The Institute of Occupational Medicine and its research publications: 1990-2005

• Part 1: Introduction
• Part 2: Epidemiology of occupational lung disease
• Part 3: Dust toxicity
• Part 4: Exposure assessment

• Part 5: Epidemiological studies...
• Part 6: Fibre research
• Part 7: Management of health at work
• Part 8: References

On April 1st 1990, the Institute of Occupational Medicine became fully independent as a self-supporting charitable organisation, its purpose being to provide quality research, consultancy and teaching services in health, hygiene and safety, and to maintain an independent position as an international centre of scientific excellence.

With the new status came a shift from research programmes to shorter term externally funded research projects, increasing the number of principal scientists seeking and supervising work, and the application of multidisciplinary skills to solving a wider range of topical and novel problems. In some topic areas where sponsor needs and IOM expertise attracted a series of projects on related topics, serial contributions to generally applicable knowledge were made. Other studies responded to self-limiting needs for information on specific topics.

Chemical analysis using mass spectrometer

The following commentary refers to IOM research reports in the period 1990-2005, and also some papers in peer review journals where important IOM work was not represented in the research reports. All the studies were of course performed in the context of the international research effort, not described in this commentary.

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Epidemiology of occupational lung disease

With the privatisation of British Coal, IOM research in the coal industry declined, though the Pneumoconiosis Field Research data remained a rich source of information on risks of coal pneumoconiosis and silicosis, occupational bronchitis and cancer.

Control limits for occupational exposure to crystalline silica continue to be a major international concern, and IOM has, with a series of studies of a population of miners for whom uniquely detailed data on silica exposure were available, been able to define exposure response relations for silica with unusual precision. The work demonstrated the need for very low limits on airborne exposure, and that very high risks result from even relatively brief exposures to respirable silica concentrations above 2mg.m3. (TM/01/03, Buchanan et al 2003).

Additionally, epidemiological studies of risks of silicosis were conducted on behalf of the hard rock quarrying (TM/92/10 [ 5Mb, 13mins/22secs] ), open cast mining (TM/92/03 [ 4Mb, 10mins/17secs] ) and heavy clay industries (TM/94/07 [ 5Mb, 12mins/21secs] ), and apparently lower risks of silicosis in the heavy clay industry than in high risk industries are currently being explored (TM/04/02). Surveys of the population exposed to silica-containing dust from the volcanic eruptions on the island of Montserrat showed that risks of silicosis were low ( TM/01/07, TM/02/02).

While exposure-response relationships for pneumoconiosis had been well established, and appropriate control limits applied by coal industries worldwide, it was not clear whether these limits were sufficient to prevent also the airflow obstruction associated with dust exposure. Hilary Cowie among others defined the exposure-response relationships in coal miners between clinically relevant deficits of lung function and dust concentrations experienced over a working lifetime (TM/99/06, Cowie et al 2006). Comparisons showed that dust control sufficient to prevent pneumoconiosis would also prevent most cases of important functional deficits (Soutar CA et al).

An important question is whether these risks of airflow obstruction can be extrapolated to other occupational insoluble dusts. By developing and validating mathematical models of accumulated lung dust burden and resulting inflammation, based on laboratory studies, Lang Tran and his co-workers confirmed that the toxicity of insoluble dusts of different compositions can be predicted according to their surface area (HSE CRR216/1999, Tran CL et al 2000).

In addition, Miller et al made an initial assessment of the feasibility of extrapolating these risks from coal miners to working populations exposed to other dusts (HSE RR470/2006). This work is important and it is hoped that it can be developed further.

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Dust toxicity

During the period, toxicological investigations of specific dusts (from the London Underground (TM/95/01 [ 5Mb, 13mins/22secs] ), from volcanic eruptions (TM/02/01), and wool mill dust (TM/93/04)) were succeeded by mathematical modelling of the quantitative toxic effects of inhaled dusts including man-made mineral fibres, coal dust, silica, and chemically inert mineral dusts (TM/94/01, Tran CL et al 2000, TM/01/04, HSE RR141/2003, Tran CL et al 2003, TM/94/01).

Studies demonstrated that surface area is a major determinant of the toxicity of inhaled chemically inert dusts (HSE RR141/2003 ). These models were used to predict possible harmful effects of exposure to nanoparticles in new technological developments (HSE RR274/2004).

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Exposure assessment

Reliability of exposure assessment is essential for good exposure-response epidemiology, and for protection of the individual. IOM’s many years of experience with prospective exposure measurement programmes was then applied to retrospective exposure assessments with various degrees of sophistication. In some cases where previous dust concentrations were not known, only current concentrations combined with job histories could be used as surrogates for past exposures (TM/92/07). In another it was possible to adjust such estimates systematically according to documented changes in manufacturing process (TM/94/07 [ 5Mb, 12mins/21secs] ).

In a study of refractory ceramic fibre workers, information from a previous survey of dust concentrations as well as a recent survey was available, and reasonably reliable past relative exposures could be estimated (TM/99/01 [ 15Mb, 36mins/1mins] ).

Developing interest in the assessment of dermal exposures led to the enumeration of new principles of exposure measurement (Cherrie JW and Robertson A 1995, CRR117/2003, TM/04/07), study of predictive exposure models (Creely KS et al 2004, Cherrie JW and Hughson GW 2005), and a series of investigations of dermal exposure under specific conditions.

