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PubMed2003

Formulation of a mathematical model to predict solar water disinfection.

A mathematical model was formulated that will facilitate the prediction of solar disinfection by analyzing the effect of sunlight exposure (x(1)) and the load of bacterial contamination (x(2)), as predictor variables, on the efficiency of solar disinfection (y). Aliquots of 0.1 ml containing average numbers of E. coli, ranging between 1 and 5 x 10(3)cells/ml raw water, were introduced into each of the 96 wells of polystyrene microtitre plates. Plates, with the lid on, were exposed to sunlight for varying exposures ranging between 1.04 x 10(3) and 8.40 x 10(3)kJ m(-2). Double strength nutrient broth was then added. After 48 h incubation wells containing visible contamination were considered as containing one cell or more that survived the exposure. Data showed that disinfection is dependent both on the load of bacterial contamination and sunlight exposure. This relationship is characterized by curves having shoulders followed by a steep decline and then tailing off in an asymptotic fashion. The shoulder size increased with the increase of the contamination load, however, the slope remains the same. Statistical analysis indicates a positive correlation among the variables (R(2) = 0.893); the mathematical model, y=1-(1-e(-kx(1)))(x(2)), represents the relationship, with k being the solar inactivation constant. The exposure required to produce a given decontamination level can be predicted using the equation: x(1)=-1/kln[1-(1-y)(-1/x(2))]e(-micro/rho.m/A), where micro is the linear attenuation coefficient (m(-1)), rho is the density, m is the mass and A is the area of the exposed part of the sample. The predictor variables (x(1), x(2)) strongly influence the efficiency of solar disinfection, which can be predicted using the suggested mathematical model. The present data provides a means to predict the efficiency of solar disinfection as an approach to improve the quality of drinking water mainly in developing countries with adequate sunshine all year-round.

Disinfection↗
PubMed2002

Fenarimol solar degradation pathways and photoproducts in aqueous solution.

The degradation photoproducts of the fungicide fenarimol obtained from irradiation of aqueous solutions with sunlight were characterised. The photoproducts resulting from samples with different exposure times were extracted and separated using chromatographic techniques. Seven main photoproducts were detected using high performance liquid chromatography with a photodiode array detector, gas chromatography with mass spectrometry detector and Fourier transform infrared spectroscopy. Structures are suggested for possible photoproducts based on the characterisation results, minimum energy geometry of the parent compound, and the mass spectral behaviour of fenarimol. These correspond to the compounds with m/z 328 (three structural isomers (a), (b) and (c)), m/z 294 (two structural isomers (a) and (b)), m/z 292, 278 and 190. Of the various major products detected, the isomer 328(a) is seen to be particularly unstable under the action of sunlight. The most stable photoproducts are found to be those with m/z 294(a), 278 and 190. However, upon prolonged solar irradiation all of these break down to produce polar, low molecular weight compounds. Comparison with our own and other results on fenarimol photolysis indicate significant solvent effects on the process. The combination of these structural characterisation results and previous data from spectroscopic and photodegradation kinetics studies allows us to suggest some possible mechanisms for the photodegradation of fenarimol under sunlight.

Fungicides, Industrial↗
PubMed2003

Solar activated ozonation of phenol and malic acid.

The effect that sunlight has on the degradation rate of two model organic compounds, phenol and malic acid, by ozone is studied. The effect seems to be due to both direct light absorption (300-320 nm photons) by ozone, which produces the pollutant degradation, and light absorption by reaction intermediates. The presence of such a light notably improves the reactivity of ozone toward the organic species, leading to a faster and complete mineralization even at large initial total organic carbon values. The use of artificial sunlight (Xe lamp) is also explored. Finally, the simultaneous presence of sunlight and other ozone degradation catalyst like transition metal ions is studied, showing the beneficial effect of such a combination.

Absorption↗
PubMed2000

Photocarcinogenesis: UVA vs UVB.

