Ultraviolet filter contact and photocontact allergy: consumer exposure and risk assessment for octocrylene from personal care products and sunscreens.

BACKGROUND: Octocrylene (OCT) is an ultraviolet (UV) filter used in personal care products (PCPs) to prevent sun-related skin damage. OCT is photostable and has the ability to photostabilize other UV filters, which has recently led to its increased use in PCPs. Emerging clinical and experimental studies indicate that OCT is both a contact and a photocontact allergen. OBJECTIVES: To quantify OCT exposure via PCPs, including aggregate exposure that arises from concurrent use of multiple PCP categories, for use in an exposure-based quantitative risk assessment (QRA). METHODS: Probabilistic modelling of exposure was performed at an individual level simulating 1 day of concurrent and single PCP use. PCP use data obtained via a questionnaire were linked to OCT concentrations gained from chemical analyses of PCPs used by the questionnaire respondents from the German-speaking part of Switzerland (n = 1196; ages ≤ 1-97 years). Acceptable exposure levels (AELs) were calculated for OCT and compared with the computed exposure estimates. RESULTS: Overall, 19%, 33% and 79% of respondents were exposed to OCT via hand cream, face cream and sunscreen, respectively. Sunscreen was the most prevalent exposure source and largest contributor to aggregate exposure. For the study population, the overall mean and median exposure to OCT via sunscreen alone exceeded the QRA-predicted AEL of 4·9 µg cm(-2). CONCLUSIONS: Use of OCT in PCPs at levels greater than the threshold for induction of skin sensitization might lead to an increased number of sensitized individuals. It is therefore desirable to perform a new safety assessment of OCT.

Characterizing the mesencephalon using susceptibility-weighted imaging.

BACKGROUND AND PURPOSE: The mesencephalon is involved in a number of human neurodegenerative disorders and has been typically imaged with T1-, T2- and T2*-weighted methods. Our aim was to collect high-contrast susceptibility-weighted imaging (SWI) data to differentiate among and within the basic mesencephalic structures: namely, the red nucleus, substantia nigra, and crus cerebri. MATERIALS AND METHODS: High-resolution SWI, 3D T1-weighted, and T2-weighted data were collected to study contrast in the mesencephalon at 1.5T and 4T. Contrast between structures was calculated for SWI high-pass (HP)-filtered-phase, T1 gradient-echo, and spin-echo T2-weighted data. RESULTS: SWI HP-filtered-phase data revealed similar contrast for the red nucleus and substantia nigra when compared with T2-weighted imaging. However, SWI was able to show structures within the red nucleus, substantia nigra, and medial geniculate body that were invisible on T2-weighted imaging. T1-weighted imaging, on the other hand, did not reveal measurable contrast for any of the structures of interest. SWI HP-filtered-phase data at 4T agreed well with india ink-stained cadaver brain studies, which appear to correlate with capillary density. CONCLUSIONS: With SWI, it is possible to create better anatomic images of the mesencephalon, with improved contrast compared with conventional T1- or T2-weighted sequences.