Presentation by Laura Bogaert at ON-DECK Knowledge translation even in Vancouver; November 7, 2017

1. The ON-DECK Study:
Results from Crystalline Silica and Asbestos
Exposure Analyses
CE Peters, M-É Parent, SA Harris, L Latifovic, L Kachuri,
L Bogaert, Canadian Cancer Registries Group, PJ Villeneuve

2. Occupational silica and asbestos exposure
Crystalline silica
•380,000 Canadian workers exposed
2
Asbestos
•152,000 Canadian workers exposed
https://www.carexcanada.ca/en/profiles_and_estimates/

3. 3
Silica and asbestos exposure by industry
https://www.carexcanada.ca/en/profiles_and_estimates/

4. 4
Silica and asbestos exposure by industry
https://www.carexcanada.ca/en/profiles_and_estimates/

5. Methods
Exposure assessment
• Occupational hygienists coded jobs for intensity, frequency, duration, and
assigned a reliability index
• We used a few metrics of exposure: ever-exposed, total duration, highest
attained intensity, and tertiles of cumulative exposure (intensity x frequency x
duration)
Statistical analysis
• Unconditional logistic regression to estimate odds ratios (OR) and 95%
confidence intervals
• Final models adjusted for age, province, BMI, secondhand tobacco smoke
exposure at work
5

6. Results
6
727 kidney cancer cases
+ 2,547 controls
3,274 total subjects
712 cases
Incomplete job
history (dates, codes
missing)
2,462 controls
Proportion ever
exposed
Yes:
38%
Yes:
49%
Silica
Asbestos
Yes:
44%
Yes:
32%
Ever exposed includes all levels of reliability: possible, probable, definite

7. 7
Characteristic Cases, n (%) Controls, n (%)
Ageatinterview
20-29 1 (0.1) 137 (6)
30-39 22 (3) 259 (10)
40-49 116 (16) 223 (9)
50-59 198 (28) 364 (15)
60-69 249 (35) 878 (36)
70-74 124 (18) 579 (24)
BMI Normal/underweight 164 (23) 962 (39)
Overweight 362 (51) 1,126 (47)
Obese 184 (26) 362 (15)
Smoking
status
Never smoker 164 (23) 636 (26)
Ex-smoker 431 (61) 1298 (53)
Current smoker 115 (16) 516 (21)
Cigarette
pack-years
Never smoker 164 (24) 638 (26)
>0-<10 129 (19) 494 (21)
10-<25 192 (28) 613 (25)
25-<40 114 (16) 353 (15)
40+ 96 (14) 313 (13)

8. Non-exposure variables that remain in the models
8Adjusted for province and age
0
1
2
3
<25 25-<30 ≥30 None Low Moderate High Very high
BMI Pack-years (categories)
OddsRatios,95%confidence
intervals
Cigarette

9. Crystalline silica exposure and kidney cancer
9Adjusted for province, age, BMI, and secondhand smoke exposure at work
•Overall, our findings do not support the hypothesis that
occupational exposure to crystalline silica increases the risk of
kidney cancer in men
•A total of 17% (cases: 17.6%; controls: 17.1%) had 10+ years of
silica exposure
•Less than 1% (all controls) were ever exposed to high
concentrations of silica
•Workers ever exposed to silica did not have a significantly elevated
risk of kidney cancer (OR 1.04, 95%CI 0.85-1.26) nor did workers
with long-term (20+yrs) low exposure (OR 1.28, 95%CI 0.96-1.69)

10. 10
38%
28%
34%37%
27%
35%
Low Medium High
0%
10%
20%
30%
40%
Cases Controls
Cumulative silica exposure among kidney cancer cases
and controls exposed to silica at work
Risk of cancer among males with cumulative lifetime
occupational exposure to silica
Cases Controls OR (95%CI)
Unexposed 68% 70% -
Low (0.1-12.9) 12% 11% 1.10 (0.83-1.45)
Medium (13-36) 9% 8% 0.95 (0.69-1.31)
High (36.1+) 11% 11% 1.05 (0.78-1.41)
C = intensity of asbestos exposure (1=low, 2=medium, 3=high), F= frequency of exposure (1= <5%, 2= 6% - <30%, 3= ≥30%),
and D= duration of employment in years.

11. Asbestos exposure and kidney cancer
11Adjusted for province, age, BMI, and secondhand smoke exposure at work
0
1
2
3
Never Ever None Low Medium High None Low Medium/high
Asbestos exposure Cumulative asbestos exposure Highest attained concentration
OddsRatios,95%confidenceintervals
Possible, probable, definite (cases=267; controls=783) Probable, definite (cases=99; controls=267)

12. Asbestos exposure and kidney cancer
12Adjusted for province, age, BMI, and secondhand smoke exposure at work
0
1
2
3
Never Ever None Low Medium High None Low Medium/high
Asbestos exposure Cumulative asbestos exposure Highest attained concentration
OddsRatios,95%confidenceintervals
Possible, probable, definite (cases=267; controls=783) Probable, definite (cases=99; controls=267)

13. Discussion
13
• Adds to literature:
• Large sample size
• Detailed exposure assessment
• Detailed confounder and risk factor information
• Found increasing BMI associated with
increased risk of kidney cancer
• History of cigarette smoking not related to
increased risk of kidney cancer in this group,
but secondhand exposure to cigarette smoke
at work is associated with increased odds

14. Summary
• Workers with exposure to silica not at increased risk of kidney
cancer
• Workers with ever exposure to asbestos had higher odds of
kidney cancer; low exposure seems to increase odds of kidney
cancer
• There appeared to be increasing odds with increasing highest
attained concentration for asbestos but not significant
• No other clear relationships were detected for cumulative
exposure of either silica or asbestos
14

15. Acknowledgements
15
Co-authors
Marie-Élise Parent, Shelley Harris, Lidija Latifovic, Linda Kachuri,
Laura Bogaert, Canadian Cancer Registries Group, Paul Villeneuve