title: Renal function is associated with indicators of arsenic methylation capacity in Bangladeshi adults.
abstract: BACKGROUND
  Arsenic (As) methylation capacity in epidemiologic studies is typically indicated by the proportions of inorganic As (%InAs), monomethylarsonic acid (%MMA), and dimethylarsinic acid (%DMA) in urine as a fraction of total urinary As. The relationship between renal function and indicators of As methylation capacity has not been thoroughly investigated.
  
  
  OBJECTIVE
  Our two aims were to examine (1) associations between estimated glomerular filtration rate (eGFR) and %As metabolites in blood and urine, and (2) whether renal function modifies the relationship of blood %As metabolites with respective urinary %As metabolites.
  
  
  METHODS
  In a cross-sectional study of 375 As-exposed Bangladeshi adults, we measured blood and urinary As metabolites, and calculated eGFR from plasma cystatin C.
  
  
  RESULTS
  In covariate-adjusted linear models, a 1 ml/min/1.73 m(2) increase in eGFR was associated with a 0.39% increase in urinary %InAs (p<0.0001) and a mean decrease in urinary %DMA of 0.07 (p=0.0005). In the 292 participants with measurable blood As metabolites, the associations of eGFR with increased blood %InAs and decreased blood %DMA did not reach statistical significance. eGFR was not associated with urinary or blood %MMA in covariate-adjusted models. For a given increase in blood %InAs, the increase in urinary %InAs was smaller in those with reduced eGFR, compared to those with normal eGFR (p=0.06); this effect modification was not observed for %MMA or %DMA.
  
  
  CONCLUSIONS
  Urinary excretion of InAs may be impaired in individuals with reduced renal function. Alternatively, increased As methylation capacity (as indicated by decreased urinary %InAs) may be detrimental to renal function.
authors.affiliation: Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Brandilyn A
authors.initials: BA
authors.lastname: Peters
authors.affiliation: Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Megan N
authors.initials: MN
authors.lastname: Hall
authors.affiliation: Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Vesna
authors.initials: V
authors.lastname: Slavkovich
authors.affiliation: Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Vesna
authors.initials: V
authors.lastname: Ilievski
authors.affiliation: Columbia University Arsenic Project in Bangladesh, Dhaka, Bangladesh.
authors.forename: Shafiul
authors.initials: S
authors.lastname: Alam
authors.affiliation: Columbia University Arsenic Project in Bangladesh, Dhaka, Bangladesh.
authors.forename: Abu B
authors.initials: AB
authors.lastname: Siddique
authors.affiliation: Columbia University Arsenic Project in Bangladesh, Dhaka, Bangladesh.
authors.forename: Tariqul
authors.initials: T
authors.lastname: Islam
authors.affiliation: Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Graziano
authors.affiliation: Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA. Electronic address: mvg7@cumc.columbia.edu.
authors.forename: Mary V
authors.initials: MV
authors.lastname: Gamble
mesh_terms: D000328:Adult; D000368:Aged; D001151:Arsenic / Q000097:blood / Q000633:toxicity* / Q000652:urine; D001152:Arsenicals / Q000097:blood / Q000652:urine; D001459:Bangladesh; D002101:Cacodylic Acid / Q000097:blood / Q000652:urine; D003430:Cross-Sectional Studies; D060766:Drinking Water / Q000737:chemistry*; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects*; D006801:Humans; D016014:Linear Models; D008297:Male; D008745:Methylation; D008875:Middle Aged; D014874:Water Pollutants, Chemical / Q000097:blood / Q000633:toxicity* / Q000652:urine
chemical_list: D001152:Arsenicals; D060766:Drinking Water; D014874:Water Pollutants, Chemical; D002101:Cacodylic Acid; C020300:monomethylarsonic acid; D001151:Arsenic
keywords: Arsenic; Bangladesh; Glomerular filtration rate; Kidney; Methylation