title: Interaction between environmental tobacco smoke and arsenic methylation ability on the risk of bladder cancer.
abstract: OBJECTIVE
  Arsenic exposure and environmental tobacco smoke (ETS) have been suspected to be associated with bladder cancer risk. We hypothesize that interaction between ETS and the ability to methylate arsenic, a detoxification pathway, modifies the risk of bladder cancer.
  
  
  METHODS
  From January 1996 to December 1999, we identified 41 newly diagnosed bladder cancer patients and 202 fracture and cataract patients at the National Cheng-Kung University (NCKU) Medical Center. The levels of urinary arsenic species [As(III), As(V), MMA(V), and DMA(V)] were determined in all subjects.
  
  
  RESULTS
  We found significant interaction between ETS and secondary methylation index (SMI) on the risk of bladder cancer (p=0.02). Among non-smokers with a high primary methylation index (PMI), the risk of bladder cancer was lower in subjects exposed to ETS (OR, 0.37; 95% CI, 0.14-0.96) than in subjects without exposure to ETS. Among non-smokers without ETS, the risk of bladder cancer was 4.7 times higher in subjects with a low SMI (95% CI, 1.30-16.81) than in subjects with a high SMI.
  
  
  CONCLUSIONS
  Ability to methylate arsenic plays an important role in reducing the risk of bladder cancer attributable to the continuation of arsenic exposure from drinking water and from ETS exposure.
authors.affiliation: Department of Medicine, Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. karen.chen@channing.harvard.edu
authors.forename: Yen-Ching
authors.initials: YC
authors.lastname: Chen
authors.forename: Huey-Jen Jenny
authors.initials: HJ
authors.lastname: Su
authors.forename: Yu-Liang Leon
authors.initials: YL
authors.lastname: Guo
authors.forename: E Andres
authors.initials: EA
authors.lastname: Houseman
authors.forename: David C
authors.initials: DC
authors.lastname: Christiani
mesh_terms: D000368:Aged; D000393:Air Pollutants / Q000009:adverse effects / Q000493:pharmacokinetics / Q000652:urine; D001151:Arsenic / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000652:urine; D002295:Carcinoma, Transitional Cell / Q000652:urine; D016022:Case-Control Studies; D002386:Cataract / Q000652:urine; D004785:Environmental Pollutants / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000652:urine; D005260:Female; D050723:Fractures, Bone / Q000652:urine; D006801:Humans; D008658:Inactivation, Metabolic; D008297:Male; D008745:Methylation; D008875:Middle Aged; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000652:urine; D013624:Taiwan; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D001749:Urinary Bladder Neoplasms / Q000209:etiology* / Q000652:urine; D014874:Water Pollutants, Chemical / Q000009:adverse effects / Q000493:pharmacokinetics / Q000652:urine
chemical_list: D000393:Air Pollutants; D004785:Environmental Pollutants; D014028:Tobacco Smoke Pollution; D014874:Water Pollutants, Chemical; D001151:Arsenic