SIM 03/2009/13 (rev)
This SIM alerts visiting staff to recent developments concerning the safe use of water-based metalworking fluids. It should be read in conjunction with the metalworking fluids information available on the HSE Website.
1. Water-based Metalworking Fluids (MWFs) are used during the machining of metals to provide lubrication and cooling. Sometimes they are referred to as cutting fluids, suds, coolants, slurry or soap. They are generally used within the concentration range 2-10% depending on the application. The supplier’s literature should be consulted for specific information. They can be:
During use they can produce mists, the extent to which this occurs will depend on the nature of the fluid and the machining operation.
Note: Neat oils are not specifically included in this SIM although the principals of effective fluid management still apply to these oils. Neat oils contain about 95% highly refined mineral oils, with some additives to improve performance. They are used neat without mixing with water where lubrication is more important than cooling (e.g. in very arduous operations). Low viscosity oils have an increased tendency to form mists in contact with rapidly rotating machinery. As they do not contain water, they have high resistance to bio-fouling. They should not be used if they contain mineral oils that are not highly refined;
2. As water contains microorganisms, diluted MWFs have a propensity for bio-growth, and thus traditionally contain a biocide. However, some MWFs have been formulated to be less susceptible to degradation by bacteria and to provide a long service life, but these fluids may also contain biocides. Such long life fluids are often referred to as “biostable”, see paras 8-13 re Bioconcept and biostable fluids.
3. Exposure to Water-based MWFs can cause:
4. A Technical Development Survey carried out in 1996 found that, historically, cases of respiratory ill health might have gone unreported because awareness of occupational respiratory illness from MWFs was low amongst users. The survey also found that the risks were not being systematically controlled. More recently, there was an outbreak of respiratory illness at Powertrain, Longbridge , a large user of MWFs, where 101 employees, from a total exposed workforce of approximately 800 employees, were diagnosed with occupational lung disease. The majority were occupational asthma, with lower numbers of cases of extrinsic allergic alveolitis (EAA), and humidifier fever. Some workers were diagnosed with more than one disease. There have been other, smaller, but similar outbreaks in the UK in the past few years.
5. MWF users have been identified as an occupational group with a higher incident rate of dermatitis compared to the 'all industry' average. Between 2002 and 2004 the rate per 100,000 workers per year was 51 for metal working machine operatives as compared to 6 for 'all industries'. Evidence suggests that this is due to the duration and frequency of wet-work, rather than the use of MWF.
6. Exposure to water-mix wash fluids in washing machines used to clean machined components of swarf and metalworking fluid may give rise to similar hazards and risks as exposure to cutting fluids.
7. The causative agent(s) within the MWFs leading to respiratory ill health in the cases investigated in the UK is yet to be determined. Bacteria or endotoxin produced when the bacteria die are thought to be the most likely cause, but constituents or contamination within MWFs may also play a role in occupational ill health. Research is ongoing to seek to improve understanding. Consequently, the currently widely accepted management strategy for MWFs includes the control of the bacterial growth within MWF. However, certain MWFs referred to as “Bioconcept” promote the growth of certain non-pathogenic bacteria (see paras 9-11).
8. It is important to be aware of the differences between “bioconcept” and “biostable” MWF, and between them and other fluids. There are implications for the way in which HSE’s guidance on the management of MWFs is interpreted, although the need for good management of the fluid is unchanged.
9. Bioconcept MWF is currently only produced by one manufacturer, and is available through a single distributor in the UK. The manufacturer claims that the MWF, through its constituents, becomes naturally populated by non-pathogenic waterborne bacteria originating from the water supply (ie unlikely to cause infection in healthy human beings) and the principle behind its use is that this prevents the proliferation of potentially harmful bacteria within the fluid. This means that the traditional MWF control method of dip slide monitoring, to count bacterial loading, will not be appropriate.
10. A characteristic of bioconcept fluids is that MWF systems will not have to be monitored for bacterial contamination by users nor will biocides need to be added. However, these fluids require optimum conditions for the natural bacterial population to survive and need careful management, including close monitoring of pH levels and working concentration, to ensure they stay within the manufacturer’s tolerances. The supplier/manufacturer evaluates premises before allowing its fluids to be used, and currently carries out monitoring of the fluid for its clients, to check that the necessary conditions are being maintained.
11. Although there have been no reported cases of respiratory ill health amongst users of Bioconcept MWF, if endotoxins are the causative (or a contributory) agent for respiratory ill-health there may be a potential for respiratory health effects as the non-pathogenic bacteria die. Research is being carried out by HSL to evaluate the manufacturer’s claims and look at appropriate management controls. It is still important that exposure to both the mist and fluid is kept to a minimum using appropriate control measures, as detailed in HSE guidance.
