Cancer Mortality of Workers Exposed to Styrene in the US Reinforced Plastics and Composite

32 Pages·2014·1.23 MB·English

James J. Collins, PhD
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Styrene Epidemiology
 Epidemiology studies focus on 3 industries:
 Styrene-butadiene rubber,
 Reinforce plastics from styrene, and
 Styrene monomer /polymer production
 IARC 2002 - “possibly carcinogenetic to humans” –
Category 2B
 Concern - lymphatic and hematopoietic tissues cancers
in epidemiology studies
 “The studies of glass fibre-reinforced plastics workers are the
most informative ….because these workers had higher styrene
exposures and less potential for exposure to other substances
than the other cohorts studied.” (519)
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Relative Risks for Lung Cancers
3
2.5
2
1.5
1
0.5
0
Reinforced Plastics Monomer & Polymers
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Relative Risk
Lung Cancer (Collins et al.)
2 Exposure/Response 2 Number of Peak Exposures
1.5
1.5
S S
M 1 M 1
R R
0.5 0.5

0 0
0.0-149.9 150-399.9 400-1199.9 1200+ None 1 day to 23.9 24 to 59.9 60 or More
Cumulative TWA Months Months Months
Number of Peaks
Exposure/Response with Smoking
1.5
Adjustment 2 Latency
1.5
S 1 S
M M 1
R 0.5 R
0.5

0 0
0.0-149.9 150-399.9 400-1199.9 1200+ 0-14.9 15-29.9 30+
Cumulative TWA
Years Since First Exposure
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Lung Cancer Etiology – Collins et al.
 Earlier nested c-c study of lung cancer cases indicated
smoking cause of lung cancer excess.
 Updated study supported this conclusion:
 No increased risk with increasing styrene exposure,
increasing peak exposures, or latency
 Increase in cancers (bladder, kidney) & other causes (non-
malignant respiratory , heart disease) associated with
smoking
 Adjustment for smoking (bronchitis, emphysema, and
asthma) produced flat exposure/response
 Limitation – No formal assessment of smoking in recent
update

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Lung Cancer (Ruder et al. Study)
2.5
Exposure/Response
2
S
1.5
M
1
R
0.5

0
Low Exposure High Exposure
2
Duration
1.5
S
M 1
R 0.5
0
Short Term (1 Year or Long Term (Over 1
Less) Year)
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Lung Cancer Etiology – Ruder et al.
 Workers ever exposed to high levels of styrene had
higher lung cancer rates than worker never exposed
to high levels
 Lung cancer excess limited to short term workers
 Limitations
 Relatively small study
 Qualitative exposure assessment
 Workers classified by longest job held

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Lung Cancer (Kogevinas et al.)
1.6
Exposure/Response
1.4
1.2
1 Tz
S
M 0.8
R 0.6

0.4
0.2
0
<75 ppm-years 100-199 200-499 500+
Cumulative TWA
Table 5 (page 258) Poisson regression
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Lung Cancer Etiology – Kogevinas
et al.
 No excess of lung cancer observed and no relation with
exposure to styrene
 Limitations
 Exposure assessment
 may not be comparable across all countries in study
 workers classified by longest held job

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