5-Methoxypsoralen 20mg tablets

The phototoxicological effects of furocoumarins have been extensively studied. In association with UVA, some of these natural constituents of botanical isolates used in cosmetics, can be photoirritant, photogenotoxic and/or photocarcinogenic. Importantly, not all furocoumarins share the same degree of potency and some are inactive. The more potent furocoumarins, 8-methoxypsoralen and 5-methoxypsoralen, have been subject to extensive mechanistic studies. The formation of adducts with DNA has been widely studied but other contributary mechanisms have also been proposed. The phototoxicological effects, ranging from photoirritation to photocarcinogenicity, are dependent on the dermal dose of furocoumarin and the fluence (dose) of filtered, artificial UVA light. This is particularly evident from photocarcinogenicity studies in animals and from the effect of sequential irradiation sessions in patients receiving Psoralen-UVA (PUVA) therapy. A currently enforced limit of 1 ppm for sun bronzing and sunscreen products for which prolonged intentional exposure to UVA is likely, and 5ppm total furocoumarin concentration in other cosmetic products, e.g., facial cosmetics, that are likely to be only exposed to adventitious and intermittent UVA irradiation, provides a suitably protective threshold when compared to the UV exposure that has been used in studies on animals and in treating PUVA patients.

Abstract licence: CC BY-NC-ND

Spectroradiometry, radiometry, and dosimetry are employed for the measurement of ultraviolet radiation (UVR) irradiance and non-ionizing exposure. Different types of UVR dosimeter have been developed for measuring personal and environmental UVR exposures since film dosimetry was pioneered in the 1970s. An important type of dosimeter is the thin film variant, which contains materials that undergo changes in optical absorbance when exposed to UVR. These changes can be measured at a specific wavelength using a spectrophotometer. Thin film dosimeters allow UVR exposure measurements on humans at various body sites during daily activities, as well as on plants, animals, and any sites of interest when utilized in a field environment. This review examines the properties and applications of five types of thin film UVR dosimeter that have different dynamic exposure limits and spectral responses. Polysulphone, with a spectral response approximating the human erythema action spectrum, was one of the first materials employed in thin film form for the measurement of UVR exposures up to 1 day, and up to 6 days with an extended dynamic range filter. Polyphenylene oxide has been characterized and employed for personal UVR exposure measurements up to approximately four summer days and has also been used for long-term underwater UVR exposures. Phenothiazine and 8-methoxypsoralen have been reported as suitable for the measurement of longer wavelength UVA exposures. Finally, polyvinyl chloride with an extended dynamic exposure range of over 3 weeks has been shown to have predominantly a spectral response in the UVB and extending up to 340 nm.

Abstract licence: CC BY-NC-ND