Simone L. Harrison

Sunlight: A major factor associated with the development of melanocytic nevi in Australian schoolchildren

BACKGROUND Case-control studies have identified melanocytic nevi (MN) as the most important phenotypic risk factor for melanoma. A knowledge of any environmental factors that cause MN may facilitate prevention of melanoma. OBJECTIVE This study was undertaken to explore the possible role of ambient solar irradiation in the development of MN in children. METHODS With a standard protocol developed after international consultation, the same medical observers examined children in three Australian cities (Melbourne, Sydney, and Townsville) that span a wide range of latitude. RESULTS A total of 1123 Australian schoolchildren 6, 9, 12, and 15 years of age were surveyed. Larger numbers of MN were found (mean 65.4 MN, standard deviation 52.9) than in previous studies of children. Prevalence increased with diminishing latitude (51.1 in Melbourne, 66.5 in Sydney and 77.2 in Townsville), particularly in children 6 and 9 years of age. Although nevus numbers were higher in children with light skin and hair, blue eyes, and freckling, the latitude gradient remained after adjustment for these and other factors in multivariate analysis. CONCLUSION Latitude of residence, and by implication ambient UV radiation, is strongly related to nevus prevalence in young Australian children. However, these differences diminish with age and may disappear by 15 years of age.

Sun exposure and melanocytic naevi in young Australian children

Queensland, Australia, has the highest rates of melanoma in the world and Queensland children have the greatest numbers of melanocytic naevi, the strongest risk factor for melanoma. Although both melanoma and naevi are broadly related to sun exposure in childhood, the relation to individual exposure early in life is difficult to study retrospectively in adults. We surveyed 506 children aged 1-6 years who had been born in Townsville, North Queensland. Sun exposure was assessed by questionnaire and melanocytic naevi were counted using a standard international protocol. Very high counts (upper quarter) of melanocytic naevi were significantly associated with sun exposure of more than 4 hours per day (adjusted relative risk ratio 3.29; 95% Cl 1.12-9.69), and with a history of sunburn (1.89; 1.11-3.21). Melanocytic naevus counts increased with age, light skin reflectance, and freckling. With exposure to intense ultraviolet light in Townsville, children develop melanocytic naevi early in life and in large numbers. We found that both acute and chronic exposure to sun are associated with their development.

Assessing vitamin D status: pitfalls for the unwary.

The use of vitamin D testing has grown rapidly in the recent times as a result of increased interest in the role of vitamin D in health. Although the generally accepted measure of vitamin D status is circulating 25(OH)D concentration, there is little consensus on which assay method should be used. Commonly used assays include competitive protein-binding assay, RIA, enzyme immunoassay, chemiluminescence immunoassays, HPLC, and LC-MS/MS, each with its own advantages and disadvantages. However, there is significant interassay and interlaboratory variability in measurements. Our simulation of the published data showed that using a deficiency cut-point of 50 nmol/L, 57% of samples assessed using a chemiluminescence immunoassay were classified as deficient compared with 41% of samples assessed using LC-MS/MS; a 20% misclassification rate. Similar rates of misclassification were seen at 75 nmol/L. This has implications for clinical practice and decision limits for vitamin D supplementation, suggesting that cut-points should be assay specific rather than universal and that greater harmonization between laboratories is required. Newer assays using alternative biological samples to determine the circulating 25(OH)D have been proposed and advances in the genetics of vitamin D and the role of vitamin D-binding protein may improve future assay accuracy.

The Eastern Australian childhood nevus study: Prevalence of atypical nevi, congenital nevus-like nevi, and other pigmented lesions

BACKGROUND Various melanocytic lesions are frequently observed. An understanding of phenotypic factors and environmental stimuli that are associated with these lesions may help explain their pathogenesis. OBJECTIVE This study was undertaken to determine the prevalence of atypical nevi, blue nevi, cafe-au-lait macules, congenital nevus-like nevi, halo nevi, nevi spili, nevi 5 mm or more in diameter, and skin-colored melanocytic nevi in a population of schoolchildren and to explore risk factors including solar radiation in the development of these melanocytic lesions. METHODS A cross-sectional study was performed by the same medical investigators to examine schoolchildren in three Australian cities that span a wide range of latitudes. RESULTS Data from 1123 white Australian schoolchildren, 6 to 15 years of age, were analyzed. Acquired melanocytic nevi (atypical nevi, nevi > or = 5 mm in diameter, and skin-colored nevi) were more likely to develop in older fair-skinned subjects who had freckles and lived closest to the equator. Café-au-lait macules and congenital nevus-like nevi were observed in 36.3% and 4.4% of the total population, respectively. Prevalence for both these types of melanocytic lesions increased significantly with decreasing latitude. Halo nevi were present in 5.3% of the subjects and were usually solitary. These lesions were related to the presence of atypical nevi primarily by virtue of their size rather than of other features of clinical atypia. CONCLUSION Like melanocytic nevi in general, large and atypical nevi are strongly influenced by geographic location and, by implication, degree of solar radiation. The same can be said for congenital nevus-like nevi, which suggests that many so-called congenital nevi are in fact acquired early in life.

