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At least 199 records · Page 11Linked to original sources
PubMed2003

Photolysis of polycyclic aromatic hydrocarbons adsorbed on spruce [Picea abies (L) Karst] needles under sunlight irradiation.

Photolysis of polycyclic aromatic hydrocarbons (PAHs) sorbed on surfaces of spruce [Picea abies (L.) Karst.] needles under sunlight irradiation was investigated. PAHs were produced by combustion of polyvinyl chloride (PVC), wood, high-density polyethylene (HDPE), and styrene in a stove. The factors of sunlight irradiation on the surfaces of spruce needles were taken into consideration when investigating the kinetic parameters. The photolysis of the 18 PAHs under study follows first-order kinetics. The photolysis half-lives range from 15 h for dibenzo(a,h)anthracene to 75 h for phenanthrene. Photolysis of some PAHs on surfaces of spruce needles may play an important role on the fate of PAHs in the environment.

Adsorption↗
PubMed1999

Mutation and DNA modification in Salmonella exposed to N-nitrosodimethylamine under UVA- and sunlight-irradiation.

Previously, we reported that when Salmonella typhimurium and Escherichia coli were treated with N-nitrosodimethylamine (NDMA) under irradiation with ultraviolet-A (UVA), mutagenesis of the bacteria took place without externally added activation enzymes. We also observed the formation of O(6)-methylguanine (O(6)-meG), N(7)-methylguanine (N(7)-meG) and 7,8-dihydro-8-oxodeoxyguanosine (8-oxodG) in calf thymus DNA treated with NDMA plus UVA. In this study, we observed the mutagenicity of NDMA under irradiation of natural sunlight in S. typhimurium. Furthermore, we detected the formation of O(6)-meG, N(7)-meG and 8-oxodG in calf thymus DNA treated with NDMA plus simulated sunlight. Regarding the mutagenesis of S. typhimurium by NDMA plus UVA, we have now identified and quantified O(6)-meG formed in the genomic DNA of the bacteria under conditions of the mutagenesis.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2004

Natural sunlight and its association to civil aviation accidents.

BACKGROUND: Glare is a temporary visual sensation produced by luminance within the visual field that is significantly greater than that to which the eyes are adapted. Glare from natural and artificial light sources can result in temporary visual impairment, increasing the risk of an accident. This study investigates the relationship between visual impairment from natural sunlight and aviation accidents. METHODS: The National Transportation Safety Board Aviation Accident/Incident Database was queried for the period January 1, 1988 to December 31, 1998 for terms, which included "sun," "glare," "vision," "blind ed," and "reflections." Reports annotated with one or more of these terms were reviewed to determine whether glare was considered a direct or contributing factor in the event. RESULTS: There were 130 accidents in which glare was found to be a contributing factor. The majority of these events occurred during clear weather and atmospheric conditions (85%), and were associated with approach/landing and takeoff/departure phases of flight (55%). CONCLUSIONS: Exposure to glare from natural sunlight has contributed to aviation accidents, primarily under otherwise optimal visual conditions at low altitude in congested airspace. Preventative techniques are presented that may protect a pilot's visual performance against the debilitating effects of glare from the sun.

Accidents, Aviation↗
PubMed2005

Mineralization of aromatics in water by sunlight-assisted electro-fenton technology in a pilot reactor.

The viability of the degradation of aqueous solutions of aniline, nitrobenzene, and 4-chlorophenol by the so-called Photoelectro-Fenton process in a pilot reactor is reported. The Electro-Fenton process stage, based on the flow of oxygen through a gas diffusion cathode to produce H2O2, allows mineralization of about a half of the TOC content in ca. 1 h, because anodic oxidation is coupled with Fenton reaction in the presence of Fe2+ catalyst. An intensity of 20 A was applied in a flow cell comprising a Ti/Pt anode and a carbon-PTFE cathode. After electrolysis, samples of the effluent were exposed to sunlight, and almost complete mineralization was reached after ca. 50 min. Effect of parameters such as electrolysis time, pH, initial concentration, and solar or UVA irradiation on the process efficiencies and the running costs are studied. The Photoelectro-Fenton process using sunlight effectively diminishes these costs. The analogous behavior of the three aromatics suggests similar degradation pathways, regardless of the different groups attached to the ring.

Aniline Compounds↗
PubMed2004

Influence of vine training and sunlight exposure on the 3-alkyl-2-methoxypyrazines content in musts and wines from the Vitis vinifera variety cabernet sauvignon.

