Bacterial contamination of food.

Man is a creature of his environment. He shares its hazards with many other living organisms and for most of the time achieves a measure of peaceful coexistence with them. But the balance is a delicate one, and very minor changes, such as an imperceptible rise in humidity or fall in temperature, may upset it surprisingly (Christie, 1971-2). Man is also a great manipulator of his environment and this manipulation may be simple or complicated. Farming, for example, is a grossly unnatural process. No environment could be less natural for a cow than life on a dairy farm (Christie, 1971). Modern man is, of course, still a beast of prey but, instead of hunting animals, he herds them within fences, grossly exploits their natural functions, especially those of lactation and procreation, carts them off to markets and abattoirs, and transforms their carcasses into cutlets, sausages and meat pies. Meanwhile he converts their milk into processed cheese or cream cake-fillings, and he then distributes all these products to households, restaurants, Pullman cars and jet airlines. This is environmental manipulation on the grand scale, a considerable technological achievement, But there are dangers on the way, natural dangers such as time and temperature, and accidental dangers such as contamination and adulteration and, unfortunately, though his beasts are slain, man is not the only organism alive at the end of it all (Christie, 1971). Micro-organisms are very much smaller than men, but they are great opportunists. Give them the opportunity and they will flourish on man’s food. They need time, they need warmth and moisture, and one or two other environmental factors such as a tolerable pH range and an acceptable gaseous atmosphere. The caveman, in his hand-to-mouth existence, gave such micro-organisms few chances, but with civilization came sophistication and the modern food-handler seems almost to go out of his way to make life smooth for food-poisoning germs (Christie & Christie, 1971).