Distribution, variability, and predictors of urinary bisphenol A levels in 50 North Carolina adults over a six-week monitoring period

Abstract

Bisphenol A (BPA) is commonly manufactured to make polycarbonate plastics and epoxy resins for use in consumer products and packaged goods. BPA has been found in several different types of environmental media (e.g., food, dust, and air). Many cross-sectional studies have frequently detected BPA concentrations in adult urine samples. However, limited data are available on the temporal variability and important predictors of urinary BPA concentrations in adults. In this work, the major objectives were to: 1) quantify BPA levels in duplicate-diet solid food, drinking water, hard floor surface wipe, and urine samples (first-morning void [FMV], bedtime, and 24-h) collected from adults over a six-week monitoring period; 2) determine the temporal variability of urinary BPA levels using concentration, specific gravity (SG) adjusted, creatinine (CR) adjusted, and excretion rate values, and; 3) examine associations between available study factors and urinary BPA concentrations. In 2009-2011, a convenience sample of 50 adults was recruited from residential settings in North Carolina. The participants completed diaries and collected samples during weeks 1, 2, and/or 6 of a six-week monitoring period. BPA was detected in 38%, 4%, and 99% of the solid food (n=775), drinking water (n=50), and surface wipe samples (n=138), respectively. Total BPA (free plus conjugated) was detected in 98% of the 2477 urine samples. Median urinary BPA levels were 2.07ng/mL, 2.20ng/mL-SG, 2.29ng/mg, and 2.31ng/min for concentration, SG-adjusted, CR-adjusted, and excretion rate values, respectively. The intraclass correlation coefficient (ICC) estimates for BPA showed poor reproducibility (≤0.35) for all urine sample types and methods over a day, week, and six weeks. CR-adjusted bedtime voids collected over six-weeks required the fewest, realistic number of samples (n=11) to obtain a reliable biomarker estimate (ICC=0.80). Results of linear mixed-effects models showed that sex, race, season, and CR-level were all significant predictors (p<0.05) of the adults' urinary BPA concentrations. BPA levels in the solid food and surface wipe samples did not contribute significantly to the participants' urinary BPA concentrations. However, a significant positive relationship was observed between solid food intake and urine-based estimates of BPA dose, when aggregated over 24-h periods. Ingestion of BPA via solid food explained only about 20% of the total dose (at the median of the dose distribution), suggesting that these adults were likely exposed to other major unknown (non-dietary) sources of BPA in their everyday environments.

Correlates of exposure to phenols, parabens, and triclocarban in the Study of Environment, Lifestyle and Fibroids

“…Although many studies report concentrations of EDCs by time of day of urine collection, few present data about month or season of data collection. In a cross-sectional study of 50 White, Black, and Hispanic adults aged 19–50 years in North Carolina in 2009, BPA concentrations were highest in winter and spring, 73 while, in the Canadian Maternal-Infant Research on Environmental Chemicals (MIREC) study, a cohort study of 2,001 pregnant women (mean age: 32 years) recruited in 2008–2011, BPA concentrations were highest in fall and winter. 74, 75 In an analysis of 177 pregnant women (mean age: 35.7 years; recruited in 2005–2011) from the Environment and Reproductive Health Study (EARTH), an open cohort study of mostly White women and men recruited from a fertility clinic in Boston, MA, 76 adjustment for season of urine collection had no influence on paraben concentrations, 9 indicating little association between season and methyl paraben concentrations.…”

Development and feasibility of randomized trial to reduce urinary bisphenols in women with obesity

“…Despite the success of the intervention to reduce BPS exposure, results should be interpreted with caution given the relatively small sample size of this study and the large number of non-detectable BPA and BPF concentrations. Only spot urine samples were collected, which may have been insufficient to reliably estimate a long-term urinary bisphenol exposure as a recent study suggested that multiple samples over several days are needed [ 39 ]. Previous studies have shown that urinary BPA concentrations vary daily [ 40 ] and may be influenced by recent food intake [ 41 ].…”

Environmental Occurrence and Ecological Risk of Bisphenol A in Erhai Lake Basin Away From Industrial Regions in China

“…A related study in Taiwan [3] pointed out that there was almost no risk of BPA intake through diet, and BPA was ingested by the human body mainly due to other exposures. Morgan [4] studied the content of BPA in the urine of 50 American adults and found that the median BPA concentration in human urine was 2.07 μg/L. Through their life contact observation, the proportion of BPA intake from the diet was about 20%, while contacting other sources seemly dominate.…”