The influence of vine training and sunlight exposure on the 3-alkyl-2-methoxypyrazines contents in musts and wines was studied by means of two previously reported methods based on headspace solid-phase micro-extraction. Experimental samples were monitored throughout grape ripening and wine making. 3-Isobutyl-2-methoxypyrazine, 3-sec-butyl-2-methoxypyrazine and 3-isopropyl-2-methoxypyrazine were identified. The 3-isobutyl-2-methoxypyrazine content decreased throughout grape ripening in all of the sample types studied. After 1 day of maceration with the skins, there was an increase, but after racking, no further increase was observed. No significant differences between samples were found during grape ripening. Wines from goblet-trained vines, however, contained significantly less 3-isobutyl-2-methoxypyrazine. Clusters protected from sunlight since the beginning of the veraison resulted in wines with a significantly lower content of this compound than the control samples.

Agriculture↗
PubMed2006

Quantitative analysis of beta-sitosterol oxides induced in vegetable oils by natural sunlight, artificially generated light, and irradiation.

UV radiation is able to induce lipid peroxidation. Photooxidation-induced beta-sitosterol oxides were monitored in four vegetable oils exposed to sunlight for 10, 20, and 30 days during May 2005 (northeastern France), exposed to artificial light generated by a high-pressure Hg lamp for 21, 42, and 63 h at room temperature, and exposed to a 10 MeV electron beam at 0.93, 2.69, and 9.30 kGy at 8 degrees C. Quantification was performed by capillary gas chromatography-mass spectrometry according to the total ion current mode and using a reconstructed ion trace chromatogram with specific ion fragments. Sunlight induced the formation of higher amounts of oxides than UV light, while no significant oxidizing effect was observed with electron beam irradiation. However, data suggested that the amount of the main oxides formed was strongly dependent on the dose rate (length of exposure). Accordingly, shorter but more intense treatments had lower oxidizing effects.

Fatty Acids, Monounsaturated↗
PubMed1985

The aetiological significance of sunlight and fluorescent lighting in malignant melanoma: a case-control study.

Information on exposure and reaction to sunlight, together with the history of exposure to fluorescent lighting, was elicited by postal questionnaire. Case-control analysis from 58 patients with malignant melanoma, 182 matched controls and 151 unmatched controls showed associations between malignant melanoma and (i) bouts of painful sunburn, (ii) reaction of untanned skin to sunlight, and (iii) number of moles (on right forearm), whereas no association could be found with exposure to fluorescent light at work.

Adult↗
PubMed1999

Is sunlight an aetiological agent in the genesis of retinoblastoma?

The incidence of unilateral, but not bilateral, retinoblastoma in human populations at different geographical locations increases significantly with ambient erythemal dose of ultraviolet B radiation from sunlight. This supports the hypothesis that sunlight plays a role in retinoblastoma formation.

Adolescent↗
PubMed1991

The mechanism of sunlight-mediated inactivation of Bacillus thuringiensis crystals.

Detailed photostability studies were carried out using purified delta-endotoxin crystals from Bacillus thuringiensis subspecies HD-1 and HD-73. The mechanism and time course of sunlight inactivation was investigated by: (a) monitoring the tryptophan damage in the intact crystals by Raman spectroscopy, (b) amino acid analysis and (c) biological assays using insects. The results demonstrate that, for purified HD-1 or HD-73 crystals, the 300-380 nm range of the solar spectrum is largely responsible for bringing about crystal damage and consequent loss of toxicity. Purified Bacillus thuringiensis crystals that were exposed to fermentation liquor after cell lysis were more quickly degraded by sunlight than were crystals from cells that were lysed in water. This effect is attributed to adsorption of chromophores by crystals exposed to the fermenter liquor and the subsequent ability of these chromophores to act as photosensitizers. The importance of a photosensitization mechanism in crystal degradation was further emphasized by irradiating Bacillus thuringiensis crystals in vacuo. The latter crystals were found to be less damaged (20% tryptophan loss after 24 h irradiation by the solar spectrum) compared with crystals from the same sample irradiated in air (60% (60% tryptophan loss). Other methods of decreasing exposure of the crystals to oxygen, e.g. by using glycerol as a humectant, were also found to be successful in controlling photodamage. The results concerning photodegradation support a photosensitization mechanism involving the presence of exogenous (and possibly endogenous) chromophores which create singlet oxygen species upon irradiation by light.

