2. Summary…
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Current occupational cancer burden in
Great Britain
What are the main causes identified in this
work and how many people are affected?
What substances can we reasonably ignore
as part of this initiative?
What about the cancer burden in the
future?
Do these data apply elsewhere?
Rushton L, Hutchings SJ, Fortunato L, et al. Occupational cancer burden in
Great Britain. Br J Cancer 2012;107:S3–S7.
3. Background…
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Over 1 million cancer deaths in Europe each
year and about 5% may be due to work
The commonest cancers are:
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breast cancer (13.5% of all cancer cases and
29% of cancer cases in women)
colorectal cancers (12.9%) and
lung cancer (12.1%)
Important differences incidence between
countries
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e.g. about a two fold difference for men between
the highest (Hungary) and the lowest (Bulgaria)
3
4. The British study…
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Current Burden of Occupational Cancer:
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to develop and apply methodology to estimate
current attributable risk, cancer numbers and DALYs
caused by work
to identify important cancer sites
to identify industries and occupations for targeting
for reduction measures
Prediction of Future Burden of Occupational
Cancer:
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Estimate size of future burden based on current and
past exposures
Identify cancer sites, carcinogens and industry
sectors where the burden is greatest
Demonstrate effects of measures to reduce exposure
5. Current Burden Methodology…
• Attributable fraction (AF): the proportion of cases due to
occupation Requires:
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Risk of Disease (Relative Risk estimates from published
literature)
•
Proportion of Population Exposed (derived from national data
sources, accounting for employment turnover and life
expectancy; adjusted for employment trends)
• Define period of relevant exposure: Risk Exposure Period
(REP) based on cancer latency
• Dose-response risk estimates and proportions ever exposed
over the REP at different exposure levels not generally
available; data therefore obtained for ‘higher’ and ‘lower’
levels
• AFs used to calculate attributable numbers (ANs)
• Estimation for IARC groups 1 (definite) and 2A (probable)
carcinogens and occupational circumstances
10. Industry Sector
Attributable Registrations
Male
Female
Total
Exposures
Construction
4573
64
4637
14
Painter + decorators
331
3
334
1
Roadmen + roofers
471
0
471
1
5375
68
5442
16
0
1969
1969
1
1083
169
1252
1
Personal + household services
256
403
659
17
Land Transport
454
42
497
9
Mining
283
12
296
10
Printing, publishing and allied trades
232
50
282
10
Public administration and defence
229
34
263
6
51
136
187
11
Farming
180
39
220
5
Welders
165
16
181
2
Manufacture of instruments, etc
204
2
206
6
Manufacture of transport equipment
164
18
182
16
Non-ferrous metal basic industries
122
34
156
18
Total construction
Shift work (including flight personnel)
Metal workers
Wholesale + retail trades
11. Predicting Future Burden in
Britain…
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AFs estimated for forecast years, e.g. 2010, 2020
… 2060
Define the risk exposure period (REP) for each
year e.g. for 2030, 1981 – 2020 (10-50 years
latency assumed for solid tumours e.g. lung
cancer, 0-20 years for leukaemia)
Some past and some future exposure until 2060
Workers at the beginning (2010) assumed to be
of all working ages
Workers recruited through employment turnover
are assumed to be only aged 15-24
Factors stay the same as 2004/5
12. Predicting Future Burden in Britain…
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Use 4 levels of exposure
High/Medium/Low/Background
Method effectively shifts the proportion of workers
exposed in different exposure level categories
(H/M/L/B) across time as exposures gradually
decrease
Forecasted numbers take into account employment
turnover and employment trends
Methods applied to top 14 carcinogens/occupations
identified as accounting for 85.7% of total current
(2004) cancer registrations
Forecast GB total cancers (deaths and registrations)
based ONLY on demographic projections (ONS) and
assuming all non-occupational risk
13. Forecast Risk Exposure Periods – 10-50 year
latency
REPs
‘Known’ exposure
1961-70
1971-80
FTYs
Forecast exposure
1981-90
1991-00
2010
2001-10
2020
2011-20
2030
2021-30
2040
2031-40
2050
2041-50
10 year estimation intervals
REP Risk exposure period
FTY Forecast target year
2060
14. Change in future exposure:
Scenarios
Estimates made for alternative scenarios of changes
in exposure levels and/or numbers exposed
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(1) Baseline scenario - based on pattern of past
exposure, but no future change in exposed
numbers or exposure levels
(2) Baseline trend scenario - based on pattern of
past and current exposure, and on linear
projections up to 20 years into the future, after
which levels assumed constant due to prediction
uncertainty.
