title: A population-based case-control study of urinary arsenic species and squamous cell carcinoma in New Hampshire, USA.
abstract: BACKGROUND
  Chronic high arsenic exposure is associated with squamous cell carcinoma (SCC) of the skin, and inorganic arsenic (iAs) metabolites may play an important role in this association. However, little is known about the carcinogenicity of arsenic at levels commonly observed in the United States.
  
  
  OBJECTIVE
  We estimated associations between total urinary arsenic and arsenic species and SCC in a U.S. population.
  
  
  METHODS
  We conducted a population-based case-control SCC study (470 cases, 447 controls) in a U.S. region with moderate arsenic exposure through private well water and diet. We measured urinary iAs, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA), and summed these arsenic species (ΣAs). Because seafood contains arsenolipids and arsenosugars that metabolize into DMA through alternate pathways, participants who reported seafood consumption within 2 days before urine collection were excluded from the analyses.
  
  
  RESULTS
  In adjusted logistic regression analyses (323 cases, 319 controls), the SCC odds ratio (OR) was 1.37 for each ln-transformed microgram per liter increase in ln-transformed ΣAs concentration [ln(ΣAs)] (95% CI: 1.04, 1.80). Urinary ln(MMA) and ln(DMA) also were positively associated with SCC (OR = 1.34; 95% CI: 1.04, 1.71 and OR = 1.34; 95% CI: 1.03, 1.74, respectively). A similar trend was observed for ln(iAs) (OR = 1.20; 95% CI: 0.97, 1.49). Percent iAs, MMA, and DMA were not associated with SCC.
  
  
  CONCLUSIONS
  These results suggest that arsenic exposure at levels common in the United States relates to SCC and that arsenic metabolism ability does not modify the association.
authors.affiliation: Section of Biostatistics and Epidemiology, Department of Community and Family Medicine, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA.
authors.forename: Diane
authors.initials: D
authors.lastname: Gilbert-Diamond
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Li
authors.forename: Ann E
authors.initials: AE
authors.lastname: Perry
authors.forename: Steven K
authors.initials: SK
authors.lastname: Spencer
authors.forename: A Jay
authors.initials: AJ
authors.lastname: Gandolfi
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Karagas
mesh_terms: D000328:Adult; D000368:Aged; D001151:Arsenic / Q000737:chemistry / Q000652:urine*; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology* / Q000652:urine*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009513:New Hampshire / Q000453:epidemiology; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000652:urine*
chemical_list: D014874:Water Pollutants, Chemical; D001151:Arsenic