Health Risk from exposure to metal working fluids

Health Risk from exposure to metalworking fluids – Exposure of workers to metalworking fluids can cause both skin irritation and respiratory ill health.  The (COSHH) risk assessment for the use of metalworking fluids should identify a range of simple control measures that can significantly reduce the risks of ill health developing.  The main health effects arising from exposure to (metalworking fluids) are to the skin and the respiratory system.  These include irritation of the skin, dermatitis oil acne and folliculitis; as well as: occupational asthma, bronchitis, irritation of the upper respiratory tract, breathing difficulties or, rarely, a serious lung disease called extrinsic allergic alveolitis.  Water-based metalworking fluids support microbial growth and, hence, can lead to biological contamination of the metalworking fluids, increasing the risks of ill health arising from exposure.  Ill health effects may also be increased by chemical contamination of the metalworking fluids from tramp oils, hydraulic fluids, polycyclic aromatic compounds (in neat oils) and nitrosamines (in water-based oils).

Health Risk from exposure to metalworking fluids

Occupational Health, metalworking fluids

Respiratory ill health

Workers exposed to metalworking fluids mist and vapour are at risk of developing work-related asthma, bronchitis, irritation of the respiratory tract and breathing difficulties, as well as extrinsic allergic alveolitis (which can cause increasingly severe breathing difficulties in recurrent episodes, following repeated exposure). Exposure may also irritate the eyes, nose and throat.

Inhalation of these biological contaminants (such as bacteria or toxins) can lead to irritation of the respiratory tract and flu-like symptoms, as well as aggravating existing asthma.

Skin problems

Dermatitis (also referred to as eczema) is a disease caused by damage to the skin and is characterised by redness, swelling and flaking skin. Symptoms may also include cracking and blistering of the skin. The disease can affect anyone at any age and can occur anywhere on the body, although it is most common on the hands. Some people have a genetic predisposition to the disease and can also be brought on by contact with certain substances.

Contact dermatitis is caused by the interaction of the skin with some chemical or physical process and can take two forms:

  • irritant dermatitis and
  • allergic dermatitis.

Irritant contact dermatitis is due to direct damage of the outer skin layer by a chemical or other substance and is often caused as a result of repeated mild irritation from substances such as soaps, detergents and water.

Allergic contact dermatitis is a rarer condition and occurs when the body’s immune system reacts to a particular substance that has previously been applied to the skin. It is not known what triggers allergic reactions or why people react to certain substances.  Some workplace studies have shown that workers who handle metalworking fluids have a prevalence of dermatitis of between 20% and 30%, which is much higher than the 4% recorded among the general population.  The causes of dermatitis in those exposed to metalworking fluids are likely to derive from multiple factors as metalworking and machining workers tend to have exposure to a wide variety of metal types, metalworking fluids, solvents and biocidal additives. The skin of such workers is often subject to mechanical damage, such as from sharp metal fines, abrasive washing techniques, etc.

It is important to understand that although dermatitis can be treated to reduce the severity of symptoms it is rare for it to be cured completely and so it is extremely important to prevent it from developing in the first instance.  Management of metalworking fluids to ensure that fluid parameters are kept within certain limits is important.  Reducing both airborne and dermal exposure are important factors in the prevention of dermatitis, asthma and other ill-health effects

The use of unrefined mineral oils may lead to skin cancer on affected skin, such as hands and the lower arms.  Prolonged exposure through wearing contaminated clothing and the habit of putting oily rags into overall pockets increases the risks of skin cancer and of scrotal cancer.  These risks are lessened by the use of highly refined oils, etc.

Routes for exposure to metalworking fluids

Metalworking fluids are usually applied by continuous jet, by a spray or by a hand dispenser.  They can only cause health effects if they come into contact with the body.  The common routes for exposure are:

  • Inhalation of the mist generated during the machining operation.
  • Direct contact (such as from splashes) with unprotected skin, particularly hands, forearms and heads.
  • Entry into the body through direct contact with cuts, abrasions or other broken skin.
  • Ingestion (arising from eating, drinking or smoking in work areas, or from poor personal hygiene).

Principles for the management of health risk from exposure to metalworking fluids

In line with all substances hazardous to health, the Control of Substances Hazardous to Health Regulations 2002 (COSHH) require that the health risks arising from exposure to metalworking fluids are controlled.  To do this, the employer should:

  • Assess the health risk from exposure to metalworking fluids and decide what precautions are needed.
  • Inform workers of the risks associated with exposure to metalworking fluids and of the control measures to be used to ensure their health and safety.
  • Prevent workers being exposed to metalworking fluids or, where this is not reasonably practicable, ensure that such exposure is controlled adequately.
  • Ensure that exposure control measures are followed at all times, and regularly checked and maintained, and that safety procedures are observed.
  • Monitor workers exposure to metalworking fluids and carry out appropriate health surveillance, where the COSHH assessment has shown this is necessary.
  • Train workers in the use of control measures and the use of any personal protective equipment that may be required.

