Methods for accounting for urine dilution in arsenic analyses: comparisons to blood arsenic
Year: 2020
Type: conference-abstract
Abstract: Background. Arsenic (As) exposure remains ubiquitous affecting hundreds of millions of people worldwide. Urinary As (uAs) is an established biomarker of As exposure; urinary creatinine (uCr), a breakdown product of creatine phosphate in muscle, is excreted constantly via urine and commonly used to correct uAs for urine dilution. However, uCr levels are influenced by meat intake, muscle mass, and other factors that may also be related to As elimination. Alternative methods utilize specific gravity, which has limitations in individuals with kidney damage and diabetes. We compared uAs corrected for uCr and specific gravity vs. blood As (bAs), an increasingly used biomarker of As exposure that is unaffected by hydration status. Methods. We examined 539 participants from the Folic Acid and Creatine Trial (FACT) study to analyze the relationship between log-transformed total bAs and log-transformed uAs with adjustments for age, sex, and BMI, with further adjustments for uCr or specific gravity in separate models. Results. Median (IQR) uAs and bAs were 112.8 (133.6) and 8.41 (5.88) µg/L, respectively. Urinary creatinine and specific gravity were highly correlated with each other (Spearman correlation = 0.86, p < 0.001). Regression models revealed that a log 10-unit increase in total bAs concentrations was related to 0.69, 0.72, and 0.57 increases in log-10 uAs when unadjusted for dilution factors, adjusted for uCr, and adjusted for specific gravity, respectively (p < 0.001). Conclusions. We compared uAs to bAs to identify which strategy for urine dilution adjustment is appropriate in epidemiologic research and found that uCr outperforms specific gravity in predicting bAs in a Bangladeshi population exposed to high As levels in drinking water. More studies are needed in populations with different sociodemographic characteristics and levels of As exposure to evaluate the consistency of the findings and the optimization of urine dilution adjustment methods in As-related research.
Source: ISEE Conference Abstracts
Institutions: Columbia University, University of Chicago
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W3170460855