Almost all three sunscreens were undetectable in plasma and urine before the first application. One to 2 h after the first application, all three sunscreens were detectable in plasma. The maximum median plasma concentrations were 187 ng/mL BP-3, 16 ng/mL 4-MBC and 7 ng/mL OMC for females and 238 ng/mL BP-3, 18 ng/mL 4-MBC and 16 ng/mL OMC for men. In the females, urine levels of 44 ng/mL BP-3 and 4 ng/mL of 4-MBC and 6 ng/mL OMC were found, and in the males, urine levels of 81 ng/mL BP-3, 4 ng/mL of 4-MBC and OMC were found. In plasma, the 96-h median concentrations were higher compared with the 24-h concentrations for 4-MBC and OMC in men and for BP-3 and 4-MBC in females.

In vitro and animal studies have reported endocrine-disrupting activity of chemicals used commonly as additives in cosmetics and skin care products. We investigated whether diethyl phthalate (DEP), dibutyl phthalate (DBP), and butyl paraben (BP) were systemically absorbed and influenced endogenous reproductive and thyroid hormone levels in humans after topical application. In a two-week single-blinded study, 26 healthy young male volunteers were assigned to daily whole-body topical application of 2 mg/cm2 basic cream formulation each without (week one) and with (week two) the three 2% (w/w) compounds. The concentrations of BP and the main phthalate metabolites monoethyl (MEP) and monobutyl phthalate (MBP) were measured in serum together with the following reproductive hormones: follicle stimulating hormone (FSH), lutenising hormone (LH), testosterone, estradiol, and inhibin B and thyroid hormones (thyroid stimulating hormone (TSH), free thyroxine (FT4), total triiodothyroxine (T3), and total thyroxine (T4)). MEP, MBP, and BP peaked in serum a few hours after application, reaching mean +/- SEM levels of 1001 +/- 81 microg/L, 51 +/- 6 microg/ L, and 135 +/- 11 microg/L, respectively. Only MEP was detectable in serum before treatment. Minor differences in inhibin B, LH, estradiol, T4, FT4, and TSH were observed between the two weeks, but these were not related to exposure. We demonstrated for the first time that DEP, DBP, and BP could be systemically absorbed in man after topical application. The systemic absorption of these compounds did not seem to have any short-term influence on the levels of reproductive and thyroid hormones in the examined young men.

In 1903, Niels Ryberg Finsen was awarded the Nobel Prize for his invention of light therapy for skin tuberculosis (lupus vulgaris). The mechanism of action has not been shown; thus, we wanted to elucidate the mechanism of Finsen's light therapy. We measured radiation that could be transmitted through his lens systems and absorption of the stain solution filters in the lamps, and related the obtained results to the possible biological effects on Mycobacterium tuberculosis. Judged from transmission characteristics all tested lens systems were glass lenses (absorbing wavelength < 340 nm). The tested filters likewise absorbed wavelengths < 340 nm. The methylene blue solution used to absorb heat, blocked out wavelengths below 340 nm and between 550 and 700 nm. Furthermore, fluorescence of M. tuberculosis indicated the presence of porphyrins and HPLC analysis of sonicated M. marinum showed that coproporphyrin III was present, which highly justified that porphyrins were present in M. tuberculosis. Production of singlet oxygen through radiation of porphyrins with light of e.g. 400 nm seems to be a most plausible explanation why Finsen's therapy worked in spite of the lack of shortwave ultraviolet radiation, which Finsen believed was the most effective radiation for treating skin tuberculosis.