The 14C activities and/or á13C values were measured for tree rings, rices, edible oils, flavors, beers, chickens and eggs. The 14C activity in 1999 ranged from 14.4 to 14.8dpm/g.C for those of tree rings and rices. The 14C activities of oils were in good agreement with the present atmospheric one. The 14C activities of flavors could differentiate petrochemically derived compounds from natural products. On the other hand, the Δ13C value could distinguish between C3 and C4 plants for the main ingredient of oils, flavors and beers. For chickens and eggs, & Delta;13C values reflected their diet. In addition, large variation of Δ13C values was observed among components of eggs.
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