Exposure to Bisphenol A and Triclosan Among Pregnant Women
Exposure to Bisphenol A and Triclosan Among Pregnant Women
Our participants tended to be well-educated, > 30 years of age, and born in Canada, and they had never smoked, had an underweight or normal body mass index (BMI) prior to pregnancy, and had a parity of 0 or 1 (see Supplemental Material, Table S1 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
Detectable urinary concentrations of free BPA, BPAG, and BPAS were found in 43.24%, 94.75%, and 23.43% of the samples, respectively (Table 1). We did not detect BPADS in any samples. The GM urinary concentration for BPAG using the machine readings was 0.80 μg/L [95% confidence interval (CI): 0.75, 0.85], similar to the result using the censoring methods (see Supplemental Material, Table S2 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf). The GM of the ratio of free BPA to total BPA was 1.01%, and the ratio of BPAG to total BPA was 90.27% (data not shown).
The log of BPAG was positively correlated with the log of free BPA (r = 0.38, p < 0.0001) and the log of total BPA (r = 0.98, p < 0.0001) (data not shown). The log of free BPA was positively correlated with the log of total BPA (r = 0.42, p < 0.0001) (see Supplemental Material, Figure S1a http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf). As log total urinary BPA increased, free BPA also increased and the ratio of free to total BPA decreased (r = –0.22, p < 0.0001) (see Supplemental Material, Figure S1b http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
In the analysis of characteristics associated with urinary concentrations, BPAG (Table 2) and total BPA concentrations (see Supplemental Material, Table S3 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf) were significantly higher in urine samples from women < 25 years of age compared with women ≥ 35, from smokers compared with former or never smokers, and from women with lower household income (< $50,000 vs. > $100,000) and lower education (≤ high school vs. ≥ university degree). We observed a significant interaction between SG and time of urine collection; for example, at the 25th and 50th percentiles of SG, urine samples collected after 1500 hours had significantly higher BPAG and total BPA than samples collected earlier in the day. However, at the 75th percentile of SG, adjusted GM concentrations of BPAG and total BPA were similar with respect to time of urine collection (Table 3; see also Supplemental Material, Table S4 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
Most of the women had detectable concentrations of total TCS, TCSG, and free TCS (Table 1). The GM urinary concentrations of total TCS and TCSG were 12.64 μg/L (95% CI: 11.38, 14.03) and 12.30 μg/L (95% CI: 11.08, 13.65), respectively. The GM of the ratio of free TCS to total TCS was 0.50%, and that for the ratio of TCSG to total TCS was 97.82% (data not shown).
All of the log-transformed TCS metabolites were highly correlated with each other (data not shown). TCSG was correlated with free TCS (r = 0.81, p < 0.0001) and total TCS (r = 1.00, p < 0.0001). Similarly, free TCS was correlated with total TCS (r = 0.82, p < 0.0001).
We observed significantly lower urinary concentrations of total TCS (see Supplemental Material, Table S5 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf) and TCSG (Table 4) in women who were smokers compared with never smokers, were < 25 years of age, did not have a university degree, and had household income ≤ $100,000. Only free TCS varied by time of urine collection, with urine collected between 0900 and 1200 hours significantly higher than that collected between 1500 and 1800 hours. A significant interaction between SG and parity was observed. Specifically at the 25th and 50th percentiles of SG, TCS levels were statistically similar between the different parity groups; however, at the 75th percentile of SG, adjusted GM TCS concentrations were higher for women with parity of 0 than those with parity of 1 (Table 5; see also Supplemental Table S6 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
Comparing the two methods for dealing with values < LOD, the median from the Kaplan-Meier was similar to the median based on machine readings, and the GM from the censored MLE compared well with the GM based on machine readings (Table 1; see also Supplemental Material, Table S2 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf). Overall, p-values for the censoring methods were similar to machine readings, but were generally more conservative (data not shown).
