13 August 2012

Ractopamine, Swine and Man

- The United Nations food standards body, the Codex Alimentarius Commission, has decided to set residue limits of the animal growth promoter, ractopamine, which also keeps pigs lean for the slaughter. Cattle are also administered this beta-adrenoceptor agonist. The ractopamine limits set by the Commission are 10 micrograms per kilogram of pig or cattle muscle, 40 micrograms per kilogram in liver and 90 micrograms per kilogram of the animals’ kidneys.

- Known as Paylean for swine and Optaflexx for cattle, 4-[3-[[2-Hydroxy-2-(4-hydroxyphenyl)ethyl]amino]butyl]phenol is banned in the European Union, Republic of China (Taiwan) and Mainland China.  Curiously, in 27 countries, including Japan, South Korea, Mexico, Canada, the United States and many others, have determined that meat from animals fed ractopamine is safe for human consumption.  As a leanness-enhancing agent, orally-given (in animal feed) ractopamine is absorbed, distributed and eliminated rapidly in pigs, cattle, laboratory animals and primates. It notably increases the rate of weight gain, improves feed efficiency and increases carcass leanness in finishing swine.

- In humans, this agent is likewise rapidly absorbed.  In a study with volunteers given a single oral dose of 40 mg, the mean half-life was around 4 hours, and it was not detected in plasma 24 hours after said ingestion. The urinary metabolites were monoglucuronide and monosulfate conjugates, with ractopamine monosulfate being the major metabolite present.

- It is considered safe as a finishing feed for swine over 240 lbs. In studies in rats and mice, acute toxicity was observed  and the oral LD50 in mouse and rat are 3547-2545 mg/kg body weight (male and female) and 474-365 (male and female), respectively.  You can access a European Food Safety Authority opinion here.  LDn represents “Lethal  Dose” and the subscript, n,  represents the percentage of test organisms killed by a specific dosage of a pathogen (a given substance or type of radiation)  and half will die at LD50. In effect, it is the index indication of the lethality of the pathogen in a “normal individual.”

 - This begs a question: if it is toxic to laboratory subjects (here, rats and mice) then why is it considered safe for man’s consumption?  Why is also there a disparity in the permissions and prohibitions among different countries?  Under 21 CFR 556.570, safe concentrations for total residues of ractopamine hydrochloride are: 0.25 ppm in muscle, 0.75 ppm in liver, and 1.5 ppm in kidney and fat. (ppm=parts per million) By the way, the liver is the target tissue.

We’re getting into more numbers here. In spite of the observations in the lab, the Joint FAO/WHO Expert Committee on Food Additives has said that it is safe for humans to consume these meats. So let’s see how technology is supposed to help us now. It is not mutagenic, genotoxic, nor considered to be a direct carcinogenic agent. Anyone familiar with the actions of beta-adrenergic agents will know that there will be some irritability, restlessness, tremors, tachycardia, and an increase in cardiac output. Clenbuterol  (another beta-adrenergic agonist) is a growth promoting compound. It is known to have the effect of enhancing weight gain and proportion of muscle to fat.

- Lest we forget, this beta-adrenergic agent is also banned by the international sports body and known controversies concerning athletes with traces of clenbuterol have arisen. And in a case of cycling recently,  I remember that the athlete was basically castigated for using performance-enhancing drugs. Compared to ractopamine, clenbuterol is known to have a much longer half-life in blood than ractopamine and thus has a greater potential for bioaccumulation

  - So what are we going to use as a meter for the safety of humans? Isn’t it possible that the continuous ingestion of meat of animals fed ractopamine may be dangerous for man?  I don’t think we should wait a generation or two to come to some sense of “sobriety” or realization that artificially enhanced food is not in our best interest. The demand for more food worldwide is apparently governing the choices we make. Even genetically modified grass is given to cattle to graze on. The reason for this method of feeding was that there was more meat and more money to be made doing it this way. You may even have already consumed this artificially enhanced food earlier today, or this week.

 - We are not talking about our individual decision to be herbivorous or omnivorous. That will be a subject for another day. What we are arriving at here is to consider, not just our safety (or self-interest), but the welfare of the future generations. I, for one, will not want my own children or grandchildren to ask me later, “why did you allow all this to happen?” Maybe, some of you are quite liberal in your choices, and that’s one’s lawful right. What we must decide is to make the responsible decision today. 

 - If it’s not good for the athlete, it may not be good for you. And mind you, I have had first-hand experience dealing with both national and international sporting events. This reminds me now of the issue of concussions in high-contact sports. I have witnessed athletes stagger even after winning a match. I hope we will not stagger in our choices as well.

 - Stay safe and have a nice day. Bon appétit!

 - Fernando Yaakov Lalana, M.D.

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