(3) ‘Intervention scenarios’ also based on past
and current exposures, and suitably chosen
target exposure levels in the future
15. Change in future exposure:
Interventions
Can test:
Introduction of a range of possible OELsor
reduction of a current limit
• Improved compliance to an existing exposure
standard
• Planned intervention such as engineering controls
or introduction of personal protective equipment
• Industry closure
Also can vary:
• Timing of introduction (2010, 2020 etc)
• Compliance levels e.g. according to workplace
size (self-employed, 1-49, 50-249, 250+
employees)
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19. Attributable Numbers of Cancer Registrations
Scenarios
All
Base (1)
Exposure
Cancer Site
2010
Exposure defined by agent; no appropriate exposure measurements
ETS
Lung
1465
0
Coal tars
Radon
Solar radiation
NMSC
Lung
NMSC
Trend (2)
(3)
(4)
(5)
(6)
2060
0
67
156
489
220
1749
Occupational circumstances, no specified carcinogen
Painters
Bladder, Lung,
461
Stomach
800
379
3069
877
411
3279
602
341
2552
475
317
2030
433
309
1503
402
190
163
640
639
481
383
347
321
Shift work
Welders
3062
140
3848
63
2134
105
1178
83
194
76
0
70
92
47
92
88
87
87
2759
2864
2785
2689
2626
2307
380
837
122
406
794
39
399
442
7
451
102
19
412
49
12
374
21
10
34
10
12
286
123
30
22
8
5
6
139
135
119
123
118
117
119
12050
12327
12938
9812
7944
6064
3705
Breast
Lung
1649
189
Carcinogens for which exposure standards can be set
Arsenic
Lung
128
Asbestos
Larynx, Lung Mesothelioma,
4281
Stomach
Diesel
Silica
Strong acids
TCDD (Dioxins)
Bladder, Lung
Lung
Larynx, Lung
Lung, NHL, STS
Tetrachloroethylene
Cervix, NHL, Oesophagus
Total
20. Monitoring success…
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The only practicable approach is to
monitor exposure levels
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No reduction in cancer levels until 2030 at
earliest (for solid tumours)
After 2030…
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Use achieved exposed numbers/proportions
exposed at new exposure levels in same
(target setting) forecast model to get achieved
AF
Apply achieved AF to same (2005 based)
cancer projections to get achieved attributable
numbers
Do not apply achieved AF to real 2030 cancer
numbers
21. Uncertainties and the impact on the
burden estimation
Source of Uncertainty
Potential impact on burden estimate
Exclusion of IARC group 2B and unknown
carcinogens e.g. for electrical workers and
leukaemia
↓
Inappropriate choice of source study for risk
estimate
Imprecision in source risk estimate
↑↓
Source risk estimate from study of highly exposed
workers applied to lower exposed target population
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Risk estimate biased down by healthy worker effect,
exposure misclassification in both study and
reference population
↓
Inaccurate latency/risk exposure period, e.g. most
recent 20 years used for leukaemia, up to 50 years
solid tumours
↓
Effect of unmeasured confounders
Unknown proportion exposed at different levels
↑↓
↑↓
↑↓
22. Cancer burden elsewhere…
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China
Li P, Deng S-S, Wang J-B, et al. Occupational and environmental cancer incidence and
mortality in China. Occup Med (Lond) Published Online First: 12 March 2012.
doi:10.1093/occmed/kqs016
23. Mesothelioma mortality rate
Delgermaa V, Takahashi K, Park E-K, et al. Global mesothelioma deaths reported to the World
Health Organization between 1994 and 2008. Bull World Health Organ 2011;89:716–724C.
24. Summary…
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Currently about 8,000 deaths and 14,000 cancer
cases due to past work in Britain
Most deaths from lung cancer, mesothelioma and
breast cancer
Most deaths associated with the construction
industry
Future burden could be much lower with
appropriate interventions
Respirable crystalline silica – we need better
compliance (and a lower limit)
Best interventions differ by agent
Monitoring exposure is the best way to track
progress
Hinweis der Redaktion
Studies could be:population or industry basedsingle or pooled study meta-analysisSelected studies with comparable exposures to GB:Large sample sizeClear case definitionAppropriate comparison populationControlled for confounders where possibleAdequate exposure assessmentNational data sources used to get the numbers ever exposed. CAREX – CARcinogen Exposure database – gives the estimated numbers exposed by country, carcinogen and industry. Included 139 agents evaluated by IARC as Groups 1,2A and some 2B across 55 industrial classes of the UN system ISIC. However, the prevalences were largely based on US and Finnish (FINJEM) rates and applied to numbers employed in the industry of other countries. LFS series of 2% household based samples from 1973Census of employment etc employer based surveys from 1971 – gives numbers by sex/ full and part time/ 4 digit SIC code.Numbers ever worked from UK population of numbers of working age over the REP – gave denominator for the proportion.Adjusted for turnover, new workers and people retiring and dying + change in broad trends in employment patterns e.g. Service industries going up, manufacturing going downThree international workshops held during the project to discuss and develop the methodology. Helped to focus the assumptions we had to make to take account of inherent limitations in available data. These included:Pragmatic decision about REP and cancer latencyDecision to assign industry sectors to ‘higher’ and ‘lower’ i.e. had proportions exposed over the REP at these two levels and then used published literature to select appropriate risk estimates for these levelsDecision to use IARC group 1 and 2A. NB study carried out using classifications in place at end of 2008. In 2009 IARC reviewed all class 1 carcinogens so if we estimated burden now more cancer sites would be included e.g. asbestos and cervical cancer, colorectal cancer
Example using silica.We know from exposure data that currently compliance to the current limit of 0.1mg/m3 is only about 33%. Table shows the impact of improving compliance compared with lowering a standard.Could vary both of these and the timing of introducing the standard. Can also express this in terms of DALYs which can be fed into economic analysesDecisions can be made on the scenarios, the AFs, ANs, DALYs etc
Right hand graph shows the AFs for each scenario.No difference between them until after 2030Left hand graph shows the same scenarios for each forecast yearShows no difference in attributable cancers between the scenarios up to 2030.Also because the total nos of lung cancers will rise anyway due to the rise population and rising proportion of the elderly the numbers of attributable cancers rises until after 2020.General conclusion is that whatever the intervention there is no impact until after 2030 because of the legacy of past exposures.
