INSTITUTE OF OCCUPATIONAL MEDICINE . Edinburgh . UK www.iom-world.org
Things just keep getting better
John CherrieI want
to
ELIMINATE
workplace
cancer
Summary…
• Exposures change over time, almost always decreasing
• What is the evidence for this? • Why are companies acting to
reduce exposures? • Is it true for all substances in
every country?
Exposure decreases over time…
Creely KS et al. (2007) Trends in inhalation exposure--a review of the data in the published scientific literature. Ann Occup Hyg.; 51(8): 665-678.
Aerosols
Exposure decreases over time…
Creely KS et al. (2007) Trends in inhalation exposure--a review of the data in the published scientific literature. Ann Occup Hyg.; 51(8): 665-678.
Gases and vapours
Exposure decreases over time…
Creely KS et al. (2007) Trends in inhalation exposure--a review of the data in the published scientific literature. Ann Occup Hyg.; 51(8): 665-678.
Fibres
Let’s do a thought experiment…
• Start with a singe factory and follow it’s progress in controlling exposures over 10 years
• Repeat at different plants and see how the pattern builds up
Simulated exposure reduction at a plant
Five plants…
Ten plants…
25 plants…
Flour dust…
van Tongeren M et al. (2009) Trends of flour dust exposure in the United Kingdom, 1985–2003 Environ. Monit., 2009, 11, 1492 – 1497.
VCM levels in a English PVC plant
12
What changes?
• High pressure water jet cleaning
• Removal of VCM residues by stripping
• Improved general ventilation
• Use of scale inhibitors• Extraction on open
reactor vessels• Reduce leaks• Air monitor• Breathing Apparatus
Investigation of changes in exposure…
Galea KS et al. (2009) Trends in Wood Dust Inhalation Exposure in the UK, 1985–2005. Ann.Occ.Hyg.
Things changed…
What were the determinants of change?
• Economic• Market downturn – reduced production, less people• Improved efficiency – buying in ready-made
components
• Legislation• Environmental – achieve emissions targets• Health and safety – inspection visits, prosecution
• Safety culture• New owners – larger company• New managers – new ideas
What were the determinants of change?
Is this a “universal truth”!
Friesen MC et al. (2012) Combining a Job-Exposure Matrix with Exposure Measurements to Assess Occupational Exposure to Benzene in a Population Cohort in Shanghai, China. Ann Occup Hyg;56:80–91.
Benzene levels in China
Time trends in exposure…
Rubber - Crude Materials, Compounding and Mixing
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
mg/
m3
NetherlandsUnited KingdomPolandGermanySweden
Time trend
per year
UK : -6%
NL : -2%
PL : -6%
SW : -6%
GE : -7%
http://exasrub.iras.uu.nl/content.html
Agostini et al. Exposure to rubber process dust and fume since 1970s in the UK; influence of origin of measurement data. J. Environ. Monit. (2010) vol. 12 (5) pp. 1170
But not always!
Vermeulen R, Coble JB, Lubin JH, et al. The Diesel Exhaust in Miners Study: IV. Estimating Historical Exposures to Diesel Exhaust in Underground Non-metal Mining Facilities. Ann Occup Hyg 2010;54:774–88.
The Theory of Planned Behaviour
Behavioural beliefs
Attitude towards the behaviour
Normative beliefs
Subjective norms
Control beliefs
Perceived behavioural
control
Intention Behaviour
Actual behavioural
control
http://people.umass.edu/aizen/tpb.diag.html
Summary…
• In most situations exposure appears to decrease over time by between about 5% and 15% per annum
• Modestly effective controls implemented every three or four years is sufficient to explain these trends
• The most likely explanation is improving manufacturing efficiency
• There are some exceptions to the rule!
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