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PubMed1994

The role of reactive oxygen species in the degradation of lindane and DDT.

We have studied the photodegradation reactions of lindane and DDT under sunlight (72 hr) or a solar simulator (2 hr) either directly or in presence of selected photodynamic sensitizers. Direct photolysis did not cause noticeable degradation of the pesticides (below 1% in both the cases). However, addition of benzophenone or rose bengal to the irradiation solution of lindane resulted in 88% and 47% degradation, respectively, under sunlight. Similar experiments carried out with DDT resulted in 89%, 50% and 32% degradation with benzophenone, rose bengal and methylene blue, respectively. All the photosensitizers used for the study have been shown to induce photooxidation reactions by generation of reactive oxygen species. These studies suggest that by employing certain naturally occurring photosensitizers with reactive oxygen generation potential under sunlight, an effective method for safe removal of pesticides and other environmentally persistent agents from the surface of earth can be developed.

Anthracenes↗
PubMed1995

Proportional melanoma incidence and occupation among white males in Los Angeles County (California, United States).

A case-control analysis of cancer registry data was used to examine the hypothesis that occupational exposure to sunlight influences the risk of melanoma. Occupation at diagnosis was available for 3,527 cutaneous melanomas and 53,129 other cancers identified by the Los Angeles County (California, United States) Cancer Surveillance Program among non-Spanish-surnamed White males aged 20 to 65 years between 1972 and 1990. Occupational exposure to sunlight was assessed by blinded expert coding of job titles as indoor, outdoor, and mixed indoor/outdoor. Relative to indoor occupations, proportionate odds ratios (OR) adjusted for age, level of education, and birthplace were 1.16 (95 percent confidence interval [CI] = 1.07-1.27) for indoor/outdoor occupations and 1.15 (CI = 0.94-1.40) for outdoor occupations. However, increasing levels of the education or training required for the occupation was associated more strongly with increased melanoma occurrence (ORs adjusted for age, occupational sun exposure, and birthplace, were 1.0, 1.63, 2.09, 2.23, and 2.99 for low-skill occupation, high school, college, postgraduate, and doctoral levels, respectively). Analysis of melanoma occurrence by job titles confirmed a clear variation by the required education or training level but not by the category of occupational sunlight exposure. The findings suggest that lifestyle factors associated with higher levels of education may be more important determinants of melanoma risk than characteristics of the work environment.

Adult↗
PubMed1992

Lethal and mutational effects of solar and UV radiation on Staphylococcus aureus.

Strains of Staphylococcus aureus, an opportunistic pathogen commonly found on human skin, were exposed to sunlight and UV C radiation, and the lethal and mutational effects measured. Sunlight killed cells with an inactivation constant of 3 x 10(-5) per joule per square metre; UV C was much more lethal, giving an inactivation constant of approximately 0.1 per joule per square metre. Some strains tested showed a sensitivity to sunlight that was dependent on the growth phase of the cells, exponentially growing cells showing a greater sensitivity. Mutational effects of irradiation were measured by the appearance of mutants sensitive to methicillin following irradiation of a multiresistant strain. Mutants appeared at a frequency of 10(-3); this high frequency of mutation in the region of the mec gene has also been observed when multiresistant strains are subjected to nutritional or thermal stress. Mutants showed the same chromosomal alteration (seen in pulse-field gel electrophoresis of SmaI-digested DNA) whether induced by solar or UV C irradiation.

DNA Damage↗
PubMed2005

Lifestyle interventions to prevent osteoporotic fractures: a systematic review.

