A European study published in the British Journal of Dermatology this year looks at just how much sunlight our children need for good health – and how too much UV radiation can cause serious long term harm.
Humans need UVB radiation from sunlight to produce vitamin D. At the same time, too much UVB radiation causes damage to the genome of skin cells, which can then degenerate and cause cancer. This study investigated a group of Polish children on summer holiday. The question researchers were seeking to clarify was how much safe sun exposure do children need to produce Vitamin D? Does the damage from UV radiation outweigh the benefits of Vitamin D production?
The sun produces radiation at different wavelengths. UVA is a long wavelength that penetrates through the skin. UVB is a short wavelength that hits the surface of the skin and causes sunburn. Prolonged sun exposure and repeated sunburn in children causes damage to the DNA in skin cells that significantly increases the risk of skin cancer in adulthood.
Blood and urine samples from 32 children were analysed for Vitamin D levels. UV-related changes to DNA were detected by specific markers in the urine samples. In addition to the blood and urine examinations, each child kept a diary of sun time, sunburn, and the use of sunscreen. The study showed that DNA damage increased far more than Vitamin D levels, concluding that consistent sun protection in childhood is important.
This study was carried out in northern Europe, but its findings are of huge relevance to us in New Zealand where we have a 37% higher Ultraviolet (UV) light intensity from the summer sun than at the same latitude in the Northern Hemisphere. Unfortunately, the importance of sun protection in children is still underestimated and some parents are concerned that sunscreen use will diminish the amount of Vitamin D in their children.
We only need a small amount of UVB radiation in order to form the vitamin D3 (cholecalciferol), which is important for the metabolism of calcium and bone, in the skin . Here’s a handy guide to how much sun exposure is needed for Vitamin D synthesis.
During winter months it is suggested that approximately 15 - 20 minutes of sun exposure between 10 AM and 3 PM at least twice a week to the face, arms, legs, or back without sunscreen is sufficient for Vitamin D synthesis.
During summer months it is suggested that approximately 15 – 20 minutes of unprotected sun exposure BEFORE 10 AM and AFTER 5 PM at least twice a week to the face, arms, legs, or back without sunscreen is sufficient for Vitamin D synthesis.
Read more Good Science. Find out how sunscreen reduces melanoma risk by 40% in young people.