Kiwis' love affair with tattoos has resulted in an unfortunate mark-up in the number of would-be blood donors turned away because of health concerns.

The New Zealand Blood Service (NZBS) knocked back 1714 potential donors between July 2009 and June 2010 because they had been inked within six months of wanting to give blood.

That was up from 1430 the previous year and 894 the year before.

According to the NZBS, a single blood donation can help save up to three lives. But marketing manager Paul Hayes said the service was cautious about recently tattooed donors because of concerns the industry didn't have set standards which are actively monitored.

"They [tattooists] might be using new needles but dipping them in the same ink pots... we just don't know," said Hayes. The biggest risk was the transfusion of Hepatitis B, he said.

New Zealanders are believed to be one of the most tattooed people in the world.

Internationally, the once taboo skin art has become mainstream – helped by hit reality TV shows set in tattoo parlours in the UK and US, and the emergence of heavily-inked sport pin-ups like new All Black Sonny Bill Williams and soccer superstar David Beckham.

During the last year NZBS has noticed a 20% decline in donors, a worrying trend given it needs 20,000 new supporters annually to maintain supply.

Hayes said tattoos was just one of a myriad of reasons potential donors are turned away. Others include various illnesses, injuries and medical conditions.

Last year, 45,200 people were stopped from giving blood for 342 different reasons.

Having a new tattoo was the 10th most common reason during the last financial year – slightly behind potential donors having had a hip replacement, 1920; and ahead of high blood pressure, 1690. Currently, 122,000 Kiwis donate blood every year.

Every week the blood service has to provide 1410 litres of blood to service hospitals nationwide.

The biggest user of blood products is cancer treatment, 20%; followed by surgery, 17%. Kiwis who are in good health, aged from 16-70 – 60 for new donors – and weighing at least 50kg, may donate blood up to once every three months.

Phone 0800 GIVE BLOOD or visit www.nzblood.co.nz