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Dowdy J.C.,Rapid Precision Testing Laboratories | Sayre R.M.,Rapid Precision Testing Laboratories | Sayre R.M.,University of Tennessee Health Science Center | Sayre R.M.,University of Memphis
Photochemistry and Photobiology | Year: 2013

We evaluated six UV nail lamps representative of major US manufacturers to evaluate radiant hazards as defined in ANSI/IESNA RP-27 Recommended Practice for Photobiological Safety. Lamps were evaluated at three positions, 1 cm above the inner surface approximating exposure to the hand and the 20 cm RP-27 non-general light source distance, oriented normal and 45° to the opening. Hazard to skin at intended use distance classified these devices into Risk Group 1 or 2 (Low to Moderate) with S(λ) weighted Actinic UV ranging 1.2-1.7 μW cm-Â and 29.8-276.25 min permissible daily exposure. At 20 cm on center and 45° UV risk to skin and eyes were all within Exempt classification. Actinic UV ranged 0.001-0.078 μW cm-Â and unweighted near UV (320-400 nm) ranged 0.001-0.483 mW cm-Â. Likewise the retinal photochemical blue light hazard and retinal thermal and cornea/lens IR were also Exempt. One device had aphakic eye hazard slightly rising into Risk Group 1 (Low). There were no other photobiological risks to normal individuals. Total exposure following programmed times and steps accumulate to only a small fraction of RP-27 permissible daily occupational exposure. These risks are further mitigated in realistic nonoccupational use scenarios as it is unlikely to be a daily occurrence. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology. Source

Sayre R.M.,University of Memphis | Sayre R.M.,Rapid Precision Testing Laboratories | Dowdy J.C.,Rapid Precision Testing Laboratories
Photochemical and Photobiological Sciences | Year: 2010

The US Food and Drug Administration is in the process of formulating final rules for sunscreen labeling and testing. They have adopted a version of the solar simulator standard proposed by COLIPA, a European cosmetic products trade association. From our files we have selected spectral data on several solar simulators that comply with the proposed rules and have compared these sources both one to another and to several standard solar spectra of Air Mass 1.0, 1.5, and 2.0. In doing so we have used additional spectral analysis procedures including examining the goodness of fit between each solar simulator spectrum and an Air Mass 1.0 (0° zenith angle) solar spectrum. The index of goodness of fit ranges from ∼78% to just over 90% compared to solar spectra representing other Air Masses of 1.5 and 2.0, the goodness of fit is lower. Unfortunately, one may not assume that complying with a standard assures that other solar simulators also complying will produce identical results. In fact, by our analysis, none of the solar simulators we examined would be expected to produce the same SPF as sunlight. © The Royal Society of Chemistry and Owner Societies 2010. Source

Dowdy J.C.,Rapid Precision Testing Laboratories | Czako E.A.,Light Sources Inc. | Stepp M.E.,Wolff System Technology Corporation | Schlitt S.C.,Cosmedico Light Inc | And 7 more authors.
Health Physics | Year: 2011

The authors compared calculations of sunlamp maximum exposure times following current USFDA Guidance Policy on the Maximum Timer Interval and Exposure Schedule, with USFDA/CDRH proposals revising these to equivalent erythemal exposures of ISO/CIE Standard Erythema Dose (SED). In 2003, [USFDA/CDRH proposed replacing their unique CDRH/Lytle] erythema action spectrum with the ISO/CIE erythema action spectrum and revising the sunlamp maximum exposure timer to 600 J m ISO/CIE effective dose, presented as being biologically equivalent. Preliminary analysis failed to confirm said equivalence, indicating instead ∼38% increased exposure when applying these proposed revisions. To confirm and refine this finding, a collaboration of tanning bed and UV lamp manufacturers compiled 89 UV spectra representing a broad sampling of U.S. indoor tanning equipment. USFDA maximum recommended exposure time (Te) per current sunlamp guidance and CIE erythemal effectiveness per ISO/CIE standard were calculated. The CIE effective dose delivered per Te averaged 456 JCIE m (SD = 0.17) or ∼4.5 SED. The authors found that CDRH's proposed 600 JCIE m recommended maximum sunlamp exposure exceeds current Te erythemal dose by ∼33%. The current USFDA 0.75 MED initial exposure was ∼0.9 SED, consistent with 1.0 SED initial dose in existing international sunlamp standards. As no sunlamps analyzed exceeded 5 SED, a revised maximum exposure of 500 JCIE m (∼80% of CDRH's proposal) should be compatible with existing tanning equipment. A tanning acclimatization schedule is proposed beginning at 1 SED thrice-weekly, increasing uniformly stepwise over 4 wk to a 5 SED maximum exposure in conjunction with a tan maintenance schedule of twice-weekly 5 SED sessions, as biologically equivalent to current USFDA sunlamp policy. Copyright © 2011 Health Physics Society. Source

