abstract
We evaluated the within-person variability of urinary BPA levels over two samples collected three years apart in 90 Women's Health Initiative participants. The intraclass correlation coefficient was 0.09 (95% CI 0.01-0.44), indicating high within-participant variability relative to the between-person variation. Concordance of BPA quartile over time was low (31.7%) and was unrelated to demographic, behavioral, or dietary factors. A single, or even several, measurements of BPA may not adequately classify long-term exposure in human studies.