Ultraviolet B and A radiations (respective wavelength ranges 280-315 and 315-400 nm) are present in sunlight at ground level. The ultraviolet radiation does not penetrate any deeper than the skin and has been associated with various types of human skin cancers. The carcinogenicity of UVB radiation is well established experimentally and, to a large extent, understood as a process of direct photochemical damage to DNA from which gene mutations arise. Although UVA is generally far less carcinogenic than UVB radiation, it is present more abundantly in sunlight than UVB radiation (> 20 times radiant energy) and can, therefore, contribute appreciably to the carcinogenicity of sunlight. In contrast to UVB, UVA radiation is hardly absorbed by DNA. Hence, the absorption by other molecules (endogenous photosensitizers) becomes more important, thus radicals and, more specifically, reactive oxygen species can be generated that can damage DNA, membranes, and other cellular constituents. These photochemical differences between UVA and UVB radiations are reflected in differences in cellular responses and carcinogenesis.

Animals↗
PubMed1998

Iris color, skin sun sensitivity, and age-related maculopathy. The Blue Mountains Eye Study.

OBJECTIVE: The purpose of the study was to assess relationships between age-related maculopathy (ARM) and iris color, skin sun sensitivity, and other sunlight-related factors. DESIGN: Cross-sectional population-based study. PARTICIPANTS: The Blue Mountains Eye Study performed a detailed eye examination of 3654 residents living in the Blue Mountains area, west of Sydney, Australia. MAIN OUTCOME MEASURES: Subjects with late age-related macular degeneration (late AMD), early ARM, and large drusen (> or = 125 microns diameter) were identified using masked grading of retinal photographs. Iris color was graded using standard photographs, and interviewers collected questionnaire data on sunlight-related factors. Logistic regression, adjusting for age, sex, AMD family history, and current smoking, was used to assess associations. RESULTS: Blue iris color was significantly associated with an increased risk of both late AMD (odds ratio [OR], 1.69) and early ARM (OR, 1.45). An increased risk of late AMD, but not early ARM, was associated with both high (OR, 2.54) and low (OR, 2.18) skin sun sensitivity, as assessed using the Fitzpatrick sun-sensitivity scale. These associations remained after adjusting for the presence of sun-related skin damage. Neither history (or treatment) of skin cancer lesions, signs of sun-induced skin damage, or number of severe sunburns was associated with either late AMD or early ARM. CONCLUSIONS: Blue iris color was associated with an increased risk of both late AMD and early ARM in this population. Abnormal skin sensitivity to sunlight was also associated with an increased risk of late AMD.

Cross-Sectional Studies↗
PubMed1997

[Influence of seasons on risk of flare-up of systemic lupus: retrospective study of 66 patients].

PURPOSE: To establish the possible connection between visceral, arthro-cutaneous and biological spreading of systemic lupus (SL) and hours of sunlight. MATERIAL AND METHODS: Retrospective study of 66 SL patients, consisting of 52 visceral and 14 arthro-cutaneous cases taking into account the chronological pattern of each new aggravation, based on 480 clinical records. RESULTS: Increased frequency in visceral aggravation was observed in the post-summer period (August-January) (n = 57), as compared with the pre-summer period (February-July) (n = 25) (RR = 1.75, P = 0.006). This post-summer visceral aggravation was correlated with cutaneous affection (RR = 4.18) and absence of previous corticotherapy (RR = 3.97). Visceral and arthro-cutaneous aggravations taken together revealed a more disturbed immune balance pattern in the post-summer period (anti-dsDNA: 30 versus 25.1 IU/L [P = 0.07]; C3: 0.83 vs 0.921 IU/L [P = 0.05]; C4: 0.146 vs 0.183 [P = 0.05]), providing evidence of greater severity. Moderate thrombopenia (50-120 10(9)/L) accompanying visceral SL with antiphospholipids (n = 33) was more frequent during the post-summer period, even in the absence of aggravation (P = 0.03). The quarterly distribution of visceral aggravations was correlated with average hours of sunlight in the preceding quarter (P = 0.01). CONCLUSION: There is a post-summer increase in the frequency and severity of visceral SL spreading correlated to cutaneous exacerbation and sunlight.

Adult↗
PubMed1997

Degradation of the cyanobacterial hepatotoxin, nodularin, under light and dark conditions.

