According to reasearch performed by Dr.Bruce Ames,professor of Biochemistry and Molecular Biology at University of California,Berkly.Various groups of chemicals from cooked food can cause tumors.For instance nitrosamines are created from fish,poltry or meat cooked in gas ovens and barbecues.When nitrogen oxides within the flames interact with the fat residues;hetrocyclic amines form from heating proteins and amino acids.Then there is the wonderfully tasty polycyclic hdrocarbons formed by charring meat.These are toxins consumed soly by meat eaters which cause cancer.Grass fed beef does not protect people from this threat to there health.Animal products often have more baggage than meets eye!Be Wise Be Green Be Healthy!!!