High Solar Ultraviolet Radiation Research Articles

Personal Solar Ultraviolet Radiation Exposure of Farmworkers: Seasonal and Anatomical Differences Suggest Prevention Measures Are Required.

Farmworkers are at risk of excess exposure to solar ultraviolet radiation (UVR) during their work activities, especially if they work in geographical areas with high ambient solar UVR levels such as in South Africa. Excess exposure to solar UVR may lead to several negative health effects such as certain cataracts and skin cancer. This study evaluated personal solar UVR exposure of a group of farmworkers to determine if they were at risk of health-related problems due to excess solar UVR exposure. Polysulphone film (PSF) badges were placed on the shoulder, arm, and top of the head of outdoor and indoor farmworkers on a macadamia nut and avocado farm in the Limpopo province for the duration of their daily work shift to evaluate their total daily solar UVR exposure. Sixteen days were assessed for each of the three, high solar UVR seasons, i.e. autumn, spring, and summer. During autumn, farmworkers' arms received the highest solar UVR exposures (geometric mean (GM) = 7.8 SED, where 1 standard erythemal dose (SED) = 100 J/m2, 95% CI 6.1-9.8 SED) while the highest exposures were on the top of the head during spring (GM = 11.6 SED, 95% CI 7.3-17.4 SED) and summer (GM = 13.9, 95% CI 10.4-17.9 SED). Statistically significant differences in solar UVR exposure were found between the body sites during spring and summer but not autumn. The relatively high daily solar UVR exposure levels of farmworkers suggest this occupational group is at risk of excess solar UVR exposure and preventive measures with awareness information to safeguard health is necessary for employers and employees.

Solar ultraviolet radiation exposure among outdoor workers in Alberta, Canada

BackgroundOutdoor workers are at risk of prolonged and high solar ultraviolet radiation (UVR) exposure, which is known to cause skin cancer. The objectives of this study were to characterize the UVR exposure levels of outdoor workers in Alberta, Canada, and to investigate what factors may contribute to their exposure. MethodsThis study collected objective solar UVR measurements from outdoor workers primarily in Alberta during the summer of 2019. Workers were recruited via the management or health and safety teams from building trade unions and employers. Calibrated, electronic UVR dosimeters were worn by workers on their hardhats, wrists, or lapels for five working days. Data on workers’ demographics, jobs, sun protection behaviors, and personal risk factors were collected using questionnaires, and meteorological data for each sampling day were noted. Mean daily exposure measured as the standard erythemal dose (SED) was calculated and compared to the international occupational exposure limit guideline (1.3 SED). Marginal models were developed to evaluate potential determinants of occupational solar UVR exposure. ResultsIn total, 883 measurements were collected from 179 workers. On average, workerswere exposed to 1.93 SED (range: 0.03–16.63 SED) per day. Just under half of workers (45%) were exposed to levels exceeding the international exposure limit guideline. In the bivariate analyses, landscape and maintenance workers, as well as trade and recreation workers, had the highest levels of exposure (average: 2.64 and 1.84 SED, respectively). Regional variations were observed, with the “other” cities/regions (outside of Edmonton and Calgary) experiencing the highest average levels (2.60 SED). Workers who placed the dosimeters on their hardhats experienced higher levels compared to the other groups. Exposure was highest on sunny and mixed days. Education, trade, city, dosimeter placement, forecast, hair colour, and number of hours outside were included in the final exposure model, of which trade, dosimeter placement, forecast, and number of hours outside at work were statistically significant. ConclusionsExposure to elevated solar UVR levels is common among outdoor workers in Alberta. The study findings can help inform future monitoring studies and exposure reduction initiatives aimed at protecting workers.

Solar Ultraviolet Radiation Exposure of South African Marathon Runners During Competition Marathon Runs and Training Sessions: A Feasibility Study.

Marathon runners spend considerable time in outdoor training for and participating in marathons. Outdoor runners may experience high solar ultraviolet radiation (UVR) exposure. South Africa, where running is popular, experiences high ambient solar UVR levels that may be associated with adverse health effects. This feasibility study explores the use of personal dosimeters to determine solar UVR exposure patterns and possible related acute health risks of four marathon runners during marathons and training sessions in Cape Town and Pretoria. Runners running marathons that started early in the day, and that did not exceed 4hours, yielded low total solar UVR exposure doses (mean 0.093 SED per exposure period run, median 0.088 SED, range 0.062-0.136 SED; average of 16.54% of ambient solar UVR). Training sessions run during early morning and late afternoon presented similar results. Several challenges hindered analysis including accounting for anatomical position of personal dosimeter and natural shade. To assess health risks, hazard quotients (HQs) were calculated using a hypothetical runner's schedule. Cumulative, annual solar UVR exposure-calculated acute health risks were low (HQ=0.024) for training sessions and moderate (HQ=4.922) for marathon runs. While these data and calculations are based on 18 person-days, one can measure marathon runners' personal solar UVR exposure although several challenges must be overcome.