The stability of the cyanobacterial hepatotoxin, nodularin, was determined during the incubation of purified toxin, and in nodularin-containing cell-free extracts and whole filaments of the nodularin-producer, Nodularia spumigena in sunlight and darkness. Levels of purified nodularin in aqueous solution remained approximately constant throughout the 9-day trials under all conditions, but decreased in cell-free extracts and whole filaments when incubated under all conditions, with losses being greatest in full sunlight, intermediate in sunlight minus ultraviolet wavelengths and lowest in continuous darkness. Photodegradation and detoxification in Artemia salina bioassays occurred when purified nodularin was irradiated with ultraviolet wavelengths using a laboratory lamp.

Animals↗
PubMed1997

Age-related discontinuous changes in the in vivo fluorescence of human facial skin.

We measured the 325-nm laser-induced fluorescence of the skin of the face and ventral forearm in seventy Japanese female volunteers, and evaluated the effects of age and exposure to sunlight. The subjects were arbitrarily grouped into 10-year age-groups. In slightly exposed areas such as the ventral forearm, the average laser-induced intensity ratio at 390 nm to 430 nm showed no significant differences with the age group. In areas markedly exposed to sunlight such as the corners of the eyes and mouth, the average laser-induced intensity ratio showed a discontinuous decrease with age. These findings suggested that dermal fluorophore changes differ with the skin areas and are affected by sunlight exposure.

Adolescent↗
PubMed2000

Skin cancer in heart transplant recipients: frequency and risk factor analysis.

BACKGROUND: The frequency of skin cancer is increased among organ transplant recipients, but the predisposing risk factors are controversial. It is also unclear whether heart transplant patients face an increased risk compared to recipients of other organs, e.g. kidney transplants. METHODS: We performed univariate and multivariate analysis of risk factors for skin cancer in 252 heart transplants and in a control series of 228 kidney transplants followed up at a single center. An extensive dermatologic examination was carried out; baseline features, type of immunosuppression, number of 3A rejection episodes, extent of sunlight exposure and skin type were recorded. Multivariate analysis (Cox regression) included: age at transplantation, sex, skin type (Fitzpatrick's criteria), presence of solar keratosis, presence of warts, type of organ, sunlight exposure. RESULTS: During follow up skin cancer was more common among heart transplants (40, 16 %) than in kidney transplants (16, 7%, p = 0.004). The cumulative incidence of skin cancer by life table analysis increased from 16% after 5 years to 33% after 10 years in heart transplant patients and from 6% to 17% in kidney transplants (p 10000 hours (relative risk = 2.8), but not organ type were significant risk factors. CONCLUSION: Age at transplant, skin type and sunlight exposure, but not type of organ and type of immunosuppressive regimen, are associated with increased risk of skin cancer in heart transplantation.

Adult↗
PubMed1993

Seasonal variation of twin births in Washington State.

Twin births are known to vary across seasons in several countries. It has been hypothesized that this variation may be due to seasonal changes in luminosity leading to pineal gland-mediated multiovulation among susceptible mothers. To describe seasonal variation of twin births in Washington State, all mothers residing in Washington State who gave birth to both a pair of twins and a singleton baby between 1984-1990 (n = 1168) were identified through linkage of computerized State birth certificates. Using a "matched-on-mother" case-control design, the estimated month of conception of twin gestations (the "case" events) were compared to that for their singleton siblings (the "control" events) to determine their relative occurrence during periods of high vs low sunlight in accordance with local climatological data. For the study population as a whole, there was only a slight tendency for twins to have been conceived during the period of high sunlight compared to their singleton siblings (OR = 1.3, 95% C.I. = 1.0-1.7). When stratified by concordant-sex vs discordant-sex, however, more discordant-sex twin pairs were conceived during the light period than corresponding singletons (OR = 1.7, 95% C.I. = 1.0-2.8), whereas no association was found for concordant-sex twins (OR = 1.1, 95% C.I. = 0.8-1.6). The presence of an association only among discordant-sex twins, all of whom are dizygotic, is consistent with the hypothesis that exposure to sunlight may stimulate multiple ovulation, and thus increase the incidence of twin gestations among twin-prone mothers.

