Methods for accounting for urine dilution in arsenic analyses: comparisons to blood and water arsenic in FACT and FOX

BACKGROUND AND AIM: Millions of people worldwide are exposed to arsenic (As). Urinary As (uAs) is a biomarker of As exposure. Urinary creatinine (uCr), a breakdown product of creatine, is used to correct uAs for urine dilution. However, uCr levels are influenced by meat intake, muscle mass, and factors related to As methylation/elimination. An alternative method utilizes specific gravity (SG), which has limitations in individuals with kidney damage and/or diabetes. We compared uAs corrected for uCr or SG vs. blood As (bAs) and water As (wAs), which do not require dilution adjustment. METHODS: We used data from 539 participants from the Folic Acid and Creatine Trial (FACT) and 343 participants from the Folate and Oxidative Stress (FOX) study. bAs and…