Solar ultraviolet radiation in South Africa: clinical consequences for the skin

Due to its latitude, topography and cloudless skies, South Africa receives high solar ultraviolet radiation (UVR). This country has a multi-ethnic population classified into black, colored, Asian and white groups, who have varying degrees of response to sun exposure. In this review, information relating to the effects of solar UVR on skin cancer development, oculocutaneous albinism, melasma, the immune system and vitamin D production are discussed in the context of the peoples of South Africa. Methods of personal photoprotection are included. Effective sun safety messages for the public need to be developed, particularly aimed at the most susceptible groups, while recognizing the issues associated with variations in skin color in the South African population.

Effects of ultraviolet radiation and nutrients on the structure-function of phytoplankton in a high mountain lake

The combined effect of high solar ultraviolet radiation (UVR) and nutrient supply in a phytoplankton community of a high mountain lake is analyzed in a in situ experiment for 6 days with 2 × 2 factorial design. Interactive UVR × nutrient effects on structural and functional variables (algal biomass, chlorophyll a (chl a), primary production (PP), maximal electron transport rate (ETR(max)), and alkaline phosphatase activity (APA)), as well as stoichiometric ones (sestonic N per cell and N:P ratio) were found. Under non-nutrient enriched conditions, no deleterious effects of UVR on structural variables, PP, photosynthetic efficiency and ETR(max) were observed, whereas only particulate and total APA were affected by UVR. However, percentage excreted organic carbon (%EOC), dissolved APA and sestonic C and P per cell increased under UVR, leading to a decrease in algal C:P and N:P ratios. After nutrient enrichment, chl a, total algal biomass and PP were negatively affected by UVR whereas %EOC, ETR(max) and internal C, P and N content increased. We suggest that the mechanism of algal acclimation to UVR in this high UVR flux ecosystem seems to be related to the increase of internal algal P-content mediated by physiological mechanisms to save P and by a stimulatory UVR effect on dissolved extracellular APA. The mechanism involved in the unmasking effect of UVR after nutrient-enrichment may be the result of a greater sensitivity to UVR-induced cell damage, making the negative UVR effects more evident.

Ambient solar UV radiation and seasonal trends in potential sunburn risk among schoolchildren in South Africa

Background. The detrimental effects of excess personal solar ultraviolet (UV) radiation exposure include sunburn, immunosuppression and skin cancer. In South Africa, individuals with minimum natural protection from melanin, including fair-skinned individuals and African albinos, and people spending extended unprotected periods outdoors are at risk of sunburn, a risk factor for skin cancer. Sunburn becomes increasingly likely during the high solar UV radiation hours around midday, and previous studies have shown that children are exposed to potentially high, sunburn-causing solar UV radiation levels while at school. Method. To estimate national potential child sunburn risk patterns, monitored ambient solar UV radiation levels at six sites in South Africa were converted into possible schoolchild solar UV radiation exposures by calculating the theoretical child exposure to 5% of the total daily ambient solar UV radiation as derived from personal child exposure studies. Results. Schoolgoing children with skin types I, II and III were identified as being at greatest risk of sunburn. There were 44 and 99 days in a year when schoolchildren with skin type III (moderately sensitive) living in Durban and De Aar, respectively, would be likely to experience sunburn. Schoolchildren with skin type I (extremely sensitive) were at risk of experiencing sunburn on 166 days in De Aar, and those with skin types I and II were at risk on at least 1 day per year at all six locations. Conclusion. Seasonal patterns show that schoolchildren with sensitive skin types may experience sunburn in spring, summer and autumn months. Differences in child sunburn risk were evident, mainly due to latitude and atmospheric aerosols. Additional factors affecting sunburn risk include schoolchildren’s use of sun protection, sun-exposed activity, and timing and duration of exposure. Understanding risk patterns and obtaining locally relevant information will assist South African skin cancer prevention and sun protection awareness

Elevated risk for squamous cell carcinoma of the conjunctiva among adults with AIDS in the United States

