NEW YORK — Houston Texans linebacker Brian Cushing tested positive for HCG, a fertility drug that is on the NFL's banned substance list.

A person familiar with Cushing's case told The Associated Press today that Cushing had one positive test last September, then subsequently tested negative several times. The person spoke on condition of anonymity because the test results were supposed to remain confidential.

"He had one low-level positive test for HCG in September, and then every test after that was negative," the person said. "He has said he has no idea where the positive test came from."

The NFL has suspended Cushing for the first four games of the season. He won the AP's NFL Defensive Rookie of the Year honor in January for outstanding on-field performance. Now, the AP is taking a revote for the award, as well as All-Pro outside linebacker because Cushing made the second team.

ESPN first reported the banned substance was human chorionic gonadotropin, which is widely taken by steroid users to help restart natural testosterone production. HCG can mitigate the side effects of ending a cycle of drugs. It's also used to induce ovulation and treat ovarian disorders in women.

In 2009, Dodgers outfielder Manny Ramirez was suspended by Major League Baseball for 50 games for testing positive for HCG.

The person familiar with Cushing's case said medical experts have talked about a surge in HCG levels for a man after a workout or after ejaculation.

U.S. Anti-Doping Agency spokeswoman Erin Hannan denied that.

"You would not see a natural spike of HCG after a workout or ejaculation," Hannan told The Associated Press. "You would only detect it in urine by actually having taken it."

Cushing, a first-round draft pick out of Southern California, was a runaway winner for the rookie award in balloting by a nationwide panel of 50 sports writers and broadcasters who cover the league. He received 39 votes, easily beating Buffalo safety Jairus Byrd, who had six.

Cushing is suspended without pay until Oct. 4, although he can participate in offseason workouts, training camp and preseason games. He will not be eligible for next season's Pro Bowl — he made the AFC team last January, but did not play, citing several injuries — or any NFL-sponsored awards.

Texans owner Robert McNair on Monday criticized the lack of information provided teams when a player has failed a drug test. He said he would like the testing system and lack of communication with the clubs addressed in the next collective bargaining agreement.

NFL Players Association executive director DeMaurice Smith responded to those comments Tuesday in an e-mail to the AP:

"Sport is at its best when fans can witness great achievements under the rules of fair play. Players who break those rules cheat the game, cheat the fans and cheat themselves," Smith wrote. "The players want a clean game as well as a clean process for enforcing those rules. We intend to address both in the collective bargaining process to make the system better."