# Risk Assessment of Bisphenol A in the Korean General Population
## 5 Further Study for BPA
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multirow{2}{*}{**Point of Departure (POD)**} & \multicolumn{5}{c}{**Margin of Exposure (MOE)**} \\ \cline{3-6}  & & **3–6 yrs** & **7–12 yrs** & **13–18 yrs** & **19–79 yrs** \\ \hline \multirow{2}{*}{Mean} & NOAEL 5000 \(\mu\)g/kg bw/day & \multirow{2}{*}{\(>\)119,000} & \multirow{2}{*}{\(>\)185,100} & \multirow{2}{*}{\(>\)294,100} & \multirow{2}{*}{\(>\)161,200} \\  & (animal toxicity) & & & & & \\ \multicolumn{2}{c}{BMD\({}_{20}\) 60 ng/kg bw/day} & \multirow{2}{*}{22} & \multirow{2}{*}{34} & \multirow{2}{*}{55} & \multirow{2}{*}{30} \\  & (animal toxicity; immunotoxicity) & & & & & \\ \multicolumn{2}{c}{EDI 0.5 ug/kg bw/day} & \multirow{2}{*}{12} & \multirow{2}{*}{19} & \multirow{2}{*}{29} & \multirow{2}{*}{16} \\  & (epidemiological study; thyroid cancer) & & & & & \\ \hline \multirow{2}{*}{95 th} & NOAEL 5000 \(\mu\)g/kg bw/day & \multirow{2}{*}{\(>\)24,800} & \multirow{2}{*}{\(>\)31,200} & \multirow{2}{*}{\(>\)48,000} & \multirow{2}{*}{\(>\)27,600} \\  & (animal toxicity) & & & & & \\ \multicolumn{2}{c}{BMD\({}_{20}\) 60 ng/kg bw/day} & \multirow{2}{*}{5} & \multirow{2}{*}{6} & \multirow{2}{*}{9} & \multirow{2}{*}{5} \\  & (animal toxicity; immunotoxicity) & & & & & \\ \multicolumn{2}{c}{EDI 0.5 ug/kg bw/day} & \multirow{2}{*}{2} & \multirow{2}{*}{3} & \multirow{2}{*}{5} & \multirow{2}{*}{3} \\  & (epidemiological study; thyroid cancer) & & & & & \\ \hline \hline \end{tabular}  
* NOAEL: No observed adverse effect level, BMDL: Benchmark dose lower confidence interval, EDI: Estimated daily intake. MOE = POD/Extrapolated exposure amount from Table 3.  
\end{table} 
Table 4: Margin of exposure (MOE) of current exposure of bisphenol A by age in Korean general population. epidemiological data is considered, when available. If possible, a positive dose-response is more convincing than a simple excess of disease risk between the exposed and non-exposed groups. Therefore, appropriate biomarkers must be considered in epidemiological studies. BPA and its metabolites were detected at parts per billion (or less) concentrations in human urine, milk, saliva, serum, plasma, ovarian follicular fluid, and amniotic fluid [27; 67]. Controlled ingestion trials in healthy adult volunteers with 5 mg d 16-BPA were unable to detect parent BPA in plasma, but by 96 h 100% of the administered dose was recovered in urine as the glucuronide [50]. In the liver and the intestines, BPA is mainly metabolized to glucuronides, to a lesser extent to sulfates, and to a minor extent to hydroxylated compounds and other metabolites [68]. Evidence suggests that only unconjugated BPA binds to estrogen receptors, and most BPA glucuronides have been found to lack estrogenic activity [68; 69; 70]. However, several studies have suggested other possible effects of BPA, such as the induction of adipocyte differentiation by BPA glucuronide and deconjugation of BPA glucuronide or BPA sulfate [71; 72; 73; 74]. Moreover, this evidence may be even more relevant in sensitive age groups, for example, the fetus, since this may be relevant with a higher concentration of unconjugated BPA in fetal than in adult serum [75]. Therefore, it is important to select a human bio-sample to confirm the correlation between BPA exposure and its health effects. According to a review of various epidemiological studies, the correlation between health effects and BPA exposure showed differences in human samples. Generally, urinary BPA is a biomarker for exposure to BPA, and some indication of health effects, such as thyroid cancer, were correlated with serum BPA levels in a Korean cohort study [63]. Finally, additional studies [76; 77; 78] on the low-dose effects of BPA were updated to determine the relationship between BPA exposure and health effects, such as thyroid function and chronic disease, in a cohort study. The inconsistent results of animal experiments on BPA exposure and thyroid function may be due to experimental design with different doses, routes of exposure to BPA, exposure duration, or age at exposure.