It’s a big topic, too much for a post. So I will focus on some aspects that might not be widely known. Even so, this is a long post that only touches briefly on the issues.
Food safety rules in privileged western countries like mine do a good job in limiting foodborne disease. The rules, however, are not set entirely by science, but rather they usually start from that standpoint and are then modified by tradition, culture, politics and industry pressures.
For example, raw-milk (unpasteurized) cheese is banned here in Australia, presumably because it is considered risky for us sensitive Aussies. But millions of French eat it routinely and safely. That leaves industry pressure and cultural background as the likely basis for this ‘food-safety’ rule.
In the USA rare beef is traditional, and it would be a courageous food-regulator that banned it. In reality, it can be perfectly safe, as can rare pork and lamb. But the FDA leniency, allowing the serving of rare steak, only applies to steaks (not even a beef roast, and certainly not to any other meat). Another cultural food-safety bias.
Sometimes, culture sets its own rules. Take pork. There used to be a significant risk of contamination by trichinosis parasites, and pork was routinely overcooked as a safety measure. This went on for so long that pork farmers started to selectively breed fatty pork, the idea being that the extra fattiness would compensate for the dryness of the overcooked pork. In the meantime, better farming practice has all but eradicated trichinosis from pork in the USA (it doesn’t exist in Australian pork). Still, pork continues to be overcooked because that is traditional. In the USA, statistically, you’re 100,000 times more likely to be killed by lightening than experience trichinosis from a serving of pork, and even then it is not life threatening and typically resolves without treatment. A rare pork chop is as safe as a rare steak, and modern pork farmers are now able to go back to selectively breeding lower-fat pigs as this understanding spreads.
As with pork, overcooking chicken has become a tradition. It is true that chickens can harbor asymptomatic salmonella infections, and that chickens sold whole risk including salmonella in the cavities or skin. But, there’s no reason to single out chicken. Salmonella is also closely associated with nuts. It has been found in almonds, cashews, pistachios, pine nuts, Brazil nuts, macadamia nuts and walnuts (and peanuts, although only a nut by culinary convention). The FDA is currently conducing a formal evaluation of the risk of salmonella in tree nuts to humans. Salmonella is easily killed by heat. Holding a chicken breast at 62C for 15m is more than enough. That’s where sous-vide comes in. At this temperature the breast will be moist, tender and safe.
So is rare steak safe? It depends. The interior of a whole piece of meat is effectively sterile. That’s right, microbes are not present in the interior of a piece of intact meat. Only the exterior is at risk of contamination. Thus a steak that is seared on the outside, with a rare interior, is considered safe. If you are still concerned, a quick pre-blanch in boiling water will kill everything, even in the nooks and crannies, or pass a blow-torch over the meat. While the interior is sterile, it can still harbor parasites, although with modern animal husbandry practices this is increasingly unlikely. Freezing can kill parasites. If you want to be absolutely sure, you may need to freeze for 1–3 weeks. Note that salmonella survives freezing perfectly well.
Parasitic infection occurs quite often in seafood, which is a wild food. It is normally served lightly-cooked (or raw), compounding the problem. Freshwater fish or fish that inhabit estuaries are particularly vulnerable, as they can come in contact with the faeces of land animals. The majority of these parasites are harmless and destroyed during digestion, and ocean seafood is often snap-frozen at sea.
While rare whole-meats can be safe, anything that pierces the surface (including needle-tenderising — jaccarding), or that mixes meat surfaces with their interiors, is a risk. Thus, ground meat, including hamburgers and sausages, should be cooked thoroughly unless you supervised the grinding. Ground meat in a sausage casing is a great anaerobic environment for C.botulinum, so much so that the name botulism derives from the Latin word for a sausage — ‘botulis’. It is the most dangerous of the microorganisms, and is fatal at one-millionth of a gram per kilogram of body weight.
It’s a myth that meat is fundamentally more risky than plant foods. The main culprit is faecal contamination, and this can occur just as easily on plant foods as on animal foods. To give some perspective, this century has seen the deadliest bacterial outbreak in modern times in Europe traced to organic fenugreek sprouts; the second-deadliest bacterial outbreak in the USA from cantaloupes (melons); the largest outbreak of hepatitis-A sourced to green onions; the largest salmonella outbreak ever to occur in the USA traced to peanut paste; and the deadliest foodborne outbreak in Canada linked to cold meats. There have been other significant outbreaks due to meat, poultry and vegetables (e.g. spinach) this century. Microbes are not fussy, and no one food-group is more susceptible to contamination than another.
If you want to really eliminate the risk of foodborne infection there is only one answer — don’t eat food. All foods carry a risk of contamination, and food safety is a misnomer, it’s only risk reduction.
On a topic like this I will point out the obvious — I am not a food safety expert. The information in this post is a personal opinion and it’s not advice. For advice, consult your local food regulator.