A bulletin for the Australian Food Industry August 1999
Contents: Refrigerated retail cabinets | Cheese from unpasteurised milk and listeriosis | Alicyclobacillus spp. - a source of flavour taints in acidic foods | Dioxins in food | Volatile nitrosamines in food and drink | Disinfection of seeds for sprouting
Dioxins in food
In recent weeks countries around the world have placed import bans on foods which may have been contaminated with dioxins.
The Australian Quarantine and Inspection Service (AQIS) put in place a 'test and hold' regime to prevent potentially contaminated egg, poultry, beef, pork or dairy products from Belgium, France and The Netherlands entering the country. The Australia New Zealand Food Authority (ANZFA) asked retailers to withdraw voluntarily suspect Belgian products from their shelves as 'an interim measure'.
The incident highlights how quickly a single contamination problem can spread internationally and how serious the consequences can be.
Dioxins are persistent chemicals produced during combustion and incineration processes and are also unwanted by-products in the manufacture of some chemicals. Dioxin is a generic term given to polychlorinated dibenzo-p-dioxins and dibenzofurans. The term 'dioxin' is also used to refer specifically to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic and widely researched member of the group.
Analysis of dioxins requires specialised facilities. Detailed information on the possible level of exposure of consumers in Europe to dioxins as a result of this incident will be generated very slowly. No Australian laboratory is equipped for dioxin analysis.
The toxicity of dioxins and 2,3,7,8 TCDD in particular has been a matter of controversy for decades. However animal studies and epidemiological studies implicate dioxin in reproduction and developmental disorders, nervous system dysfunction and cancer. The World Health Organization (WHO) designates dioxin as a known cancer-causing compound although long term effects in humans have not been directly established. A number of industrial plant accidents, most notably at Seveso, Italy, in 1976, produced immediate human health effects in the form of chloracne, a disfiguring skin disease. Follow-up studies of persons affected in the Seveso incident are continuing.
Food contaminationMost food contamination with dioxins occurs as a result of industrial emissions. Because of the ubiquity of dioxins and related chemicals, trace amounts can be found in many foods.
However the Belgian incident can be traced directly to dioxin contaminated fat used in animal feed. Initial investigation focused on egg and chicken based foods which could be sourced to chickens consuming feed contaminated with fats supplied by a single firm, Verkest, near Ghent. Recall and destroy procedures were instigated by the European Commission. The recall extended to all products with an egg content greater that two per cent which included a range of manufactured products. Dates of manufacture included the entire period from January 15 to June 1.
Further investigation revealed that pig and cattle fodder could also be contaminated and the recall procedures embraced many more products. The contaminated feed had also been transported to other European countries such as France and The Netherlands whose products were caught in the recall.
How the contamination occurred is still the subject of investigation with the principals of the firm Verkest being arrested and charged with fraud. Dioxin contamination was traced to one 80-tonne batch of fat produced by the rendering company near Ghent in January. This fat was then sold to 10 animal feed producers in Belgium, one in France and one in the Netherlands. A second company in Belgium is now under investigation.
Food Science Australia
PO Box 52, North Ryde 1670. Tel +61 2 9490 8397 Fax +61 2 9490 8499
Email enquiries@csiro.au