Beta agonists antagonize beef exports in Asia

Mar 2, 2012

The growth of beef exports around the world has resulted in more conflicts over how individual countries raise their production animals. Increased U.S. beef export efforts, coupled with mutual interest in expanded trade in areas of Asia and Europe to a lesser extent, have sparked controversy over our meat production practices.

At the heart of the controversy is ractopamine, a feed supplement available for finishing beef cattle, hogs and turkeys in the U.S. Consumers are likely more familiar with the product names, Optaflexx, Zilmax and Paylean.

When used in the last weeks prior to slaughter, supplemented animals gain noteworthy amounts of additional meat relative to their species.

The supplement increases feed efficiency and redirects the body’s metabolic energies into producing muscle tissues rather than fat stores. It has been called a leanness-enhancing agent as well as a growth stimulant due to these effects, but both are vastly simplified descriptors.

Ractopamine and meat bearing its residues are widely banned, with 160 countries worldwide banning it in some form. Among the countries which ban it are China, Taiwan and the European Union (EU).

These bans naturally cause difficulties when it comes to U.S. export of beef and pork. A recent issue which garnered mainstream media attention was the Taiwanese government pulling U.S. beef from stores after some shipment samples were found containing residues.

While China is poised on a decision over reducing trade regulations against the U.S. and Taiwan is voicing interest in joining the newly-formed Trans-Pacific Partnership (TPP), the issue of ractopamine use in meat is heating up.

Though China recently banned the production and sale of ractopamine products in its country, rumors exist that it may lift its ban on imported meat bearing ractopamine residues. No official statement has been made so far.

With the help of some public figures, Chinese and Taiwanese consumers have been putting pressure on their governments to maintain ractopamine bans.

Given their close ties, Taiwanese citizens are concerned that if China lifts its ractopamine ban, the move will set a precedent which will be used to force them to lift their own ban.

Taiwan’s interest in joining TPP is spurring political and public outcry in that country. The government is complaining that Taiwan seceding to U.S. trade pressures for Taiwan to import U.S. beef should not be a condition of joining the trade partnership. Taiwanese farmers complain that allowing in U.S. beef will put them at a disadvantage.

The issue of human health impacts of ractopamine is a sticking point for a number of countries, including China and Taiwan. Officials in both countries claim the substance is toxic and has poisoned consumers. Heresay reports of Chinese and Taiwanese consumers having “heart issues” following consumption of U.S. meat are used in part as reasoning for the ban. Existing research does not support claims of such effects on the tiny scale a single serving of meat would represent.

On the other side of the U.S., the European Food Safety Authority issued an opinion statement on ractopamine. The authority cited concern over the substance as possibly carcinogenic, though no research results suggest this. The authority also cited “significant subpopulations”— namely, people with cardiac concerns—as being potentially threatened by ractopamine’s effects. Concern for “all the uncertainties” was also cited in the opinion backing the EU’s ban of the substance.

Ractopamine was originally studied for its use in asthma patients. In the research trials with mice, it was noticed that treated mice were more muscular and leaner. This detail spurred interest in it as a possible feed supplement for production animals.

Ractopamine is part of the beta agonist family, a class of chemicals which repartitions nutrient use within the body. Market animals, which typically reach physical maturity right around slaughter, start laying down more fat than muscle. Ractopamine counters that and encourages continued lean muscle production. When used in the last month to few days prior to slaughter, it can represent noteworthy gains in meat production.

Feed supplements containing ractopamine have been cleared by the Food and Drug Administration (FDA) for use in the finishing of market cattle and hogs.

All are approved for market animals only. Use of any product on breeding or show animals, or animals below the stated size/age requirements, is prohibited and this fact is widely publicized. Some sources noted that people taking the feed supplement to improve muscle gain in weight-lifting or body building settings is also strictly illegal.

Some opponents of ractopamine use in production animals—notably those in the U.S. who have anti-animal agriculture agendas— claim it is inhumane. The rationale is that the added muscle mass (which amounts to about 30 to 50 additional pounds for a treated steer at slaughter) negatively impacts animal mobility and causes increased injury from unnatural stress on bones and joints.

A statistically significant increased incidence of ambulatory injury (i.e. limping or more serious injury) was noted in ractopamine-treated pigs in a 2006 FDA study.

But the study detailed the injuries as being in keeping with normal market injury occurrence. Additionally, none of the study’s pigs had to be removed from the study due to their injuries.

The product packaging has since been updated with an advisory label recommending awareness of the issue and altered handling of treated livestock to compensate.

One of the big complaints against ractopamine is that, unlike most medicated feed supplements and drugs administered to production animals, there is no withdrawal period. This lack of withdrawal period is due to the nature of the drug: its effectiveness drops off quickly after administration. Because of this lack of withdrawal period, residues can be found in the meat of animals fed supplements containing ractopamine.

A 2002 USDA study determined that no detectable residues were identified in any test cattle after a sevenday withdrawal period.

Only one test animal had any detectable residues after three days—and even then the detected levels were very small at none in the muscle, 2.5 parts per billion in the liver, and 3.4 parts per billion in the kidneys—which suggests a shorter withdrawal period may be sufficient to clear any traces of ractopamine from an animal’s tissues entirely should a withdrawal protocol be set.

A World Health Organization (WHO) study on ractopamine supported this conclusion, finding that 74 percent of ractopamine given to test cattle cleared the animals’ systems in two days.

After four days, 93 percent of the chemical had cleared the animal’s system.

According to FDA data from 2003, acceptable daily intake of ractopamine via residues in meat for consumers is 1.25 micrograms per kilogram of body weight per day. The same data lists maximum residue levels in animal muscle tissue at 0.25 parts per million (25 micrograms per kilogram of animal weight).

To put this into a realworld perspective, a 180-pound (lb.) man would have to consume roughly 9 lbs. of meat a day from animals treated with ractopamine to reach FDA’s acceptable daily intake level.

As of July 2011, the Codex Alimentarius Commission of WHO proposed its own set of requirements for ractopamine. Codex suggested an acceptable daily intake of 0-1 micrograms per kilogram of bodyweight per day, and maximum residue limits on ractopamine in animal muscle tissue at 10 parts per billion (or .01 parts per million, 1 microgram per kilogram of animal weight).

These proposals have yet to be enacted.

Though many studies of the effects of ractopamine have been conducted on mice, rats, dogs, monkeys, hogs and cattle, only one study was conducted on humans. Six adult men were given oral doses of 5, 10, 15, 25 and 40 mg of ractopamine, plus a placebo over six occasions. Treatment effects noted were increased heart rate and increased blood pressure peaking at a half hour after dosage and feelings of restlessness in the higher dosages.

To again return to the real world perspective, a 180-lb. man would have to consume well over 430 lbs. of meat from treated animals to come close to the lowest dosage used in the human study, assuming FDA’s stated maximum residue levels.

The U.S. is among one of about two dozen countries which allow the use of ractopamine in food animals.

Other countries include Canada, Mexico and Australia. Countries supporting the use of ractopamine generally rely on the outcomes of studies such as those cited above and others.

The U.S., WHO and the World Trade Organization (WTO) have suggested that—at least in the case of China, Taiwan and a couple other Asian countries—the bans on ractopamine in imported meat have more to do with protectionist trade barriers than concern over public health. The ractopamine bans in those countries are listed as sanitary and phytosanitation issues, which make them non-sciencebased barriers to trade.

WTO regulations require that any trade barriers be science-based and backed by sound research. — Kerry Halladay, WLJ Editor