The purpose of this study was to evaluate the clinical effectiveness of lifestyle interventions for preventing osteoporotic fractures in people at high risk. Data sources were electronic bibliographic databases, reference lists of systematic reviews, meta-analyses and included trials, registers of trials and conference databases. There was no language restriction. Study selection comprised randomized controlled trials (RCTs), with appropriate comparator groups and at least 8 weeks of follow-up, reporting a fracture endpoint. Two reviewers independently abstracted data on the population, interventions evaluated, trial quality and outcomes of interest: fractures at any site, spinal, hip and wrist fractures. Six RCTs, enrolling over 1,656 participants, met the inclusion criteria. Overall, trials were of uncertain quality. We categorized trials by type of intervention: exercise (n=3), multifactorial interventions (environmental modifications, exercise programs and review of medical conditions, medication and aids) (n=2) and exposure to sunlight (n=1), and used random effects meta-analyses to combine data within these categories. Exercise was associated with a non-significantly lower risk of spinal fractures (RR=0.52, 95% CI=0.17 to 1.60). Multifactorial interventions were associated with a lower risk of hip fracture, which was of borderline statistical significance (RR=0.37, 95% CI=0.13 to 1.03). Exposure to sunlight was associated with a non-significantly lower risk of hip fracture (RR=0.17, 95% CI=0.02 to 1.35). While withdrawals from treatment were poorly reported, there was no indication of adverse effects of treatment. Multifactorial interventions may reduce the risk of hip fractures when delivered by residential care staff and health visitors. More RCTs of higher quality, recording fractures at all sites susceptible to osteoporotic fractures, are necessary to evaluate exercise interventions, exposure to sunlight and the place of lifestyle alongside pharmacological interventions.

Aged↗
PubMed1999

Risk factors for hip fracture in men from southern Europe: the MEDOS study. Mediterranean Osteoporosis Study.

The aims of this study were to identify risk factors for hip fracture in men aged 50 years or more. We identified 730 men with hip fracture from 14 centers from Portugal, Spain, France, Italy, Greece and Turkey during the course of a prospective study of hip fracture incidence and 1132 age-stratified controls selected from the neighborhood or population registers. The questionnaire examined aspects of work, physical activity past and present, diseases and drugs, height, weight, indices of co-morbidity and consumption of tobacco, alcohol, calcium, coffee and tea. Significant risk factors identified by univariate analysis included low body mass index (BMI), low sunlight exposure, a low degree of recreational physical activity, low consumption of milk and cheese, and a poor mental score. Co-morbidity including sleep disturbances, loss of weight, impaired mental status and poor appetite were also significant risk factors. Previous stroke with hemiplegia, prior fragility fractures, senile dementia, alcoholism and gastrectomy were associated with significant risk, whereas osteoarthrosis, nephrolithiasis and myocardial infarction were associated with lower risks. Taking medications was not associated with a difference in risk apart from a protective effect with the use of analgesics independent of co-existing osteoarthrosis and an increased risk with the use of anti-epileptic agents. Of the potentially 'reversible' risk factors, BMI, leisure exercise, exposure to sunlight and consumption of tea and alcohol and tobacco remained independent risk factors after multivariate analysis, accounting for 54% of hip fractures. Excluding BMI, 46% of fractures could be explained on the basis of the risk factors sought. Of the remaining factors low exposure to sunlight and decreased physical activity accounted for the highest attributable risks (14% and 9% respectively). The use of risk factors to predict hip fractures had relatively low sensitivity and specificity (59.6% and 61.0% respectively). We conclude that lifestyle factors are associated with significant differences in the risk of hip fracture. Potentially remediable factors including a low degree of physical exercise and a low BMI account for a large component of the total risk.

Aged↗
PubMed2001

Exposure to a solar eclipse causes neuronal death in the retina.

