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Hand holds holds a bowel cancer screening kit card, in a toilet situation. Faecal smears are made, over a number of days, on the sets of windows, of guaiac impregnated filter paper, which can be seen under each tab. The guaiac reacts with hydrogen peroxide, when tested in the laboratory, to indicate the presence of blood, which may be occult, or hidden. Such an indication would show the need for further tests to establish the possible presence of polyps or colorectal (bowel) cancer.