By ADRIANNE APPEL
UPI Correspondent
BOSTON, July 31 (UPI) -- Estimates of the number of people who can donate blood are off by as much as one-third, meaning blood banks may have to work harder to recruit donors, a new study reported this week.
The study in Transfusion, the journal of the American Association of Blood Banks, estimates that 66 million fewer people are eligible to donate blood -- only about 37 percent of the U.S. population.
"The conventional method of calculating eligible donors indicates that there are approximately 177 million eligible donors in the U.S. population," said Jeffrey McCullough, a professor at the University of Minnesota School of Public Health and a blood-banking expert. "This study indicates that only 111 million individuals in the U.S. are eligible to donate blood."
Conventional estimates only look at age, those over 17 years old, as determining who can donate, he said. But a more accurate count would take into account people who have traveled, are sick, have received a recent tattoo or are on medication, among other factors, McCullough said.
The study used the criteria of the American Association of Blood Banks to determine who would be eligible.
"One major implication is that because there aren't nearly as many people who are available as potential donors as previously believed, the 'cushion' of people who might be approached as blood supplies decrease is much smaller than has been assumed," McCullough told United Press International.
"It will be incumbent on blood collection organizations to become more creative in their approaches to potential donors," McCullough said.
"Currently the blood supply is adequate to meet the overall needs of patients," he said. But "there are times of the year or locations throughout the U.S. when blood supplies are dangerously low. Sometimes elective surgery must be postponed due to lack of blood," McCullough said.
McCullough said his team will determine further who is eligible to donate and pass this information on to blood-banking organizations.
"Blood collection organizations can develop new recruitment approaches to hopefully encourage those who do not now donate to consider doing so.
"As our population changes over the next decade, these new approaches will be essential because the size of the eligible donor population will continue to decrease," McCullough said.
Artificial blood doesn't offer much promise yet, he said.
"Artificial blood has been under development for years, and hundreds of millions of dollars have been spent on this effort with little success thus far," McCullough said. Also, the products use red blood cells, so there is no way to avoid the need for donations, he said.
Paying donors is not permitted, McCullough said.
"Paying donors is inconsistent with worldwide ethical principles, and also, studies throughout the world have almost always shown that inserting money into the donation process attracts donors who have a higher-than-usual risk of disease transmission. So it would decrease blood safety," he said.
Blood supplies typically run low in the summer, and this year is no exception, Stephanie Millian, spokeswoman for the American Red Cross, told UPI.
"Right now we're at a two-day blood inventory. We expect that to increase as we move into fall," she said. "Optimally, we'd like to have a three- to five-day blood supply.
"We're not at that point where it's a critical situation. But if there is any emergency, we want enough blood on the shelf to address that," she said.
"There are always fewer people available during the summer months and holidays. Students are a good percent of the blood supply and they are out for the summer. You have students and families taking vacations," she said.