Solar ultraviolet A radiation and nonmelanoma skin cancer in Arica, Chile.

In this work, we present the maximum daily values of solar ultraviolet A radiation (UV-A) as a function of time. The results indicated that such values reached a maximum of 93.9 W/m2 in 2010 and a minimum of 16.5 W/m2 in 2012. The annual averages of both UV-A and solar ultraviolet B radiation (UV-B) from 2007 to 2013 were recorded. UV-A was always higher than UV-B. However, UV-B is more energetic due to its intrinsic wavelength. The nonmelanoma skin cancer mortality incidences per 100,000 inhabitants in Arica and in Chile as a function of time between 2007 and 2013 indicated that these mortality rates varied from 3.12 (Arica) to 0.88 (Chile) in 2007 and 2.71 (Arica) to 0.88 (Chile) in 2013. The nonmelanoma skin cancer prevalence rates per 100,000 inhabitants in Arica were 22.2 in 2007 and 19.5 in 2013. The relationship between NMSC and exposure to UV-A is given. In Arica, we report high levels of UV-A and the highest NMSC rates compared with other regions in our country.

Association between non-melanoma and melanoma skin cancer rates, vitamin D and latitude.

Vitamin D synthesis takes place in the skin due to solar ultraviolet-B (UVB) radiation. Several studies have shown the association between low sun exposure, non-melanoma skin cancer (NMSC) and a lack of vitamin D synthesis. Since such synthesis in the body depends on the exposure of the skin to solar UVB radiation (290-320 nm), experimental measurements of this type of solar radiation are important. Tarapaca University in Arica, Chile, established a solar UV radiation laboratory in 2006 and since then this laboratory has performed systematic experimental solar UVB measurements using a calibrated biometer instrument. The results, which are presented in the current study, showed the association between NMSC and MSC rates, and the time required to produce 1,000 IU vitamin D with latitudinal variation. Solar UV index (UVI) levels reported in 6 cities from the north to the south of Chile indicated that the UVI ratio of monthly mean values was 1.8 times higher in Arica than in Punta Arenas in January (summer in Chile), whereas it was 14 times higher in June (winter). This factor is an important consideration, since vitamin D synthesis is directly associated with the exposure of individuals to solar UVB radiation. A similar trend was observed in Antofagasta, Santiago, Concepcion, Valdivia and Punta Arenas. It can be concluded from these data that there is a direct association between NMSC rates and mortality, and UVB radiation, meaning that this type of cancer would not depend on vitamin D synthesis and therefore on calcium uptake. By contrast, MSC rates increased with decreased levels of vitamin D, and thus calcium uptake, in all cities, with the only exception being Punta Arenas.

Ultraviolet light exposure, skin cancer risk and vitamin D production.

The danger of overexposure to solar ultraviolet radiation has been widely reviewed since the 1980s due to the depletion of the ozone layer. However, the benefits of mild exposure of the skin to ultraviolet (UV) light have not been widely investigated. Numerous reports have demonstrated that an association exists between low light exposure to the sun, non-melanoma skin cancer and a lack of vitamin D synthesis. As vitamin D synthesis in the body depends on skin exposure to UVB radiation from the sun (wavelength, 290-320 nm), experimental measurements for this type of solar radiation are important. The present study analyzed data obtained from a laboratory investigating UV radiation from the sun at the University of Tarapacá (Arica, Chile), where systematic experimental UVB measurements had been performed using a calibrated biometer instrument since 2006. These data were compared with skin cancer data from the local population. The results demonstrated that the incidence of skin cancer systematically increased from 7.4 to 18.7 in men and from 10.0 to 21.7 in women between 2000 and 2006 in Arica, respectively; this increase may be due to multiple factors, including the lack of adequate levels of vitamin D in risk groups such as post-menopausal women and senior age. This marked increase may also be due to the high levels of UV radiation measured in this region throughout the year. However, it is not certain that the local population has adequate vitamin D levels, nor that their skin has been predominantly exposed to artificial light that does not allow adequate vitamin D synthesis. Thus, the current study presents the association between skin type IV, the time to induce solar erythema and the time required to produce 1,000 international units of vitamin D.

Skin cancer risk affected by ultraviolet solar irradiance in Arica, Chile.

The present study analyzed the risk of skin cancer due to ultraviolet erythemal irradiance (UVery) in Arica, Chile, using measurements of the solar ultraviolet index (UVI) between 2006 and 2011. The daily maximum value by biometer Yankee Environmental Systems (YES) solar ultraviolet B (UVB)-1 was measured between 2007 and 2012, and seasonal variations were clearly observed, with higher UVI levels during the summer when UVI usually reached extreme values of >11. The maximum UVI value was 15.6 in the summer of 2008 and the minimum was 2.2 in the winter of 2008. The UVI mean values that were collected monthly at noon between 2006 and 2010 fluctuated between 13 and 6, and reached higher values in January and lower values in June and July. Thus, a seasonal UVI response was observed during the two seasons. The accumulated UVery/day was calculated between September 2006 and 2007, the time when Arica normally receives the highest UVI levels. It was also noted that 60% of the days in September demonstrated values of >3.41 kJ/m2/day, while 3.3% of cloudy days had values of <2.0 kJ/m2/day. The mean value of UVery during 2007 was 3.23 kJ/m2/day and the variation was 1.9-4.6 kJ/m2/day. These UVery values were several times higher than the minimal erythemal doses (MEDs) corresponding to the skin types most frequently observed in Chile, skin types III and IV. The MED for skin type IV was 0.60 kJ/m2. The results demonstrated that the skin cancer rate was increased due to the fact that individuals from Arica are exposed to several times more UVery than the MED for their skin type during the spring and summer seasons.

