Surveillance and Occurrence Studies on Ochratoxin A

Published in the Period 1995-2003

Ochratoxin A (OTA) was discovered during laboratory studies in the mid-1960s and was encountered as a natural contaminant in maize in 1969 in the USA. Since then, the toxin has been found in many commodities worldwide and its role in the so-called mycotoxic porcine nephropathy has been well established. As the most significant toxic property of OTA is nephrotoxicity, a provisional tolerable weekly intake based on that effect in animals has been established and retained by the Joint FAO / WHO Expert Committee on Food Additives (JEFCA) at 100 ng/kg bw per week.

Ochratoxin A is the mycotoxin that, apart from aflatoxins, has received most attention from researchers and health authorities, at least from the point of view of the quantity of published occurrence studies. In the period 1995-2003, ochratoxin A appeared in no less than 239 published articles or reports pertaining to surveys and occurrence studies. Of these, 149 dealt exclusively with the presence of ochratoxin A in foods, body tissues and fluids, and the remainder referred to the simultaneous investigation of the presence of OTA and/or other mycotoxins in the same matrices. Cereals as a group, and wheat and barley specifically, were the foodstuffs most investigated for the presence of ochratoxin A, with 25, 24 and 13 papers, respectively. Wine, coffee and beer also accounted for 27, 25 and 15 papers, respectively. Other commodities that were the subject of surveys or occurrence studies were spices, dried fruits, herbal drugs and milk. Two articles about the presence of OTA in airborne dusts in households and workplaces were also identified (Richard, J. L. et al, 1999; Brera, C. et al. 2002).

In 1995, the European Commission (EC) established a collaborative scientific co-operation task (SCOOP Task 3.2.2), co-ordinated by Denmark, to provide data on dietary exposure to OTA in the EU, in parallel with a similar exercise carried out on aflatoxins. Thirteen member states collaborated in that survey, which represented the most comprehensive survey available at that time. Eight countries estimated intakes based on national consumption data, and five countries estimated the intakes based on plasma levels of OTA as a biomarker. The similarity in the estimates from the two approaches suggested that the main sources of OTA are known and accounted for in food surveys. One of the conclusions of the report of the Task published in 1997 (EUR 17523) was that the main contributor to the OTA intake in the EU Member States seemed to be cereals and cereal products. Other possible contributors were coffee, beer, pork, products containing pig blood/plasma, pulses and spices. Nevertheless, it was recognised that the report was based on a limited amount of data. Given the number of studies conducted and available since 1995, the EC considered it appropriate to update and complete that Task with a second (SCOOP Task 3.2.7), established in 1999 and co-ordinated by Italy, in order to determine whether recent data would change the conclusions of the first report. The new report was presented in 2002 and again cereals were the main contributors (50%) followed by wine (13%), coffee (10%), spices (8%), others (6%), beer (5%), cocoa (4%), dried fruits (3%) and meat (1%). Besides these specific Tasks, four meetings have been organised by the EC to provide a forum where interested parties could communicate the results of investigations undertaken and progress with regard to the application of prevention measures to avoid contamination by OTA. These meetings took place between May 2001 and October 2003. As an example of the significant activity developed by the private sector in this field, it may be worth mentioning an article published in 2003 offering a review of analytical data and research carried out by the French grape juice industry since 1999 (Roset, M., 2003).

Very often, studies directly promoted by governmental agencies are an important source of information. In that respect, it is worth mentioning the study initiated and sponsored by the German Federal Ministry of Health aimed at determining the exposure of the consumer to, and the contamination of foods with, Ochratoxin A. This study involved seven scientific institutes and the results were published in 2000 (Wolff, J. et al, 2000). Within a period of 30 months, almost 7000 food and blood samples were examined. The types of foods included in the study included 29 food groups with 137 sub-groups. In addition to 25 different beverages, milk and milk products, meat and meat products, sweets, pasta, seasonings, oils and oil seeds were also analysed. A related paper was published on a nationwide evaluation of data about OTA in coffee collected by German Food Control in the period 1995 - 1999, in which a total of 613 analysed samples complying with a detection limit lower than 0.6 microgrammes/kg were evaluated (Otteneder H. & Majerus, P., 2001).

