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Triclosan is an antibacterial compound commonly used in cosmetics and personal care products for everyday use. As previously shown, triclosan is found in the plasma, urine and milk from large parts of different human populations. Recent studies have revealed that triclosan is able to activate the human pregnane X receptor in vitro and thus possibly affecting metabolism of drugs in humans via the induction of CYP3A4. Besides, triclosan has been shown to affect thyroid hormonal levels in rats in vivo. In the present study, we investigated if an everyday exposure to triclosan via triclosan-containing toothpaste for 14 days in 12 adult humans caused an increase in plasma 4b-hydroxycholesterol, indicative of CYP3A4 induction, and ⁄ or alterations in thyroid hormonal status. The plasma triclosan concentrations increased from 0.009-0.81 ng ⁄ g to 26-296 ng ⁄ g (ranges) upon exposure. Despite this, there were no significant changes in plasma levels of either plasma 4b-hydroxycholesterol or thyroid hormones during the exposure. This indicates that the normal use of triclosancontaining toothpaste is not likely to alter metabolism of drugs via CYP3A4 induction or cause adverse events because of thyroid disturbances in humans.

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A sensitive method for the determination of triclosan in plasma and milk is presented. Following hydrolysis of possible conjugates, triclosan is extracted with n-hexane/acetone, partitioned into alcoholic potassium hydroxide, and converted into its pentafluorobenzoyl ester. After sulfuric acid cleanup, sample extracts are analyzed by gas chromatography/electron capture negative ionization mass spectrometry. The limit of quantification was 0.009 ng/g for a 5-g plasma sample and 0.018 ng/g for a 3-g milk sample. The coefficient of variation for the method was 6%. The method was tested on more than 70 human plasma and milk samples, of which all plasma samples and more than half of the milk samples were above the limit of quantification. The presented method has lowered the limit of quantification for triclosan in human matrixes significantly as compared to previous methods and makes possible the analysis of triclosan in humans under normal exposure conditions.

No abstract