Prediction of skin cancer occurrence by ultraviolet solar index.

An increase in the amount of solar ultraviolet light that reaches the Earth is considered to be responsible for the worldwide increase in skin cancer. It has been reported that exposure to excessive levels of solar ultraviolet light has multiple effects, which can be harmful to humans. Experimental ultraviolet light measurements were obtained in several locations in Chile between 2006 and 2009 using wide-band solar light Biometer YES, calibrated according to World Meteorological Organization (WMO) criteria and integrated into the National Meteorological Center of Chile ultraviolet network (DMC). The aim of this study was to determine skin cancer rates in relation to experimental data accumulated during one year of studying the solar ultraviolet index in Chile, in order to explain the possible effect of radiation on skin cancer. The rate of skin cancer per 100,000 persons was considered in Arica, Santiago, Concepción and Valdivia and extrapolated to other cities. Results of the present study showed that the incidence of skin cancer was markedly correlated with accumulative ultraviolet radiation, and rates of skin cancer could be extrapolated to other locations in Chile. There is a steady increase in the rate of skin cancer in cities located nearest to the equator (low latitude) that receive greater accumulated solar ultraviolet radiation, due to the accumulative effects of this type of radiation on the skin. It can be concluded that Arica is a city at sea level that receives higher levels of ultraviolet solar radiation than other locations, which may explain the higher prevalence of skin cancer in the population of this location, compared with other cities in Chile.

Ultraviolet light exposure influences skin cancer in association with latitude.

The increase in the amount of solar ultraviolet (UV) light that reaches the earth is considered to be responsible for the worldwide increase in skin cancer. It has been reported that excessive levels of UVA and UVB light have multiple effects, which can be harmful to humans. Experimental measurements were obtained using wide-band solar light YES biometers from 2006 to 2009 in Arica, Chile and from 2003 to 2006 in Valdivia, Chile, both instruments having been calibrated according to the World Health Organization (WHO) criteria and integrated into the Chilean Meteorological Organization network. To explain the possible effect of radiation on skin cancer, revised pathological reports in Arica and Valdivia were analyzed. In Arica, data on men and women were collected between 1997 and 1998-2002, and in Valdivia, between 1997-2000 and 2001-2007. In this study, comparative values of ultraviolet index (UVI) from the above datasets, were analyzed. Arica is a city located in the subtropical zone of northern Chile, 25 meters above sea level, with a latitude of 18˚49'S and a longitude of 70˚19'W. It has a microclimate characterized by stable meteorological conditions throughout the year, including low precipitation (<5 mm per decade), predictable winds, a high percentage of clear sky days and high ground reflectivity due to the presence of light sand. Due to its location near sea level, the population performs a great number of outdoor activities. Valdivia is a city located in the southern part of Chile, 19 meters above sea level with a latitude of 39˚38'S and a longitude of 73˚5'W. The aim of the present study was to determine the relationship between latitude and the risk of skin cancer in two cities with different latitudes. The incidence of skin cancer per 100,000 persons significantly (P<0.05) increased in both genders between the periods 1997-2000 and 2001-2007 in Arica. However, it decreased in men between the periods 1993-1997 and 1998-2002 in Valdivia. The results of this study indicate a steady increase in the incidence of skin cancer in Arica, most probably due to the high levels of UV light and the latitude to which individuals are exposed throughout the year, as well as the accumulative effect of this type of radiation on the skin. It can be concluded that Arica presented a greater UVI than Valdivia, which can explain the high prevalence of skin cancer in this population according to the pathological reports.

Ultraviolet light exposure and skin cancer in the city of Arica, Chile.

An increase in the amount of solar ultraviolet light that reaches the Earth is considered to be responsible for the worldwide increase in skin cancer. Solar ultraviolet B (UVB) light (290-320 nm) has multiple effects that can be harmful to human beings. The city of Arica in Chile receives high UV levels. This can explain the high prevalence of skin cancer in the Arica population. In the present study, pathological reports of skin cancer were collected from an Arica hospital and retrospectively examined to investigate the possible effects of UV radiation. Among the malignant skin tumor types, basocellular and spinocellular carcinomas were more common in men (44.4 and 16.6%, respectively) than in women (24.9 and 10.7%, respectively). Basocellular carcinoma was observed in individuals 40-79 years of age. The incidence of skin cancer significantly increased (P<0.05) between 2000 and 2006 per 100,000 population. The factor of incidence of skin cancer per 100,000 population significantly increased (P<0.05) between 1980 and 2000 in both genders, but was higher in men (0.79-1.99) than in women (0.63-1.56). The results of the study indicate a steady increase in the incidence of skin cancer in Arica, Chile, most probably due to the high levels of ultraviolet light to which individuals are exposed throughout the year, and the cumulative effect of this type of radiation on the skin.

Programa educativo sobre fotodaño y fotoprotección en la población de Arica: primavera de 1995 / Education program about photodamage and photoprotection in the Arica population: spring 1995

Un exhaustivo Programa Educativo sobre Fotodaño y Fotoprotección se despliega sobre un sector específico de educadores a cargo de lactantes, pre-escolares y escolares de la ciudad de Arica, durante la Primavera de 1995