The Institute of Occupational Medicine (IOM) was founded in 1969 by the National Coal Board (NCB) as an independent charity in Edinburgh, UK and retains its charitable purpose and status today. The "Institute" has a subsidiary, IOM Consulting Limited, which became fully independent in 1990 and now celebrates its 25th year within the IOM Group as an independent consultancy and also the commercial part of the IOM organization. It specializes in asbestos surveys and services, occupational hygiene services, nanotechnology safety, laboratory analysis and expert witness consulting services. IOM is therefore one of the UK's major independent "not for profit" centres of science in the fields of environmental health, occupational hygiene and occupational safety.
Coal and pneumoconiosis The IOM was set up by Dr John Rogan, the chief medical officer of the NCB, who had initiated the Pneumoconiosis Field Research (PFR), persuaded the then chairman, Lord Robens, to found a scientific institute to take over the running of this research. The original senior members of staff, under Rogan, were Henry Walton, deputy director and head of Environment Branch, Dr Michael Jacobsen, head of statistics and Dr David Muir, head of Medical Branch.
The early history of the IOM is inextricably bound up with the NCB and the PFR. The PFR had started in the early 1950s with the objective of determining how much and what types of coal dust caused pneumoconiosis and what airborne dust concentrations should be maintained in order to prevent miners from becoming disabled by the air they breathed. These ambitious and clear objectives were remarkably far-sighted, implying a requirement to measure both exposure to airborne dust and health outcomes in a large cohort of miners over a prolonged period, and to use these quantitative data to set protective health standards in the industry. 50,000 coalminers were eventually recruited into the study from 25 collieries representative of conditions across Britain.
The early work involved measuring dust exposure by counting the number of particles collected from the air by sampling devices. A substantial advance was achieved with the measurement of exposure by weighing the dust collected by MRE 113a respirable dust samplers, which were invented specifically for the research by Henry Walton and Robert Hamilton.
The first results from the PFR were reported in 1970 in the scientific journal Nature.Jacobsen M, Rae S, Walton WH, Rogan JM. (1971) New Dust Standards for British Coal Mines. Nature 227(5257): 445-447. The research underpinned the recommendations for more stringent airborne dust standards in British coalmines and the PFR was ultimately used as the basis for many national dust standards around the world. IOM's research in coal mining continued until about 1990, with many important scientific papers on respiratory diseases amongst miners having been published. In 1985, an important association between risk of pathological emphysema and dust exposure was demonstrated, leading ultimately to recognition of this disease as a quantifiable risk of coal mining. Recent analysis of the mortality of a subset of the miners originally studied has found an association between the risk of lung cancer and quartz exposure, and raised mortality from chronic lung disease and pneumoconiosis associated with increasing dust exposure.
In the 1980s the IOM's epidemiological expertise was used in three original studies led by Dr Anthony Seaton into the effects of polyvinyl chloride dust, wool dust and shale mining on the lung health of workers. All showed positive associations and the results were used in regulatory standard setting in the UK and United States.
This research into risks from inhaling dusts remains an important part of the IOM's research. The occupational exposure limits for crystalline silica continue to be a major international concern and from its previous research IOM has been able to define an exposure-response relationship for crystalline silica with unusual precision.Buchanan D, Miller BG, Soutar CA. (2003) Quantitative relations between exposure to respirable quartz and risk of silicosis. Occupational and Environmental Medicine; 60(3):159-164. This work demonstrated the need for very low limits on exposure to airborne crystalline silica because of the high risk of disease from even relatively brief exposures to high airborne concentrations.
IOM studies have defined the relationships between decreases in lung function and dust concentrations amongst coal miners. These studies showed that dust control sufficient to prevent pneumoconiosis would reduce substantially the risks of impairment of lung function. However, an important question was whether these risks could be extrapolated to other occupational insoluble dusts. By developing and validating mathematical models of accumulated lung dust burden and resulting inflammation, IOM research has shown that the toxicity of several insoluble dusts of different compositions can be predicted from their surface area.
Asbestos and other mineral fibres In 1971, Dr John MG Davies was recruited from Cambridge University to head a new Pathology Branch at IOM, and to continue his research into asbestos-related diseases. An extensive programme of research on the toxicology of fibres has shown that persistence of some asbestos fibres in the lung as a result of their insolubility was an important determinant of carcinogenicity and fibrogenicity, and that fibre length was also critically important in determining toxicity.Donaldson K, Brown GM, Brown DM, Bolton RE, Davis JM. (1989) Inflammation generating potential of long and short fibre amosite asbestos samples. British Journal of Industrial Medicine; 46: 271-276. This research expanded to consider fibres and other materials introduced as substitutes for asbestos, such as calcium silicate and aramid fibres. From 1990, the Colt Foundation, relevant industries and the Health and Safety Executive supported a programme of laboratory research into the health effects of man-made mineral fibres that helped to clarify the quantitative relationships between health risks and fibre dimensions and biopersistence.Miller BG, Searl A, Davis JMG, Donaldson K, Cullen RT, Bolton RE, Buchanan D, Soutar CA. (1999) Influence of fibre length, dissolution and biopersistence on the production of mesothelioma in the rat peritoneal cavity. Ann Occup Hyg; 43: 155-166. This work was awarded the prestigious Bedford Prize by the British Occupational Hygiene Society.
