Locks of Love sends the best of the hair it receives to a wig manufacturer, Taylormade Hair Replacement in Millbrae, Calif., which weeds through the selection still further, rejecting up to half.

“We hate throwing it away but ultimately we have to clear the place out,” said Greg Taylor, the president and owner of Taylormade. “There is a disparity between the hundreds and hundreds of braids and ponytails and the number of hairpieces we’ve produced.”

Mr. Taylor sells the wigs wholesale to Locks of Love for less than $1,000. Since the charity began in December 1997, it has provided about 2,000 wigs to recipients for free or a reduced price. The group makes clear in its literature and on its Web site that most of the wig recipients are not children with cancer. Rather, they are children who suffer from alopecia areata, an autoimmune disorder that destroys follicles and results in hair loss. About 2 percent of the population, including half a million children, are estimated to have alopecia.

Image Nick Swisher donated hair in May. Credit... Ben Margot/Associated Press

But many alopecia sufferers seem unaware that they are the group’s main priority; only about 10 apply for a wig each week, Ms. Coffman said. Many donors, too, seem ignorant or only partly aware of the group’s focus. Maggie Varney, a hairdresser and owner of a salon in St. Clair Shores, Mich., said she was shocked to learn that hair she collected from her clients and sent to Locks of Love was not used for wigs for children with cancer. In reaction, she formed her own nonprofit, Wigs 4 Kids, in 2003, which receives a few dozen donations of hair a month that are made into wigs that go predominantly to children with cancer.

Two other groups also serve people with cancer. Pantene Beautiful Lengths, started in June last year, has the resources of Pantene, the $3 billion global hair product division of Procter & Gamble, including teams of publicists who stage cutting fests. Already the program has received 18,000 ponytails — 8,000 more than originally projected — and distributed 2,000 wigs to women with cancer, said Seth Klugherz, the North American Pantene brand manager.