Sayre R.M.,University of Tennessee Health Science Center | Sayre R.M.,Rapid Precision Testing Laboratories | Dowdy J.C.,Rapid Precision Testing Laboratories | Gottschalk R.W.,Galderma Laboratories L.P.
Journal of Cosmetic and Laser Therapy | Year: 2011

This report documents the optical characteristics of a number of photodynamic therapy (PDT) light sources of varied types, measured and indexed relative to estimated effectiveness for activation of the PDT chromaphore protoporphyrin IX (PpIX). PDT sources in use at several clinics, including intense pulsed light (IPL) sources, lasers, and continuous wave (CW) light sources, were spectroradiometrically measured and indexed relative to their overlap to an absorption spectrum of PpIX. The sources were highly disparate, varying in power from irradiance in the mW/cm 2 range for the CW sources up to ∼30 J/cm 2 per flash for the IPL sources. Our PpIX Index ranged by a factor of nearly 100 (0.0080.630) in estimated PpIX PDT effectiveness following the distinct spectral characteristics of the light sources surveyed. Application of this PpIX Index, tempered with an understanding of the biology of the lesion being treated and effective spectrum of the light source reaching the lesion requiring therapy, provides a rational algorithm to approximate equivalent light doses prior to clinical protocols to establish equivalent patient outcomes employing alternative PDT light sources. © 2011 Informa UK, Ltd. Source

Skobowiat C.,University of Memphis | Sayre R.M.,Rapid Precision Testing Laboratories | Sayre R.M.,University of Memphis | Dowdy J.C.,Rapid Precision Testing Laboratories | Slominski A.T.,University of Memphis
British Journal of Dermatology | Year: 2013

Background 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1), 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), and glucocorticoids (GC) and their receptor (GR) play a key role in tissue-specific regulation of GC action. Objectives To determine the expression of genes encoding 11β-HSD1 (HSD11B1), 11β-HSD2 (HSD11B2) and GR (GRa; also known as NC3R1) and their protein products, and levels of cortisol in human skin explants and/or cocultured keratinocytes/melanocytes after treatment with ultraviolet (UV) A, B or C wavebands. Methods Skin from foreskins and/or cocultured human keratinocytes/melanocytes were irradiated with UVA, UVB or UVC (skin) and incubated for 12 and 24 h. Methods of reverse transcription- polymerase chain reaction, Western blotting, enzyme-linked immunosorbent assay and immunohistochemistry (IHC) were used to determine expression and localization of corresponding genes or antigens. Results UVB enhanced the HSD11B1 gene and protein expression in a dose-dependent manner, while UVA had no effect. Similarly, UVC increased 11β-HSD1 protein product as measured by IHC. UVB and UVC enhanced cortisol production and decreased epidermal GR expression, while UVA had no detectable effects. Although both UVA and UVB stimulated HSD11B2 gene expression, only UVA increased 11β-HSD2 protein product levels with UVB and UVC having no effect. Conclusions We suggest that these differential, waveband-dependent effects of UV radiation on the expression of cutaneous HSD11B1, HSD11B2 and GRa genes and their corresponding protein products, and cortisol production are to protect and/or restore the epidermal barrier homeostasis against disruption caused by the elevated cortisol level induced by UVB and UVC. © 2012 British Association of Dermatologists. Source

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