Dr J. Howard Bradbury AM 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 cyanogens present in cassava, the staple food of tropical Africa, See http://biology.anu.edu.au/hosted_sites/CCDN/

Cassava is the third most important food source in the tropics and is the staple food of tropical Africa. Its production has increased more than threefold from 1980 to 2005 and the population has increased   twofold in Africa, compared with a 1.5 fold increase worldwide (1). The large increase in cassava production is partly because of population pressure and also because it is easy to grow, yields well in poor soils and is able to withstand drought. Cassava produces cyanogens (linamarin and a small amount of lotaustralin) that can cause cyanide poisoning, konzo, TAN and other diseases. We hope to limit and eventually eliminate these diseases, by reducing the per capita intake of cyanogens particularly by people in Africa.

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 (22), I worked at 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 and on three occasions at Oxford University. My major research interests during this period were on the chemistry of wool and keratin fibres (23) and later on the nuclear magnetic resonance spectroscopy of proteins, enzymes and carbohydrates (24). I was awarded a DSc degree and the David Syme Research Prize by Melbourne University, the Rennie Memorial Medal and H G Smith Memorial Medal by the Royal Australian Chemical Institute for research and a DSc by ANU.

In the 1980's my research group analysed the root crops of the South Pacific (25). I took early retirement from teaching and research in chemistry, and have been involved as a plant chemist for >20 years in Evolution, Ecology and Genetics, Research School of Biology working on cyanogenic glucosides in cassava. In 2007 I was awarded the inaugural "$2 a day award" by the Institution of Chemical Engineers (IChemE) (26). In 2007 I was appointed a Member of the Order of Australia.

Research Interests
Measures to control cyanide intake
1. Cassava cyanide diseases and neurolathyrism network (CCDNN)  
In 2001 we established a free information network called the Cassava Cyanide Diseases Network for those who were interested and concerned with cyanide diseases due to consumption of cassava. In 2009, after an International Workshop on konzo and neurolathyrism held in Ghent, Belgium, at which the close medical similarities between these diseases were highlighted, it was decided to expand the network to include neurolathyrism. The CCDNN has nearly 400 members from 60 countries, and we produce a six monthly newsletter called Cassava Cyanide Diseases and Neurolathyrism News (CCDN News) (2).

2. Development and application of simple methods to determine total cyanide in cassava and thiocyanate in urine
In 1995 we developed a simple picrate kit that can be used by non-chemists and requires only water to operate, to determine total cyanide in cassava flour (3). It has a 10 level colour chart from 0-800 ppm for work in the field and can also be used accurately by elution of the colour and measurement of its absorbance in a spectrometer. The method was successfully field-tested in Mozambique in 1996 (4). We improved and adapted the method to determine total cyanide in roots (5) and in other cyanide containing plants (6). Under drought conditions the cassava plant produces much more linamarin than normal and the mean total cyanide content of flour produced was found to be >100 ppm, which caused konzo, an irreversible paralysis of the legs particularly in children and young women (7,8). The World Health Organisation safe level for cyanogens in cassava flour is 10 ppm.

We developed a simple picrate kit method to determine thiocyanate in urine and this was successfully field-tested in Mozambique in 1999 (9). Urinary thiocyanate measurements of school children give a good measure of recent intake of cyanide, because ingested cyanide is detoxified in the body to produce water soluble thiocyanate, utilising sulphur from essential S-containing amino acids.

Kits allowing 100 analyses are given away for free to health workers and agriculturalists in developing countries and are sold for AU$500 to workers in first world countries. Up to the present time nearly 500 kits have been given away, which has allowed many health workers in developing countries to measure for the first time the poison in the food they eat. In first world countries 300 kits have been sold. We have increased the sensitivity of the present method 10 fold, to determine both total cyanide and acetone cyanohydrin (10).

