Cyanide Contents of Leaves of Commonly Consumed Cassava Varieties from Three Geographical Regions of Ghana

Consuming a cyanogenic plant is an etiological factor to the persistence of iodine deficiency in the post salt iodization phase. Ghana, notably the Northern belt, still reports of iodine deficiency after 14 years of mandatory consumption of iodized salt by an Act of Parliament. The study aimed at determining the cyanide contents of leaves of commonly consumed cassava varieties in Ghana and investigating the effects of some environmental factors on cyanide content. Three communities each from Southern, Middle and Northern Ghana served as the study sites from where young, non-diseased and fully-spread cassava leaves were sampled from plants of commonly consumed cassava varieties. Cyanide was analyzed by the standard colorimetric method based on the chloramine-T/pyridine-barbituric acid protocol (4500-CN E). Cassava leaves from Northern Ghana had significantly higher mean cyanide content (177.22 ± 20.82 ppm) than those from Middle (130.83 ± 33.00 ppm) and Southern Ghana (127.24 ± 37.54 ppm) (P < 0.001). Two-factor ANOVA showed significantly higher adverse environmental effects on cyanide contents of leaves of unimproved cassava varieties than improved ones (R 2 = 0.627, P = 0.023). From multiple regression analysis, temperature was the most significant environmental factor explaining 33% of the variability in cyanide content (R 2 = 0.331, P = 0.002), followed by altitude (R 2 = 0.106, P = 0.049) and rainfall (R 2 = 0.084, P = 0.062). The high cyanide contents of cassava leaves from Northern Ghana, due principally to the high atmospheric temperature, may be a contributory factor to the high prevalence of goiter and the persistence of iodine deficiency in that geographic region.