Phthalates and bisphenol A (BPA) have been suspected as risk factors for obesity and diabetes mellitus (DM) among humans. However, associations between phthalates and environmental phenols are often inconsistent across different populations. In this study, we recruited the adult population (n = 3782) of the Korean National Environmental Health Survey (KoNEHS) 2015–2017 (Cycle 3) and assessed the associations between urinary biomarkers of phthalate, BPA, and paraben exposure with obesity and DM. A potential collider issue with the use of urinary creatinine (Cr) or specific gravity (SG) exists when adjusting urinary dilution; therefore, a covariate-adjusted standardization (CAS) was employed for adjustment, and the results were compared. In the present population, the direction of the association often varied depending on the choices made to adjust urinary dilution. When using CAS, the direction of association resembled those of previously reported experimental observations. With Cr or SG adjustment, ORs for obesity decreased in the highest quartiles of monocarboxyoctyl phthalate (MCOP) [OR (95% CI) = Cr: 0.71 (0.54, 0.93); SG: 0.68 (0.52, 0.90)], monocarboxy-isononyl phthalate (MCNP) [OR (95% CI) = Cr: 0.67 (0.52, 0.87); SG: 0.68 (0.52, 0.89)], and mono(3-carboxylpropyl) phthalate (MCPP) in the urine [OR (95% CI) = Cr: 0.60 (0.47, 0.76); SG: 0.61 (0.48, 0.77)]; however, with CAS, these negative associations disappeared. Instead, mono-benzyl phthalate (MBzP) [OR (95% CI) = 1.31 (1.03, 1.66)], BPA [OR (95% CI) = 1.62 (1.27, 2.06)], or ethyl paraben (EtP) [OR (95% CI) = 1.51 (1.19, 1.91)] concentrations in the highest quartile showed positive associations with a higher risk of obesity. On the other hand, for DM, an overall decrease in ORs was observed for phthalate metabolites and BPA following SG adjustment and disappeared with CAS adjustment. In addition, the highest quartiles of BPA, methyl paraben (MeP), and ethyl paraben (EtP) showed a significantly higher risk of DM than those in the lowest quartiles following CAS [OR (95% CI) = BPA: 1.65 (1.06, 2.59); MeP: 1.68 (1.08, 2.60); and EtP: 2.74 (1.77, 4.24), respectively]. The present observations outline the importance of using an appropriate adjustment method for urinary dilution in association studies on obesity and DM. In addition, several phthalates, BPA, and parabens were identified as potential chemical risk factors for these outcomes. Further studies are warranted in other populations to confirm these observations.

邻苯二甲酸盐和双酚A（BPA）已被怀疑是人类肥胖和糖尿病（DM）的危险因素。但是，邻苯二甲酸酯和环境酚之间的关联在不同人群中常常不一致。在这项研究中，我们招募了2015-2017年韩国国家环境健康调查（KoNEHS）（周期3）的成年人口（n = 3782），并评估了邻苯二甲酸盐，BPA和对羟基苯甲酸酯暴露与肥胖和DM的尿液生物标志物之间的关联。调整尿液稀释度时，可能会出现使用尿肌酐（Cr）或比重（SG）的对撞机问题；因此，采用协变量调整后的标准化（CAS）进行调整，并比较了结果。在目前的人口中 结合的方向通常根据调整尿液稀释度的选择而变化。使用CAS时，缔合方向类似于先前报道的实验观察。通过Cr或SG的调整，在邻苯二甲酸单羧基辛酯（MCOP）最高四分位数中，肥胖的OR降低[OR（95％CI）= Cr：0.71（0.54，0.93）；SG：0.68（0.52，0.90）]，邻苯二甲酸单羧基-异壬酯（MCNP）[OR（95％CI）＝ Cr：0.67（0.52，0.87）； MS：95。SG：0.68（0.52，0.89）]和尿液中邻苯二甲酸单（3-羧丙基）邻苯二甲酸酯（MCPP）[OR（95％CI）= Cr：0.60（0.47，0.76）；SG：0.61（0.48，0.77）]；但是，在CAS中，这些消极关联消失了。而是使用邻苯二甲酸单苄酯（MBzP）[OR（95％CI）= 1.31（1.03，1.66）]，BPA [OR（95％CI）= 1.62（1.27，2.06）]或对羟基苯甲酸乙酯（EtP）[OR （95％CI）= 1.51（1.19，1。91）]在最高四分位数中的浓度与肥胖风险呈正相关。另一方面，对于DM，SG调整后，邻苯二甲酸酯代谢物和BPA的OR总体下降，而CAS调整后消失。此外，在CAS [OR（95％CI）= BPA：1.65（1.06，1.06）之后，最高BPA，对羟基苯甲酸甲酯（MeP）和对羟基苯甲酸乙酯（EtP）的DM风险显着高于最低四分位数的DM风险。 2.59）；MeP：1.68（1.08，2.60）；和EtP：分别为2.74（1.77，4.24）]。本观察结果概述了在肥胖与DM的关联研究中使用适当的调整方法进行尿液稀释的重要性。此外，几种邻苯二甲酸盐，BPA和对羟基苯甲酸酯被确定为这些结果的潜在化学危险因素。