Downloaded 31 times
![Validity...
R² = 0.96
0.0
20.0
40.0
60.0
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100.0
0.0 10.0 20.0 30.0 40.0 50.0 60.0
EstimatedB[a]P(mg/m3)
Measured B[a]P (mg/m3)](https://image.slidesharecdn.com/exposureassessmentforepidemiology2017final-180201230552/75/Exposure-assessment-for-epidemiology-32-2048.jpg)
![Estimates…
Job B[a]P Inhalable dust
Yard Foreman 3 2
Oven top - Airstream 3 2
Wharf Man 5 5
Quench Car Operator 7 6
Foreman - HMAG 7 4
Suprintendent - all areas 9 13
Superintendent - Briquetting 9 14
Foreman - Briquetting 11 14
Oven Foreman 12 5
Process Foreman 12 5
Sampler 15 18
Backend man 16 21
Press Operator 16 13
Pug man 17 22
Screen Man 20 15
Oven Top 30 15
Oven tops - Pre 1970 31 16
Cleaning Bussettes 32 9
Cleaning tar tanks 42 42
Assistant Fitter 44 15
Pump Man 45 3
Shuttle 46 33
Plater - Rigger - Briquetting 47 36
Plater - Rigger - liquid pitch 55 34
Shift Fitter 64 23
Plater - Rigger 77 33
Pitch Man 101 7
Rough Brush Painter 204 157
Job No Start End Job Duration
(yr)
Average %
of job
B[a]P
Exposure
(μg/m3)
Cumulative
(μg/m3.yr)
1a J-52 J-54Pug 2.00 33% 13 10
1b J-52 J-54Press 2.00 33% 13 9
1c J-52 J-54Backend 2.00 33% 10 8
2 J-54 J-56Fitter 2.00 100% 66 149
3 J-56 J-61Shift Foreman 5.00 100% 32 178
4 J-61 J-71Shift
Superintendant -
Whole plant
10.00 100% 18 203
5 J-71 J-80Shift
Superintendant -
Briquetting plant
8.59 100% 17 160
Total J-52 J-80 31.58 23 716](https://image.slidesharecdn.com/exposureassessmentforepidemiology2017final-180201230552/75/Exposure-assessment-for-epidemiology-35-2048.jpg)
Uploaded byUniversity fo Aberdeen and IOM
Exposure assessment for epidemiology
The document discusses occupational epidemiology focusing on exposure estimation to hazardous substances, with specific emphasis on asbestos and its health risks, including the potential for lung cancer and mesothelioma. It covers methodologies for assessing exposure, occupational exposure limits, and highlights a case study of asbestos in urban environments. The importance of quantitative exposure assessment is underscored as central to reliable risk evaluation.
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Exposure assessment for epidemiology
- 1. Occupational Epidemiology and ExposureEstimation John Cherrie
- 2. Summary… • asbestos andman-made mineral fibres • a general definition of exposure and the exposome • from the source to dose • the occupational history • strategies for estimating exposure • occupational exposure limits • a case study - asbestos in the city
- 3. Scope of thissession... • Mostly occupational (and some environmental) • Chronic exposure • To hazardous substances • By inhalation • Occupational epidemiology • Non-occupational epidemiology / risk assessment
- 4. Asbestos… • Stanton andWrench(1972) and Pott and Friedrichs (1972) in vivo induction of mesothelioma • Mid-1970s glass and rockwool industries commission studies • Doll (1955) lung cancer • Wagner et al (1960) mesothelioma • 1964 New York conference
- 5. Asbestos lung cancerepidemiology…
- 6. European MMMF studies… •Five glasswool plants, seven rock/slagwool plants and two glass continuous filament plants • Total of 13,788 subjects • Employed between 1940 and 1978 Lung cancers SMR 95% CI Rock/slag 97 138 112 - 168 Glasswool 149 112 94 - 132 GCF 14 93 51 - 157
- 7.
- 8.
- 9. Co-exposures… • Asbestos – Usedin some form or other in all of the plants – Four plants used cloth, yarn or cement products in production processes • Polycyclic Aromatic Hydrocarbons (PAH) – Bitumen and tar used in some plants • Polychlorinated Biphenyls (PCBs) • Ionising radiation • Formaldehyde • Possible arsenic exposure
- 10.
