Mexican health authorities are cracking down on cattle merchants who use the banned substance clenbuterol to make the meat from livestock less fatty.
The effort was launched after clenbuterol turned up in the urine of 109 players from various countries taking part in the Under-17 soccer world championship, an event hosted by Mexico in June and July.
"Steps taken by the Mexican government have reduced the number of cases of such contamination from 555 in 2005 to 89 in 2010," Mikel Arriola, director of the Federal Commission for Protection against Health Risks, said in a conference call to Mexican Soccer Federation headquarters.
Authorities have been combating the use of clenbuterol in cattle, but the importance of doing so took on new relevance during the soccer tourney.
To prevent further such incidents now that Mexico is playing host to the Pan American Games, the government is taking tougher measures against the use of clenbuterol, Arriola said.
Authorized in some countries as a bronchodilator for people suffering from asthma, clenbuterol is prohibited by the International Olympic Committee and other global sporting bodies.
Mexico, like the United States and the European Union, also bans the use of clenbuterol in food-producing animals.
Arriola said that from June to October 2011, authorities visited several livestock markets in seven of Mexico's 31 states. "We took 6,421 samples in 14 operations, and when 99 percent of the samples tested positive, the markets were closed down," he said.
"We're going to continue the inspections to avoid contamination of the general population," he said.
About the cases of clenbuterol poisoning in Mexico, Arriola said that no deaths were reported from that cause between 2005 and 2010.
He said that when a person has swallowed than contaminant he is liable to suffer vomiting and fever, "but it's not something very serious in terms of medical care." EFE