Non-melanoma skin cancers comprise basal cell carcinomas and squamous cell carcinomas. These are rarely lethal but surgical treatment is painful and often disfiguring. The temporal trends of the incidence of non-melanoma skin cancers are difficult to determine, because reliable registration of these cancers has not been achieved. However, specific studies carried out in Australia, Canada and the United States, indicate that between the 1960s and the 1980s the prevalence of non-melanoma skin cancers increased by a factor of more than two.
The risk of non-melanoma skin cancers has been examined with respect to personal exposure, and the following conclusions can be drawn:
Malignant melanoma, although far less prevalent than non-melanoma skin cancers, is the major cause of death from skin cancer and is more likely to be reported and accurately diagnosed than non-melanoma skin cancers. Since the early 1970s, malignant melanoma incidence has increased significantly, for example an average 4 per cent every year in the United States. A large number of studies indicate that the risk of malignant melanoma correlates with genetic and personal characteristics, and a person’s UV exposure behaviour. The following is a summary of the main human risk factors: Malignant Melanoma
Helps some skin conditions – UV is used in the treatment of skin conditions such as psoriasis. This is a condition where the skin sheds its cells too quickly and develops itchy, scaly patches. Exposure to UV slows the growth of the skin cells and relieves the symptoms.
Helps moods – Research suggests that sunlight stimulates the pineal gland in the brain to produce certain chemicals called ‘tryptamines’. These chemicals improve our mood.
Helps some animals’ vision – Some animals (including birds, bees and reptiles) are able to see into the near UV light to locate many ripe fruits, flowers and seeds that stand out more strongly from the background. The fruits, flowers and seeds often appear quite different from how humans see them. For example, when seen in UV light, some flowers have different line markings, which may help direct bees and birds to the nectar.
Aids some insects’ navigation – Many insects use UV emissions from celestial objects as references for navigating in flight. This is why a light sometimes attracts flying insects by disrupting their navigation process.