Preserving food in domestic kitchens during modern times is achieved using household freezers. Accepted advice to householders was to freeze food on the day of purchase. An initiative by a supermarket group in 2012 (backed by the UK's Waste & Resources Action Programme) promotes the freezing of food "as soon as possible up to the product's 'use by' date". The Food Standards Agency was reported as supporting the change, providing the food had been stored correctly up to that time.
Human diet was estimated to cause perhaps around 35% of cancers in a human epidemiological analysis by Richard Doll and Richard Peto in 1981. These cancer may be caused by carcinogens that are present in food naturally or as contaminants. Food contaminated with fungal growth may contain mycotoxins such as aflatoxins which may be found in contaminated corn and peanuts. Other carcinogens identified in food include heterocyclic amines generated in meat when cooked at high temperature, polyaromatic hydrocarbons in charred meat and smoked fish, and nitrosamines generated from nitrites used as food preservatives in cured meat such as bacon.
^ "Pesticides in Organic Farming". University of California, Berkeley. Retrieved 2014-06-17. Organic foods are not necessarily pesticide-free. Organic foods are produced using only certain pesticides with specific ingredients. Organic pesticides tend to have substances like soaps, lime sulfur and hydrogen peroxide as ingredients. Not all natural substances are allowed in organic agriculture; some chemicals like arsenic, strychnine, and tobacco dust (nicotine sulfate) are prohibited.
Baking, grilling or broiling food, especially starchy foods, until a toasted crust is formed generates significant concentrations of acrylamide, a known carcinogen from animal studies; its potential to cause cancer in humans at normal exposures is uncertain. Public health authorities recommend reducing the risk by avoiding overly browning starchy foods or meats when frying, baking, toasting or roasting them.
Most food has its origin in plants. Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. Cereal grain is a staple food that provides more food energy worldwide than any other type of crop. Corn (maize), wheat, and rice – in all of their varieties – account for 87% of all grain production worldwide. Most of the grain that is produced worldwide is fed to livestock.