Dr Howard Bradbury Emeritus Fellow Phone: 61 2 6125 0775 Fax: 61 2 6125 5573 Howard.Bradbury@anu.edu.au

Main Research Interest
To eliminate cyanide poisoning, konzo, tropical ataxic neuropathy (TAN) and other diseases due to consumption of cassava, which contains a cyanide compound. See http://online.anu.edu.au/BoZo/CCDN/

Research Interests
My major research interest is to eliminate cyanide poisoning and other cyanide diseases based on the consumption of cassava. Cassava is the third most important food source in the tropics after rice and maize and is the staple food of at least 600 million people. Because it is easy to grow, yields well in very poor soils without fertiliser and is able to withstand drought, its use is increasing worldwide.

We have tackled the cyanide problem by first of all developing very simple picrate methods, that can be used by workers in developing countries with no additional resources, to determine total cyanide levels in roots, leaves and cassava products such as flour and gari (1,3) Since cyanide is detoxified in the body to thiocyanate, which is removed in the urine, determination of urinary thiocyanate content gives a good measure of cyanide intake over previous days. We therefore developed a picrate method to determine urinary thiocyanate (6). These kits were all tested in the field with our coworkers in Mozambique and shown to be very reliable (2). In the laboratory the picrate method gives results that are just as accurate for determination of cyanide as those produced by other chemical methods (9). Kits allowing 100 analyses have been given away for free to health workers and agriculturalists in developing countries and are sold for AU$350 to workers in first world countries. Up to the present time, 370 kits have been given away and nearly 190 kits sold.

Using the kits in our study area in Mozambique we found that cyanide levels in cassava flour in normal years averaged 45 ppm compared with the World Health Organisation safe level of 10 ppm (2). However in a year of low rainfall the cassava plant produces more of the cyanide compound (linamarin) and average amounts in cassava flour can exceed 100 ppm (10). These high levels cause acute intoxication (vomiting, nausea, dizziness, stomach pains, weakness, headache and diarrhoea) and occasional death and the occurrence of konzo in children and women of child bearing age. Konzo is an upper motor neuron disease that causes permanent paralysis of both legs. There may be 100,000 cases of konzo in Africa.

A survey showed that processing in West Africa to produce gari reduces the cyanide content much more effectively than the methods used in Eastern, Southern and Central Africa to produce flour. Furthermore, konzo does not occur in West African countries such as Nigeria. Clearly, there is a great need for much better methods of removal of cyanide from flour in Eastern, Southern and Central Africa (14).

Wetting method
In 2005 a simple wetting method was developed which removes nearly all the cyanide from cassava flour. Cassava flour is placed in a container and its height marked on the inside of the container. Water is added with thorough mixing until the wet flour volume comes up to the mark on the container. The wet flour is spread out in a thin layer on a basket or a tray and left in the shade for about 5 hours. The cyanide compound is broken down by the enzyme present to produce hydrogen cyanide gas that escapes to the air. The wet flour is used for cooking, in order to prevent spoilage which may occur if it is left overnight (15-17). The method is a gift from God.

The method reduces the total cyanide content 3-6 fold and has been successfully field tested in northern Mozambique. The method is simple, requires no extra work or equipment and the traditional thick porridge made from treated flour tastes better than that made from untreated flour. Programs of konzo rehabilitation and prevention supported by the Australian Agency for International Development (AusAID) are in progress in Mozambique and Tanzania.

Background
I studied chemistry at Melbourne Technical College and Melbourne University followed by a PhD degree in polymer chemistry at Birmingham University. After a postdoctoral fellowship at Harvard University, I worked for six years for CSIRO Wool Research Laboratories and then moved to the Chemistry Department at the Australian National University in 1961. I had sabbatical appointments at Cornell University as a visiting professor and on three occasions at Oxford University. My major research interests during this period were on the chemistry of wool and keratin fibres and later on the nuclear magnetic resonance spectroscopy of proteins, enzymes and carbohydrates. I was awarded a DSc degree and the David Syme Research Prize by Melbourne University, the Rennie Memorial Medal and the H G Smith Memorial Medal by the Royal Australian Chemical Institute for research and a DSc by ANU.

In the 1980's I became interested in food analysis and my research group analysed the root crops of the South Pacific (18). Since I took early retirement from teaching and research in chemistry, I have been involved as a plant chemist in the School of Botany and Zoology, focussing my attention on cassava. The plant produces cyanogenic glucosides and an enzyme which catalyses their hydrolysis to hydrogen cyanide, if the plant is attacked by predators. The cyanogens in cassava are a health hazard. We have developed simple chemical methods for their analysis (1-6) and the wetting method that reduces the cyanide content of cassava flour 3-6 fold. As a result in 2007 I was awarded the inaugural "$2 a day award" by the Institution of Chemical Engineers (IChemE). In 2007 I was appointed a Member of the Order of Australia.

