More than three quarters of eligible Australians are not being screened for bowel cancer despite it being offered for free, which is putting them at risk from the second biggest cause of cancer death in the country.

A study, published in BMC Public Health on Wednesday, found that just 25% of eligible men and 20% of women were screened for bowel cancer during the study period.

Spokesperson for the Cancer Council, Associate Professor David Smith, said people need to take more advantage of the government's screening program.

"The findings show that only a fraction of eligible people are being screened for bowel cancer despite there being a clear evidence that early detection via screening reduces bowel cancer deaths."

Smith said the results, which came from the 45 and Up study of 250,000 people, are "reasonably representative" of the population, but the reality could actually be worse.

"Because the group was selected from Medicare … these people may in fact be slightly more inclined to be health literate, to have healthy practices and lifestyles. And therefore we think this is probably, if anything, an overestimate of the proportion of people who are actually taking bowel cancer tests," he told Guardian Australia.

The screening test for bowel cancer is considered highly effective, however less than 40% of cases are found early.

"The survival of people detected with early bowel cancer is about 93% after five years, compared with less than 10% if it's widespread," said Smith. "Obviously there are different stages of bowel cancer in between those two, but early detection certainly leads to better prognosis."

The tests are a little awkward, which may be why there is such a low rate of testing.

The first screening test involves "faecal occult blood testing, which is to see if you've got blood in your poo", said Professor Geoffrey Dobb, vice-president of the Australian Medical Association. "Many people feel a bit yucky about collecting a sample."

"It's strange these days when just about every other bodily function is an acceptable topic of dinner table conversation. This seems to be the final frontier. That's probably adding to people's reluctance to actually have the test done," said Dobb.

The Cancer Council said there is an opportunity to increase the number of people getting tested under the government's screening program which offers a free test at age 50, 55 and 65. From July this year people who turn 60 in 2013 will also be included.

The tests will be available to everyone over 50 on a two-yearly basis by 2034, but the Cancer Council is calling for it to be enacted now.

Smith also wants the test to be promoted at the point of testing for breast cancer or prostate cancer, which have a much higher rate of testing among the same age group.

"We need to address this issue to help save more lives," said Smith.