Adolescent↗
PubMed2006

Effects of nitrite and nitrate on DNA damage induced by ultraviolet light.

UV light is a major cause of human skin cancers. Nitrite and nitrate are well-known potential risk factors for gastric cancer. Little attention has been paid to the relationship between UV light and nitrite or nitrate on cancer. We examined the effects of nitrite and nitrate on the damage to nucleosides and DNA induced by UV light from a mercury lamp and by sunlight at neutral pH. A biologically relevant dose of nitrite and nitrate increased the generation of nucleobases and malondialdehyde on the reaction of nucleosides and DNA with UV light. The efficiency of nitrite enhancing the reaction was higher than that of nitrate at low doses. The contribution of the hydroxyl radical as the reactive species was suggested from the results of the inhibitory effects of hydroxyl radical scavengers. Nitrite and nitrate also enhanced the formation of nucleobases and malondialdehyde from DNA induced by sunlight. In the presence of 5 muM nitrite, the concentration in human skin cells, the product yields by sunlight were 5-10-fold greater than those in the absence of nitrite. The addition of 80 muM NO(3)(-), a concentration in human skin cells, also increased the yields significantly. Nitrite and nitrate may play a role in enhancing the genotoxic effects of UV light in humans.

Animals↗
PubMed1998

Outdoor work and the risk of pterygia: a case-control study.

AIM: To investigate the relationship between outdoor work and pterygium formation in a hospital-based case-control study in Singapore. METHOD: Sixty-one patients with pterygium (49 males, mean age 54.2 years) and 125 controls (41 males, mean age 50.2 years), excluding patients with cataract and age-related macular degeneration presenting at outpatient clinics of the Singapore National Eye Centre were interviewed face-to-face with a standard questionnaire. Demographic data and information on outdoor work and eye protection, were collected. RESULTS: Thirty-eight subjects (20.4%) were outdoor workers and 148 (79.6%) were indoor workers. Outdoor workers were more likely to be male smokers and alcohol drinkers with lower family income and higher sunlight exposure than indoor workers. The crude odds ratio for pterygium in outdoor workers was 7.0 (95% confidence interval 3.2, 15.3). The adjusted odds ratio was 4.2 (95% confidence interval 1.7, 10.1). CONCLUSION: There is a statistically significant association between outdoor work and pterygium formation, which may be related to the higher exposure to sunlight and dust in outdoor workers. Efforts may be made to educate outdoor workers to wear proper equipment to protect their eyes against excessive sunlight.

Adult↗
PubMedDate not supplied

Sunburn and p53 in the onset of skin cancer.

Squamous cell carcinoma of the skin (SCC) can progress by stages: sun-damaged epidermis, with individual disordered keratinocytes; actinic keratosis (AK), spontaneously regressing keratinized patches having aberrant cell differentiation and proliferation; carcinoma in situ; SCC and metastasis. To understand how sunlight acts as a carcinogen, we determined the stage at which sunlight mutates the p53 tumour-suppressor gene and identified a function for p53 in skin. The p53 mutations induced by ultraviolet radiation and found in > 90% of human SCCs were present in AKs. Inactivating p53 in mouse skin reduced the appearance of sunburn cells, apoptotic keratinocytes generated by overexposure to ultraviolet. Skin thus appears to possess a p53-dependent 'guardian-of-the-tissue' response to DNA damage which aborts precancerous cells. If this response is reduced in a single cell by a prior p53 mutation, sunburn can select for clonal expansion of the p53-mutated cell into the AK. Sunlight can act twice: as tumour initiator and tumour promoter.

Animals↗
PubMed1999

Vitamin D levels in prepubertal children in Southern Tasmania: prevalence and determinants.

