Health & Science
You, me and UV
by Kim Griggs
Childhood exposure to the sun significantly increases the risk of skin cancer over a lifetime and new research shows that children are still soaking up too much sun in school playgrounds.
Twenty-one years ago, British scientists discovered a strange “hole” in the ozone layer over Antarctica. The following year, another team of scientists figured out that the hole in the ozone layer, which protects Earth from the sun’s ultraviolet rays, was caused by the release of non-toxic refrigerants – chlorofluorocarbons, or CFCs – into the atmosphere. By 1987 – in snappily short order compared to the various inter--national twists and turns on climate change – an international agreement to phase out the use of the offending chemicals had been ratified.
For New Zealand, the ozone hole means that each year ozone-poor air from our southern neighbour continent sweeps over our islands when the hole breaks up. And although scientists say it’s no longer widening, many years will pass before the ozone layer is restored to what it was.
“For ozone over New Zealand to go back to how it was in 1980, we expect this to happen between 2035 and 2050, most likely around 2040,” says Dr Greg Bodeker of the National Institute of Water and Atmospheric Research. “The Antarctic ozone hole will take a bit longer to recover, probably more like 2060, 2065.”
So can Kiwis relax about the sun? Not a chance.
“We would have to be careful, anyway, even if there were no ozone depletion, just because of our high UV environment,” says Bodeker. Even when the ozone hole improves, we’re always going to have high levels of skin-damaging UV radiation. That’s because in summer we receive more radiation as we are tilted towards the sun and at the closest point of our elliptical orbit. Our pollution-free skies also let through loads of UV and our often mild summertime temperatures lull people into spending too long in the sun.
“That is the greatest challenge in New Zealand: the moderate temperature related to the high UV,” says Tony Reeder from the Department of Preventative and Social Medicine at the University of Otago. “People coming here from Europe are really caught out until they get burnt once or twice.”
Our UV level also varies widely from summer to winter, says Reeder. “We have low levels [of UV] in the winter and incredibly high levels in summer, so it’s difficult behaviourally for people to adjust to that.”
Consequently, skin cancer is the most common cancer in New Zealand; it kills between 250 and 300 of us each year. To boot, New Zealand has one of the highest melanoma death rates in the world, with New Zealand women topping the melanoma charts: out of every 100,000 women, nearly 40 will get melanoma.
But it’s youthful exposure that has been fingered as particularly bad. The Ministry of Health’s cancer control strategy points out that “exposure during childhood and adolescence contributes significantly to lifetime skin cancer risk”.
And although an increase in indoor activities, such as the use of television, videos and computers, may be reducing kids’ UV exposure, the school playground, according to new research, is still a key place for kids to soak up too much sun. Between October 2004 and April 2005, University of Otago researcher and PhD candidate Caradee Wright measured the UV exposure of primary and intermediate schoolchildren in five different regions of New Zealand.
The years 4 and 8 students who took part in the study wore UV monitors and also filled in an activity diary detailing what they’d been doing, whether they’d been inside or outside and what sun protection they’d been using.
Wright’s results show that the kids’ UV exposure was higher on weekdays than during the weekend; passive pursuits, such as sitting and reading, ranked highest in terms of personal UV exposure, while being physically active was coupled with a lack of attention to sun protection. Boys had higher UV exposure rates than girls. And the older kids, the Year 8 children, experienced higher UV exposure rates than Year 4 students.
“The mean total daily personal UV exposure was relatively low,” says Wright in a paper she published on her research. “However, some children still received sufficient UV, depending on skin type, to elicit sunburn.” So, according to this study, schools have an important role to play in protecting kids, who get most of their UV exposure from Monday to Friday in the summer terms.
A new initiative by the Cancer Society and the Health Sponsorship Council aims to broaden the protection provided by schools – primary and intermediate in the first instance. Those that put in place the recommended policies on sun protection will be able to become accredited “SunSmart” schools.
“This programme raises the level of protection offered compared to some of the other sun-protection programmes out there,” says Dr Judith Galtry, the Cancer Society’s skin cancer prevention adviser. The programme advocates the usual “slip, slop, slap”, but also encourages schools to provide trees or other shade structures, and to consider minimising the time spent outdoors between 11.00am and 4.00pm in the summer terms. It can be a drawcard to parents for schools to have the accreditation, says Galtry. But it’s a balancing art – our kids also need to run around for exercise and have sunlight exposure for vitamin D production.
“It’s a matter of arranging things at the right times. It just requires a bit of reorganisation and rethinking things,” says Reeder. Kids should still be running around, “but hopefully, in the summer, not in the middle of the day”.
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