Licht-im-Terrarium: Literaturdatenbank
Licht-im-Terrarium: Literaturdatenbank |
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De Flora, S., & D'Agostini, F. (1992). Halogen lamp carcinogenicity. Nature, 356(569). Added by: Sarina (2013-10-03 15:51:50) |
| Resource type: Journal Article DOI: doi:10.1038/356569a0 BibTeX citation key: DeFlora1992 View all bibliographic details  |
Categories: Englisch = English Keywords: Glühlampe = Incandescent Lamp, Ultraviolett = Ultraviolet Creators: D'Agostini, De Flora Collection: Nature |
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| Abstract |
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The risk of indoor pollution by chemicals and radionuclides is much in the news. Less attention is paid to hazards associated with exposure to harmful ultraviolet radiations emitted by certain illumination systems, which are used more and more extensively in the workplace and at home. The potent genotoxicity of the light emitted by uncovered quartz halogen lamps was demonstrated recently both by using a mutagenicity test in his- Salmonella typhimurium1 and a DNA repair test in Escherichia coli.2 At variance with solar irradiation, exerting mutagenic effects over a broad ultraviolet range, and with fluorescent light, delivering mainly ultraviolet B emissions, the mutagenicity of halogen lamps is due to far-ultraviolet wavelengths. Moreover, the spectrum of sensitivity of E. coli strains lacking DNA repair mechanisms is similar for halogen lamps and a monochromatic ultraviolet (254 nm) source. We observed some residual mutagenicity even after filtering both natural and artificial light through various cloths, but mutagenicity was prevented by glass and plastic covers. These findings prompted us to investigate the carcinogenicity of halogen lamps using animal models. We recently started a large study, using MF1 and SKH-1 hairless mice, after completing a pilot study with SKH-1 adult mice in which four control mice were kept under natural light-dark cycle. Four mice were exposed 12 h per day at 50 em distance from a 12 V, 50 W uncovered halogen quartz lamp equipped with a dichroic mirror, accounting for an illuminance of 10,000 lux. Under these conditions a mutagenic response was induced in S. typhimurium in less than 1 min. A further group of four mice was exposed to the same lamp, but a 2-mm-thick transparent glass sheet, totally preventing genotoxic effects, was interposed close to the lamp. After 12 months, the appearance of these mice and of the four controls was normal. By contrast, all four animals exposed to the uncovered lamp started to develop skin lesions, the earliest appearing after 3-4 months and growing in size and number, up to 15-20 per animal, until overlapping and covering large portions of the regions of skin directly exposed to the light. Skin tumours of up to 3 em in diameter were detected. Histological analysis revealed the presence in all four animals of relatively benign forms, such as papillomas and appendage/basal tumours, as well as atypical squamous cell proliferation of increasing malignancy - keratoacanthoma- like tumours, carcinomas in situ and squamocellular carcinomas (P. Piallo, personal communication). Although based on only 12 animals, the results obtained in our pilot study are striking and fully confirm the expectations of in vitro genotoxicity studies. Extrapolation of animal data to humans is not straightforward. Nevertheless, the illumination doses and times in our study, although high, are not so far from the levels to which some people are exposed, particularly in the workplace. Note that the aforementioned genatoxicity data, as well as physical measurements, provide evidence for the emission by halogen lamps of farultraviolet radiation, which is likely to be the range of wavelength inducing melanoma. It is also important that the light emitted by halogen lamps is much more genotoxic than sunlight, which is well known to contribute to cancer prevalence and mortality in humans, and than fluorescent light, whose carcinogenicity is under debate5. Luckily, prevention is simple. Suitable glass or plastic covers, already used in some commercially available models, should be made compulsory for all new halogen lamps, and should be installed on all lamps already in use. Added by: Sarina Last edited by: Sarina |