BACKGROUND: A solar eclipse was observed in Europe on 11 August 1999. Several individuals suffered from transient or persisting retinal damage, caused by gazing at the eclipse without adequate eye protection. Retinal damage is the most serious hazard of exposure to light. but the mechanisms by which this type of exposure produces retinal damage and its cellular correlates are not yet established. We used an animal model to monitor the mechanisms of retinal damage following excessive light exposure, and in particular to study whether observation of the eclipse induces death of retinal cells. METHODS: In the geographic area where the experiment was conducted, a partial (90%) solar eclipse was observed. Experimental albino rats were exposed to these eclipse conditions, and control rats were exposed to normal sunlight. Another group of control animals was exposed to the same conditions, but was provided with protective light filters of the type recommended for human use. The DNA fragmentation in retinal sections of the various groups was analysed by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labelling. This analysis revealed that exposure to both normal sunlight and to the eclipse resulted in neuronal apoptosis. Immunohistochemical techniques were used to evaluate possible glial-vascular alterations. RESULTS: Dying cells could first be detected 24 h after exposure, the largest number of which were found 6 days later in the photoreceptor layer. Control levels were attained 14 days after the exposure. Retinal ganglion cells underwent apoptosis in both groups (normal sunlight and eclipse exposure), whereas in the neuroglial cells there was an up-regulation of the intermediate filament content. The number of dying cells in both groups was greater in animals whose pupils had been dilated pharmacologically during exposure. On the other hand, the protective filters were effective in preserving the rat retinal cells from apoptosis. CONCLUSIONS: These results show, for the first time, that the cellular correlates of solar retinopathy are neuronal apoptosis accompanied by glio-vascular responses. Cellular apoptosis is an irreversible process, which could manifest itself as permanent visual impairment. The activation of non-neuronal cells, such as glial and endothelial cells, could be responsible for the more transient clinical symptoms.

Animals↗
PubMed2005

Occupational risks for uveal melanoma results from a case-control study in nine European countries.

OBJECTIVE: Uveal melanoma is a rare disease with poor prognosis and largely unknown etiology. We studied potential occupational risk factors. METHODS: A population based case-control study was undertaken during 1995-1997 in nine European countries using population and colon cancer controls with personal interviews. Occupational exposure to sunlight and artificial UV radiation was assessed with a job exposure matrix. In total, 320 uveal melanoma cases were eligible at pathology review, and 292 cases were interviewed, participation 91%. Out of 3357 population controls, 2062 were interviewed, 61%, and out of 1272 cancer controls 1094 were interviewed, 86%. RESULTS: Using population controls, occupational exposure to sunlight was not associated with an increased risk (RR=1.24, 95% CI=0.88-1.74), while an excess risk found with use of colon cancer controls was attributed to confounding factors. An excess risk in welders was restricted to the French part of the data. Cooks, RR=2.40; cleaners, RR 2.15; and laundry workers, RR=3.14, were at increased risk of uveal melanoma. CONCLUSION: Our study does overall not support an association between occupational sunlight exposure and risk of uveal melanoma. The finding of an excess risk of eye melanoma in cooks in several European countries is intriguing.

Adult↗
PubMed1988

Technique for using films accidentally exposed to light.

Light-exposed films cannot be used clinically because, after processing, they are completely black. Two methods are described in which light-exposed films could be used clinically with application of the principle of solarization: (1) as duplicating films with the use of sunlight and (2) as receptors for images of foliage with the use of sunlight. Light-exposed duplicating films could be used as receptors for images of foliage through use of sunlight exposures.

Light↗
PubMed1994

Suicides in California (1968-1977): absence of seasonality in Los Angeles and Sacramento counties.

Since the turn of the century, there have been numerous publications on the seasonality of suicide. Rarely has the duration of sunlight exposure or any other weather parameter been quantitated in studies of suicide seasonality. To explore the relationships between sunlight and suicide, we examined California weather and suicide data from 1968 to 1977. Los Angeles County and Sacramento County were well-suited to the investigation, as complete data were available for these large population centers. There was no evidence of seasonality to suicides in L.A. County or Sacramento, despite a pronounced seasonality to weather. To investigate the acute temporal effects of weather on suicides, all occurrences of 10 successive above- or below-average sunshine days were identified. Suicides of for intervals of 5 days were then compared by Mann-Whitney analyses for 25 days after the selected intervals. For L.A. County, there were no significant findings. For Sacramento County, however, there was evidence for sunlight inhibition of suicides at days 21-25 after the above-average sunshine. Suicides after 10 days of below-average sunshine were increased as much as 70% about the 10-year average. Further replication studies with larger data sets are needed for an adequate examination of the correspondences of suicide data and weather measurements.

