When used as a food additive, ractopamine added to feed can be distributed by the blood to the muscle tissues, where it serves as a full agonist to murine (mouse or rat) TAAR1, a receptor protein (not necessarily in humans).

Its use in finishing swine yields about 3 kg (6.6 lb) of additional lean pork per animal, and improves feed efficiency by 10%.

"[15] On 6 July 2012, the international reference standard Codex Alimentarius Commission narrowly approved the adoption of a maximum residue limit (MRL) of 10 parts per billion (ppb) for muscle cuts of beef and pork.

Countries with major meat export markets had been lobbying for the establishment of such a standard for several years to use it as leverage to erode individual national-level bans in World Trade Organization disputes.

The maximum residue limit for ractopamine for meat in the USA is 50 parts per billion (ppb), or five times the standard set by the Codex Alimentarius.

[23][24][25] Hundreds of commercial feed facilities, including some from overseas, are enrolled in the CRFPCP, a programme that is essentially based on self-certification and backed up by a randomized testing policy.

In 2015, an 18-year-old female karateka (martial arts practitioner) from Egypt gave a urine sample in order for her drugs test to be administered.

[42][43] In September 2009, the trade representatives from the US and EU signed a memorandum of understanding, which established a new duty-free import quota in the European Union for grain-fed, high-quality beef as part of a compromise solution.

[45] In June 2019, customs inspectors in China detected ractopamine in a shipment of Canadian pork products destined for Chinese consumption.

[46] It was also revealed that the Canadian Cattlemen's Association said in a statement that "We are fully confident in our meat production systems in Canada and the safeguards we have in place.

[50] This resulted in mass protests in the capital city, Taipei, by swine farmers insisting that the ban remain in place.

Health Minister Hou Sheng-mou (侯勝茂) declared no lifting of the ban would occur unless related laws were amended.

Although the use of ractopamine in livestock is still banned and enforced on the domestic industry, and the government has maintained a "zero tolerance" policy on pork imports that contain it, Taiwan's legislature amended the food safety act in August 2012 to allow the import of beef products containing up to a maximum residue level of 10 parts per billion of the additive.

[53] Ractopamine is allowed as its half-life is lower, leading to reduced residues in the food, and the dose required to affect humans is much higher than other beta agonists.

[54] On 30 December 2008, the Malaysian Veterinary Services Department quarantined 10 of the 656 pig farms in Malaysia, as the livestock were found to contain the banned chemical.

[58] The metabolic fate of ractopamine hydrochloride is similar in the target species (pigs and cattle), laboratory animals, and humans.

[citation needed] In swine, ractopamine is correlated with adverse effects, especially hyperactivity, trembling, and broken limbs, leading to censure by animal rights groups.

The positive genotoxic results are explained with limited evidence to be due to a secondary auto-oxidative mechanism from ractopamine-catechol-producing reactive intermediates.

[citation needed] Dose-dependent changes of heart rate and cardiac output are observed within the first hour after administration of ractopamine and gradually return to baseline values.