Found this interesting article on the FoodUSA website:
In 2003, the EU prohibited the use of carbon monoxide for meat and tuna products. In its decision, the European Commission's food safety regulator stated that "the stable cherry-colour can last beyond the microbial shelf life of the meat and thus mask spoilage."
Several countries including Japan, Canada and Singapore also ban the use of carbon monoxide in tuna.
Carbon monoxide when used in the modified atmosphere packaging (MAP) technique makes meat appear fresher than it actually is by reacting with the meat pigment myoglobin to create carboxymyoglobin, a bright red pigment that masks any of the natural aging and spoilage of meats, according to a petition filed with the Food and Drug Administration (FDA) by Michigan-based Kalsec.
"At the very least, the public has a right to know about the use of carbon monoxide in their food," states Don Berdahl, Kalsec's vice president and technical director. "If the FDA won't prohibit it, the government should require a label that informs consumers about the presence of carbon monoxide and the health dangers it presents."
You can read the rest of the article here.
Personally, I think new meat labelling laws are urgently required so all consumers can make informed choices about the food they buy. For example, maybe a label indicating whether the meat came from a factory-farm (and may contain antibiotic residue and/or other other basteria/pathogens) ...and even WHICH FARM the meat is coming from, for point of origin traceback in the event that any serious outbreak occurs. Just my humble thoughts on the subject.