OBJECTIVE: To describe the prevalence and determinants of 25-hydroxy D3(25(OH)D) in children. DESIGN: Cross-sectional study. SETTING: Southern Tasmania between June and November 1997. SUBJECTS: Two hundred and one 8-y old male and female children taking part in a cohort study whose principal endpoints were blood pressure and high-density lipoprotein (HDL) cholesterol. RESULTS: The mean 25(OH)D level was 79 nmol/l (s.d. 29.5, median 73, range 12-222). Boys had higher levels than girls (82.1 vs 72.8 nmol/l, P=0.02). 25(OH)D was associated with sunlight exposure in winter school holidays (r=0.20, P=0.005) and winter weekends (r=0.16, P=0.02), the month after school holidays (87.5 vs 69.5 nmol, P<0.0001) and body mass index (r=-0.23, P=0.001). Dietary intake of vitamin D was low (mean 40 IU/day, range 5.2-384) and was not associated with 25(OH)D levels (r=0.01, P=0.91). Variation in skin melanin density was weakly associated with 25(OH)D (r=0.09, P=0.19). CONCLUSIONS: Sunlight is the major determinant of vitamin D stores in our population. Neither variation in skin type within Caucasians nor diet modified this association to any significant extent. Extrapolation of these findings to sunlight bone mass associations in a very similar population suggests that a minimum level of around 50 nmol/l in the population is required for optimal bone development in prepubertal children but this needs to be confirmed with further controlled trials of vitamin D supplementation and bone mass. SPONSORSHIP: Arthritis Foundation of Australia, Roche Pharmaceuticals.

Body Mass Index↗
PubMed2002

The effect of conventional vitamin D(2) supplementation on serum 25(OH)D concentration is weak among peripubertal Finnish girls: a 3-y prospective study.

OBJECTIVES: To study the effect of vitamin D supplementation and the impact of summer season on serum 25-hydroxyvitamin D (S-25(OH)D) in Finnish 9-15-y-old girls. DESIGN: Three-year follow-up study with vitamin D(2) supplementation using D(2) 10 microg daily from October to January for the first and from October to February for the second winter as well as 20 microg daily from October to March for the third winter. SETTING: Paavo Nurmi Centre, University of Turku, Turku, Finland. SUBJECTS: A total of 171 female volunteers aged 9-15 y. METHODS: Vitamin D and calcium intakes were estimated by a semi-quantitative food frequency questionnaire (FFQ). S-25(OH)D was measured by radioimmunoassay. RESULTS: The median daily dietary intakes of vitamin D and calcium were 3.8 microg (interquartile range (IQR) 2.7-5.0) and 1451 mg (IQR 1196-1812), respectively, over 3 y. The prevalence of severe hypovitaminosis D (S-25(OH)D<20 nmol/l) was 14% and of moderate hypovitaminosis D (20 nmol/l < or = S-25(OH)D < or = 37.5 nmol/l) 75% at baseline in winter. None of the participants had severe hypovitaminosis D in summer. The effect of 10 microg of D(2) daily was insufficient to raise S-25(OH)D from baseline. The daily supplementation of 20 microg of D(2) increased S-25(OH)D significantly in wintertime compared with the non-supplement users (to 45.5 vs 31.8 nmol/l; P<0.001). None of the subjects with vitamin D(2) supplementation approximately 20 microg daily had severe hypovitaminosis D; however, 38% of those participants had moderate hypovitaminosis D at 36 months. Sun exposure in summer raised mean S-25(OH)D to 62.0 nmol/l. Both the daily supplementation of approximately 20 microg of D(2) and summer sunlight exposure had more effect on those who had severe hypovitaminosis than those who had a normal vitamin D status (increase of 24.2 vs 0.9 nmol/l (P<0.001), and 38.8 vs 18.2 nmol/l (P<0.001), respectively). CONCLUSION: Vitamin D supplementation daily with 20 microg is needed to prevent hypovitaminosis D in peripubertal Finnish girls in winter. Sunlight exposure in summer is more effective than approximately 20 microg of D(2) supplementation daily in winter to raise S-25(OH)D. Both the daily supplementation with 20 microg of D(2) and summertime sunlight exposure had more effect on those who had severe hypovitaminosis D than those who had a normal vitamin D status. SPONSORSHIP: Supported by the Yrjö Jahnsson Foundation and the Medical Research Foundation of the Turku University Central Hospital.

25-Hydroxyvitamin D 2↗
PubMed2005

Risk factors for cataract subtypes waterclefts and retrodots: two case-control studies.