Results
Participant Characteristics
Our participants tended to be well-educated, > 30 years of age, and born in Canada, and they had never smoked, had an underweight or normal body mass index (BMI) prior to pregnancy, and had a parity of 0 or 1 (see Supplemental Material, Table S1 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
BPA
Detectable urinary concentrations of free BPA, BPAG, and BPAS were found in 43.24%, 94.75%, and 23.43% of the samples, respectively (Table 1). We did not detect BPADS in any samples. The GM urinary concentration for BPAG using the machine readings was 0.80 μg/L [95% confidence interval (CI): 0.75, 0.85], similar to the result using the censoring methods (see Supplemental Material, Table S2 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf). The GM of the ratio of free BPA to total BPA was 1.01%, and the ratio of BPAG to total BPA was 90.27% (data not shown).
The log of BPAG was positively correlated with the log of free BPA (r = 0.38, p < 0.0001) and the log of total BPA (r = 0.98, p < 0.0001) (data not shown). The log of free BPA was positively correlated with the log of total BPA (r = 0.42, p < 0.0001) (see Supplemental Material, Figure S1a http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf). As log total urinary BPA increased, free BPA also increased and the ratio of free to total BPA decreased (r = –0.22, p < 0.0001) (see Supplemental Material, Figure S1b http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
In the analysis of characteristics associated with urinary concentrations, BPAG (Table 2) and total BPA concentrations (see Supplemental Material, Table S3 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf) were significantly higher in urine samples from women < 25 years of age compared with women ≥ 35, from smokers compared with former or never smokers, and from women with lower household income (< $50,000 vs. > $100,000) and lower education (≤ high school vs. ≥ university degree). We observed a significant interaction between SG and time of urine collection; for example, at the 25th and 50th percentiles of SG, urine samples collected after 1500 hours had significantly higher BPAG and total BPA than samples collected earlier in the day. However, at the 75th percentile of SG, adjusted GM concentrations of BPAG and total BPA were similar with respect to time of urine collection (Table 3; see also Supplemental Material, Table S4 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
Triclosan
Most of the women had detectable concentrations of total TCS, TCSG, and free TCS (Table 1). The GM urinary concentrations of total TCS and TCSG were 12.64 μg/L (95% CI: 11.38, 14.03) and 12.30 μg/L (95% CI: 11.08, 13.65), respectively. The GM of the ratio of free TCS to total TCS was 0.50%, and that for the ratio of TCSG to total TCS was 97.82% (data not shown).
All of the log-transformed TCS metabolites were highly correlated with each other (data not shown). TCSG was correlated with free TCS (r = 0.81, p < 0.0001) and total TCS (r = 1.00, p < 0.0001). Similarly, free TCS was correlated with total TCS (r = 0.82, p < 0.0001).
We observed significantly lower urinary concentrations of total TCS (see Supplemental Material, Table S5 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf) and TCSG (Table 4) in women who were smokers compared with never smokers, were < 25 years of age, did not have a university degree, and had household income ≤ $100,000. Only free TCS varied by time of urine collection, with urine collected between 0900 and 1200 hours significantly higher than that collected between 1500 and 1800 hours. A significant interaction between SG and parity was observed. Specifically at the 25th and 50th percentiles of SG, TCS levels were statistically similar between the different parity groups; however, at the 75th percentile of SG, adjusted GM TCS concentrations were higher for women with parity of 0 than those with parity of 1 (Table 5; see also Supplemental Table S6 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf).
Comparing the two methods for dealing with values < LOD, the median from the Kaplan-Meier was similar to the median based on machine readings, and the GM from the censored MLE compared well with the GM based on machine readings (Table 1; see also Supplemental Material, Table S2 http://ehp.niehs.nih.gov/wp-content/uploads/123/4/ehp.1408187.s001.508.pdf). Overall, p-values for the censoring methods were similar to machine readings, but were generally more conservative (data not shown).
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