3. Wetting method to remove cyanide from flour
In 2005 we developed a simple wetting method to remove cyanide from cassava flour which is truly a gift from God. The flour is placed in a container and its height marked on the inside of the bowl. Water is added with thorough mixing until the wet flour comes up to the mark. It is then spread out in a thin layer on a basket or tray and left in the shade for 5 hours or in the sun for 2 hours. The hydrogen cyanide gas produced by breakdown of linamarin by the enzyme (linamarase) in the flour escapes through the thin layer of wet flour. The wet flour is mixed in boiling water to make the traditional thick porridge (ugali) (11-13). The method reduces the total cyanide content 3-6 fold and was successfully field-tested in Mozambique in 2005 (1,14). It is simple, requires no extra work or equipment and the traditional thick porridge tastes better because the bitter taste of linamarin (15) has been removed.  

An illustrated, coloured poster, originally produced by Dr Dulce Nhassico in Portuguese (14), was translated into English, modified and translated into many different languages. We now have the poster in Amharic, Ateso, English, French, Hausa, Kifiliru, Kiswahili, Kiyaka, Macua, Portuguese, Shona, Spanish and Tshiluba. We send out these laminated posters for free by Courier and currently about 5000 have been delivered (2).

4. Prevention of Konzo
Konzo is an irreversible paralysis of the legs that occurs particularly in children and women of child-bearing age, due to the uptake of large amounts of cyanogens from bitter cassava. Epidemics of konzo occur as a result of drought (see 2 above) and war, when people are displaced from their homes and forced to eat bitter cassava from the bush. Konzo occurs in the Democratic Republic of Congo (DRC), Mozambique, Tanzania, Central African Republic, Cameroon and Angola.

In Kaykalenge village, Bandundu Province, DRC, there were 34 cases of konzo, 17 of which were contracted in 2009. In a collaborative project with Professor J.P.Banea, Sr C. Mandombi and coworkers, the wetting method to remove cyanogens from cassava flour was taught to the mothers and 96% of them have used it over a period of more than one year. Since its introduction there have been no new cases of konzo in the village. Measurements of urinary thiocyanate levels in school children have shown that the percentage of children in danger of contracting konzo (those with a urinary thiocyanate level of > 300 µ Mole/L) has dropped from 49% at the begginning of the study to 12% in December 2010. This study is continuing for a second year.

This is the first time that the crippling disease konzo has been prevented and it is serving as a model for a current larger intervention funded by AusAID.

A second collaboration in Uvira, Sud-Kivu Province, DRC with Mr A.K. Karumba and coworkers in APAA-Congo, involves the education of village people in the dangers of contracting cyanide poisoning and konzo from consumption of bitter cassava and introduction of the wetting method (see 3) to prevent this. Nearly 30 villages have been visited and subsequent surveys  have shown (1) that all people eat cassava at least once a day (for many their only meal for the day) and (2) that they use the wetting method on cassava flour if they are unsure of its cyanogen content (17,19).

In Mozambique, where there are 2000 cases of konzo, the Department of Health has approved the wetting method as a good method to reduce the cyanogen content of cassava flour (16,17). In southern Tanzania more than 200 women in konzo-prone villages were taught to use the wetting method and konzo sufferers were rehabilitated in an AusAID funded program in 2008-9 (18).

5. Mild processing of cassava leaves to retain key nutrients
Cassava leaves are used extensively in Africa as a good source of protein and vitamins which complements nutritionally starchy cassava roots. The traditional method of removing the large amount of cyanogens present in the leaves consists of pounding the leaves followed by boiling for 15-60 minutes, which destroys vitamins and S-containing amino acids, which are necessary to convert ingested cyanide to thiocyanate (see 2). We have developed a simple method which involves pounding of leaves followed by washing in water at ambient temperature, to remove cyanogens whilst conserving key nutrients (21).

6. Wetting method to remove cyanide from gari
Whereas cassava flour is preferred and used in most of eastern, southern and central Africa, gari is the processed cassava product of choice in West Africa. Because gari is produced by grating cassava roots followed by a fermentation process, the residual cyanide content is only about 20 ppm, compared with about 45 ppm for cassava flour. Lactic fermentation lowers the pH of gari to about 4.1 and under these conditions the residual cyanide, present as acetone cyanohydrin, is stable. We have found that if the pH is raised to 5, by adding excess pH 5 buffer or cassava flour (1:1) and heating at 50 0 C for 4 hours, the total cyanide content can be reduced by 50%. The final wetting method involves mixing gari with flour (1:1), wetting with water and standing for 4 hours in the sun. We hope that this method may prove useful to reduce the amount of TAN in Nigeria (20).

