Reducing Health Risks from Exposure to MWFs – UK Risk Management Strategy

Martin Stear

The Health and Safety Executive (HSE) is developing good practice guidance for work with metal working fluids (MWFs), setting out standards for the reduction of health risks to workers exposed to MWFs. This is scheduled for launch in September 2002. This very practical guidance will enable companies to compare their results to those derived from good practice, so that they can gauge their performance. In addition to good practice methods for controlling mist and managing sump fluids, the guidance will include guide values for mineral oil and water-mix metalworking fluid mist and for sump fluid contaminant levels. It is being developed in conjunction with relevant UK trade associations and trade unions.

The move has been made in the light of two developments. The first is a study showing current practice in control of metalworking fluid exposures in 31 engineering companies. The findings gave some cause for concern. Many of the companies visited were found to have poor control of fluid strength, poor sump replenishment methods and poor control of contamination. Failing to manage sump fluid conditions can not only affect the quality of the machined work piece and the tool, but also increase the risk of ill health among operators.

The highest mineral oil personal sampling result found in the study was 3.7 milligrammes per cubic metre for the 8-hour time-weighted average (TWA). 90 per cent of results were less than 2.8 mgm^-3. The results for personal exposure to water-mix mist ranged as high as 13 mgm^-3, but with 90 per cent of results returning a value less than 0.8 mgm^-3. High bacteriological contamination and endotoxin levels were found in many sumps (up to 200 million bacteria per millilitre, and up to 2 million endotoxin units per millilitre).

The second development is that the Health and Safety Commission's (HSC's) Advisory Committee on Toxic Substances (ACTS) has concluded that new occupational exposure limits cannot be derived for mineral oil or water-mix metalworking fluids. It has also recommended that the mineral oil mist Occupational Exposure Standard should no longer apply to metalworking fluids. If the HSC decides, after external consultation, to follow the advice from ACTS, there would be a need for a new source of standards for control; the proposed guidance would meet that need.

The HSE study, carried out in conjunction with the Health and Safety Laboratory, used new air-sampling techniques to measure workers' exposure to mineral oil and water-mix metalworking fluid mist. Information was also collected on the fluids and processes used, and on control procedures, in order to ascertain current practice in controlling exposure. In addition, fluid samples were taken from machine sumps to measure for bacteriological content, endotoxins, fines levels and other contaminants.

The main health concern associated with metalworking fluids is dermatitis, with around 200 cases of contact dermatitis a year - related to exposure to cutting oils and coolants - reported to EPIDERM (a scheme in which dermatologists report cases of occupational skin disorders). The true number of cases is almost certainly higher, however. There is also an association between exposure to these fluids and respiratory effects, including bronchitis and asthma.