In their Correspondence in The Lancet Diabetes & Endocrinology, Roy Gerona and colleauges asserted that indirect measurement of bisphenol A (BPA) metabolites in urine underestimates exposure to BPA in human biomonitoring studies. The indirect method quantifies levels of total BPA in a two-step procedure (enzymatic deconjugation and extraction), whereas the direct method eliminates the enzymatic deconjugation but requires concurrent determination of three species: BPA glucuronide, BPA sulfate, and free BPA. Both human pharmacokinetic and laboratory studies have shown the validity of the indirect method, the approach used by most laboratories routinely measuring BPA. Human pharmacokinetic and laboratory studies have good agreement regarding levels of BPA and its conjugates, including studies in humans that compared levels using direct and indirect methods. Pharmacokinetic studies from several laboratories using controlled dosing with isotopically labeled BPA agree with each other, showing that BPA in the body is conjugated and eliminated quantitatively (84–109% of total administered dose) in urine, mainly as BPA-glucuronide.^{,  ,}  Laboratory experiments also show distribution of concentrations of BPA metabolites similar to those in human pharmacokinetic studies: more BPA glucuronide than BPA sulfate, and more BPA sulfate than free BPA.^{,  ,  ,  ,} 

中文翻译：

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BPA和风险评估。

在《柳叶刀》糖尿病与内分泌学的通讯中Roy Gerona和colleauges断言，在人体生物监测研究中，尿液中双酚A（BPA）代谢产物的间接测量低估了BPA的暴露。间接方法通过两步过程（酶解结合和提取）定量总BPA的水平，而直接方法消除了酶解结合的作用，但需要同时测定三种物质：BPA葡糖苷酸，BPA硫酸盐和游离BPA。人体药代动力学和实验室研究均显示了间接方法的有效性，这种方法是大多数实验室常规测量BPA的方法。人体药代动力学和实验室研究在BPA及其结合物的水平方面有很好的一致性，包括在人体中使用直接和间接方法比较水平的研究。^{，  ，} 实验室的实验还表明BPA浓度的分布代谢物相似于人体药代动力学研究：比不含BPA更BPA葡萄糖醛酸比硫酸BPA，多硫酸BPA。^{，  ，  ，  ，}