Selected Publications
1. Nhassico, D., Muquingue, H., Cliff, J., Cumbana, A. and Bradbury, J.H. (2008) Rising African cassava production, diseases due to high cyanide intake and control measures. J. Sci. Food Agric. 88, 2043-2049. [PDF]

2. http://biology.anu.edu.au/hosted_sites/CCDN/

3. 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. [PDF]

4. 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. [PDF]

5. 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, 593-601. [PDF]

6. 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. [PDF]

7. 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. [PDF]

8. 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. [PDF]

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

10. Bradbury, J.H. (2009) Development of a sensitive picrate method to determine total cyanide and acetone cyanohydrin contents of gari from cassava. Food Chem. 113, 1329-1333. [ PDF ]

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

12. 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. [PDF]

13. Bradbury, J.H. and Denton, I.C (2010) Rapid wetting method to reduce cyanogen content of cassava flour. Food Chem. 121, 591-594. [PDF]

14. Muquingue, H., Nhassico, D., Cliff, J., Sitoe, L., Tonela, A, and Bradbury, J.H. (2005) Field trial in Mozambique of a new method for detoxifying cassava in cassava products. CCDN News, No 6, 3-4. [ PDF]

15. King, N.L.R. and Bradbury, J.H. (1995) Bitterness of cassava: identification of a new apiosyl glycoside and other compounds that affect its bitter taste. J. Sci.Food Agric. 68, 223-230. [PDF]

16. Cliff, J., Muquingue, H., Nhassico,D., Nzwalo, H, and Bradbury, J.H. (2011) Konzo and continuing cyanide intoxication from cassava in Mozambique J Chem Toxicol. 49, 631-635. [PDF]

17. Bradbury, J.H., Cliff, J. and Denton, I.C. (2011) Uptake of wetting method in Africa to reduce cyanide poisoning and konzo from cassava. J Chem Toxicol. 49, 539-542. [PDF]

18. Mlingi, N.L.V., Nkya, S., Tatala, S.R., Rashid, S. and Bradbury, J.H. (2010) Recurrence of konzo in southern Tanzania: rehabilitation and prevention using the wetting method. J Chem Toxicol 49, 673-677. [PDF]

19. Karumba, A.K., Denton, I.C. and Bradbury, J.H. (2009) Cyanide poisoning and konzo from cassava in South Kivu Province, DRC. CCDN News, No 13, p 2. [PDF]

20. Bradbury, J.H. and Denton, I.C. (2010) Simple method to reduce the cyanogen content of gari made from cassava. Food Chemistry, 123, 840-845. [PDF]

21. Bradbury, J.H. and Denton, I.C. (2011) Mild methods of processing cassava leaves to remove cyanogens and conserve key nutrients. Food Chem. 127, 1755-1759. [PDF]

22. Doty, P., Bradbury, J.H. and Holtzer, A.M. (1956) Polypeptides IV: The molecular weight, configuration and association of poly-gamma-benzyl glutamate in various solvents. J. Amer. Chem. Soc. 78, 947-954.

23. Bradbury, J.H. (1973) The structure and chemistry of keratin fibres. Advances in Protein Chemistry, 27, 111- 211.

24. King, N.L.R. and Bradbury, J.H. (1971) Simplification of the proton magnetic resonance spectroscopy of ribonuclease by difference spectroscopy. Nature 229, 404-406.

25. 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.

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

Funding
I have had research grants from the Australian Centre for International Agricultural Research (ACIAR) starting in 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 (2). Funding has also been obtained from GRM/Kyeema and in 2005-2011 from AusAID for konzo rehabilitation and prevention in Tanzania and DRC.

Other Activities
In 1989 I started the Asia Pacific Food Analysis Network (APFAN) and was the Coordinator of APFAN until 1999. APFAN promotes food safety and good nutrition by serving the needs of food analysts particularly in developing countries.