A lecture given at the Weightmans Disease Conference, Birmingham 2010

1. The impact of environmental asbestos exposure and it's relevance in cases of low level occupational exposure John Cherrie Research Director www.OH-world.org

2. Summary… Asbestos Historical uses of asbestos and the consequences Risk models Changes over the last 40 years Contaminated land Low-level occupational exposure Background levels Conclusions?

3. 3 Asbestos minerals Serpentine Chysotile (white asbestos) Amphibole Amosite (brown asbestos) Crocidolite (blue asbestos) Tremolite Anthophyllite Actinolite

5. they are long (l > 5mm) and

6. because of their shape (l/d > 3)also because they are persistent in the lung

7. 5 Health effects of asbestos exposure Pleural Mesothelioma Bronchogenic carcinoma Pleural Plaque Asbestosis

8. The epidemiology and toxicology… Doll (1955) lung cancer Wagner et al (1960) mesothelioma 1964 New York conference Stanton and Wrench(1972) and Pott and Friedrichs (1972) induction of mesothelioma in experiments

9. HSE guidance from 1970

10. A serious public health risk...

11. HSE funded research… No evidence of increased risk associated with non-industrial workplaces or ‘low risk’, including motor mechanics and workers handling gaskets and mats Only non-occupational exposure associated with increased risk was living with an exposed worker Increasing trend in female rates suggest mesothelioma with no known occupational or domestic exposure may be caused by environmental asbestos exposure Peto et al. (2009) Occupational, domestic and environmental mesothelioma risks in Britain. Report RR696

12. Occupations affected… Historically, insulation workers, shipbuilders and locomotive engineers Asbestos exposure was widespread About 65% of males and 25% of females at risk worked in medium or higher risk jobs The most frequent occupations on death certificates for mesothelioma include carpenters and joiners; plumbers, heating and ventilating engineers; and electricians and electrical fitters

13. Low exposed jobs… Motor mechanic, Draughtsmen, Engineers, Stores & warehousemen, Armed forces, Drivers & road transport workers Cleaners, Retail workers, Doctors, nurses & hospital workers, Teachers & school workers, Kitchen workers, Office workers

14. Asbestos exposures today...

15. The risks... for lung cancer risk is proportional to cumulative exposure 1% increase in risk for each year at 1 fibre/ml for mesothelioma risk is related to cumulative exposure and age at first exposure where n= 3.2 and KM = 3.10-8

16. Hodgson and Darnton model…

17. 15 Gas masks…

18. 16 Death amongst gas mask workers… 1950 1960 1970 1980 1990 2000

19. 17 Asbestos in soil – where? In brown field sites In green field sites Gardens to be - on construction sites Existing gardens on any brown field site Gardens near major asbestos sites? Gardens in rural areas adjacent to asbestos source?

20. 18 Example of sampling site on tracks

22. 20 Air Sample analysis for low levels… Samples analysed by electron microscopy (SEM or TEM) for asbestos fibres Airborne asbestos concentrations calculated from each sample Often need to combine results from several samples over several days to get the necessary sensitivity

23. Mesothelioma risk…

24. Arc chutes… Arc chutes containing asbestos were fitted over and between the copper components No visible dust but after handling arc chutes there was a white residue on his hands No cutting or drilling required “Sindanyo” - 50% chrysotile (white) asbestos and 50% Portland cement Only 2-days per week in this work Exposure probably < 0.1 fibres/ml Hodgson and Darnton model suggests mesothelioma risk 30 per million

25. Background levels in air…

26. in the UK in 1980s… Risk for children living near an asbestos factory could be between 2 in 10,000 to 2 in 1,000

27. Conclusions… Mesothelioma epidemic is almost at its peak Current incidence represents exposure in 1960s and 70s As time goes on proportionately more cases will come from “low” or “moderate” jobs Past environmental exposure may have been a risk for mesothelioma In the past living with an asbestos work was also associated with a risk

28. My slides are on… www.OH-world.org