The Eastern Australian Childhood Nevus Study: Site differences in density and size of melanocytic nevi in relation to latitude and phenotype

It has been postulated that site-specific variation in melanocytic nevus density and size is explained by differential response to sunlight. We observed the density and size of nevi at different body sites in relation to age, phenotype, latitude, and other measures of ultraviolet exposure. A standard protocol was used to assess nevi, phenotype, and sun exposure in 1123 Australian schoolchildren at 3 contrasting latitudes. Associations with phenotype (red hair, skin reflectance, sun sensitivity, and tanning) varied by body site. In Queensland, gender differences in nevus density on the back and lower limbs, unrelated to sun exposure, were similar to gender differences for melanoma. Small nevi (2-4 mm) were most dense on the arms, whereas large nevi (> or =5 mm) were most dense on the posterior trunk where they were related to age, decreasing latitude, male sex, and freckling. Our findings support the hypothesis of site-specific differences in nevus proliferative potential.

The Contributions of Solar Ultraviolet Radiation Exposure and Other Determinants to Serum 25-Hydroxyvitamin D Concentrations in Australian Adults: The AusD Study

The Quantitative Assessment of Solar UV [ultraviolet] Exposure for Vitamin D Synthesis in Australian Adults (AusD) Study aimed to better define the relationship between sun exposure and serum 25-hydroxyvitamin D (25(OH)D) concentration. Cross-sectional data were collected between May 2009 and December 2010 from 1,002 participants aged 18-75 years in 4 Australian sites spanning 24° of latitude. Participants completed the following: 1) questionnaires on sun exposure, dietary vitamin D intake, and vitamin D supplementation; 2) 10 days of personal ultraviolet radiation dosimetry; 3) a sun exposure and physical activity diary; and 4) clinical measurements and blood collection for 25(OH)D determination. Our multiple regression model described 40% of the variance in 25(OH)D concentration; modifiable behavioral factors contributed 52% of the explained variance, and environmental and demographic or constitutional variables contributed 38% and 10%, respectively. The amount of skin exposed was the single strongest contributor to the explained variance (27%), followed by location (20%), season (17%), personal ultraviolet radiation exposure (8%), vitamin D supplementation (7%), body mass index (weight (kg)/height (m)(2)) (4%), and physical activity (4%). Modifiable behavioral factors strongly influence serum 25(OH)D concentrations in Australian adults. In addition, latitude was a strong determinant of the relative contribution of different behavioral factors.

Antibody responses to 26 skin human papillomavirus types in the Netherlands, Italy and Australia

Solar UV radiation is the main risk factor for cutaneous squamous cell carcinoma (SCC), but infections with skin human papillomavirus (HPV) types have also been linked to the development of SCC. Little is known about the natural history of these infections and whether the seroprevalence of skin HPV types is affected by ambient or individual levels of sun exposure. This study investigated this by analysing sera for antibodies to 26 skin HPV types from five phylogenetic genera obtained from 807 healthy individuals from the Netherlands, Italy and Australia, countries with strong differences in sunlight intensity. Overall HPV seroprevalence was similar across the three countries (50-57 % for beta-HPV types, 40-48 % for gamma-HPV types), and the most frequent beta-HPV and gamma-HPV types were the same in all countries. The highest seroprevalences for 24 of the 26 skin HPV types were observed in Italy (14 types) and Australia (ten types). Seroprevalence among men was generally higher than among women, and the male sex was significantly associated with both beta-HPV [odds ratio (OR) 2.81, 95 % confidence interval (CI) 1.64-4.82] and gamma-HPV (OR 2.42, 95 % CI 1.40-4.18) antibodies in Australia. The only measure of sun sensitivity or UV exposure significantly associated with skin HPV seroprevalence was found for weekend sun exposure in Australia and beta-HPV antibodies. It was concluded that type spectra and HPV seroprevalence are similar in countries with different sunlight intensity, and that levels of UV exposure do not play a strong role in the development of skin HPV antibodies in this study population.

