Integration of in vivo and in vitro data for the evaluation of parabens in body cream

Although literature studies have reported body burden of topical formulation ingredients, several controversies remain. Parabens are preservative ingredients widely used in personal care products (PCPs). Integrating in vitro transdermal permeation and biomonitoring studies provides an efficient approach to evaluating the safety or potential hazards associated with exposure to these ingredients. In this study, an experimental biomonitoring group comprising 20 women from Alfenas (aged 18–41 years) was evaluated by analyzing serum, oral fluid, and urine samples. Serving as their own experimental controls, participants applied a paraben-free body cream for 7 days, followed by a non-paraben-free body cream for an additional 7 days. Subsequently, transdermal permeation of the non-paraben-free body cream was evaluated as ex vivo using pig skin in a Franz-type vertical diffusion cell, with analyte quantification performed via high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV). The analysis of internal dose bioindicators in urine was inconsistent with previous literature findings, whereas oral fluid samples were unrepresentative of the alterations observed in serum samples. In serum, statistically significant differences were observed between Phases 1, 2 and 3 (control and paraben-free body cream, respectively) compared with Phases 4 and 5 (non-paraben-free body cream) for methylparaben (MeP) (p-value= 9.39 × 10⁻¹¹) and propylparaben (PrP) (p-value = 1.66 × 10⁻¹¹). These results closely aligned with the ex vivo pig ear skin permeation data; following 6 h of exposure, approximately 70.65 μg/cm² of MeP permeated into the epidermis, while 10.4% was retained within the layer. Because over 71% of PrP remained retained in the skin, transdermal permeation could not be quantified using the present analytical methodology. Overall, this study demonstrates that cosmetic ingredients can undergo transdermal permeation following topical application of body cream, exceeding the safety margin threshold for allergic sensitization 21.9 μg/cm² established by the Handbook of Cosmeceutical Excipients. This finding is supported by the increased systemic exposure observed during short-term serum biomonitoring; however, further studies investigating the allergenicity of parabens are required.尽管已有文献报道了外用制剂成分的身体负荷（body burden），但目前仍存在诸多争议。对羟基苯甲酸酯（parabens）是个人护理产品（personal care products, PCPs）中广泛使用的防腐成分。整合体外经皮渗透与生物监测研究，可为评估此类成分暴露相关的安全性或潜在危害提供高效途径。本研究针对来自阿尔菲纳斯（Alfenas）的20名女性受试者（年龄18~41岁）组建实验生物监测队列，通过分析血清、口腔液（oral fluid）与尿液样本开展评估。受试者以自身作为实验对照，先涂抹无对羟基苯甲酸酯身体乳7天，随后更换为含对羟基苯甲酸酯的身体乳继续涂抹7天。随后，采用Franz型垂直扩散池（Franz-type vertical diffusion cell），以猪皮肤为离体模型，评估该含对羟基苯甲酸酯身体乳的经皮渗透情况，并通过高效液相色谱-紫外检测法（high-performance liquid chromatography coupled with ultraviolet detection, HPLC-UV）对分析物进行定量。尿液中内剂量生物标志物的分析结果与既往文献报道不一致，而口腔液样本无法反映血清样本中观察到的变化。在血清样本中，与第4、5阶段（即含对羟基苯甲酸酯身体乳涂抹阶段）相比，第1、2、3阶段（分别对应对照期与无对羟基苯甲酸酯身体乳涂抹期）的对羟基苯甲酸甲酯（methylparaben, MeP）与对羟基苯甲酸丙酯（propylparaben, PrP）水平存在统计学显著差异（MeP的p值=9.39×10⁻¹¹，PrP的p值=1.66×10⁻¹¹）。上述结果与离体猪耳皮肤渗透数据高度吻合：暴露6小时后，约70.65 μg/cm²的对羟基苯甲酸甲酯渗透进入表皮，另有10.4%留存于皮肤层内。由于超过71%的对羟基苯甲酸丙酯留存于皮肤中，本研究的分析方法无法对其经皮渗透量进行定量。总体而言，本研究证实，外用身体乳涂抹后，化妆品成分可发生经皮渗透，且其渗透量超过《药用化妆品辅料手册》（Handbook of Cosmeceutical Excipients）所设定的过敏性致敏安全阈值21.9 μg/cm²。短期血清生物监测中观察到的全身暴露量增加，也支持了这一结论；不过，仍需开展进一步研究以探讨对羟基苯甲酸酯的致敏性。