Lynette McCartan from Lagom Safety Ltd on the occupational health hazards associated with Metal Working Fluids in manufacturing.
Lynette McCarton at Lagom Safety Ltd.
Metal Working Fluids (MWF)s is a general term for lubricants and coolants used during the machining or treatment of metal components which are used in various manufacturing processes. MWFs vary in composition by their physical, chemical and tribological characteristics and can contain many additives and ingredients which are well known as irritants or allergens.
MWFs are usually selected for the metal being tooled and their cutting performance whereas associated health hazards are unlikely to be considered in the selection process.
Working with or around MWFs can cause health hazards therefore they must be understood and managed well. Health hazards associated with MWFs can be categorised into dermal (both allergic and irritant), respiratory and cancer with the main routes of exposure being from inhalation of mists, aerosols and dermal contact.
There are several types of MWFs available such as Soluble Oils, Straight Oils, Neat Oils and (Semi) Synthetic MWFs. Soluble Oils types have been associated with specific health hazards such as Dermatitis whereas skin disorders are most likely to be caused by water based, synthetic and semi synthetic MWFs. Respiratory conditions are most likely to be caused by Straight Oils and Synthetic MWFs. Metals can dissolve into the MWF depending on machine process, metals or alloys being tooled also causing health hazards. It is also thought during the MWF operations that Particulate matter (PM) such as metal particulates resemble the same traffic-related PM as they both include alveolar and ultrafine particles that contain polycyclic aromatic hydrocarbons and metals.
The level of exposure will depend on factors such as proximity, role, exposure time, maintenance and other control measures. Causes of health hazards from MWFs can be difficult to determine as there are a wide number of industries where these health hazards can be caused. Occupational illness can be complex and multi-causal making it difficult to determine if it was work related. Factors such as lifestyle, diet and smoking should be considered. Although cancer is known to be caused by MWFs, this is not as widely reported as respiratory and dermal health hazards.
Respiratory health hazards
Established respiratory hazards such as Occupational hypersensitivity pneumonitis (OHP), Occupational Asthma (OA) are the most commonly reported lung disease. OA can be experienced by those who have non occupational asthma. Chronic bronchitis and asthma has been associated with MWF aerosols and can irritate the lungs, nose and throat. Exposure to aerosols and mists can worsen pre-existing respiratory conditions. Other health hazards such as humidiﬁer fever, increased coughing, phlegm and Rhino Conjunctivitis have been identified. Microbiological contamination such as bacteria, moulds and viruses can grow in the right conditions and can cause respiratory tract irritation and flu like symptoms. It can also exacerbate those with asthma and cause allergic contact dermatitis. Rich media for microbial proliferation in MWFs sustains bacteria, mould and fungal which can reduce performance and increase adult onset asthma and OHP.
Asthmagens and respiratory sensitisers can cause workers to become hyper-responsive and potentially have symptoms ranging from a runny nose to asthma, although not everyone will respond in the same way. Some health hazards are thought to require a prior sensitisation to an antigen (AG).
Water based MWFs support microbial growth that in turn introduces biological contaminants such as endotoxins, exotoxins, and mycotoxins. These are believed to cause adverse respiratory effects such as chronic bronchitis and asthma. Surviving bacteria in sumps from Biocide use can grow and produce a flu like response and reduces lung function.
MWFs contain additives and contaminants of metals such as Ethanolamine, colophony, pine oils, nickel, cobalt that can aggravate pre-existing asthma or irritation to non-asthmatic employees.
Dermal health hazards
Dermatitis can occur due to repeated or prolonged exposure to MWFs through contact with the skin, particularly hands and forearms or by entering your body through cuts and abrasions, broken skin or poor hygiene practices. Research shows numerous health hazards associated with MWFs and have been widely agreed such as dermatitis (both allergic and irritant), chronic Bronchitis, and irritation (of nose, throat, lungs), folliculitis, oil acne, and keratoses, burning and itching.
Contact dermatitis or irritant contact dermatitis caused by skin contact with MWFs can depend on the additive, composition, metal being used, and the exposed individual’s tendency for developing allergies. The cause of irritation/dermatitis can be biological, chemical or mechanical. Metal fines and swarf also increase the risk of skin abrasion.
Exposure to cutting oil can cause oil acne or folliculitis, furnculosis, hyperpigmentation, keratoses of the skin, epitheliomas and skin cancers. Contact dermatitis is caused mainly by water-soluble or synthetic MWFs and it predisposes people to allergic sensitization because it compromises the epidermal barrier and allows allergens to penetrate.
Allergic dermatitis can be caused by using biocides and some soluble metals. Pseudomonads can be found in sumps and the rotten egg smell caused by hydrogen sulphite is caused by bacteria growing in sumps that can deplete oxygen. It can smell sulphourous. Sulfate reducers can produce hydrogen sulfide, other toxic gases and adverse health effects to those who are exposed to MWFs aerosols.
Carcinogenicity can occur from exposure to MWFs. Potential carcinogens can be hydrocarbons, chlorinated paraffins, aliphatic amines, nitrosamines, PAHs, formaldehyde-releasing agents, diethanolamine, and many other additives.
Stomach, large intestine and pancreatic cancer are most frequently reported cancers. Neat oils are thought to cause digestive cancers, prostate cancers and leukaemia. Exposure to mineral oils can cause squamous cell cancer of the skin, particularly the scrotum.
MWF mist has been known to cause a rare lung condition called lipoid pneumonia, due to oil retention within the lung. Some studies saw an increase bladder, oesophageal, laryngeal, colon, rectal cancer, stomach cancer and malignant melanoma with Straight oil exposure. Soluble MWF is also associated with cancer of the larynx, oesophagus, skin, and brain. Synthetic MWF is associated with cancer of the oesophagus, liver, and prostate. However other risk factors for larynx cancer are smoking, alcohol and wood dust. Cervical and breast cancer was noted in large female workforces.
It is recognised that occupational illness can result from concentrations lower than the recommended Workplace Exposure Limit.
Employers should apply a systems approach to MWFs to ensure all areas are being controlled as protection of workers cannot be achieved unless they do so.
The following are areas should be implemented to assist manage MWFs: Management Commitment; Purchasing Policy; MWF Selection and Use; Risk Assessment and Signs; Fluid Maintenance; Mist Control; Temperature; Concentration Levels; Biocide Treatment; Health Surveillance; PPE and Hygiene; Maintenance; Waste and Disposal; Employee and Other Training.
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