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Recommendations to Control Exposures Suggested by NIOSH in Comprehensive Health Effects Review of Metalworking Fluids

NIOSH Update:

Contact: Fred Blosser (202) 260-8519
January 22, 1998

The National Institute for Occupational Safety and Health (NIOSH) today recommended actions to reduce workplace exposures to metalworking fluids. The recommended measures would substantially lower the risks of serious respiratory disorders, including occupational asthma, associated with job-related exposure to the widely used fluids.

NIOSH recommended a limit of 0.5 milligrams per cubic meter of air, as a time-weighted average up to 10 hours per day during a 40-hour work week, for exposures to metalworking fluid aerosols, a level that is technologically feasible for most metalworking operations. The Institute also recommended 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.

NIOSH made the recommendations in a new document, “Criteria for a Recommended Standard: Occupational Exposure to Metalworking Fluids,” which offers the single most comprehensive source of information to date on the health effects of metalworking fluids.

“The actions we are recommending, including a substantial reduction in the exposure limit for metalworking fluid aerosols, are technologically feasible and prudent for public health,” said NIOSH Director Linda Rosenstock, M.D., M.P.H. “Further, they are based on experience from the shop floor itself. Our research has found that some workplaces, as a matter of course, already have implemented these approaches to protect workers’ health and reduce costs.”

Metalworking fluids are used to reduce heat and friction and to improve product quality in machining and grinding operations. They include a wide range of petroleum oils and synthetic materials, sometimes combined with additives or diluted with water. Workers can be exposed to the fluids by breathing aerosols generated in the machining process, or though skin contact when they handle parts, tools, and equipment covered with the fluids. Some 1.2 million workers in machine finishing, machine tooling, and other metal-working and metal-forming operations are potentially exposed.

Occupational exposures to metalworking fluids may cause a variety of respiratory conditions, including hypersensitivity pneumonitis, chronic bronchitis, impaired lung function, and asthma. Work-related asthma in general is one of today’s most prevalent occupational disorders, imposing significant costs in health care and workers’ compensation. Exposures to metalworking fluids also are associated with allergic and irritant dermatitis. Substantial evidence also shows that past exposures to some metalworking fluids were associated with increased risk of some types of cancer. Although actions taken in the last several decades likely have reduced that risk, it is not known if these actions have totally eliminated the risk. The potential for a hazard supports the recommendation for reducing aerosol exposures, NIOSH found.

The criteria document recommends a comprehensive approach for controlling exposures, including:

  • 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 metalworking fluids 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 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.

Recommendations in the criteria document were developed after input from health and safety specialists in industry, labor, the public health community, and other government agencies. NIOSH will work closely with partners and stakeholders to disseminate the information to businesses, industry associations, workers and labor organizations, health and safety professionals, and other agencies.

NIOSH is the Federal agency responsible for conducting research and making recommendations for the prevention of work-related disease and injury. It is part of the Centers for Disease Control and Prevention.

Copies of “Criteria for a Recommended Standard: Occupational Exposure to Metalworking Fluids,” NIOSH (DHHS) Publication No. 98-102, are available from the toll-free NIOSH information number, 1-800-35-NIOSH (1-800-356-4674). Additional information on NIOSH research is available from the toll-free information number and on the NIOSH home page on the World Wide Web at