Amino Acids↗
PubMed1984

Fibroblasts from patients with hereditary cutaneous malignant melanoma are abnormally sensitive to the mutagenic effect of simulated sunlight and 4-nitroquinoline 1-oxide.

Because of a possible etiologic link between mutations and carcinogenesis, we compared fibroblasts derived from skin biopsies of several patients with hereditary cutaneous malignant melanoma and the dysplastic nevus syndrome for sensitivity to the mutagenic and/or cytotoxic effect of broad-spectrum simulated sunlight and of a UV mimetic carcinogen, 4-nitroquinoline 1-oxide (4NQO). The genetic marker was resistance to 6-thioguanine; loss of colony-forming ability was the assay for cytotoxicity. All five strains tested were more sensitive than normal to the killing effect of 4NQO (slopes of survival curves were 2- to 3-fold steeper), but only one strain was hypersensitive to killing by Sun Lamp radiation. Two strains were tested for mutagenicity. The response of each to the mutagenic action of these agents corresponded to its response to cell killing. Both strains were hypermutable after exposure to 4NQO, but only one showed a higher than normal frequency of mutants induced by simulated sunlight. The finding that nonmalignant fibroblasts from patients with a hereditary variant of malignant melanoma are abnormally susceptible to carcinogen-induced mutations suggests that hypersensitivity to mutagens contributes to risk of melanoma in patients. It also supports the somatic cell mutation hypothesis for the origin of cancer.

4-Nitroquinoline-1-oxide↗
PubMed1991

A role for sunlight in skin cancer: UV-induced p53 mutations in squamous cell carcinoma.

Sunlight is a carcinogen to which everyone is exposed. Its UV component is the major epidemiologic risk factor for squamous cell carcinoma of the skin. Of the multiple steps in tumor progression, those that are sunlight-related would be revealed if they contained mutations specific to UV. In a series of New England and Swedish patients, we find that 14/24 (58%) of invasive squamous cell carcinomas of the skin contain mutations in the p53 tumor suppressor gene, each altering the amino acid sequence. Involvement of UV light in these p53 mutations is indicated by the presence in three of the tumors of a CC----TT double-base change, which is only known to be induced by UV. UV is also implicated by a UV-like occurrence of mutations exclusively at dipyrimidine sites, including a high frequency of C----T substitutions. p53 mutations in internal malignancies do not show these UV-specific mutations. The dipyrimidine specificity also implicates dipyrimidine photoproducts containing cytosine as oncogenic photoproducts. We believe these results identify a carcinogen-related step in a gene involved in the subsequent human cancer.

Aged↗
PubMed1993

Mutation hotspots due to sunlight in the p53 gene of nonmelanoma skin cancers.

To identify the sites in the p53 tumor suppressor gene most susceptible to carcinogenic mutation by sunlight, the entire coding region of 27 basal cell carcinomas (BCCs) of the skin was sequenced. Fifty-six percent of tumors contained mutations, and these were UV-like: primarily CC-->TT or C-->T changes at dipyrimidine sites. Such mutations can alter more than half of the 393 amino acids in p53, but two-thirds occurred at nine sites at which mutations were seen more than once in BCC or in 27 previously studied squamous cell carcinomas of the skin. Seven of these mutation hotspots were specific to skin cancers. Internal-cancer hotspots not located at dipyrimidine sites were not mutated in skin cancers; moreover, UV photoproducts were absent at these nucleotides. The existence of hotspots altered the process of inactivating p53 in BCC compared to other cancers: allelic loss was rare, but 45% of the point mutations were accompanied by a second point mutation on the other allele. At least one of each pair was located at a hotspot. Sunlight, acting at mutation hotspots, appears to cause mutations so frequently that it is often responsible for two genetic events in BCC development.

Aged↗
PubMed2004

Photodegradation of pentachlorophenol by sunlight in aquatic surface microlayers.

Photodegradation of pentachlorophenol (PCP) in aquatic surface microlayer (SM) was examined under natural sunlight. SM samples were collected using a glass plate, along with corresponding subsurface waters. PCP was added to samples of the SM and subsurface water. When all samples were exposed to the same natural sunlight conditions, the first order photodegradation rates of PCP in the SM water samples were different from those of PCP in corresponding subsurface water samples. The difference was correlated with the enrichment of dissolved organic carbon (DOC) in SM compared to the corresponding subsurface waters. Enhanced photodegradation in SM may be due to increased abundance of photoreactants related to the UV-absorbing properties of dissolved organic materials in the SM as the result of photo-induced reactions. Effects of environmental factors, pH and salinity, on photodegradation process of PCP in SM were also evaluated.