Sun exposure at school.

Abstract. There is strong evidence that sun exposure during childhood and adolescence plays an important role in the etiology of skin cancer, in particular cutaneous melanoma. Between the age of 6 and 18, most children and adolescents will spend around 200 days per year at school and may receive a substantial fraction of their daily total solar ultraviolet radiation (UVR) exposure while at school. This study estimated the average daily erythemally effective dose of 70 grade 8 students from a high school in Townsville during 5 school days in July 1998. Through UV measurements of shade locations at the school and a combination of frequency counts and a questionnaire of grade 8 students, it was possible to determine the fraction of solar UVR reaching under the shade structures during lunch breaks and routine outdoor activities. Also, a routinely operating UV‐Biometer provided the annual variation of the daily dose that was used to calculate exposure levels for the 70 students. Our results suggest that up to 47% of the daily total dose fell within the time periods where students were outdoors during school hours. For students not seeking shade structures during the breaks (which usually was the case when involved in sport activities such as basketball or soccer), the average daily dose could have been as high as 14 SED (standard ery‐themal dose). Using results from the questionnaire of 70 grade 8 students, their average annual dose while at school was 414 SED or 2 SED per schoolday. However, the distribution of average daily erythemal effective dose per grade 8 student over the whole year showed that on 31 % of all school days in 1998, this dose was exceeded. Because most previous attempts to change arguably poor sun‐protective behavior of young Australian children and adolescents at school showed little success, one way of decreasing the amount of harmful UVR reaching unprotected skin is the more careful design of shade structures at schools.

Sun Exposure and the Incidence of Melanocytic Nevi in Young Australian Children

The number of melanocytic nevi (MN) is an important risk factor for cutaneous melanoma. The present study further investigated the relationship between sun exposure, the incidence of MN, and the prevalence of large acquired MN (≥5 mm). A cohort of 479 preschool children born in Townsville, Australia was examined for MN in 1991 and a year later. Sun exposure was assessed by questionnaire. The erythemally effective dose of solar UV radiation was estimated from questionnaire data combined with local UV biometry. Almost all (97.7%) children had acquired new MN (median, 12), with a median incidence rate of 11.0 per year (interquartile range, 7.0-16.5). Total number of hours of sun exposure during follow-up (P = 0.034) and tendency to burn (P = 0.028) were independent risk factors for MN incidence. Sunburn experience during follow-up failed to reach significance when adjusted for tendency to burn. Lifetime number of sunburns (P < 0.001) and the severity of sunburns experienced during follow-up (P < 0.001) were significantly related to the presence of large acquired MN at follow-up. Reducing the total number of hours of sun exposure is particularly relevant in sun-sensitive children and may restrain the development of MN, whereas avoiding sunburn in young children might prevent large MN, subsequently reducing the risk of melanoma. (Cancer Epidemiol Biomarkers Prev 2008;17(9):2318–24)

Estimation of the Annual Solar UVR Exposure Dose of Infants and Small Children in Tropical Queensland, Australia

Abstract— The solar ultraviolet radiation (UVR) exposure of infants and small children was measured for 1 week using UVR‐sensitive polysulfone film attached to the shoulder and chest of the subjects. For the infant study, shoulder and chest badges received similar exposures, while the 2%‐year‐olds received higher exposures on the shoulder than on the chest. Also, the 2Vi‐year‐olds generally received higher exposures than the infants. The median total daily exposures for both groups were 39 and 92 J/m2. The maximum total daily exposures measured were 640 J/m2 (chest) and 240 J/m2 (shoulder) for the infants and 2060 J/m2 (shoulder) and 840 J/m2 (chest) for the 2% year‐olds. Using this exposure data, monthly and annual exposure doses were calculated for both groups and compared to similar data from the UK. The annual exposure dose for infants is 8.4 kj/m2 or 84 standard erythemal dose (SED) for both shoulder and chest. The annual exposure dose for 2V2 year‐old children is 39.4 kj/m2 or 394 SED for the shoulder and 28.8 kj/m2 or 288 SED for the chest. Apart from the generally higher annual exposure doses experienced by the infants and 2% year‐old children in Townsville, the main difference to the UK is the almost nonexistent drop in monthly exposure doses between summer and winter in Townsville compared to the UK. In the UK, the winter‐month exposure dose is only 0.5% of the summer‐month dose. However, in Townsville it is around 40%.