California↗
PubMed1989

Solar and UVC-induced mutation in human cells and inhibition by deoxynucleosides.

Optimum conditions were established for quantitating the induction of hypoxanthine guanine phosphoribosyl transferase-deficient (HGPRT-) mutants in HeLa cells and in a human amelanotic melanoma cell line (MM96L). Compared at a fluence of equal toxicity (D37, fluence required to decrease cell survival to 37% of unirradiated control), noon sunlight in summer was slightly more mutagenic in MM96L than in HeLa cells (17 and 12 HGPRT- mutants per 10(6) survivors respectively). UVC (predominantly 254 nm) exhibited similar mutagenicity as equitoxic sunlight in HeLa but was 8-fold more effective in MM96L than equitoxic sunlight. Addition of a mixture of deoxyguanosine (20 microM), deoxyadenosine (20 microM), deoxycytidine (100 microM) and thymidine (20 microM) to the culture medium during the 7-day expression period following irradiation gave a 3-fold reduction in the UVC-induced mutation frequency of MM96L but not HeLa cells. The results suggest that these melanocytic cells are highly susceptible to mutagenesis by short wavelength UV, in a mechanism sensitive to deoxynucleosides.

DNA Damage↗
PubMed1986

The low incidence of multiple sclerosis in areas near the equator may be due to ultraviolet light induced suppressor cells to melanocyte antigens.

It has been shown by Elmets et al. (1) that ultraviolet irradiation of the skin followed by the application of a normally sensitizing antigen results in tolerance induction to the antigen. This tolerance is due to the induction of suppressor T-cells specific for the antigen. Multiple sclerosis is more common in certain climates distant from the equator where there is less ultraviolet light (sunlight). I postulate that people near the equator are exposed to more sunlight and that the ultraviolet light from the sunlight aids in the induction of suppressor cells specific for melanocyte associated antigens. Since melanocytes are of neural crest origin and share antigenic determinants with neural tissues these suppressor cells may act to protect against multiple sclerosis which is probably an autoimmune disease directed against neural tissues.

Autoantigens↗
PubMedDate not supplied

The prevalence of Vitamin D deficiency and effects of ultraviolet light on Vitamin D levels in elderly Turkish population.

Vitamin D deficiency is commonly found in the elderly and is associated with osteoporosis and hip fractures. In this study, Vitamin D status of 138 female and 87 male subjects living in old age homes (OAH) and 171 female and 24 male subjects living in own homes (OH) from Central Anatolia were assessed. A questionnaire was applied to collect information about wearing features and degree of sunlight exposure and benefiting from ultraviolet index calculated (BFUI). We have found Vitamin D deficiency in 33.4% among our subjects. Also, 40.1% of subjects living in OAH (54.1% of females and 18.4% of males) and 24.4% of subjects living in OH (27.9% of females and 4.2% of males) were Vitamin D deficient. Vitamin D deficiency was significantly higher in subjects living in OAH than subjects living in OH (P = 0.001) and also higher in females than males (40.7% versus 15.3%, P < 0.001). Subjects with Vitamin D deficiency were older (P < 0.001), BFUI was lower (P < 0.001) and parathyroid hormone (PTH) was higher (P < 0.001) than those having normal level of 25(OH)D. There was a significant negative correlation between 25(OH)D levels and age (P < 0.001, r = -0.248) PTH and 25(OH)D (P = 0.004, r = -0.340), and positive correlation between 25(OH)D and BFUI (P < 0.001, r = 0.340). Vitamin D deficiency is very common in Turkish elderly subjects especially living in OAH and there is a significant low exposure to sunlight among them. Simply by asking clothing habits and exposure to sunlight, we can able to identify risk of Vitamin D insufficiency in elderly subjects.

Age Factors↗
PubMed2004

Alternative methods to evaluate the protective ability of sunscreen against photo-genotoxicity.