In 1977, Henry Walton and Dr Steve Beckett invented a microscope eyepiece graticule used for counting asbestos fibres.Walton WH, Beckett ST. (1977) A microscope eyepiece graticule for the evaluation of fibrous dusts. Ann Occup Hyg; 20: 19-23. This device was designed to improve the reliability of the measurements and it has since become part of the international standard methodology for fibre measurement. A programme ensued on the measurement of fibrous aerosols such as asbestos, raising important issues in comparability of counts by different laboratories, and leading to the establishment of quality control schemes for asbestos. In 1979 the IOM was appointed by the Health and Safety Executive as the British Central Reference Laboratory for asbestos fibre counting, and the following year the World Health Organization similarly appointed IOM as its central reference laboratory for man-made mineral fibre counting.
From 1985 IOM collaborated with the International Agency for Research on Cancer in a major European epidemiological study of the carcinogenicity of mineral wool fibres. As part of this work IOM helped develop novel methods to estimate retrospectively exposure of workers in the study, ultimately demonstrating that there was no evidence of a carcinogenic effect of these fibres on the lung. IOM scientists also conducted a study of the respiratory health of workers manufacturing Refractory Ceramic Fibre in Europe, showing small though inconsistent effects on respiratory health associated with inhalation of these fibres.
Workplace exposure, measurement and modelling From its earliest years, IOM has had a tradition of using quantitative exposure measurements to explore links between the working environment and health and has pioneered the development of new methods to measure the concentration of aerosols in ways that are relevant to human biology. The MRE 113A respirable dust sampler developed for use in our pneumoconiosis research was the first landmark and led to greater insight into the causes of this disease. Under Dr Jim Vincent's leadership, an innovative research programme, begun by Dr Trevor Ogden, was aimed at designing new sampling instruments for coarser aerosols. The culmination of this work was the development of the IOM inhalable dust sampler, which has become established as the device of choice for measuring the part of an aerosol that penetrates beyond the larynx.Vincent JH, Mark D. (1986) A new personal sampler for airborne total dust in workplaces. Annals of Occupational Hygiene; 30: 89-102. IOM scientists played a key role in defining the internationally agreed size fractions of dust relevant to human lung disease, i.e. inhalable, thoracic and respirable.
Research on chemical exposure has more recently focussed on exposure modelling, data management and studies for regulatory risk assessment. Studies in relation to metals, including dermal exposure to nickel, zinc and lead, have been carried out. Work on the measurement of exposure to oil mist aerosol and vapour has been undertaken for offshore oil workers. In collaboration with some of the leading European human exposure scientists, IOM has been developing a new generation exposure model for use in connection with the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulations in Europe – the model is known as the Advanced REACH Tool or ART.
IOM scientists have developed a strong interest in the assessment of dermal exposure, leading to the enumeration of new principles of exposure assessment, the development of predictive exposure models, and investigations into dermal exposure under specific working conditions. Estimating historical skin exposures of farmers dipping sheep in pesticide solutions for an epidemiological study proved particularly challenging, but this research demonstrated a strong association between concentrated organophosphate pesticides and neurological symptoms.Pilkington A, Buchanan D, Jamal GA, Gillham R, Hansen S, Kidd M, Hurley JF, Soutar CA. (2001) An epidemiological study of the relations between exposure to organophosphate pesticides and indices of chronic peripheral neuropathy and neuropsychological abnormalities in sheep farmers and dippers. Occup Environ Med; 58: 702-710. As a consequence the UK government withdrew these pesticides from the market until safer handling systems were devised. In addition, new sampling instruments to measure dermal exposure to chemicals and new theoretical models to help understand how skin exposure may arise. These instruments and models may in the future help provide more reliable assessments of the risks from chemicals to the skin. IOM scientists are also developing a molded cassette with a 15mm inlet for use as a personal sampling pump to test inhalable dust levels.
Other research at IOM has shown that chronic fatigue is common amongst those who consider their health is affected by pesticides and suggested there was an association between exposure to organophosphates and chronic fatigue symptoms.
Human sciences and personal protective equipment