Estimating historical skin exposures of farmers dipping sheep in pesticide solutions proved particularly challenging, and was solved by measuring exposures during typical dipping activities, modelling these exposures in relation to characteristics of the activity, then applying the model to newly obtained task histories, to estimate individual historical exposures (TM/99/02a [ 8Mb, 20mins/33secs] , TM/99/02c [ 6Mb, 15mins/25secs] ).

Evaluating personal protection

Methods were also developed for estimating exposures to musculo-skeletal stresses in studies of back pain and upper limb disorders (TM/93/05, TM/99/03 [ 5Mb, 11mins/19secs] ), and the range of exposures to isocyanates in Britain was assessed (HSE RR311/2005).

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Epidemiological studies, risk assessment, exposure assessment

Occupational epidemiological studies in addition to those elsewhere mentioned included respiratory health in refractory ceramic fibre workers (TM/01/07), respiratory and cardiovascular morbidity in steel workers (TM/96/05 [ 8Mb, 20mins/33secs] ), neuropathy in sheep farmers (TM/99/02c [ 6Mb, 15mins/25secs] ), and mortality of coke workers and steel workers (TM/96/06), among others.

An increasing trend has been to participate in international studies, of vitreous fibre production workers (Boffetta P et al 1997), rock/slag wool workers (Consonni D et al 1998) and titanium dioxide production workers (Boffetta P et al 2004).

Epidemiological studies of the relations between asthma and occupation were conducted in stock farmers (TM/95/06 [ 6Mb, 15mins/26secs] ), in furniture upholsterers (TM/93/02 [ 6Mb, 14mins/23secs] ), and in the general community (TM/97/01 [ 5Mb, 11mins/19secs] , TM/97/05). The latter study cast some doubt on claims based on uncontrolled clinical studies that occupational asthma leads to a higher rate of unemployment than normal.

Skills in retrospective exposure and health risk estimation were also applied to estimation of the health risks associated with environmental exposure to urban air pollution (TM/01/08, Miller BG 2001), including to some specific agents, and asbestos (TM/05/01,TM/05/07).

Valuable work on development of air samplers continued (Aitken RJ et al 1993, 1999, Jones AD et al 2005).

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Fibre research

The Colt Foundation, industry sources and the Health and Safety Executive generously supported a programme of laboratory research into the health effects of man-made mineral fibres that helped to clarify the quantitative relations between health risks and fibre dimensions and biopersistence.

A series of reports described methodological issues and initial results. The final results and statistical analyses of relationships were described in papers in peer review journals (Miller BG 1999a, b).

IOM remains among the leaders in development of techniques of measurement of asbestos and other fibres; continuing to develop proficiency testing schemes (Brown PW et al 2002), providing reference standards (Tylee BE et al 1996) and new methods of airborne sampling (HSE CRR349/2001).

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Management of health at work

A series of investigations of management issues of health at work (HSE CRR445/2002) including in construction (HSE CRR447/2002), and farming, and on stress led to the design of an interactive database for recording and monitoring information on sickness absence including work-relatedness, intended for general use (HSE RR310/2005).

Experience of the management of working in hot and humid conditions underground led to the development of a code of practice (TM/97/06 [ 5Mb, 13mins/22secs] ) a draft British Standard for the assessment of heat strain for workers wearing protective equipment (TM/99/03 [ 5Mb, 11mins/19secs] ), and studies of the degree of protection afforded by firefighters’ clothing (Graveling RA et al 1999).

Reviews

Topics reviewed included such varied subjects as non-auditory effects of noise, incidence of ill health in agriculture, trends in inhalation exposure, multiple chemical sensitivity, and silica exposure and cancer.

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References

• Aitken RJ, Baldwin PEJ, Beaumont GC, Kenny LC, Maynard AD. (1999). Aerosol inhalability in low air movement environments. Journal of Aerosol Science; 30: 613-626.
• Aitken RJ, Vincent JH, Mark D. Application of porous foams as size selectors for biologically relevant samplers. Applied Occupational and Environmental Hygiene 1993; 8: 363-369.
• Graveling RA, Johnstone JBG, Butler DM, Crawford J, Love RG, Maclaren WM, Ritchie P. (1999). Study of the degree of protection afforded by firefighters’ clothing. London: Home Office Fire Research and Development Group. (Research Report Number 1/99).
• Miller BG. (2001). Predicting the impact of reduction in all-cause mortality rates. In: DEFRA. An economic analysis to inform the review of the air quality strategy objectives for particles: a second report of the Interdepartmental Group on Costs and Benefits. London: Department for Environment, Food and Rural Affairs: 107-110.
  

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Dr Colin Soutar, MD, FRCP, FRCPE, FFOM
IOM CEO 1990-2005

I pay tribute to all my IOM colleagues, whose determination, inspiration and loyalty enabled the Institute to thrive through a difficult period of change, and particularly to the scientific leaders Adele Pilkington, Alan Bradley, Alan Jones, Alastair Robertson, Alister Scott, Alison Searl, Brenda McGovern, Brian Miller, Christine Sewell, Dick Cullen, Eugene Waclawski, Fintan Hurley, Geoff Smith, Heather Collins, Hilary Cowie, John Davis, Ken Dixon, Ken Donaldson, Jane Tierney, John Cherrie, Lang Tran, Margaret Hanson, Mark Lovett, Nigel Crawford, Peter Ritchie, Raymond Agius, Richard Graveling, Richard Love, Robert Aitken, Robert Bolton, Robin Howie, Stuart Goddard, Sheila Groat, Trevor Cattermole.

Thanks and congratulations to you all. My best wishes for a successful future go to the IOM and to my successor Philip Woodhead.