This example assumes we have halved the current limit and then tests how effective improving compliance is by workplace size. The most effective interventions are the last 2 when a) compliance improves in those companies employing less than 50 employees (200 more saved compared with previous intervention when compliance is improved in only those companies employing more than 50 employees)b) All workplaces have improved compliance including the self-employed (another 200).This is because silica exposure now occurs largely in the construction industry which is largely small companies and the self-employed.
Will rise to nearly 13,000 by 2060 given current trends in employment and exposure levels (>12,300 if current levels maintained). Aging population is a factor.No impact seen until 2030 because of general increase in cancers due to aging populationWith modest intervention (e.g. scenario 3) over 2,000 cancers can be avoided (including 376 lung, 928 breast cancers, 432 NMSC)With stronger interventions (e.g. scenario 6) nearly 8,500 can be avoided (including 1,732 lung, 3,062 breast and 3,287 NMSC)Effective interventionsSilica - improve complianceDEE - need for v. low exposure limit indicatedShift work – If increasing risk with duration of exposure is valid then limiting years of night work reduces burdenIntervention scenariosETS: Compliance (3) 98% services 90% other (4) 95%/80%Radon: Reduce exposed numbers by 10% in (3) 2010, (4) 2020, (5) 2030, (6) 50% in 2010Solar radiation: Move (3) 1/3, (4) 2/3, (5) all to next lower exposure category resp., (6) move all to lowest exposure categoryShift Work: Restrictions on length of employment result in (3) 20% 30% 50%, (4) 10% 20% 70%, (5) 0% 10% 90%, at 15+ years, 5-14 years and <5 years resp. (6) 100% at <5 yearsFor occupations (and coal tars), excess risk reduced to: (3) 75%, (4) 50%, (5) 25% of current risk in 2010, 2020, 2030 resp., (6) 50% of current risk in 2010For chemicals: (3) = existing (asbestos, RCS) or proposed standard, 90% compliance (4) = half this standard (5) = quarter of standard (except asbestos, DEE where 10%) (6) = existing/proposed standard, 99% compliance (except asbestos, DEE where 1% of standard, 90% compliance)Intervention (3) for the chemical agents represents 90% compliance to an existing (RCS, asbestos) or possible standard, e.g. 0.1 mg/m**3 for DEE based on a standard used in Austria or our estimated H/L boundary exposure levels for arsenic, strong acids and tetrachloroethylene (L/B for TCDD). H/L was chosen as these carcinogens are either genotoxic or possibly genotoxic there is no recognised threshold below which excess risk can be assumed to be zero (background exposed). For the other agents it represents a 25% reduction in RR for the occupations and for coal tars and a modest limit on night shift work from 30% 40% 30% working 15+, 5-14 and <5 years respectively to 20% 30% 50% in these categories. For radon exposed numbers are reduced by 10%, and for solar radiation a third of workers are moved into the next lowest category of time spent outdoors. Together these interventions would avoid over 2,000 cancers a year by 2060, highlighted green are >100.Intervention (6) for the chemical agents represents 99% compliance to an existing (RCS) or possible standard, e.g. our estimated H/L boundary exposure levels for arsenic, strong acids and tetrachloroethylene (L/B for TCDD). For asbestos and DEE where it represents 90% compliance to a stringent 1/100th of the current exposure standard. For the other agents it represents a 50% reduction in RR for the occupations and for coal tars and a limit on night shift work to <5 years duration. For radon exposed numbers are reduced by 50% immediately, and for solar radiation all workers are moved into the lowest category of time spent outdoors. Together these interventions would avoid over 8,000 cancers a year by 2060, highlighted blue are >100.
The method should be used for comparing the effect of alternative interventions, or comparing avoidable numbers of attributable cancers between exposures. NB don’t apply achieved AF to real 2030 cancer numbers as these will have increased because of the increasing proportions of the elderly. Note: there will probably have been many changes in the contribution of other environment and lifestyle risk factors.