Fears that the animal pyres lit during the foot and mouth crisis emitted dangerous levels of carcinogenic chemicals are unfounded, according to the Food Standards Agency . The food watchdog warned that there was a possible health risk from the burning pyres last month, because dioxins and PCBs (polychlorinated biphenyls) produced during the burning process could possibly enter the food chain through foods produced near to the pyre sites. In a recent food survey however, the agency only found acceptable levels of the chemicals.