Akron, Ohio ? The U.S. Food and Drug Administration today will impose stricter rules on blood donations, in hopes of lessening the risk of spreading the human form of mad cow disease in the nation’s blood supply.

But America’s Blood Centers, the country’s second-largest blood supplier, worries that the new rules will hurt, not help, the national blood supply by turning away an estimated 300,000 donations a year.

The new FDA policy is aimed at potential blood donors who have lived or traveled in the United Kingdom or Europe, where the human form of mad cow disease variant Cruetzfeldt-Jakob disease has killed 111 people. Those who died of the disease were infected by eating beef tainted by mad cow disease. There has been no evidence of the disease being transmitted via blood.

People meeting just one of the following limits will not be eligible to donate blood:

l If you lived in France for five years or more between 1980 and the present.

l If you have visited or lived in the United Kingdom for a total of three months or more between 1980 and 1996.

l If you received a blood transfusion in the United Kingdom after 1980.

l If you were in the military or were a military dependent, who spent six months or more on bases in northern Europe between 1980 and 1990 or in southern Europe between 1980 and 1996.

The American Red Cross enacted its own, stricter deferral policy last October. The organization said then that it expected to lose 6 percent or 360,000 of its donors.

Nationwide, the policy turned away just 1 percent of potential donors, said Karen Kelley of the Red Cross in Ohio.