1. 2015. 03. 24 이 장 우

2. 1. Introduction  Bisphenol A is a high production volume chemical -Annual production of over six billion pounds -polycarbonate plastics or epoxy resins can be found in a variety of consumer products, which include reusable food and beverage containers, baby bottles, plastic dinnerware, toys, compact disks, and metal food can linings.  Exposure -Information on preschool aged children exposure to BPA is rather limited. -BPA has been detected in several media including food, air, and dust samples collected at residences and child care centers -Wilson showed that dietary ingestion was major route of exposure for 257 preschool children to BPA at their homes and daycare centers.  Metabolism -BPA is efficiently absorbed (>95%) from the gut, and it primarily undergoes phase II metabolism by conjugation with glucuronic acid in the liver. -BPA is mainly eliminated in the urine as BPA-glucuronide with an average elimination half-life of about six hours in humans.

3. 1. Introduction  Objectives -we are unaware of any published studies in the U.S. that have assessed the quantitative relationships between preschool children’s exposures to BPA and urinary biomonitoring. -The objectives were to quantify the concentrations of total BPA in a subset of the 257 preschool children’s (ages 2~5 years) and then to examine the quantitative relationships between the children’s intake doses of BPA through the dietary ingestion, nondietary ingestion, and inhalation routes and their excreted amounts of urinary BPA.

4. 2. Materials and Methods  2000-2001 -CTEPP study (257 children) -several environmental (i.e., soil, dust, and air) and personal media (i.e., solid food, liquid food, and hand wipes  2001 -CTEPP study (81 children) -urine sample (6 spot urine, 48h-period)  2004 -US Environmental Protection Agency’s (US EPA) National Exposure Research Laboratory  2006 -CDC laboratory -Analysis

5. 2. Materials and Methods  Field sampling -Summarized in the supporting information -Spot urine samples were collected from the children using bonnets placed under toilet seats and then transferred to polypropylene containers with lids  Human subjects review -This was an observational research study, as defined in 40 Code of Federal Regulations (CFR) Part 26.402. -Approved by an independent institutional review board  Sample analyses -Online SPE (Ye et al., 2005)  Quality control procedures for urine -QC sample (low : 2.4 ng/mL, high : 16.2 ng/mL) -RSD (low : 18.8 %, high : 13.7 %) -Cross check : US EPA vs CDC (absolute difference : 1.15 ± 1.0 ng/mL, relative difference : 28 %)

6. 2. Materials and Methods  Statistical analysis -All BPA concentrations that were less than the LOD were assigned a value of LOD divided by the square root of two -Creatinine and specific gravity are common correction methods for adjusting for variable dilutions in adult urine samples; however, creatinine may not be a reliable adjustment measure for children. -Estimated daily intake  Presented in the supporting information  Assumption (absorption rate : 100 %, eliminated 100 % of dose, inhalation rate : 50 %) -Pearson correlation -Multivariable regression

7. 2. Materials and Methods

9. 3. Results

12. Figure 1. The estimated Ohio preschool children’s intake doses of BPA by route compared to their excreted amounts of total urinary BPA. The exposure data were calculated by route for 81 out of 257 preschool children using the environmental and personal media data reported in Wilson et al.9 and the urinary biomonitoring data reported in the present study

13. 3. Results

15. 4. Discussion -Our children’s estimated maximum aggregate intake dose (4.7 ug/kg/day) was 10 times lower than RfD (reference dose), TDI (Tolerable Daily Intake) and BE (biomonitoring equivalent)  RfD, TDI : 50 ug/kg/day, BE : 2 mg/L -we showed that dietary ingestion of solid and liquid foods was probably the major route of exposure for 257 preschool children (Wilson et al., 2007) -we quantified the urinary BPA concentrations and then assessed the quantitative relationships between the children’s excreted amounts of BPA and their estimated intake doses of BPA by route  Dietary intake accounted for >95% of the children’s excreted amounts of BPA in urine.  Additional regression modeling also showed that solid food (p = 0.04) compared to liquid food (p = 0.78) was significantly contributing to the children’s dietary intake doses of BPA.  This information suggests that packaging materials and/or containers were the major source of the BPA

16. 4. Discussion  Limitations to the interpretation of our data.  N=81 may not reflect the everyday BPA exposures of other preschool children in Ohio, in the U.S., or in other countries.  Changes in diet, fluid intake, individual toxicokinetics, and/or urine output would likely affect the variability of BPA in urine over time  it is unclear whether these children had steady-state or intermittent exposures to BPA (steady state exposure : non-dietary, intermittent exposure : dietary)  Some measurement error would likely occur as the urine collection period could partly reflect BPA intake from the prior day. -Further research is needed to understand the important factors that may impact the temporal variability of BPA in children’s urine. 16

17. 5. Conclusions -our current work showed that dietary ingestion through the consumption of both solid and liquid foods was the major route of these 81 CTEPP Ohio preschool children’s exposures to BPA, and this route likely contributed to >95% of their excreted amounts of urinary BPA.

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