A bulletin for the Australian Food Industry September 1997
Contents: Training and national food hygiene legislation | ANZFA draft standard on food additives | Unusual chemical poisoning incident | Chlorfluazuron (CFZ) residues in meat | Hepatitis A transmission by foods | Garibaldi charges dropped | Cheese from unpasteurised milk | Date marking of processed foods for export | Fungi and food spoilage
Unusual chemical poisoning incident
An unusual food poisoning incident involving curing salts was recently reported in England (Archives of disease in childhood 76 (4) 1997 pp.367-68). Three brothers aged 10, 14 and 19 years were admitted to hospital suffering severe headache, dizziness and nausea two hours after eating homemade sausages.
The diagnosis in each case was methemoglobinemia, a condition usually associated with young infants but which also can affect adults. Excess nitrite or excess nitrate which is converted to nitrite in the diet can lead to the disorder.
Nitrite in the gut may be absorbed into the bloodstream where it is oxidised to methemoglobin. The methemoglobin formed in this way can no longer transport oxygen thereby leading to the potentially fatal methemoglobinemia.
In the reported case the boys' father, a butcher, told authorities that he had marinated the offending batch of sausages in 'saltpetre' for several days before they were consumed. Saltpetre is a generic term but in this country and in England usually means sodium or potassium nitrate. When the suspect material in this case was analysed it was found to contain 50 per cent sodium nitrate and 50 per cent sodium nitrite. Nitrates and nitrites can both cause methemoglobinemia but nitrites are more toxic as they have greater oxidative potential.
Nitrites either as the potassium or sodium salt are widely used in this country and elsewhere in cooked, cured meats. Nitrites are responsible for the attractive pink colour of cured meats and when heated have a specific anti-bacterial function. Their use is limited by law to a maximum concentration of 125mg/kg.
The use of nitrates in Australia is much more restricted. Nitrates are permitted in slow cured, fermented meats where they act as a continuing source of nitrite during processing and maturing. Their concentration is limited to a maximum of 500mg/kg. There is also permission in the Australian Food Standards Code to use nitrates to a maximum of 50 mg/kg in a range of cheeses. This permission is included to accommodate some imported products which traditionally have incorporated nitrates as preservatives.
All three patients recovered after treatment from the incident in England. The eldest brother was reported to have eaten ten sausages.
Food Science Australia
PO Box 52, North Ryde 1670. Tel +61 2 9490 8397 Fax +61 2 9490 8499
Email enquiries@csiro.au