What Are the Health Risks of Bacteria-Contaminated Metalworking Fluid?
Bacteria-contaminated metalworking fluid can have more far-reaching effects than poor coolant performance. Exposure can occur through skin contact, splashing, or by breathing in the mist produced when metalworking fluid is used. Effects can include skin irritation, allergic contact dermatitis, respiratory irritation, asthma, and, rarely, hypersensitivity pneumonitis. The risk from bacteria-contaminated metalworking fluid cannot be based simply on the bacterial count, but on the fluid chemistry, degree of contamination, mist generation, exposure duration, and worker sensitivity.
In fact, a sour sump is only an indicator; a fluid does not need to smell bad to require attention.
Contamination Changes the Fluid
Water-miscible metalworking fluids provide an environment that supports bacteria, fungi, and other microorganisms. These organisms can break down components of the fluid and excrete cells, fragments, and other biological matter. NIOSH points out that microbial growth introduces endotoxins, exotoxins, and mycotoxins into water-based fluids.
Microbial growth can play a contributing role in the development of odor from fluid, emulsion breakdown, and corrosion. These issues often go together with tramp oil, metal fines, incorrect concentration, and poor circulation in the coolant sump.
How Are Workers Exposed?
Direct contact with the coolant can occur when it contacts the workers’ hands, arms, face, and/or contaminated clothing. Cuts and abrasions on the skin can further heighten the risk, and the worker may also be exposed to the liquid via contact with wet parts, tools, and machine surfaces during the course of a shift.
The machining process can also turn the liquid into a mist or aerosol that reaches the breathing zone. High-pressure coolant delivery, exposed rotating equipment, poor enclosure design, and inadequate mist collection systems can all increase the likelihood of inhalation of liquid mist. Inhalation and skin contact are exposure routes identified by OSHA.
Respiratory Effects Need Prompt Attention
Exposure to metalworking-fluid mist is associated with such symptoms as cough, chest tightness, wheezing, shortness of breath, and rhinitis. Occupational exposure is a factor in asthma, chronic bronchitis, and decreased lung capacity. It is not always possible to blame one bacterium. The symptoms may be due to the fluid itself, the additives, the microbes, the byproducts of their metabolism, or a combination of these. That uncertainty is why the shop should investigate exposure conditions, not just the odor.
“UV-C can extend coolant life by continuously reducing the microbial load without adding more chemicals to the sump. The best results come from treating it as part of a complete fluid-management program, because filtration, tramp-oil removal, correct concentration, and system cleaning still determine how well the coolant performs.”–Jason Gardiner, CEO
Can Contaminated Coolant Affect the Skin and Eyes?
Metalworking fluids can be associated with irritant or allergic contact dermatitis. Symptoms can range from a red, itchy, dry, or scaling rash to cracked or even persistently irritated skin areas. Splashing of the fluid can cause eye irritation as well. Bacteria may be a factor, but concentration, alkalinity, additives, tramp oil, metal particulates, and prolonged dampness can also contribute. The selection of gloves is important – loose-fitting or inappropriate gloves can become entangled in rotating parts. Contaminated clothing should be removed and changed rather than left on during the remainder of the shift.
Hypersensitivity Pneumonitis Is Uncommon but Serious
Hypersensitivity pneumonitis, abbreviated HP, is an inflammatory response in the lungs that develops after repeated exposure and the development of sensitization to a particular airborne material. OSHA considers it a rare but recognized hazard from inadequately managed metalworking fluids and microbial products.
Symptoms can include fever, chills, a deep cough, tiredness, and shortness of breath. They can mimic an ongoing cold or flu. Cases of HP among metalworking fluid-exposed workers have been documented by the CDC when the fluid has been contaminated with nontuberculous mycobacteria, but detection of a particular organism does not confirm that it caused a specific illness.
What Warning Signs Should a Shop Take Seriously?
Recurring respiratory or skin issues among employees merit investigation, particularly if the symptoms diminish or disappear when away from the work area. Strong odor, noticeable surface growth or tramp oil layers, and rapid fluid breakdown are also signs that coolant management needs improvement. Odor is not a reliable indicator of safety, either. A biocide may reduce odor but not remove biomass, which can continue to flourish in pipes, sludge, or biofilm areas. The facility should keep records of reported concerns or medical issues, fluid condition, maintenance activities, and lab reports to look for patterns.
Testing and Exposure Control Work Together
Microbial monitoring gives insight into fluid condition, but the dip-slide does not indicate overall risk to the workers. Concentration, pH, filtration, oil skimming, maintenance, and mist exposure should also be considered.
Enclosures, local exhaust ventilation, correctly aimed nozzles, and properly maintained mist collectors all reduce the risk of inhalation. Splashguards, appropriate hygiene practices, and removal of contaminated clothing help prevent skin exposure. OSHA also recommends obtaining the Safety Data Sheet for the fluid and following the supplier recommendations for maintenance and biocides. Reach out to the professionals at Big Sky Decon for more information about the health risks of bacteria-contaminated metalworking fluid.
What Do Shops Ask About Contaminated Metalworking Fluid?
Q: Can workers get an infection from contaminated coolant?
A: The larger recorded health concerns from metalworking fluid exposure are irritation, dermatitis, and respiratory issues, rather than infection. That said, heavily contaminated fluid should never be ignored. Anyone with compromised skin integrity, an impaired immune system, or ongoing symptoms should consult a qualified medical professional and describe their work environment.
Q: Is bad-smelling coolant always dangerous?
A: A strong or unusual odor indicates fluid degradation and the possibility of microbial growth, which requires investigation. However, odor is not an indicator of what type of microorganisms may be present or a measure of exposure. Fluid without an offensive odor can still contain organisms, irritants, or airborne materials.
Q: Will adding more biocide solve the health risk?
A: Not necessarily. Too much or the wrong kind of biocide can be a risk on its own, and the active ingredients may not penetrate the biofilm or other material to reach the microorganisms. The fluid supplier can advise on selecting and using biocides. Gross contamination may require cleaning out the system and replacing the fluid with a properly formulated recharge.
Q: What should happen when several workers report similar symptoms?
A: The facility should make records of the reported concerns and promptly investigate coolant conditions, mist exposure, ventilation, and other practices. Affected workers should receive appropriate medical evaluation. Recurring symptoms should not be assumed to be an annual “cold,” especially if they improve when the employee is away from the work area.