Numerous epidemiological investigations show that sunlight is carcinogenic to humans and that the use of sunscreen may be effective in decreasing the risk of skin cancer. The biological activity of a sunscreen is evaluated by its ability to protect human skin from erythema as represented by a Sun Protection Factor (SPF). We propose that the sunscreen's protective effect against sunlight-induced genotoxicity, including mutation, should also be taken into account. In this study we examined the protective ability of sunscreens against natural sunlight and UV-induced genotoxicity in Drosophila somatic cells. We prepared three kinds of sunscreen samples, each with an SPF value of 20, 40 or 60 and compared their protective activities with commercial sunscreens. When a sunscreen of SPF 20, 40 or 60 was pasted on the plastic cover of a petri dish in which Drosophila larvae were exposed to the sun or UV lamps, genotoxicity decreased as the SPF of the sunscreen increased, relative to levels of genotoxicity observed in samples without sunscreen. However, the protective abilities of sunscreens were unexpectedly not so different from each other. To reveal the relationship between the protective activity of sunscreen and the wavelength of light with which larvae were irradiated through the sunscreen, we measured the transmittance of light through the petri dish cover on which the sunscreen was pasted. Effective protection was demonstrated by removing components of light whose wavelengths were below 315 nm. We suggest, that the measurement of anti-genotoxic activity and the determination of the wavelengths of light transmitted through the sunscreen should be an alternative method for evaluating the effectiveness of a sunscreen.

Animals↗
PubMed2005

Intermittent and chronic ultraviolet light exposure and uveal melanoma: a meta-analysis.

OBJECTIVE: To examine the association between ultraviolet light exposure and uveal melanoma. DESIGN: Meta-analysis. METHODS: A review of 133 published reports on risk factors for uveal melanoma revealed 12 studies that provided sufficient information to calculate odds ratios (ORs) and standard errors for ultraviolet light exposure factors. Data from these studies were extracted and categorized into intermittent ultraviolet exposure factors (welding, outdoor leisure, photokeratitis) and chronic ultraviolet exposure factors (occupational sunlight exposure, birth latitude, lifetime ultraviolet exposure index). Summary statistics were calculated for all risk factors reported by > or =4 independent studies. MAIN EXPOSURE MEASURES: Welding, outdoor leisure, photokeratitis, occupational sunlight exposure, birth latitude, and lifetime ultraviolet exposure index. RESULTS: For intermittent ultraviolet exposure, welding was found to be a significant risk factor (5 studies, 1137 cases; OR, 2.05 [95% confidence interval [CI], 1.20-3.51]). Outdoor leisure was found to be nonsignificant (4 studies, 1332 cases; OR, 0.86 [95% CI, 0.71-1.04]). Photokeratitis conferred susceptibility in 3 reports studying this variable, but there were too few studies to validate meta-analyses. For chronic ultraviolet exposure, meta-analysis found occupational sunlight exposure to be a borderline nonsignificant risk factor for development of uveal melanoma (4 studies, 572 cases; OR, 1.37 [95% CI, 0.96-1.96]). Latitude of birth was found to be nonsignificant (5 studies, 1765 cases; OR, 1.08 [95% CI, 0.67-1.74]). CONCLUSION: This meta-analysis yielded inconsistent results associating ultraviolet light with development of uveal melanoma. There was evidence implicating welding as a possible risk factor for uveal melanoma.

Environmental Exposure↗
PubMed2004

EPR study of light illumination effects on radicals in gamma-irradiated L-alanine.

Exposure of gamma-irradiated L-alanine samples to sunlight and to light from a regular, fluorescent lamp resulted in significant changes in their EPR resonance patterns, both to spectral shapes and intensities. The experimental EPR spectra were numerically decomposed into three components reflecting contributions of three different radicals (R1-R3) generated by ionizing radiation in alanine. The light exposure caused a decay of the measured EPR signal intensity. For similar light intensities and exposure times the decay was much more pronounced in samples illuminated by sunlight than in samples illuminated by the fluorescent lamp. In both cases light-induced decay of R1 radicals was observed. Sunlight illumination resulted in a moderate decay of R2 radicals and in a doubling of the R3 radical population. On the other hand, fluorescent light caused a significant increase of R2 radicals and did not change the amount of R3 radicals. A quantitative analysis of the variations of the three radical contributions to the total EPR spectra upon fluorescent light exposure suggests a net R1-->R2 free radical transformation. These effects of light on the alanine dosimetric signal should be taken into account in dosimetry protocols, assuring protection of alanine dosimeters from extended exposure to light.