UNLABELLED: Waterclefts and retrodots are independently associated with visual impairment, yet a review identified no data on risk factors. PURPOSE: To investigate risk factors for these two human lens cataract subtypes. METHOD: Two nested case-control studies: The host study comprised 1078 subjects (55 years) attending the Somerset and Avon Eye Study (SAES). In total, 197 watercleft cases (Oxford grade 0.2 in either eye) and 199 retrodot cases (Oxford grade 1.0 in either eye) were individually age/gender matched to controls. Detailed ophthalmic and potential risk factor data were collected, including body mass index (BMI), smoking, alcohol, diabetes, hypertension, analgesics, vitamin supplementation, nutrition, sunlight exposure, dehydration, hormonal (women), blood lipids, glucose, urea, creatinine, uric acid, and vitamin levels. RESULTS: For waterclefts, univariable analysis identified BMI, alcohol intake, vitamin status, sunlight, urea, creatinine, and uric acid as possible risk factors. Multivariable analysis identified two independent associations. Total number of 'any' analgesics in the previous year: adjusted P<0.01 (U-shaped risk profile, unadjusted high vs medium use (=reference) OR 2.39, 95% CI 1.35-4.26 with medium use vs none (=reference) OR 0.43, 95% CI 0.26-0.72); total sunlight: adjusted P=0.03 (unadjusted highest exposure vs lowest (=reference) OR 3.25, 95% CI 1.11-9.50). For retrodots, univariable analysis identified alcohol, HRT, and lipids. Multivariable analysis identified two independent associations. Mean number of alcohol units consumed per month, adjusted P=0.02 and HDL cholesterol levels, adjusted P=0.02 (unadjusted ORs NS both). CONCLUSION: This is the first available published information on risk factors for the human cataractous lens features waterclefts and retrodots.

Aged↗
PubMed2006

South Australian adolescent ophthalmic sun protective behaviours.

AIMS: To study student's knowledge of the effects of sunlight on the eyes, as well as their sun protective behaviours. METHODS: In total, 640 [corrected] students aged 13-18 years were surveyed in South Australia, during August-September 2004, using a standardized previously used survey. Scores were calculated regarding knowledge about ultraviolet light, sunlight effects on eyes, as well as eye and body protection. Risk factor scores were produced for each student. The data were analysed by the analysis of variance (ANOVA), as well as the Cochran-Mantel-Haenszel methods. Results were compared to the same survey conducted in 1995 in Queensland Australia. RESULTS: This group demonstrated a moderate level of knowledge, similar to the 1995 survey. Students in the older age groups demonstrated significantly higher knowledge. The majority of students (74%) owned a pair of sunglasses; however, 44.5% almost never wore their glasses. The reported frequency of wearing sunglasses was significantly related to advertising, believing sunglasses protect the eyes, as well as personal, family, and peer attitudes towards wearing sunglasses. CONCLUSION: The results of our survey suggest no significant change in knowledge and behaviours of students, compared to the 1995 survey. We feel it is imperative that adolescents be made more aware of the damaging effects of sunlight and the benefits of eye protection. Health promotion campaigns should target the youth and consider that as a group, they are significantly influenced by the media, peers, and family attitudes.

Adolescent↗
PubMed1994

Stability of zeranol, nandrolone and trenbolone in bovine urine.

The stability of some growth promoting agents in cattle urine, under various temperature storing conditions, was investigated. Bovine urine samples obtained from previous excretion studies which contained zeranol, nandrolone and trenbolone respectively, were stored frozen, at room temperature and in direct sunlight. On days 0, 2, 4, 7 and 10, zeranol and nandrolone were quantified by selective ion monitoring analysis on a gas chromatography-mass selective detector and trenbolone by using an enzyme linked immunosorbent assay. Zeranol and its metabolite taleranol are stable under all of these storage conditions. There is a remarkable decrease in the concentration of 17 alpha-19-nortestosterone, the main metabolite of nandrolone in cattle, when stored at room temperature and in direct sunlight. There is also a decrease in concentration of trenbolone when stored in direct sunlight. From the results it can be concluded that urine specimens obtained from cattle for residue analysis should be frozen as soon as possible after collection.

Animals↗