Squamous cell carcinoma of the conjunctiva (SCCC) has been associated with HIV infection in equatorial Africa, but the evidence for association with HIV in developed countries, where SCCC is rarer, is controversial. We investigated the risk for SCCC and other eye cancers in the updated U.S. HIV/AIDS Cancer Match Registry Study. We calculated standardized incidence ratios (SIRs) to estimate excess risk for SCCC, primary ocular lymphoma, ocular Kaposi sarcoma (KS), and other eye tumors among 491, 048 adults (age > 15 years or older) with HIV/AIDS diagnosed from 1980 to 2004. We calculated relative proportions (per 105) to gain insight into risk factors. We identified 73 eye cancers (15 SCCC, 35 primary ocular lymphoma, 17 ocular KS, and 6 other). Overall SIRs were elevated for SCCC (SIR, 12.2, 95% CI 6.8 – 20.2), primary ocular lymphoma (21.7, 95% CI 15.1–30.2), and ocular KS (109, 95% CI 63.5–175). Risk for SCCC was elevated regardless of HIV acquisition category, CD4 lymphocyte count, and time-relative to AIDS-onset. Relative proportions of SCCC risk were highest with age ≥50 (8/105), Hispanic ethnicity (7/105), and residence in regions with high solar ultraviolet radiation (10/105). We show significantly increased incidence of SCCC among persons with HIV/AIDS in the United States. The associations with age and geography are in accord with etiological role for ultraviolet radiation in SCCC.

Multiple Strategies of Bloom-Forming Microcystis to Minimize Damage by Solar Ultraviolet Radiation in Surface Waters

The occurrence of bloom-forming cyanobacteria is one of the most obvious sign of eutrophication in freshwaters. Although in eutrophic lakes water transparency in the ultraviolet (UV) region is strongly reduced, bloom-forming cyanobacteria are exposed to high solar UV radiation at the surface. Here, we show that, in a natural phytoplankton community from a very eutrophic lake, Microcystis synthesizes UV sunscreen compounds identified as mycosporine-like amino acids (MAAs). The biomass-specific MAA concentration was significantly correlated with the occurrence of Microcystis but not with other algal groups, even though they were dominant in terms of biomass. Based on a photo-optical model, we estimated that the maximum MAA concentration per cell observed (2.5% dry weight) will confer only approximately 40% of internal screening to a single layer of Microcystis cells. Thus, the formation of a colony with several layers of cells is important to afford an efficient UV screening by internal self-shading. Overall, we propose that Microcystis uses a combination of photoprotective strategies (MAAs, carotenoids) to cope with high solar UV radiation at the water surface. These strategies include also the screening of UV radiation by D-galacturonic acid, one of the main chemical components of the slime layer in Microcystis.

Elevated risk for squamous cell carcinoma of the conjunctiva among adults with AIDS in the United States

Squamous cell carcinoma of the conjunctiva (SCCC) has been associated with HIV infection in equatorial Africa, but the evidence for association with HIV in developed countries, where SCCC is rarer, is controversial. We investigated the risk for SCCC and other eye cancers in the updated U.S. HIV/AIDS Cancer Match Registry Study. We calculated standardized incidence ratios (SIRs) to estimate excess risk for SCCC, primary ocular lymphoma, ocular Kaposi sarcoma (KS) and other eye tumors among 491, 048 adults (aged > 15 years or older) with HIV/AIDS diagnosed from 1980 to 2004. We calculated relative proportions (per 10(5)) to gain insight into risk factors. We identified 73 eye cancers (15 SCCC, 35 primary ocular lymphoma, 17 ocular KS and 6 other). Overall SIRs were elevated for SCCC (SIR, 12.2, 95% CI 6.8-20.2), primary ocular lymphoma (21.7, 95% CI 15.1-30.2) and ocular KS (109, 95% CI 63.5-175). Risk for SCCC was elevated regardless of HIV acquisition category, CD4 lymphocyte count and time relative to AIDS-onset. Relative proportions of SCCC risk were highest with age >or=50 (8/10(5)), Hispanic ethnicity (7/10(5)) and residence in regions with high-solar ultraviolet radiation (10/10(5)). We show significantly increased incidence of SCCC among persons with HIV/AIDS in the U.S. The associations with age and geography are in accord with etiological role for ultraviolet radiation in SCCC.

Episode of unusual high solar ultraviolet radiation over central Europe due to dynamical reduced total ozone in May 2005

Abstract. In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter called "ozone mini-hole" was caused by an elevation of tropopause height accompanied with a poleward advection of ozone-poor air from the tropics. The resultant increase in UV-radiation is of particular significance for human health. Dynamically induced low ozone episodes that happen in late spring can considerably enhance the solar UV-radiation in mid latitudes and therefore contribute to the UV-burden of people living in these regions.

