Cassava (Manihot esculenta Crantz) is widely cultivated in the State of Sao Paulo, Brazil, mostly as raw material for industrial purposes (production of cassava flour, starch, etc.). A small proportion of cassava production is destinated to "in natura" consumption, obtained essentially from backyard plantations. In this case, many varieties are used, with unknown cyanide contents, which can cause severe human intoxication. The main aim of this research was to evaluate the cyanide content range of these varieties. Roots of 206 varieties, collected at 126 sites in the State of São Paulo, Brazil, were analyzed as to their cyanide contents, using the Liebig method, with maceration for a 24-hour period. Results showed a cyanide content variation from 16 to 482 mg.kg-1 of HCN in the tuber root fresh pulps. On the other hand, most of the varieties (67%) under testing presented root cyanide contents below 100 mg.kg-1. So, this cyanide content may be considered as the uppermost level to be used with security on the selection of new genetic materials with lower HCN contents.
cassava; Manihot esculenta Crantz; cyanide; toxicity levels