ReviewChildhood exposure to ultraviolet radiation and harmful skin effects: Epidemiological evidence
Introduction
Through outdoor activities and recreation children can experience moderate to high levels of exposure to ambient solar ultraviolet (UV) radiation in the course of their daily lives. The organs most susceptible to UV-related damage are the skin and eyes, and this paper reviews available epidemiological evidence regarding harmful skin outcomes of solar UV exposure during childhood and teenage years. Children are at very low risk of UV-related skin damage compared with adults, but the most common UV-related skin diseases occurring in adults may be observed in the first two decades of life as well, namely photoaging (seen as premature mild skin wrinkling in teenagers) and specific pigmentary signs of UV exposure such as freckling and development of melanocytic naevi (moles). After severe UV damage, benign keratinocytic skin tumours, actinic keratoses, and malignant skin tumours: melanoma, and basal cell and squamous cell carcinomas (BCC and SCC) develop, though among skin cancers, only melanoma occurs to any measurable incidence in childhood. On the other hand childhood appears to be a period in life when people are susceptible to initiation of latent harmful effects of UV manifest decades later in adulthood (Balato et al., 2007) (Thomas et al., 2007). Here we review the epidemiology of childhood actinic skin damage and conclude with evidence mostly from migrant studies of the role of childhood UV exposure in the development of adult skin cancers, in particular melanoma.
Section snippets
Ultraviolet radiation exposure in childhood and adolescence
Several epidemiological studies have provided estimates of sun or UV exposure during childhood and adolescent years, and the relative contribution of childhood UV to lifetime exposure. A few of these studies have relied on modelling and most estimates have been obtained from volunteers and/or selected groups.
An extensive review of early life sun exposure which summarised the mean UV exposure, proportion of the ambient UV radiation received and time spent outdoors daily based on 29 studies
Photoaging
In addition to dermatological assessment of the visible clinical signs of skin photoaging (Green et al., 2011), changes can be assessed by skin surface microtopography using silicone casts of the skin of the back of hand reflecting the level of underlying UV-induced deterioration of dermal elastin fibres (Battistutta et al., 2006). Skin damage scores range from 1 (least) to 6 (highest) with progressive flattening and creasing of the skin surface with increasing UV damage.
In otherwise healthy
Skin cancers in children
Since the incidence of BCC and SCC among children and teenagers in general is negligible, only sporadic melanoma in children and teenagers has been considered in detail for the purposes of this paper.
Skin and pigmentary characteristics
As for adults, differences in melanoma risk in children according to racial skin colour are clearly seen. In the National Cancer Database for all US hospital-based oncology patients (1985–2003), non-Hispanic white children comprised around 90 to 95% of all melanoma cases from aged 5 to 19 years (Lange et al., 2007). Within white children up to age 15, there have been very few population-based epidemiological studies of constitutional risk factors for incident primary melanoma. The largest was
Childhood as a susceptible life stage for adult UV radiation effects
Besides UV-induced skin damage manifest in children, harmful longer-term effects occur, that are latent until later in adulthood. It is possible that sunlight exposure during childhood and adolescence confers a greater increase in risk of melanoma compared with risk incurred by exposure at older ages. This theory is based on the plausible notions of heightened susceptibility of young melanocytes to initiation of UV carcinogenesis through alteration of melanocyte DNA by sun exposure and
Primary prevention
Worldwide, strategies for primary prevention have been mainly focused on reducing sunburn and sun exposure overall in white-skinned people of all ages in an attempt to diminish their skin cancer risk. These strategies include encouraging the use of hats, appropriate clothing and sunscreen, as well as avoidance of the sun, particularly at peak hours of the day, and avoidance of artificial forms of UV radiation such as sunbeds (Stanton et al., 2004). Children and adolescents have been major
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