The 20th edition of the Australian Total Diet Survey, which was carried out by Food Standards Australia New Zealand (FSANZ) between July 2000 and April 2001, included Ochratoxin A among the investigated contaminants. These surveys are conducted approximately every two years and try to estimate the level of dietary exposure of the Australian population to a range of substances through the testing of food samples prepared to a "table ready" form. There were no detections of OTA in nut and cereal products tested. The report and more detailed information are provided on the FSANZ Web site ( www.foodstandards.gov.au ).

Since 2001 the Food Standards Agency (FSA) in the UK has continued the activities on mycotoxin surveillance developed formerly by the Ministry of Agriculture, Fisheries and Food (MAFF). A number of surveys have been completed since then on the presence of OTA in milk, retail rice and dried vine fruits, the information being available on the FSA web site ( www.foodstandards.gov.uk ). Among the surveys conducted by MAFF before 2001, may be highlighted the study on human exposure through the analysis of samples of duplicate diets, plasma and urine collected from 50 volunteers, and the 1998 survey of retail products involving the analysis of a total of 501 samples of dried vine fruits, figs, cocoa, chocolate, pulses, red wine and grape juice. Detailed information on both studies was published in the Food Surveillance Information Sheets (1999) No. 172 and No. 185, respectively.

In relation to the presence of OTA in human body fluids, 21 articles were published about studies performed on human blood and 8 articles dealt with human milk. According to these studies, Ochratoxin A was found in human blood and milk samples in many countries in Europe and worldwide (Canada, Croatia, Czech Republic, Egypt, Finland, France, Germany, Italy, Hungary, Japan, Morocco, Norway, Sierra Leone, Spain, Sweden, Tunisia, Turkey, UK, etc.) clearly indicating a continuous and widespread exposure to this mycotoxin. Finally, it is worth pointing out the study published by Razzazi, E. et al. in 2001, reporting the presence of OTA in pet foods, including the finding of the toxin in feline kidney tissue of animals not artificially fed the toxin.

References

Brera, C., Caputi, R., Miraglia, M., Iavicoli, Y., Salerno, A. and Carelli., 2002, Exposure assessment to mycotoxins in workplaces: aflatoxins,and ochratoxin A occurrence in airborne dusts and human sera. Microchemical J., 73, 167 – 173.

European Commission. Assessment of dietary intake of ochratoxin A by the population of EU Member States, (1997). Reports on tasks for scientific cooperation. Report EUR 17523.

JEFCA, (2001), Safety evaluation of certain mycotoxins in food. WHO Food Additives Series 47; FAO Food and Nutrition Paper 74. (WHO ISBN : 92 4 166047 3; FAO ISBN : 92 5 104664 6).

Otteneder, H. and Majerus, P., (2001), Ochratoxin A in coffee : nation-wide evaluation of data collected by German Food Control 1995 - 1999. Food Additives and Contaminants, 18, 431 - 435.

Razzazi, E., Bhom, J., Grajewski, J., Szczepaniak, K., Kubber - Heiss, A.J. and Iben, C. H., (2001), Residues of ochratoxin A in pet foods, canine and feline kidneys. J of Animal Physiology and Animal Nutrition, 85, 212 - 216.

Richard, J. L., Plattner, R. D., May, J. and Liska, S. L., (1999), The occurrence of ochratoxin A in blood in general population in Croatia. Toxicology Letters, 146, 99 – 103.

Roset, M., (2003), Survey on Ochratoxin A in Grape Juice, Fruit Processing, May/June, 167 - 172.

Wolff, J., Bresch, H., Cholmakov - Bodechtel C., Engel, G., Gareis, M., Majerus, P., Rosner, H. and Scheuer, R., (2000). Ochratoxin A : Contamination of Foods and Consumer Exposure. General Introduction. Archives fur Lebensmittelhygiene, 51, 84.

(followed by eleven research articles : pages 85 - 128).