, nickel), act as allergens and cause allergic reactions in susceptible individuals. Lesions that resemble irritant dermatitis may appear, usually on the fingers and hands, but they do not clear when the person is away from the job or with treatment. The affected worker should be evaluated with patch testing for the components of MWFs to see if there is an allergen reaction.

Minimizing the Risks
NIOSH guidelines for controlling exposure include:

• Use of engineering controls as the primary method for reducing exposures. These measures could include controls to minimize splashing and mist generation, proper maintenance of fluids to prevent microbial contamination, and ventilation.
• Protective clothing and equipment to reduce exposures where engineering controls are being instituted, or where intermittent tasks expose workers to concentrations that cannot be kept below the recommended limit by engineering controls alone.
• Use of good personal hygiene and housekeeping practices, including prompt washing to remove MWFs from the hands or other exposed skin areas and keeping floors and equipment clean.
• Safety and health training to help workers recognize potential hazards from metalworking fluids, such as the appearance of bacterial growth in fluids, and to take effective protective action.
• Medical monitoring to identify any early signs of asthma or other health problems and workplace environmental monitoring to generate data for evaluating the effectiveness of control measures.

The Washington State DOL brochure offers the following guidelines for minimizing skin contact with MWFs through environmental measures:

• Keep the work area clean, including the machines, from MWFs and grime.
• Have functioning splashguards on the machines.
• Change to a less irritating MWF if feasible.
• Ensure correct dilution of the additives in the fluids.
• Maintain MWFs at the manufacturer-specified concentration and pH.
• Ensure fluid cleanliness by recirculating and filtering-straining them to remove swarf and other solid contaminants.
• Avoid using MWFs that have become contaminated with excessive microbial organisms.

Workers can help prevent dermatitis by:

• Wearing clean clothes while on the job.
• Laundering clothing that becomes contaminated with MWFs.
• Avoiding placing MWF-soaked rags in pockets.
• Wearing protective aprons.
• Wearing protective nitrile gloves (avoid latex because of possible allergic reaction), if possible.
• Following proper personal cleanliness procedures, such as washing hands with mild, nonabrasive soaps to remove fluids-at least twice during the workday. Never use cleaning solvents to wash the skin to remove fluids. Wipe off hands during the day with towels that are not contaminated with fluids or swarf.

Various measures can help protect the skin from irritant effects and keep the skin in optimal shape:

• Use moisturizers before and after work. Thick creams or ointments work best by healing the skin faster and offering more protection than thinner, water-based products. Try working the moisturizer cream into the skin and wearing clean, thin cotton gloves for a couple of hours or to bed to hasten the recovery of dry, fissured, irritated skin. Petroleum jelly and creamy petroleum jelly formulations work well.
• Use a mild soap at home to protect the skin from further damage.

Prevention is important, but sometimes problems develop despite taking precautions. In all cases, it's important to seek medical attention early and to explore any additional actions to reduce exposure to MWFs.