Environmental Constraints on Spawning Depth of Yellow Perch: The Roles of Low Temperature and High Solar Ultraviolet Radiation

AbstractThe roles of temperature and ultraviolet radiation (UVR) in determining the spawning success of yellow perch Perca flavescens were investigated in two Pennsylvania lakes with different dissolved organic carbon (DOC) concentrations. In situ incubation experiments were used to manipulate temperature and UVR and to examine hatching time and hatching success. Extensive scuba surveys were used to document actual spawning depths. Differences in the temperature and UVR profiles of the two lakes led to contrasting responses of incubated yellow perch eggs. Higher temperatures in the surface waters of the higher‐DOC lake led to hatching times that were 10–26 d shorter than those in the surface waters of the low‐DOC lake or in the deeper waters of the higher‐DOC lake. The high levels of UVR in the surface waters of the low‐DOC lake killed 100% of the eggs before hatching. Ultraviolet radiation had little effect on survival in the higher‐DOC lake or in deeper waters of the low‐DOC lake. Scuba surveys revealed that spawning in the low‐DOC lake occurred at greater depths than previously recognized. Ninety‐two percent of the eggs spawned in the low‐DOC lake were located at depths greater than 3 m, while 76% of eggs in the higher‐DOC lake were spawned in water less than 1 m deep. Temperature and UVR are both important in determining among‐lake differences in spawning depths of yellow perch. Yellow perch are able to spawn at shallow depths in higher‐DOC lakes, where warmer temperatures accelerate developmental rates and DOC blocks potentially damaging UVR. In low‐DOC lakes, yellow perch must spawn at greater depths to avoid UVR damage. Spawning at greater depths may be costly due to the substantially slower developmental rates at lower temperatures. Our data suggest that the conflicting selective pressures of UVR and temperature create an optimal spawning‐depth range for yellow perch that differs among lakes as a function of DOC concentration.

Damaging UV radiation and invertebrate predation: conflicting selective pressures for zooplankton vertical distribution in the water column of low DOC lakes.

In nature most organisms have to manage conflicting demands of food gathering, predator avoidance, and finding a favorable abiotic environment (oxygen, temperature, etc.) in order to maximize their fitness. In the vertical water column of lakes with high solar ultraviolet radiation (UV) and invertebrate predators, zooplankton face two particularly strong and conflicting selective pressures. During daylight hours invertebrate predators often induce an upward vertical migration of zooplankton prey while potentially damaging UV forces a downward migration. We used 2.2 m long columns suspended vertically in a lake to conduct 2x2 factorial experiments to examine patterns of depth selection behavior by zooplankton in the presence and absence of both the invertebrate predator Chaoborus and UV. We hypothesized that Chaoborus and UV both affect the distribution of zooplankton and a combination of both factors would lead to a narrowing of depth distribution. We found that when Chaoborus were present zooplankton tended to be distributed at shallower depths in the columns, while in the presence of UV they exhibited a deeper distribution. Chaoborus themselves were always found near the bottom of the columns regardless of the UV treatment. Simultaneous exposure to predators and UV resulted in a peak of zooplankton (especially Daphnia catawba) distribution at intermediate depths. In a significant number of cases, depth range was narrowed in response to Chaoborus, UV, or both.

Health and performance of military personnel in cold climatic environment of the western Himalayas

Indian Armed Forces are constrained to deploy a large number of troops in the western Himalayas in the interest of national security and territorial integrity. The region represents extremely rugged, arid and cold climatic conditions. The altitude ranges from 8000 to 23000 feet with winter temperatures ranging from −35°C to −55°C in some regions. Low environmental humidity, hypo-baric hypoxia and high solar ultra-violet radiation with its attendant problems further compound the hardships faced by the troops in these climatic conditions. The role of the Armed Forces medical personnel is extremely challenging, as they have to ensure maintenance of health and physical fitness of the troops to ensure optimal performance during peace and during operations. These considerations include nutrition, physical fitness programmes suitable for the terrain and climatic conditions, protection against cold and hypoxia induced health problems, clothing and shelter taking into consideration the ergonomie factors, human waste disposal and prompt medical attention and evacuation in case of illness. An overview of the effects of cold hypoxic environment on health and performance of Indian troops, measures employed by the Armed Forces to maintain health of troops including psychological factors and the incidence of various cold induced health problems during peace time compared to operational period over the last 10 years is presented in this paper.