And why should this concern Congress?

(The Hill) — Congressional Democrats sent a letter to Rep. Fred Upton (R-MI), chairman of the House’s Committee on Energy and Commerce, urging congressional hearings to investigate a delay in the implementation of human growth hormone testing in the NFL.

“This delay is a cause for concern,” wrote Reps. Henry Waxman (D-Calif.), G.K. Butterfield (D-N.C.), and Bobby Rush (D-Ill.) in a letter that indicated concern that as many as 20 percent of NFL players could be using the growth hormone.

The NFL Player’s Association has balked at implementing the test, which was agreed to in the most recent collective bargaining agreement between players and owners. The players have questioned the validity of the testing program, expressing concern that the test group that blood samples would be measured against does not fairly represent the body chemistry of a professional football player.