- 11. Definition of exposure... “Inepidemiology exposure denotes any of a subject’s attributes or any agent with which he or she may come into contact that may be relevant to his or her health.” Armstrong, White and Saracci (1990)
- 12. Two-thirds of thedeaths in the world are caused by noncommunicable diseases, especially cancer and cardiovascular disease Only about 10% of this mortality attributed to genetic variation
- 13. The exposome iscomposed of every exposure to which an individual is subjected from conception to death. Chris Wild
- 14. The Exposome… • Theexposome is composed of every exposure to which an individual is subjected from conception to death. • It comprises: – processes internal to the body such as metabolism, gut microflora, inflammation… – external exposures including infectious agents, chemical contaminants, diet… – social, economic and psychological influences. Wild, C. P. (2012). The exposome: from concept to utility. International Journal of Epidemiology, 41(1), 24–32.
- 15. Agnostic investigations… • SteveRapport recommends searching for potential causes without any prior hypothesis • Approach lends itself to “omics” technologies • Although other approaches can also adopt this approach • Follow-up with more focused epidemiological and mechanistic studies
- 16. From source todose
- 17. Routes of exposure... •Inhalation – exposure level, duration of exposure • Dermal – concentration on skin, area of skin exposed, duration of exposure • Ingestion – mass of chemical being swallowed
- 18. Biological relevance... • Thechosen exposure metric should be biologically relevant – what substance – what averaging time – what sub-fraction of an aerosol Cherrie and Aitken. Measurement of human exposure to biologically relevant fractions of inhaled aerosols. Occup Environ Med (1999) vol. 56 (11) pp. 747-52
- 19. Biological relevance… Cherrie andAitken. Measurement of human exposure to biologically relevant fractions of inhaled aerosols. Occup Environ Med (1999) vol. 56 (11) pp. 747-52
- 20. Fibre analysis criteria... •Fibres are harmful because… – they are thin (d < 3mm) – they are long (l > 5mm) and – because of their shape (l/d > 3) • also because they are persistent in the lung
- 21. Modern measurement… • Personalsampling is straightforward • More relevant to personal exposure • Are more biologically relevant • Can provide information on temporal variation Cherrie. The beginning of the science underpinning occupational hygiene. The Annals of Occupational Hygiene (2003) vol. 47 (3) pp. 179-85
- 22. Information sources for assessingexposure in epi... • Personnel records • Other company records • Subject • Relatives or friends • Co-workers • Community records • Environmental monitoring records
- 23. Strategies for assessment... •Industry • Job title • Job-Exposure matrices • Individual “expert” evaluation • Exposure measurements • Biological monitoring
- 27. Historic monitoring data... •Benefits… – quantitative data • Drawbacks… – may be unbalanced or incomplete – changes in sampling or analytical methods – variations in sampling strategy – changes in process or control measures
- 28.
- 30. Work area determinesexposure level…
- 31. Structured assessment based ontheory… Where... ei = intrinsic emission h = handling hlv = local controls etc. C=f(ei , ℎ, hlv…)
- 32. Validity... R² = 0.96 0.0 20.0 40.0 60.0 80.0 100.0 0.010.0 20.0 30.0 40.0 50.0 60.0 EstimatedB[a]P(mg/m3) Measured B[a]P (mg/m3)
- 33. Estimates made usinga spreadsheet…
- 34.
