New precision UV sensors helpful, but shouldn’t replace good sun protection
Wearable UV sensors are increasingly marketed to help people tailor their sun exposure to their Vitamin D needs, but there are warnings they could cause more harm than good.
An array of personalised UV meters are now available as wristbands, patches and clothing clips linked to smartphone apps, alerting users when they have received enough UV radiation for their body to produce sufficient Vitamin D, but not so much as to increase their skin cancer risk.
New sensor measures sunburn-causing rays
Last month RMIT University researchers headed by Professor Vipul Bansal announced a breakthrough in UV sensor precision, having developed an invisible ink that directly measures UVA, UVB (which causes sunburn) and UVC, and changes colour at different UV saturations.
Professor Bansal told doctorportal: “Previous sensors have been unable to distinguish between the different types of rays, and had to rely on estimates based on total UV, which means they suffered from significant accuracy problems.”
For instance, one randomised controlled trial of 91 people found those who were given old-generation UV sensors experienced more frequent sunburns than those not given sensors at all (OR:1.60). The authors concluded either sensor inaccuracies or user behaviours could be to blame.
Professor Bansal said his team’s new generation of precision sensors would be available by 2020 at a cost of around $1 a day in forms such as stickers and wristbands.
“Personally, I’m vitamin D deficient so I’m always worried about how much time I should spend in the sun,” he told doctorportal. “I was passionate about this work because people like me need some sort of tool to give them an idea what’s enough sun exposure, and what’s too much.”
Currently, the Cancer Council Australia recommends that if the UV index is 3 or above – as calculated by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) – people should wear full sun protection including sunscreen, sleeved clothing and a hat.
However, Professor Bansal said dark-skinned people had difficulty relying on the UV index, as it was a “blunt tool” that failed to take into account variations in UV-absorption rates according to skin tones.
The RMIT sensors have been developed in six different colours to be matched to individuals’ particular skin tones.
Users urged not to completely rely on sensors
Adjunct Associate Professor Craig Sinclair, Head of Prevention at the Cancer Council Australia, told doctorportal accurate UV sensors could be valuable education tools by revealing how quickly UV causes harm to the skin. However, he urged users not to rely on sensors to determine whether or not to apply sun protection.
“In the summer months, especially in the middle of the day, you really need to put sun protection on before you head outside because sunburn can happen so quickly,” he said.
He added: “There is no evidence to suggest that regular use of sunscreen has any impact on Vitamin D levels, especially given the intensity of UV in most of Australia, and the ability of the body to convert that to Vitamin D.”
Associate Professor Sinclair said it was risky for people to self-assess their skin type when deciding on sun protection measures.
“Having dark skin might be the equivalent of SPF 3 or 4 or 5. There’s definitely some protective benefit from dark skin but it doesn’t overcome the primary message – come the summer months, everyone needs sun protection.”
He added: “We don’t want these UV sensors to potentially cause more harm than good if they delay the time people use sun protection.”
Professor Bansal told doctorportal he strongly supported the Cancer Council’s sun safety messages. He suggested that people who used wearable sensors follow sun safety guidelines as per usual, and apply sunscreen to the device.
“The sensor will change more slowly if the wearer applies sunscreen to it, and will indicate when they have had enough exposure,” he said.
The Cancer Council recommends the SunSmart phone app, which advises Australians when to use sun protection.