Alanine↗
PubMed2006

Comparative effectiveness of solar disinfection using small-scale batch reactors with reflective, absorptive and transmissive rear surfaces.

This study investigated the enhancement of solar disinfection using custom-made batch reactors with reflective (foil-backed) or absorptive (black-backed) rear surfaces, under a range of weather conditions in India. Plate counts of Escherichia coli ATCC11775 were made under aerobic conditions and under conditions where reactive oxygen species (ROS) were neutralised, i.e. in growth medium supplemented with 0.05% w/v sodium pyruvate plus incubation under anaerobic conditions. While the addition of either an absorptive or a reflective backing enhanced reactor performance under strong sunlight, the reflective reactor was the only system to show consistent enhancement under low sunlight, where the process was slowest. Counts performed under ROS-neutralised conditions were slightly higher than those in air, indicating that a fraction of the cells become sub-lethally injured during exposure to sunlight to the extent that they were unable to grow aerobically. However, the influence of this phenomenon on the dynamics of inactivation was relatively small.

Absorption↗
PubMed1985

Vitamin D metabolites in adolescents and young adults with cystic fibrosis: effects of sun and season.

To assess mineral metabolism in patients with cystic fibrosis and to study the effects of season and sunlight exposure on generation of vitamin D metabolites, we quantified serum levels of calcidiol and calcitriol, other measures of bone metabolism, and radiographic bone mass in 20 adolescents and young adults with CF and 20 age-matched normal volunteers. Levels of calcidiol were lower in patients with CF than in controls and lower in Massachusetts than in Arizona in both study groups. Controls in Arizona had higher (P less than 0.05) levels of calcitriol than in Massachusetts throughout the year. All control subjects in both states had higher levels of calcitriol than did patients with CF. Patients in Massachusetts had significantly lower levels of calcitriol in winter than in summer. Summer levels of calcitriol in CF were significantly higher in Massachusetts than in Arizona; during winter, lower levels were found in Massachusetts than in Arizona. Mean bone density in patients with CF was 88% and 89% of normal American standards in Massachusetts and Arizona, respectively. These data indicate a seasonal, sunlight-related influence on levels of vitamin D metabolites in patients with CF receiving approximately 1000 IU vitamin D per day. Older patients with CF with progressively diminishing sunlight exposure may be at increased risk for development of osteopenia. The detected radiographic abnormalities of bone mineralization may also be related to malabsorptive deficiencies of calcium and phosphorus.

25-Hydroxyvitamin D 2↗
PubMed1998

Effect of high irradiance and iron on volatile odour compounds in the cyanobacterium Microcystis aeruginosa.

The cyanobacterium, Microcystis aeruginosa was exposed to direct sunlight for 3, 6 or 9 h in media containing either low or high concentrations of iron, in order to determine any effects on the composition of volatile odour compounds (VOCs) released under photooxidative conditions. The most abundant VOCs detected included aliphatic hydrocarbons (C15-C21), naphthalene and the terpenoid compounds, beta-cyclocitral, and beta-ionone. Exposure to sunlight and low iron concentrations resulted in a decrease in beta-cyclocitral, beta-ionone, heptadecane and the total VOCs concentration after 9 h with respect to the control cultures. Six VOCs detected in the low iron cells were not detected in any of the high iron cells. However, those VOCs present in the high iron cells, in general, occurred at higher concentrations than the equivalent low iron cells after exposure to the sunlight conditions. Consequently, it was concluded that exposure to both high irradiance and high iron concentrations influenced the VOCs composition in cyanobacteria and this was interpreted to represent a cellular change during the photooxidation-promoting conditions.

Hydrocarbons↗