- 35. Estimates… Job B[a]P Inhalabledust Yard Foreman 3 2 Oven top - Airstream 3 2 Wharf Man 5 5 Quench Car Operator 7 6 Foreman - HMAG 7 4 Suprintendent - all areas 9 13 Superintendent - Briquetting 9 14 Foreman - Briquetting 11 14 Oven Foreman 12 5 Process Foreman 12 5 Sampler 15 18 Backend man 16 21 Press Operator 16 13 Pug man 17 22 Screen Man 20 15 Oven Top 30 15 Oven tops - Pre 1970 31 16 Cleaning Bussettes 32 9 Cleaning tar tanks 42 42 Assistant Fitter 44 15 Pump Man 45 3 Shuttle 46 33 Plater - Rigger - Briquetting 47 36 Plater - Rigger - liquid pitch 55 34 Shift Fitter 64 23 Plater - Rigger 77 33 Pitch Man 101 7 Rough Brush Painter 204 157 Job No Start End Job Duration (yr) Average % of job B[a]P Exposure (μg/m3) Cumulative (μg/m3.yr) 1a J-52 J-54Pug 2.00 33% 13 10 1b J-52 J-54Press 2.00 33% 13 9 1c J-52 J-54Backend 2.00 33% 10 8 2 J-54 J-56Fitter 2.00 100% 66 149 3 J-56 J-61Shift Foreman 5.00 100% 32 178 4 J-61 J-71Shift Superintendant - Whole plant 10.00 100% 18 203 5 J-71 J-80Shift Superintendant - Briquetting plant 8.59 100% 17 160 Total J-52 J-80 31.58 23 716
- 36. Occupational Exposure Limits (OELs)… •Concentrations (e.g. mg/m3) averaged over either 8-hr or 15-min • Personal exposure • Each country sets its own limits, – There can be up to two orders of magnitude difference Health-based OEL OEL based on socioeconomic factors
- 37. Setting limits onexposure… • In Europe The Scientific Committee on Occupational Exposure Limit Values (SCOEL) advises the EC on OELs – assemble all relevant data on the hazards of the substance – determine whether it is adequate for the setting of an OEL – identify the most important adverse effects that may arise – review the quality of key studies. – establish whether there is a non-threshold mechanism – establish a ‘no observed adverse effect levels’ (NO(A)ELs) or ‘lowest observed adverse effect levels’ (LO(A)Els) – establish a value for an 8-hr OEL, plus Uncertainty Factor – can the OEL be measured Bolt, H.M. & Huici-Montagud, A., 2008. Strategy of the scientific committee on occupational exposure limits (SCOEL) in the derivation of occupational exposure limits for carcinogens and mutagens. Archives of Toxicology, 82(1), pp.61–64.
- 38. Some problems withOELs… • As an example, respirable crystalline silica – Silica causes silicosis, COPD and lung cancer – We currently have an OEL of 0.1 mg/m3 – Many workplaces don’t comply with this limit but few are prosecuted – The cancer risks associated with long-term exposure at the OEL are high – Surely we should reduce the limit… ... but we’re not
- 39. Asbestos in thecity... • Asbestos roofing dumped near a school • Children have broken into the bags and were playing with the asbestos • How do you advise the parents?
- 40. Asbestos… • a groupof six naturally occurring fibrous silicate minerals which have been used commercially… – chrysotile (white) – crocidolite (blue) – amosite (brown) • can cause asbestosis, lung cancer and mesothelioma aWARNING CONTAINS ASBESTOS Breathing asbestos dust is dangerous to health Follow safety instructions
- 41. A serious publichealth risk...
- 42. The risks... • forlung 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
- 43. Mesothelioma risk fora child... Age 10, exposed to 1fibre/ml for one day
- 44. So what shouldwe do?
- 45.
- 46. What are yourconclusions?
- 47. Summary... • exposure estimationis central to reliable risk assessment • quantitative exposure assessment is more useful than categorical evaluations • even short-term exposure to asbestos may create important risks Useful information… Human Exposure Assessment (IPCS EHC214) available at www.inchem.org/documents/ehc/ehc/ehc214.htm
Editor's Notes
- #3 2
- #4 3
- #5 4
- #6 5
- #7 6
- #8 7
- #9 8
- #10 9
- #11 10
- #12 11
- #15 HEALTH INEQUALITIES
- #17 16
- #18 17
- #19 18
- #20 Use PAH or Pb as an example here vs Quartz or coal dust – solubility, GI tract absorption
- #21 20
- #23 22
- #24 23
- #25 113 men who worked in an asbestos factory. Example of industry approach
- #26 Nested case-control study. Cohort 31k men – data from pension fund. Job information and limited info about industry only. OR for engine crew for mesothelioma was 9.75, 20 year latency Lymphoma OR = 2.78 amongst Deck personnel on tankers and leukaemia OR = 2.26 to 6.86 depending on duration of employment Example of job-title approach
- #27 OR = 1.13 for low vs no exposure = 1.41 for high vs no exposure
- #28 27
- #32 31
- #33 32
- #35 34
- #36 Pink are jobs where there was measurement data
- #39 Lifetime lung cancer risk associated with 45 years of exposure to crystalline silica: 0.1 mgm-3 13 to 60 per 1,000 0.05 mgm-3 6 to 26 per 1,000 0.025 mgm-3 3 to 23 per 1,000
- #40 39
- #41 40
- #42 41
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- #44 43
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- #48 47