Probably no athletes taking part in the Pan American Games will be risking their careers by eating tacos on the streets of Guadalajara.

Fears over testing positive for the banned substance clenbuterol will outweigh any craving for meaty and tasty local treats.

Five members of the national soccer team and weightlifter Diana Cha were suspended recently after they tested positive for clenbuterol, a banned substance that can cause an increase in aerobic capacity.

The Mexican Soccer Federation (FMF) suspects the soccer players ate contaminated chicken or beef at a training camp in Mexico City prior to last summer's Gold Cup competition.

Cases are not limiited to Mexico. Three-time Tour de France champion Alberto Contador of Spain tested positive for the drug at the 2010 event. He also insisted it was due to food contamination.

Although banned in Mexico, clenbuterol is still used by some farmers to fatten cattle.

Officials from the World Anti-Doping Agency have met with the Pan American Games Organizing Committee (Copag) several times in recent months to discuss the issue and appear satisfied at measures taken to ensure that athletes housed at the Villa Panamericana will not be exposed to contaminated meat.

All meat served in the athletes village will come from accredited slaughterhouses that have been thoroughly inspected for safety, Copag President Carlos Andrade told the Reporter recently.

Jalisco Health Secretary Alfonso Petersen this week rejected calls by some trainers for athletes only to eat fish in Mexico.

He said the number of reported of cases clenbuterol contamination in recent years is very small, noting that measures enacted in Jalisco to outlaw the practice of fattening livestock with the banned substance have largely been successful.