Iranian scientists conducted a study on the seriousness of meat grilled on open fire on human health saying they release gases like those emitted from vehicle exhaust.Scientists say that the reason lies in the smoke produced from burning wood, which gives grilled meat a delicious taste, explaining that computer programmes developed by scientists on the processes occurring in the course of grilling meat over charcoal, and the results of tests conducted by scientists in Iran and abroad, have shown that such meat contains varying harmful materials depending on the method used in grilling.They said the seriousness of the compounds found in the smoke when meat is grilled causes changes in the DNA of human beings, and this in turn leads to malignant tumors.They added that the properties of the smoke produced by burning wood are more harmful than smoking cigarettes for a long period of time.