Environmental Monitoring↗
PubMed1990

An evaluation of the relative contributions of exposure to sunlight and of diet to the circulating concentrations of 25-hydroxyvitamin D in an elderly nursing home population in Boston.

We investigated the vitamin D status of a Caucasian elderly population in a long-term-care facility in Boston. Comparison was made with a group of free-living elderly people. The sunlight exposure of residents was monitored and its effect on the serum concentrations of 25-hydroxyvitamin D [25(OH)D] was compared with contributions from diet and multivitamins. Seasonal changes in serum 25(OH)D concentrations caused by sunlight exposure were greatest in the free-living subjects and declined in magnitude as the mobility of the volunteers decreased. Diet failed to provide an adequate amount of vitamin D for volunteers who had minimal outdoor activity. Use of a multivitamin supplement containing 10 micrograms (400 IU) vitamin D maintained serum 25(OH)D concentrations greater than 37.5 nmol/L.

Activities of Daily Living↗
PubMed1993

Effects of skin thickness, age, body fat, and sunlight on serum 25-hydroxyvitamin D.

We tested the hypothesis that the age-related decline in skin thickness may contribute to the age-related decline in serum 25-hydroxyvitamin D [25(OH)D]. We measured skinfold thickness on the back of the hand, serum 25(OH)D, height, and weight in 433 normal postmenopausal women. We also noted the average daily hours of sunlight in the month in which the observations were made and in the preceding 2 mo. Serum 25(OH)D was positively related to hours of sunlight (with a time lag of 2 mo) and to skin thickness, and negatively to body mass index (wt/ht2). Serum 25(OH)D fell significantly after age 69 y. Seasonal variation of serum 25(OH)D was greater in lean than in fat subjects, which we attributed to the larger fat mass and consequent larger pool size in the latter group. The results suggest that the tendency for serum 25(OH)D to fall with age is due in part to the age-related decline in skin thickness.

Adipose Tissue↗
PubMed1977

Sunlight and cataract: an epidemiologic investigation.

Cataract prevalence data from two large U.S. sources were divided according to small geographic areas for which average annual sunlight hours were determined from a map prepared by the U.S. Weather Bureau. Several non-cataract disease controls were chosen from the same geographic locations (separately for each data set). It was found that the cataract-to-control ratios for persons aged 65 years or older were significantly larger in locations with large amounts of sunlight compared to those in locations with small amounts (P less than .05). Discussion of some possible biases in the data leads to the conclusion that the biases, if they exist, are probably not large. The authors believe, however, that more research should be done before the association between sunshine and cataract is considered established.

Aged↗
PubMed1991

Ocular and facial skin exposure to ultraviolet radiation in sunlight: a personal exposure model with application to a worker population.

A model of ocular and facial skin exposure to UVB is presented that combines interview histories of work activities, leisure activities, eyeglass wearing, and hat use with field and laboratory measurements of UV radiant exposure. Site-specific exposure is expressed as the product of personal ambient exposure, defined as the ambient exposure while an individual is exposed to sunlight, and factors that describe the ratio of site-specific to personal ambient exposure. Ocular exposure is further corrected by the UV attenuation of typical eyewear. The model was used to compute cumulative and yearly exposures in a population of 838 watermen who work on the Chesapeake Bay and are highly exposed to sunlight. The model was found to be predictive of conditions known to be caused by excessive sun exposure--skin elastosis, climatic droplet keratopathy, and squamous cell carcinoma--and has been useful in several epidemiological studies.

Eye↗
PubMed1992

Repair of DNA damage induced in systemic lupus erythematosus skin fibroblasts by simulated sunlight.

Skin fibroblasts derived from three normal individuals and three patients exhibiting the disease systemic lupus erythematosus (SLE) were exposed to the simulated sunlight produced by a solar simulator. The induction and repair of DNA damage induced by this treatment were examined. The total number of lesions repaired by excision, as well as the removal of pyrimidine dimers and E. coli endonuclease III--sensitive sites did not differ significantly in the three SLE cell strains compared with normal cells. However, abnormalities in the formation and maintenance of DNA-protein crosslinks (DPC) and DNA single-strand breaks (SSB) were found in SLE-4 and SLE-5 following simulated sunlight exposure. In contrast, SLE-3 cells exhibited responses similar to normal cells in reference to SSB and DPC formation. These findings correlate well with the previously determined UV sensitivity of these SLE cell strains.

Adult↗