Control measures

In general, the introduction and maintenance of simple control measures will significantly reduce the risks of ill health developing from exposure to metalworking fluids.

General control measures

  • Ensure that the most appropriate metalworking fluids have been selected.
  • Devise a safe system of work for working with metalworking fluids and instruct workers in this safe system of work.
  • Ensure that suitable splash guards are provided, fitted and used appropriately.
  • Minimise the production of metalworking fluids mist and vapour, such as by controlling the volume and rate of delivery of the metalworking fluids to the tool.
  • Avoid the use of compressed air to remove excess metalworking fluids from machined parts, plant or equipment.

Extraction and ventilation

  • Provide suitable extraction systems (such as local exhaust ventilation), where the need is identified in the (COSHH) risk assessment
  • Ensure that any enclosures or extraction systems provided to remove or control mist or vapour are used properly.
  • Ensure that there is a time delay before opening the doors on (CNC) machine enclosures to ensure that all mist and vapour have been removed by the ventilation.
  • Introduce regular monitoring (checks) of the equipment and arrange for any damaged or defective splash guards, extraction systems, etc. to be repaired.
  • Ensure that the extraction system is checked and serviced regularly and that it is subject to statutory examination (by a competent person) at least once in every fourteen month period.
  • Ensure that there is adequate general ventilation in the work area – open workroom doors and windows to improve natural ventilation, where appropriate.

Avoiding skin contact and skin protection

  • Introduce suitable measures to reduce the potential for contact with metalworking fluids
  • Reduce contact with wet workpieces and surfaces.
  • Instruct workers not to put bare hands into fluid sumps and not to use oily rags to wipe them clean.
  • Provide suitable personal protective equipment and ensure that it is worn as appropriate.  Suitable PPE may consist of gloves (or gauntlets), overalls, aprons, goggles or face shields.
  • Instruct workers on the risks of contamination of the inside of gloves (with metalworking fluids) when putting them on or taking them off.

Sump fluid control

  • Ensure that waste materials (especially unwanted food, drink, cigarette stubs) are not disposed of into the sump.
  • Instruct workers to inform a supervisor if they observe any layers of scum or large amounts of tramp oil on top of the sump fluid, or if the sump fluid becomes dirty or smelly.
  • Introduce and follow good working practices when mixing fluids, cleaning and topping up sumps etc.
  • Monitor the levels of bacterial contamination using dip slides, or other means of measuring the level of bacterial activity.
  • Consider a contract management service for the for the metalworking fluids (offered by some suppliers).

Personal Hygiene

  • Provide suitable hand washing facilities, including running hot and cold water, soap and towels.
  • Provide, and encourage the use of, suitable pre-work barrier creams and after-work conditioning creams.  This barrier cream should be designed to provide a protective layer between the skin and the metalworking fluids, while the after-work conditioning cream is intended to replace the natural skin oils removed by washing and by contact with the metalworking fluids.
  • Ensure that any cuts and abrasions are covered with a suitable waterproof dressing.
  • Instruct workers in the need for high standards of personal hygiene
  • Instruct workers to wash regularly with soap and water to remove metalworking fluids from skin. Instruct workers to avoid using abrasive or solvent cleaners.
  • Instruct workers to wash their hands thoroughly before eating, drinking or smoking.
  • Store personal protective equipment in the changing facilities provided or another clean storage area.
  • Ensure that a sufficient number of suitable overalls are provided and that they are changed regularly.
  • Instruct workers not to put oily rags into their pockets.
  • Provide a laundry service for dirty overalls and instruct workers not to take hem home for washing.
  • Prohibit eating, drinking and smoking in areas where metalworking fluids are used.

Health Surveillance

Health surveillance of skin conditions among workers exposed to metalworking fluids may be used to identify those with dermatitis and those in the early stages of skin disease. Such health surveillance is often carried out by an occupational health nurse or other suitably trained individual who will administer a questionnaire and carry out a visual examination of the hands for signs of dermatitis. Health surveillance is generally only carried out annually, or at best every six months, so it is important to train the workers to recognise skin symptoms and provide guidance on how to protect the skin in the intervening time.  It is good practice to have workplace checks on the condition of the hands and lower arms of workers (potentially) exposed to metalworking fluids on a more frequent basis, such as monthly (as part of the general checks on the availability, condition and cleanliness of item of PPE, for instance).

  •  Appoint a responsible person to carry out health surveillance, as identified by the risk assessment.
  • Carry out asthma health checks.
  • Refer anyone affected by exposure to metalworking fluids to an occupational health professional.
  • In the event of any ill health being identified, ensure that prompt action is taken to identify the likely cause and ensure it is prevented or adequately controlled.
  • Keep workers informed of the collective findings of health surveillance.


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