The Health Impact of Metalworking Fluids on the Automation Industry

By Joe Lazzara, Scientific Technologies Inc.

A drama has been unfolding that may significantly impact machinery and metalworking plants. The subject is not as easily determined as a machine guard; but rather the more difficult to measure, long-term impact of metalworking fluids on workers’ health. The stakeholders include the United Auto Workers, Canadian Auto Workers, NIOSH, OSHA, various industry trade groups, fluid users and manufacturers. Machine tool users and manufacturers should consider steps now to assess metalworking fluid concentrations and reduce employee exposures, before a proposed tenfold reduction in the allowable limits forces the issue.

Metalworking fluids are commonly used in machining operations to cool and lubricate the cutting tool and work piece, while removing the metal fines, chips and swarf. The chemical composition of the metalworking fluids has evolved to three primary classifications: straight fluids, which are all oil based; soluble fluids containing blends of oil and water; and synthetics which contain little or no oil. This evolution of the fluids has complicated the health impact analyses.

Existing OSHA Limits Under Pressure

Current OSHA regulations allow a permissible exposure level (PEL) for oil mist (mineral oil) of 5 milligram per cubic meter of air (mg/m_). Oil mist at this concentration will produce a noticeable fog in a machining area.

In late 1993, the UAW petitioned OSHA to reduce the PEL to 0.5 mg/m3 by issuing an emergency temporary standard. The UAW based their petition primarily on several epidemiological studies sponsored by joint programs through the UAW, GM and Ford, which indicated a possible link between fluid exposure and several health effects, including respiratory complications. OSHA denied the petition as an emergency measure, but acknowledged that the issue had merit. The following year the American Automobile Manufacturers Association (AAMA), while proactive on evaluating the exposure risk to metalworking fluids and acknowledging that the current OSHA allowable level of 5 mg/m_ appeared to be inadequate, disagreed with the UAW that the limit should be changed to as low as 0.5 mg/m3. AAMA believed that the 0.5 limit was not scientifically supported and would prove difficult to pass OSHA’s hurdles of significant risk and economic feasibility. Even today, the question remains as to how low a PEL will provide acceptable worker protection?

Epidemiological studies of potential workplace exposures are very difficult to measure and assess. Ideally, a scientist designing a controlled test would like to eliminate as many variables in the analysis as possible. Real world studies rarely afford such an opportunity. The evolving nature of the metalworking fluids, over the past several decades, with significant changes in both formulations and processing techniques of the base chemistry, has made any long term data analysis of the toxicological properties of the fluid mist more difficult. This complexity is compounded by the difficulty of characterizing changes in the "in-use" fluid composition over time. Certain studies have also indicated that some soluble or synthetic fluids can foster bacterial and fungal growth. Are reported respiratory effects related to the fluid exposure caused by the bacterial breakdown byproducts known as endotoxins, or to the formulation or in-use chemical changes of the metalworking fluids themselves? Has the use of tobacco products been adequately accounted for in the studies indicating respiratory effects? What is the concentration and duration of the exposure levels? These questions are just a sampling of how difficult extended field studies are to conduct, analyze the data and report the results.

Exposure Assessment and Reduction

Although this area of exposure assessment is filled with complexities, the ability to quantitatively evaluate the metalworking fluid exposure is essential to protect the health of the workforce. The pervasiveness of the fluids and their importance to the machining process suggests that metalworking fluids cannot be completely eliminated from the workplace. Most likely, a successful program of fluid control will include a total systems approach, employing a combination of engineering methods and management issues.

The ANSI organization has completed a Technical Report, ANSI B11 TR-2-1997, on the subject of mist control, entitled "Mist Control Considerations for the Design, Installation and Use of Machine Tools Using Metalworking Fluids." This is an excellent reference document to the variety of engineering controls available to reduce workplace fluid exposures. Topics covered include the proper design of: fluid delivery systems, machine tool considerations for reducing mists, machine guards and enclosures for controlling airborne contaminants, exhaust ductwork and mist collectors. Other subjects include proper fluid selection, system maintenance and testing collection systems. You will find this document written in a common language that does not require an engineering staff to decipher.

OSHA Regulatory Update

In response to the original UAW petition in 1993, and a decision by OSHA to include metalworking fluid exposure in the "top five" of their priority rulemaking list, OSHA established a Standards Advisory Committee (SAC) of fifteen members in 1997. The purpose of the Committee was to explore the technical, health and economic feasibility issues relating to the metalworking fluid exposures, and to recommend to OSHA a course of action. After two years and ten meetings, the Standards Advisory Committee, by majority vote, recommended last month (September, 1999) that OSHA pursue full regulation with an airborne permissible exposure level (PEL) of 0.5 mg/m3. The regulation should include additional topics as skin exposure, engineering controls, medical surveillance, training and recordkeeping. With full consideration for the major undertaking this regulatory path would require, OSHA responded that the agency would pursue rulemaking on this issue as "time and resources would allow".

It is also interesting to note that four dissenting members of the Committee instead recommended that OSHA encourage voluntary industry guidelines and partner with various initiatives already underway through industry groups. Their proposal advocated that more immediate and effective protection could be achieved this way than by the long and contentious rulemaking process.

Labor remains a strong advocate of reducing the exposure levels down to 0.5 mg/m3. For example, during the 1996 contract negotiations with the Big Three automotive manufacturers, the UAW succeeded in securing the agreement of all three companies to an internal PEL of 1.0 mg/ m3 for new equipment purchases. Suppliers to the automotive industry should expect similar pressure from labor.

What to Do Now?

First, I would suggest you make an effort to assess your current exposure levels of metalworking fluids. You may find that your workers’ compensation provider can perform this service at very little cost through one of their industrial hygienists. Next, obtain some of the excellent reference publications covering much of this very complicated issue. Besides the ANSI B11 TR-2-1997 on Mist Control (available from the AMT, 703-893-2900), the Organization Resources Counselors has produced a worthwhile guidance document on the total systems management of metalworking fluids, available at no charge from their web site at www.orc-dc.com. The technical Proceedings from two AAMA sponsored comprehensive symposia on the topic may be purchased from www.amazon.com by searching on metalworking fluids.

Finally, study the implementation of some of the engineering controls suggested in the above documents. Besides improving the working environment, you may find that the improvements can be economically justified by reducing the consumption, recycling and disposal costs of your metalworking fluids.

I would sincerely like to thank Dave Felinski, AMT Safety Director for his invaluable research and assistance in the preparation of this column. Until next month, be safe out there!

Lazzara on Automation Safeguarding is a monthly column written for Safetyonline.com and Plantautomation.com.

Joe Lazzara is president and CEO of Scientific Technologies Inc. (STI, Fremont, CA), the largest provider of automation safeguarding solutions in North America. Lazzara began his career with Hewlett Packard in 1973 where he had responsibility for safety and environmental issues for one of HP’s largest divisions. He joined STI in 1981 as vice president and became president in 1989 and CEO in 1993. Lazzara received a bachelor’s of environmental engineering degree from Purdue University and an MBA from Santa Clara University.