SAFETY ASPECTS OF PROCESSING CASSAVA TO GARI IN NIGERIA

Cassava roots are perishable and contain potentially toxic cyanogenic glucosides. Therefore, they need to be processed. Gari is a favorite cassava food in Nigeria which is produced mainly by female small-scale processors. They buy the fresh roots and hire the grater, presser and fryers necessary for the semi-mechanized procedure. The need for a rapid turnover of capital can result in short-cuts in processing. These short-cuts have been associated with high residual amounts of cyanogens in gari and hence, with dietary cyanide exposure. The processors are liable to eat a lot of cassava products, and they may also be exposed to hydrogen cyanide by inhalation during processing. Cyanide exposure was assessed by determining urinary levels of the main metabolite, thiocyanate, in a representative group of gari processors in Ibadan. The mean urinary thiocyanate level ± SEM was 101±12 μM in 40 adult processors and 263±35 μM in 10 children producing gari; in eight adult controls from the same social group the level was 50±6 μM. These differences can be partly explained by the different amounts of insufficiently processed cassava consumed, but the high levels seen in the children, who also had the longest working hours, suggests that inhalation exposure may contribute. This pilot study emphasizes that if gari processing is to be promoted as an effective way of removing cyanogens from cassava roots, measures to avoid short-cuts in the process and occupational inhalation exposure among processors should be developed and promoted as well.