Arsenic and bladder cancer variation in estimates

Data analysis showing the difference in risk estimates for bladder cancer across different countries

1. Arsenic and cancer: how geography determines policy Arindam Basu, 11th August, 2017

2. About 200 million people in Bangladesh and 100 million people in India are exposed to Arsenic in DW

3. Hotspots of Arsenic

4. Overview of Arsenic Metabolism

5. Arsenic metabolism and nutrition (source: BMJ)

6. Arsenic-caused skin cancer and lesions

7. Arsenic skin cancer

8. As caused bladder cancer

9. Inhaled and ingested Arsenic causes lung cancer

10. Prevalence of Arsenic exposure Worldwide

11. Prevalence of As Exposure, part 2

12. If the prevalence and source of As Vary Across the World, do the risk estimates of cancers caused by Arsenic also differ in populations across the world?

13. Concept of Population Attributable Risk Population Attributable Risk = function of Prevalence of Exposure & Relative Risk Estimate

14. W orldwide, h ow do arsenic cancer risk estimates vary across populations?

15. Arsenic exposure and bladder cancer risk meta analysis, citation: Christoforidou, E. P., Riza, E., Kales, S. N., Hadjistavrou, K., Stoltidi, M., Kastania, A. N., & Linos, A. (2013). Bladder cancer and arsenic through drinking water: A systematic review of epidemiologic evidence. Journal of Environmental Science and Health, Part A , 48 (14), 1764–1775. http://doi.org/10.1080/10934529.2013.823329 ) 19 Studies across different countries Different comparisons were selected

16. Tally of the Variability Across Populations (Christoforidou, 2013) United States Taiwan Argentina Chile Bangladesh Finland Pakistan Denmark

17. Variation in the risk estimates based on studies with individual data with updated information from other populations

18. Forest plot of the meta-analysis

19. Results of the meta analysis Smaller effect sizes are contributed by countries where the exposure to As is low, for example United States, and larger effect sizes are contributed by countries where the exposure levels are higher

20. What may explain the discrepancy in risk estimates? Smoking interacts with Arsenic to increase the risk Diet and micronutrient intake can interact with the methylation: high protein diet and micronutrients will supply the needed substrates for methylation and offset the diversion of methyl groups even in face of high As load Genetic differences?

21. Gaps, and policy implications for Arsenic control Data on all arsenic-caused cancers would be beneficial Studies from India, & Bangladesh for individual risk estimates are missing Arsenic is currently labelled as Type I Carcinogen by IARC Different levels of acceptable As exposure in different countries: in India, Bangladesh, Argentina, Chile: 50 ug/L as acceptable level; in Taiwan, United States, Europe: 10 ug/L; worldwide, WHO recommends 10 ug/L - this needs to be revised in the light of new evidence