Skin checks should be part of annual health checks. Photo / Warren Buckland
Farmers and outdoor workers need to be slapping on sunscreen all year round, according to Northland plastic surgeon David Crabb.
"We are living at a latitude that is way beyond our design specs,'' he said.
Cloud cover only filtered out some of the ultraviolet rays, meaning more than 80 per cent was still coming through the clouds and Northlanders were getting a high dose of radiation whenever they were outside.
"Sunscreen is not just needed in summer. It needs to be worn in winter as well,'' he said.
Northland's maritime setting meant cooling winds could make people think it was safe outside because they weren't feeling overheated like they would be in a similar latitude in the Northern Hemisphere.
People who lived in similar latitudes to New Zealand, such as southern Spain or northern Morocco, had developed cultural ways of dealing with hot summers.
"They tend to keep out of the sun when it is hottest and have siestas. In New Zealand, we tend to stay outside more because we don't feel as hot.
"It's a trap.
"Actually it is just as intense, if not more, as New Zealand lacks the dust and industrial pollutants that help to filter the sun so it is less harmful.''
Crabb said anyone working in the outdoors was in a high-risk occupation.
"Farmers are at particularly high risk and over the summer they will often head to the beach, where the UV exposure is doubled from the sun above and the reflections from the water,'' Crabb said.
"Farmers and fishermen are also prone to cataracts, which is another effect of UV damage.''
Cataracts are a form of eye damage that causes cloudy vision. If left untreated, cataracts can lead to poor sight.
"Our bodies have evolved to have very clever ways of dealing with ultraviolet radiation, which alters according to latitude.
"People living near the poles tend to have white and thin skin, as they evolved to live with low light levels on the forest edges. They needed to be able to absorb enough light to produce vitamin D, which is essential for life.
"The closer to the equator, skin evolved to be darker and thicker to protect the body from too much UV radiation.''
People with Celtic and northern European heritage – including Maori – were at high risk of developing skin cancers from too much sun exposure, he said.
Pigmentation helped with mopping up damage at a cellular level but skin thickness gave most of the protection from the sun.
"Maori might have the perfect skin colour for living at this latitude. However, the Celtic side of their ancestry might mean their skin is not as thick as it needs to be so they can definitely still develop skin cancers,'' he said.
Crabb recommended farming activities such as haymaking be done in the cool of the evening when the effect of UV rays was easing.
He said UV damaged the cell DNA and the effects were cumulative.
"The damage adds up and then the cells start to misbehave when they replicate once a month.''
The body's immune system included dendritic cells which draped like a spider's web over cells to act as a monitoring system for the cellular system.
"They will mark where there are faults so the white cells can come in and kill the abnormal cells.
"Unfortunately, UV radiation also eventually damages this monitoring system so it leaves the body more susceptible to growing abnormal and cancerous cells.''
Crabb said Northland had a high incidence of the three main types of skin cancer – basal cell carcinomas, squamous cell carcinomas and melanomas.
More treatment options were now available, including surgery and non-surgical creams.
"There are now some good treatments being developed for melanomas as well. It's no longer a death sentence as long as it is found and treated as early as possible.
"It's very important that melanoma is found and removed when it is small.
"If the tumour ball of a melanoma is less than 0.75mm in diameter, the chance of it spreading is very low and it can be surgically removed with no further treatment needed.
"Once a tumour is over 1mm to 1.5mm in diameter, the chances are higher that is going to go walkabout. It can pop up elsewhere in the body. It can also arise in areas that are seldom exposed to the sun.''
Crabb recommended an annual skin check should be a priority for everyone.
"Going to see your GP for an annual skin check should be the gold standard. Most GPs have some dermalogical training and there are a number of skin specialist GPs in Northland who can quite quickly identify any suspicious skin lesions."
Sunscreens should always have a Sun Protection Factor over 50 and be worn all year round, he said.
"Don't put off getting checked as presenting late can mean a bad outcome. A stitch in time saves nine,'' he said.