About metalworking fluids

Metalworking Fluids (MWFs) are neat oils or water-based fluids used during the machining and shaping of metals to provide lubrication and cooling. They are sometimes referred to as suds, coolants, slurry or soap.

The main health risks from working with metalworking fluids

Exposure to metalworking fluids can cause:

• irritation of the skin or dermatitis; and
• lung diseases, such as occupational asthma, occupational hypersensitivity pneumonitis, bronchitis, irritation of the upper respiratory tract and other breathing difficulties.

Fluid and mist from water-mix wash fluids and washing machines used to clean machined components may be hazardous in much the same way as fluid and mist from metalworking machines, and the same principles of risk assessment, prevention and control should be applied.

How harm is caused

Metalworking fluids are mostly applied by continuous jet, spray or hand dispenser and can affect your health:

• if you inhale the mist generated during machining/shaping operations;
• through direct contact with unprotected skin, particularly hands, forearms and face;
• through cuts and abrasions or other broken skin; and
• through the mouth if you eat, drink or smoke in work areas, or from poor personal hygiene, eg not washing hands before eating.

Key messages for managing the health risks

Control of Substances Hazardous to Health Regulations (COSHH) requires exposure to metalworking fluids by inhalation, ingestion or skin contact to be prevented where reasonably practicable, or failing that, adequately controlled.

• HSE COSHH website
• e - COSHH essentials metalworking fluids guidance sheets

You should:

• maintain fluid quality and control bacterial contamination of fluids;
• minimise skin exposure to fluids, see Control of skin risks during machining MW2;
• prevent or control airborne mists, see CNC machining MW1   and
• where there is exposure to fluid or mist, carry out health surveillance.

To achieve the necessary control and risk reduction, among other actions, you will need to:

• check and maintain exposure control measures, such as enclosures and local exhaust ventilation;
• check levels of bacterial contamination using dip slides, or other means of measuring the level of bacterial activity, in both metalworking and associated fluids eg in washing machines, and act on the readings obtained in line with your risk assessment;
• ensure that, as a minimum, a responsible person carries out the required health surveillance
• refer anyone affected by exposure to a competent occupational health professional;
• take prompt action after any diagnosis of ill health to identify the likely cause and ensure it is prevented or adequately controlled; and
• keep workers informed of all findings.
  Working safely with metalworking fluids: A guide for employees