12. “Longlife” or “Biostable” MWFs are encountered more frequently than “Bioconcept” MWFs. It is HSE’s current view that existing MWF guidance remains valid and fit for purpose for biostable MWFs, and that users of these fluids should still demonstrate that they do not have excessive microbial contamination of their fluid.
13. The UKLA Metalworking Fluid Product Stewardship Group, in conjunction with HSE, has recently completed production of a DVD ‘The Safe Handling and Use of Metal Working Fluids’. The DVD runs for approximately 35 minutes, is modular and allows topic selection via a menu. The content:
The DVD is intended to provide an information and training resource for both users and the lubricants industry. It is hoped that additional modules will be produced, looking at key issues in more detail, such as the management of fines and tramp oil, and effective use and management of mist extract systems.
14. The DVD is available to play from the MWF pages of the HSE website. Copies of DVDs have been sent to Operational PIs (in non-construction groups), Occupational Health Specialists and DDMs . A limited number of further copies can be requested from the Sector contact (see para 27).
15. SIMs 03/2005/03, 03/2006/06 and 03/2007/03 provided information on proposed interventions with large and small users of MWFs. Questionnaires, designed to explore MWF management were sent to all 164 large users, of which 116 (71%) were returned. HSE Inspectors visited 43 large users and improvement notices were served on 11 of them in respect of inadequate management of MWFs, and all known small users were invited to a half-day MWF SHAD, with non-attendees being prioritised for a visit.
16. Analysis of the findings from the visits shows there were no discernible differences between large and small users of metal working fluids that arose solely because of employment size. The main findings of the visits were:
17. Manufacturing Sector will be considering these results when deciding if further action is necessary to ensure control of MWFs, and during the process of reviewing the existing information and guidance.
18. The content of the above guidance documents have been amended to take into account feedback received from stakeholders. The majority of the amendments are minor and seek to provide clarification, but there are some significant changes to MW3 and MW5.
19. MW3 “Sump cleaning: Water-mix fluids” - no longer requires the second clean of the system unless the subsequent dipslide test indicates a continuing bacterial problem, and the flow diagram has been amended accordingly.
20. MW5 “Managing Sumps and Bacterial Contamination” has been amended to allow the dipslide frequency to be extended beyond one week if a suitable and sufficient assessment shows that good control has been maintained over a sustained period. Testing will still be required, but the frequency should be determined by a suitable and sufficient assessment of existing controls and monitoring regime. If good, sustained control cannot be demonstrated then weekly testing should still be the norm.
21 HSL is undertaking an extensive research programme to improve knowledge of causes of ill health and controls for MWFs. HSL is also carrying out work to develop guidance on investigation of any further outbreak of respiratory disease from MWF. Further details are available – see para 27.
22 Inspectors are reminded that successful MWF management requires employers to:
*For conventional MWF, 'controlling bacterial contamination' will mean employers should reduce as far as possible bacterial levels in conformance with published guidance in COSHH Essentials (MW5 “Managing sumps and bacterial contamination”).
23 Bioconcept MWF users will not be reducing bacterial contamination as its use relies on the establishment of a stable non-pathogenic bacterial population in MWF sumps. While the research detailed in para 11 is being completed, employers using Bioconcept MWFs should:
If necessary, inspectors should seek assistance from the Specialist Group occupational hygiene team and the Manufacturing Sector (para 27).
24. Freedom of Information exemption 43 - commercial interests
25. Where there is either a poor or no risk assessment for the use of MWFs and existing control measures to prevent exposure are inadequate the risk gap will be substantial. Table 5.1 of the Enforcement Management Model should be referred to for the initial enforcement expectation, taking account of the duty holder and strategic factors. This will usually be an improvement notice (IN). A schedule for a suitable IN is available at Metalworking fluids - improvement notice schedule [3].
26. However, due to uncertainty about the cause of respiratory ill health (para 7), the range of factors for successful control (para 22) and the absence of an exposure limit for airborne MWF, inspectors are advised to seek advice from an SG Occupational Hygienist about the extent of controls that are ‘reasonably practicable’ where enforcement is being considered.
27. Simon Edwards, Manufacturing Sector (VPN 501 6040)
28. SIM 03/2005/03 – cancel and destroy
SIM 03/2006/06 – cancel and destroy.
SIM 03/2007/03 – cancel and destroy.
