In some cases, the process of preparation rather than the food itself comes under scrutiny. For instance, in early medieval Christianity, certain uncooked foods were of dubious status: a penitential ascribed to Bede outlined a (mild) penance for those who ate uncooked foods, and Saint Boniface wrote to Pope Zachary (in a letter preserved in the Boniface correspondence, no. 87) asking him how long bacon would have to be cured to be proper for consumption. The Kapu system was used in Hawaii until 1819. Aside from formal rules, there are cultural taboos against the consumption of some animals. Within a given society, some meats will be considered to be not for consumption that are outside the range of the generally accepted definition of a foodstuff. Novel meats, "i.e." animal-derived food products not familiar to an individual or to a culture, generally provoke a disgust reaction, which may be expressed as a cultural taboo. For example, although dog meat is eaten, in certain circumstances, in Korea, Vietnam, and China, it is considered inappropriate as a food in Western countries. Likewise, horse meat is rarely eaten in the English-speaking world, although it is part of the national cuisine of countries as widespread as Kazakhstan, Japan, Italy, and France. Sometimes food prohibitions enter national or local law, as with the ban on cattle abattoirs in most of India, and horse slaughter in the United States. Even after reversion to Chinese rule, Hong Kong has not lifted its ban on supplying meat from dogs and cats, imposed during British colonial rule. Environmentalism, ethical consumerism and other activist movements are giving rise to new prohibitions and eating guidelines. A fairly recent addition to cultural food prohibitions is the meat and eggs of endangered species or animals that are otherwise protected by law or international treaty. Examples of such protected species include some species of whales, sea turtles, and migratory birds. Similarly, sustainable seafood advisory lists and certification discourage the consumption of certain seafoods due to unsustainable fishing. Organic certification prohibits certain synthetic chemical inputs during food production, or genetically modified organisms, irradiation, and the use of sewage sludge. The Fair Trade movement and certification discourage the consumption of food and other goods produced in exploitative working conditions. Other social movements generating taboos include Local Food and "The 100-Mile Diet", both of which encourage abstinence from non-locally produced food, and veganism, in which adherents endeavour not to use or consume animal products of any kind.