Travelers from the U.S. to Mexico have been advised of water unsafe to drink, and now the NFL is warning its players about eating meat south of the border, as well as in the most populated country on earth.

In a memo issued jointly by the league and its union, players were cautioned that some meat produced by Mexico and China could trigger a positive result for performance-enhancing drugs.

The substance in this case is clenbuterol, an anabolic substance banned by the NFL as well as other sports bodies. It is also banned by the FDA for use with animals meant for human consumption, but of course that only applies to U.S. meat-producers.

“Consuming large quantities of meat while visiting (Mexico and China) may result in a positive test for clenbuterol in violation of the (NFL) Policy (on Performance-Enhancing Substances),” the letter to players read. It was shared on social media by the likes of Ravens wide receiver Steve Smith and Cardinals cornerback Patrick Peterson.

Duane Brown found out about the dangers of Mexican meat the hard way. Following a trip to Baja, California, during Houston’s November bye week last season, the Texans’ offensive lineman tested positive for clenbuterol.

With one PED violation already on his NFL record, Brown was set to be hit with a 10-game suspension as a repeat offender before the union helped him file an appeal. According to ESPN, he was able to produce receipts showing that he had consumed about 10 hamburgers and two steaks while in Baja, and he was eventually cleared.

JOHNNY MANZIEL was booked and posted bond in a domestic violence case Wednesday, one day before the former Browns quarterback faces his first court hearing.

The Heisman Trophy winner and former Texas A&M star was indicted by a grand jury last month after his ex-girlfriend alleged he hit her and threatened to kill her in January.

He is expected to appear briefly before a Dallas judge Thursday morning.

49ERS: Linebacker Michael Wilhoite signed a one-year deal, nearly two months after the restricted free agent was tendered a contract. He started all 12 games he played last season.

SEAHAWKS: Seattle released five players, including former starting center Drew Nowak.

Along with Nowak, the Seahawks released running back Cameron Marshall, tight end Ronnie Shields, defensive end Josh Shirley and wide receiver Tyler Slavin.