Cassava, cyanide

Gomez, G., M.A. Aparicio, and C.C. Willhite. 1988. Relationship between dietary cassava cyanide levels and broiler performance. Nutr. Rep. Inter. 37 63-75. 

Cyanide is naturally present in some foods and in certain plants such as cassava. Cyanide is contained in cigarette smoke and the combustion products of synthetic materials such as plastics. Combustion products are substances given off when things burn. 

Thiocyanate ion, SCN , inhibits formation of thyroid hormones by inhibiting the iodination of tyrosine residues in thyroglobufin by thyroid peroxidase. This ion is also responsible for the goitrogenic effect of cassava (manioc, tapioca). Cyanide, CN , is liberated by hydrolysis from the cyanogenic glucoside finamarin it contains, which in turn is biodetoxified to SCN. 

Fed cassava diets containing 4, 37, 70, or 103 mg total cyanide/kg ration to day-old chicks for 8 weeks... 

Linamurin is the principal cyanogenic glycoside in cassava its toxicity is due to hydrolysis by intestinal microflora releasing free cyanide (Padmaja and Panikkar 1989). Rabbits (Oryctolagus cuniculus) fed 1.43 mg linamurin/kg BW daily (10 mg/kg BW weekly) for 24 weeks showed effects similar to those of rabbits fed 0.3 mg KCN/kg BW weekly. Specihc effects produced by linamurin and KCN included elevated lactic acid in heart, brain, and liver reduced glycogen in liver and brain and marked depletion in brain phospholipids (Padmaja and Panikkar 1989). 

Whole blood, 4-45 mg total CN/L Whole body, 7 mg HCN/kg BW Daily dietary intake of 15-31.5 mg hydrogen cyanide from cassava... 

Cassava, Manihot esculenta, roots, total cyanide (mg/kg FW) ... 

Casadei, E., P. Jansen, A. Rodrigues, A. Molin, and H. Rosling. 1984. Mantakassa an epidemic of spastic paraparesis associated with chronic cyanide intoxication in a cassava staple area of Mozambique. 2. Nutritional factors and hydrocyanic acid content of cassava products. Bull. World Health Org. 62 485-492. 

Cooke, R.D. and D.G. Coursey. 1981. Cassava a major cyanide-containing food group. Pages 93-114 in B. Vennesland, E.E. Conn, C.J. Knowles, J. Westley, and F. Wissing (eds.). Cyanide in biology. Academic Press, New York. 

Dufour, D.L. 1988. Cyanide content of cassava (Manihot esculenta, Euphorbiaceae) cultivars used by Tukanoan indians in northwest Amazonia. Econ. Botany 42 255-266. 

Gomez, G., M. Valdivieso, J. Santos, and C. Hoyos. 1983. Evaluation of cassava root meal prepared from low- or high-cyanide containing cultivars in pig and broiler diets. Nutr. Rep. Inter. 28 693-704. 

Okeke, G.C., F.C. Obioha, and A.E. Udeogu. 1985. Comparison of detoxification methods for cassava-borne cyanide. Nutr. Rep. Inter. 32 139-147. 

Tewe, 0.0. 1982a. Protein supplementation of cassava diets for growing pigs effects on performance, nutrient utilization and cyanide metabolism. Nutr. Rep. Inter. 25 451-462. 

Tewe, 0.0. 1984. Effect of cassava-based diets varying in cyanide content on the performance and physio-pathology of the African giant rat (Cricetomys gambianus Waterhouse). Anim. Feed Sci. Technol. 11 1-9. 

Tewe, 0.0. 1988. Performance, nutrient utilization and cyanide metabolism in African giant rats (Cricetomys gambianus Waterhouse) fed varying dietary levels of cassava peels. Anim. Technol. 39 77-82. 

Tewe, 0.0. and E. Pessu. 1982. Performance and nutrient utilization in growing pigs fed cassava peel rations containing different cyanide levels. Nutr. Rep. Inter. 26 51-58. 

Ukhun, M.E. and E.N. Dibie. 1989. Cyanide content of cassava mash and gari flour and influence of water activity (aw) during storage. Bull. Environ. Contam. Toxicol. 42 548-552. 

You may be exposed to cyanide by breathing air and drinking water, touching soil or water containing cyanide, or eating foods that contain cyanide. Many plant materials, such as cassava roots, lima beans, and almonds, naturally contain low-to-moderate levels of cyanide. The concentration of hydrogen cyanide in unpolluted air is less than 0.0002 parts per million (ppm ... 

Oral exposure to cyanide usually results from accidental, homicidal, or suicidal ingestion of cyanide salts. Sodium cyanide and potassium cyanide are the most frequently studied cyanide compounds. Copper cyanide, potassium silver cyanide, silver cyanide, and calcium cyanide are other compounds that humans could encounter through oral or dermal exposure. Cassava roots and certain fruit pits contain compounds that can be broken down to form cyanide. Cassava roots form the staple diet of some populations in Africa, Central and South America, and Asia. However, it must be noted that cassava roots are notoriously deficient in protein and other nutrients and contain many other compounds, in addition to cyanide, that could be responsible for some of the observed toxic effects. Thiocyanate is a metabolite of cyanide that is formed in the body after exposure to cyanide compounds. When possible, all oral exposures are expressed as mg CN/kg/day. 

Effects on the adrenal gland, including swelling of the adrenal cortex, hemorrhage, and fibrosis, were observed in dogs fed 1.04 mg CN /kg/day as cassava, as well as in dogs fed rice with the same concentration of cyanide, as sodium cyanide, for 14 weeks (Kamalu 1993). 

Ocular Effects. Macular degeneration and optic atrophy were reported in humans who ingested cassava containing an unknown concentration of cyanide (van Heijst et al. 1994). 

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