Previous tests had cleared them of bowel cancer. But the government tested the samples again after reports of some defects in the tests. In the event 4,444 Australians have been told they have tested positive, creating an uproar. Particularly so when reports say that more than 70 people die from bowel cancer in the country every week.
But the Chief Medical Officer for the Federal Government, professor Jim Bishop, says there was no need to panic.
"We're testing for blood in the bowel motions and the great majority of people with abnormal blood in the bowel motions won't have bowel cancer but it is most important to follow up and those few that do have an adenoma or a polyp can be detected early," he counselled when talking to ABC Radio.
In 2008, five years after home kits were introduced, the manufacturers changed the testing kit. The Health Department says this was necessary because some samples were over-heating in the mail, leading to inaccurate results. But it was the changes that led to more inaccuracies, authorities say.
The Government sent replacement kits to 108,000 people. The results from the apparently new and improved tests show 7 per cent have returned positive.
Authorities say it is perfectly normal. But the Gut Foundation, a non-profit organisation which raises awareness of digestive diseases, says a normal rate for positive test results would only be 5 per cent. Seven is a matter of concern.
The Foundation's chief, Terry Bolin, noted that the tests had gone from being not sensitive enough to being too sensitive. "There were too many false negatives 15 months ago and now there are a large number of positives," he said.
Both he and professor Bishop say the thousands of people who returned a positive test in their last screening should book in for a colonoscopy immediately.