Ultraviolet protection factor of fabrics: comparison of laboratory and field-based measurements.

BACKGROUND/PURPOSE: Spectrophotometry has become an accepted laboratory-based method for the determination of the ultraviolet protection factor (UPF) of fabrics. However, the validity of the UPF determined in the laboratory has been a controversial issue with regard to its significance in the field. To compare UPF values obtained by spectrophotometry, determination of the minimal erythema dose (MED), and biological dosimetry, we conducted laboratory and field-based measurements on various fabric materials. METHODS: One cotton, two viscose, and two polyester fabrics were enrolled into the study. Spectrophotometric (SP) testing was performed in accordance with the European standard. In vivo "on skin" (IV) testing on human subjects was performed with and without fabric protection. For determination of MED, a solar-simulator was used. In another part of the study, biological dosimetry (BD) testing was employed for laboratory testing with solar-simulated radiation (laboratory BD testing) as well as field-based measurements with natural sunlight in stationary (stationary BD testing) and "real life" exposure situations (mobile subject BD testing). For field-based measurements one light-weight polyester fabric was selected. RESULTS: The differences of the mean UPF values obtained by the laboratory-based methods were significant (MANOVA; P = 0.05), except for fabric no. 2 (MANOVA; P = 0.097). In 4 of the 5 fabrics tested, UPF values obtained by IV testing were significantly lower than those obtained by SP testing (t-test; P = 0.05). In 3 fabrics, SP testing revealed significantly higher UPF values in comparison to laboratory BD testing (t-test; P = 0.05). The differences of UPF values obtained by the laboratory and field-based measurements employed for the light-weight polyester fabric were significant (ANOVA; P = 0.05). In comparison to SP testing (UPF 3.8), stationary BD testing resulted in significantly lower (UPF 3.5) and mobile subject BD testing in a significantly higher UPF of 4.4 (t-test; P = 0.05). The UPF obtained by mobile subject BD testing differed significantly from the UPF obtained by stationary BD testing (t-test; P = 0.05). CONCLUSIONS: Comparison of the presented methods indicates that IV testing generally results in lower UPF values. By contrast BD testing in "real life" exposure situations reveals relatively high UPF values. Although an overestimation of the spectrophotometrically measured UPF has been observed in comparative laboratory testing, UPF values obtained by field-based measurements are in relatively good agreement, or even surpass UPF values obtained by spectrophotometry. It is, therefore, suggested that SP testing provides "safe" UPF values which may be also valid in extreme real exposure situations. Biological UV dosimetry is, however, a promising alternative method for UPF testing: the test is easily performed in realistic exposure situations, the test is relatively inexpensive, and the measurements are valid.

The cutaneous uptake of atmospheric oxygen contributes significantly to the oxygen supply of human dermis and epidermis.

It has been known since 1851 that atmospheric oxygen is taken up by the human epidermis. The contribution to total respiration is negligible. Until now the significance for the local oxygen supply of the skin has remained unknown. With a newly developed sensor, the oxygen fluxoptode, it has become possible to make local measurements of the transcutaneous oxygen flux (tcJ(O2)). In this study the sensor was calibrated so that absolute values of tcJ(O2) could be reported. At rest, tcJ(O2) was determined on normal, humidified skin on the volar forearm of 20 volunteers of different age groups. In order to evaluate the contribution of the blood flow to the oxygen supply of the skin, tcJ(O2) was recorded at the end of a 5 min suprasystolic occlusion of the forearm. At normal skin surface partial oxygen pressure (163 +/- 9 Torr), tcJ(O2) was 0.53 +/- 0.27 ml O2 min(-1) x m(-2). A 5 min interruption of blood flow resulted in an increase of 9.5 +/- 6.3 % in tcJ(O2). The value of tcJ(O2) was unaffected by the age of the subject. Published data on the oxygen diffusion properties of skin and simulations of intracutaneous profiles of oxygen partial pressure indicated that under these conditions, the upper skin layers to a depth of of 0.25-0.40 mm are almost exclusively supplied by external oxygen, whereas the oxygen transport of the blood has a minor influence. As a consequence, a malfunction in capillary oxygen transport cannot be the initiator of the development of superficial skin defects such as those observed in chronic venous incompetence and peripheral arterial occlusive disease.