Selected Publications
1. Egan, S.V., Yeoh, H.H. and Bradbury, J.H. (1998) Simple picrate paper kit for determination of the cyanogenic potential of cassava flour. J. Sci. Food Agric.76, 39-48.

2. Cardoso, A. P., Ernesto, M., Cliff, J., Egan, S. V. and Bradbury, J. H. (1998) Cyanogenic potential of cassava flour: Field trial in Mozambique of a simple kit. Intern J Food Sci Nutr, 49, 93-99.

3. Bradbury, M G, Egan, S V and Bradbury, J H (1999) Picrate paper kits for determination of total cyanogens in cassava roots and all forms of cyanogens in cassava products. J. Sci. Food Agric., 79, 595-601.

4. Djazuli, M. and Bradbury, J.H. (1999) Cyanogen content of cassava roots and flour in Indonesia. Food Chemistry 65, 523-525.

5. Haque, M.R. and Bradbury, J.H. (1999) Preparation of linamarase solution from cassava latex for use in the cassava cyanide kit. Food Chemistry, 67, 305-309.

6. Haque, M.R. and Bradbury, J.H. (1999) Simple method for determination of thiocyanate in urine. Clinical Chemistry, 45, 1459-1464.

7. Cardoso, A.P., Ernesto, M., Cliff, J. and Bradbury, J.H. (1999) High levels of total cyanogens in cassava flour related to drought in Mozambique. Roots 6, 4-6.

8. Ernesto, M., Cardoso, A.P., Cliff, J. and Bradbury, J.H. (2000) Cyanogens in cassava flour and roots and urinary thiocyanate concentration in Mozambique. J. Food Comp. Anal. 13. 1-12.  

9. Haque, M., and Bradbury, J.H. (2002). Total cyanide determination of plants and foods using the picrate and acid hydrolysis methods. Food Chem   77, 107-114.

10. Ernesto, M., Cardoso, A.P., Nicala, D., Mirione, E., Massaza, F., Cliff, J., Haque, M. and Bradbury, J.H. (2002) Persistent konzo and cyanogens toxicity from cassava in northern Mozambique, Acta Tropica,   82, 357-362.

11. Ernesto, M., Cardoso, A.P., Nicala, D., Mirione, E, Massaza, F.,, Cliff, J., Haque, M. and Bradbury, J.H. (2002) Strategy for the elimination of konzo in Mozambique. Roots, 8, 8-11.

12. Haque, M. and Bradbury, J.H. (2004). Preparation of linamarin from cassava leaves for use in a cassava cyanide kit. Food Chem. 85, 27-29.

13. Cardoso, A.P., Ernesto,M., Nicala, D., Mirione, E., Chavane, L., N'zwalo, H., Chikumba, S., Cliff, J., Mabota, A.P., Haque, M. and Bradbury, J.H. (2004) Combination of cassava flour cyanide and urinary thiocyanate measurements of school children in Mozambique.. Int J Food Sci Nutr 55, 183-190.

14. Cardoso, A.P., Mirione, E., Ernesto, M., Massaza, F., Cliff, J., Haque, M. and Bradbury, J.H. (2005) Processing of cassava roots to remove cyanogens. J. Food Comp. Anal. 18, 451-460.

15. Bradbury, J.H. (2006) Simple wetting method to reduce cyanogen content of cassava flour. J Food Comp. Anal., 19, 388-393.

16. Cumbana, A., Mirione, E., Cliff, J. and Bradbury, J.H. (2007) Reduction of cyanide content of cassava flour in Mozambique by the wetting method. Food Chem., 101, 894-897.

17. http://online.anu.edu.au/BoZo/CCDN/

18. Bradbury, J.H. and Holloway, W. D. 1988. Chemistry of tropical root crops : significance for nutrition and agriculture in the Pacific, Australian Centre for International Agricultural Research (ACIAR). Monograph No 6, 201 pp.

19. Bradbury, J.H. (2007) Cyanide removal from flour helps millions. Australasian Science 28, 33-36.

20. Bradbury, J.H. (2008) Simple solution fights konzo. tce – The Chemical Engineer, February 2008, 24-25.

Funding
I have had research grants from the Australian Centre for International Agricultural Research (ACIAR) from 1984 for research projects on tropical root crops. From 1994 to 2004 ACIAR provided funding for development of cassava cyanide kits and their supply free of charge to workers in developing countries and for collaboration with coworkers in Mozambique on elimination of cyanide-based diseases in Africa (17). Funding has also been obtained from GRM/Kyeema and in 2007-8 from AusAID for konzo rehabilitation and prevention in Mozambique and Tanzania.

Other Activities
In 1989 I started the Asia Pacific Food Analysis Network (APFAN) and was the Coordinator of APFAN until 1999. APFAN aims to promote food safety and good nutrition by serving the needs of food analysts particularly in developing countries. In 2000 I started the Cassava Cyanide Diseases Network (CCDN) which now has over 250 members from 45 countries. I am the editor of their newsletter called CCDN News, that is published every six months.