Introduction
Metalworking fluids are used during the machining of metal and may be applied as a jet or a spray. They are used as lubricants or coolants during processes such as turning on a lathe or CNC*-machining.
What are the concerns?
Cutting fluids often contain hydrocarbons such as naphtha or paraffin oils, and emulsifiers to aid in dilution. Inhaling mist or vapour, or skin exposure are the primary ways in which people may be exposed. Repeated contact with the skin can cause painful dermatitis, irritation, or reddening. Inhaling the mist or vapour can produce symptoms of asthma, bronchitis, and respiratory tract irritation.
If water-based metalworking fluids are recycled there is a risk of bacterial growth in the fluid which can cause dermatitis or respiratory problems.
Dermatitis is one of the most prevalent harms caused by metalworking fluids:
Some biocides, incorporated as part of the mixture, have the potential to cause dermatitis.
Metal elements, such as chromium, nickel or cobalt may be present in the jet or spray generated from a machining process; these may also be a direct cause of dermatitis.
Respiratory problems
There is an increased risk of asthma, bronchitis, breathing difficulties and respiratory tract irritation associated with inhaling vapours or mists of metalworking fluids. Exposure can also cause irritation to eyes, nose and throat. In addition, longer-term repeated exposure may result in allergic alveolitis (also known as hypersensitivity pneumonitis), with accompanying breathing difficulties.
Under certain conditions, and particularly if water-based metalworking fluids are recycled or re-used, bacteria and fungi may grow well in that medium. Subsequent inhalation of mists or vapours containing those biological agents can exacerbate asthma, cause respiratory tract irritation, or other flu-like illnesses.
Cancer
Historically, mineral oils have been linked to skin cancer especially on areas of skin subject to repeated exposure. Oil-soaked rags and clothing have also been linked to scrotal cancer.
What precautions should be taken?
Tasks involving the storage, handling and use of metalworking fluids should be assessed and appropriate instructions and training provided for workers. Workplaces should obtain a copy of the safety data sheet (SDS) from the supplier and consider the risks and precautions for the specific product you are using.
General controls
Control or limit the production of mists and vapours using:
- Splash guards
- Reducing the flow rate to the cutting edges of tools
- Enclosure systems with a delay to allow mists or vapours to settle or be ventilated out
- Local exhaust ventilation (LEV)
Skin protection
- Wear suitable gloves, overalls and goggles
Sump fluid management
- Avoid build-up of scum or ‘tramp oil’ on the surface of a sump
Others
- Change dirty clothing and overalls frequently
Health monitoring
Good practice for PCBUs is to have programs in place for regular skin examinations and checks of respiratory function by competent, registered medical practitioners, at a frequency recommended by the practitioner. Workers should be attentive for any changes in their health that they feel may be linked to working with metal-working fluids, discuss with their supervisors and seek further expert advice.
Further information
SafeWork Australia - Model Code of Practice: Managing risks of hazardous chemicals in the workplace | Safe Work Australia
Health and Safety Executive, UK – Working safely with metalworking fluids – A guide for employees indg365.pdf (hse.gov.uk)
United Kingdom Lubricants Association – Good practice guide for safe handling and disposal of metalworking fluids UKLA-HSE-Good-Practice-Guide-for-Safe-Handling-and-Disposal-of-Metalworking-Fluids.pdf