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Are Australian Food Standards Adequate to Prevent Exposure to Benzene?

Published: 10 Mar 2006

By Joe Lederman
© FoodLegal, March 2006.

On 2 March 2006, various news sources[1] reported that tests in the UK and France had found benzene, a known carcinogenic chemical, in soft drinks. This followed similar reports from the USA of the discovery of traces of benzene in juices and sodas.

A similar discovery 15 years ago in France of benzene in Perrier bottled water caused the withdrawal of millions of bottles of the water from supermarket shelves. This article looks at the source of benzene in food and whether current Australian food standards adequately address the risk of benzene present in a wider range of foods.

What is benzene?

Benzene is mainly found in petrol or vehicle emissions. The deleterious health effects of exposure to benzene are well known and include a link with higher incidences of cancer and leukemia. According to the report in the Australian Drinking Water Guidelines [2] published by the National Health and Medical Research Council in 2004, benzene has never been found in drinking water in Australia. The limit set by the guidelines for the presence of benzene in drinking water is 0.001 mg/L, which is the lowest level measurable by routine analysis.

Presence of benzene in foods

It is believed that the benzene in soft drinks in the UK and France is the result of the chemical reaction between Benzoic Acid (the active component of the commonly used preservative Sodium Benzoate) and Ascorbic Acid (Vitamin C). This reaction was first observed by Professor Glen Lawrence in the early 1990s (Lalita K. Gardner and Glen D. Lawrence, ‘Benzene production from decarboxylation of benzoic acid in the presence of ascorbic acid and a transition-metal catalyst’ (1993) 41(5) Journal of Agricultural and Food Chemistry 693). He found that Benzoic Acid can react with Ascorbic Acid in the presence of a transition metal compound (eg Copper Sulphate or Iron Sulphate) to form benzene.

What is Benzoic Acid?

The term Benzoic Acid in food includes not only the aromatic carboxylic acid known as Benzoic Acid[4] but also its salts such as Sodium Benzoate[5], Potassium Benzoate and Calcium Benzoate. These are commonly used as preservatives in foods and are labelled with numbers 210, 211, 212 or 213. The most common form of Benzoic Acid is Sodium Benzoate (211) because of its solubility in water. It is effective in acidic conditions and is therefore used in acidic foods such as salad dressings, carbonated drinks, jams, fruit juices, vinegars, pickled foods and acidic sauces.

What is Ascorbic Acid?

Ascorbic Acid[6] refers to a type of organic acid, usually Vitamin C[7], which is commonly added to food as a vitamin supplement or anti-oxidant. It includes those additives labelled on ingredient lists with the numbers 300, 301, 302, 303 or 304. Vitamin C naturally occurs in sour fruits and vegetables many of which may be used for the production of drinks and sauces, for example, oranges, lemons and tomatoes.

Foods potentially vulnerable to the factors for the benzene reaction

The necessary factors for the benzene reaction are Benzoic Acid, Ascorbic Acid and a small amount of a transition metal compound. Since transition metal compounds exist naturally and quite commonly in many foods, the main necessary ingredients are Benzoic Acid and Ascorbic Acid. Maximum limits for the addition of Benzoic Acids and some forms of Ascorbic Acid are provided in Schedule 1 of Standard 1.3.1 of the Australia New Zealand Food Standards Code while limits for the addition of other Ascorbic Acid and permitted transition metal compounds are provided in Standard 1.3.1 and 1.3.2. It is also possible in Standard 1.3.1 to add Benzoic Acids to foods which naturally contain both Ascorbic Acid and a transition metal compound, for example fruit juices or pickled vegetables that contain both Vitamin C and Iron. There are many examples where the addition of Benzoic Acid is allowed to foods containing Ascorbic Acid. Under Standard 1.3.1 - Schedule 1 of the Australia New Zealand Food Standards Code, Benzoic Acid can be added to such foods as:

  • ice confectionery sold in liquid form;
  • mushrooms in brine or water;
  • certain preparations of cherries;
  • fruit and vegetables in vinegar, oil, brine or alcohol;
  • low joule chutney, low joule jams and low joule spreads;
  • fruit and vegetable preparations including pulp;
  • chilli paste;
  • imitation fruit;
  • icings and frostings;
  • semi-preserved fish and fish products;
  • liquid table-top sweeteners
  • supplementary sports foods
  • fruit and vegetable juices, fruit and vegetable products
  • coconut milk, coconut cream, and coconut syrup
  • water based flavoured drinks
  • alcoholic beverages (not including spirits and liqueurs)
  • dairy and fat-based desserts, dips, snacks
  • sources and toppings (including mayonnaise and salad dressings)
Many of these foods contain natural Vitamin C. In addition, Vitamin C is being commonly added to fortify many foods. The same food standards allow a combination of benzoic acid and Ascorbic Acid in fruit wines, vegetable wines, and mead.

Current Food Standards on Benzoic Acid and Ascorbic Acid

While the overseas news reports reaching Australia were concerned with the presence of benzene in soft drinks, it is quite possible that, given these factors, benzene might be present in a wide range of other foods. It would appear that the current Australia New Zealand Food Standards Code contains food standards that have not taken into account the known benzene risk which could result from the abovementioned chemical reaction in a variety of different foods.