Serum analysis in women and in vitro skin assay for the assessment of exposure to parabens in antiperspirants

The present study assessed the exposure to methylparaben (MP) and propylparaben (PP) from antiperspirants in serum of 24 women aged 20-30 years old and an in vitro skin assay. An effective liquid chromatography-tandem mass spectrometry method for the determination of MP and PP levels in serum was developed and validated in the range of 10-100 μg/L; the method was fast, simple, sensitive, linear, precise, and accurate. In addition, a simple and rapid liquid chromatography-ultraviolet detection method for the determination of MP and PP levels in antiperspirants was developed and validated in the range of 2-26 mg/L, which presented satisfactory linearity, precision, and accuracy. Using these two methods, 20 commercial antiperspirants were evaluated, and only three showed MP and PP in the formulation. The antiperspirant containing 0.2% and 0.1% w/w MP and PP, respectively, was given to the volunteers, to estimate the internal dose, and submitted to a pig ear skin permeation assay in Franz diffusion cells, presenting a permeation flux of 32% for MP and 71% for PP. In this assay, both MP and PP permeated the skin; however, there was no correlation between antiperspirant use and paraben serum concentration in the volunteers. Graphical abstract.