Low-dose ultraviolet-A1 phototherapy for lichen sclerosus et atrophicus.

Lichen sclerosus et atrophicus (LSA) is a chronic inflammatory skin disease characterized by white porcelain-like sclerotic skin lesions. It is most commonly seen in adult females and usually affects the genitoanal area. Extragenital LSA appears in 15-20% of cases. We report a 9-year-old Caucasian girl suffering from extragenital LSA that was resistant to conventional treatment. After 40 treatment sessions with low-dose UVA1 phototherapy, all skin lesions were resolved completely. Moreover, the improvement of skin status has been sustained during 6-months of follow-up. Long-wave UVA irradiation has been shown to induce intensively collagenase activity in human dermal fibroblasts. We suggest that UVA1 irradiation could be an effective treatment in patients suffering from extragenital LSA.

[Ultraviolet-A1 (UVA1) phototherapy in lichen sclerosus et atrophicus]. / UVA1-Phototherapie bei Lichen sclerosus et atrophicus.

Two patients, a nine year old girl and a 59 year old woman, presented with extensive and recalcitrant lichen sclerosus et atrophicus (LSA). Both patients were treated with low-dose ultraviolet-A1 (UVA1) phototherapy (340-400 nm) for ten weeks. The cumulative UVA1 dose was 800 J/cm(2), the single UVA1 dose was 20 J/cm(2). After 40 treatment sessions, the previously sclerotic skin lesions had almost completely cleared in both patients. In addition 20-MHz ultrasound examination and histological specimen revealed no further signs of sclerosis. UVA1 phototherapy seems to be a new and effective treatment for LSA with optimal patients' acceptance due to the absence of systemic side effects. UVA1 should be therefore considered as therapeutic option for LSA.

[Phototherapy in severe atopic dermatitis. Comparison between current UVA1 therapy, UVA1 cold light and combined UVA-UVB therapy]. / Phototherapie bei schwerer atopischer Dermatitis. Vergleich zwischen herkömmlicher UVA1-Therapie, UVA1-Kaltlicht- und kombinierter UVA-UVB-Therapie.

Severe atopic dermatitis, especially when involving the face, does not respond well to conventional therapy. In the present prospective randomized trial, we compared therapeutic efficiency of medium-dose UVA1, medium-dose cold light UVA1 (15 treatment courses with 50 J/cm2 each) and combined UVA-UVB phototherapy. Four (13.3%) of 30 UVA1 treated patients, one (3.4%) of 30 UVA1 cold light treated patients and three (30%) of 10 patients treated with combined UVA-UVB discontinued therapy course before finishing treatment protocol because skin status did not improve or even deteriorated. In the other patients treated over a period of three weeks, skin status improved significantly or even cleared completely in 80.8% of UVA1 treated and in 89.7% of UVA1 cold light treated patients resulting in a significant decrease of the SCORAD-Score (UVA1 group from 68.6 +/- SD 10.9 to 29.8 +/- SD 7.1 and UVA1 cold light group from 72.5 +/- SD 13.4 to 23.8 +/- SD 11.6; p < 0.05 each). In the UVA-UVB treated group, the SCORAD-Score also decreased (from 71.0 +/- SD 9.4 to 41.6 +/- 10.5), but significantly less than in both UVA1 treated groups (p < 0.05 each). Four weeks after completing therapy UVA1 treated patients showed a prolonged therapy benefit as compared to UVA-UVB treated patients. Plasma levels of eosinophil cationic protein and soluble interleukin-2 receptor significantly decreased under UVA1 phototherapy but not under UVA-UVB therapy. Compared to conventional UVA1 phototherapy, UVA1 cold light phototherapy showed advantages due to the absence of potentially proinflammatory effects based on temperature-induced increase of skin blood flow (quantified by Laser doppler scanning) and increased sweat production (determined by the patient using a visual analog scale).