Three-fourths of Americans want to know if their food contains genetically engineered ingredients, according to a poll released yesterday by the Pew Initiative on Food and Biotechnology. Fifty-eight percent of the respondents did not want such ingredients in the food supply, period. However, when they were told that the ingredients were already in many food products on grocery store shelves, nearly half of the respondents said the products must therefore be safe. Despite pressure from environmental and consumer groups, the U.S. has said it won’t require labeling of genetically engineered foods. Labeling is already required in Japan, South Korea, Australia, and most of Europe.