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October 18, 2004

The truth about coal tar in your food

Food colouring and other additives derived from coal tar have come in for some bad press recently. Hugh Westbrook delves into the issues surrounding tartrazine, saccharine and other ingredients many of us don’t know we’re eating.

Food colouring and other additives derived from coal tar have come in for some bad press recently. Hugh Westbrook delves into the issues surrounding tartrazine, saccharine and other ingredients many of us don’t know we’re eating.

In March 2004, trading standards officers in Surrey, England, discovered that illegal levels of food colourings were being used in a large number of Indian restaurants. The news was given widespread coverage, as was one specific fact about one of the colourants used, tartrazine. BBC News Online was typical of many publications when it described tartrazine as “a dye made from coal tar”.

A quick venture across the Internet will tell you that coal tar is described as the basis for around half a dozen regularly used food colourings. These include tartrazine, carmoisine red (E122) and brilliant black (E151), while artificial sweetener saccharin is derived from coal tar. Further searches will take you to many articles which then discuss the health problems associated with apparently eating coal tar. One such example includes Dr Joseph Mercola’s website, where he says that colours derived from coal tar are dangerous “due to the high content of toxic substances, such as mercury, lead and fluoride, found in coal”.

The issue of coal tar-based products is also controversial in non-food circles. Cosmetic manufacturers in California may have to put warning labels on products containing coal tar because of their reported carcinogenic qualities. In the European Union, wood preservative creosote, a mixture of substances obtained from the distillation of coal tar, has been banned from sale to consumers because of carcinogenic concerns.

If you put all this together, there is surely a compelling case to suggest that food colourings and additives made from coal tar are extremely dangerous. Think again.

Food colourings not actually based on coal tar

Coal tar, the black viscous liquid left over when coal is cooked to make coke, became the source for scientific experimentation around 150 years ago, with scientists deriving a range of useful substances from it. Food colourings were one such product. ‘Were’ is the operative word. In spite of the warnings across the Internet, food colourings are no longer derived from coal tar.

Technically, such products are now referred to as ‘synthetic coal tar derivatives’ or azo dyes. They are now derived from the petrochemical industry.

Food industry consultant Mike Saltmarsh told that people use phrases like coal tar derivative in a pejorative fashion. “If you look at the specifications, these are extremely pure compounds,” he said. “These dyes are not much less pure than sucrose and are over 99% pure.

Saltmarsh said that crude coal tar is no longer used. “Now you start with oil and break it down into basic components and then carry out a series of synthetic reactions. What you’re eating is a very pure compound.”

Colour ‘one of the greatest life enhancers’

Advocates of food additives have no doubt about the safety of their products. The UK’s Food Additives and Ingredients Association argues that adding colour to food through additives is vital because “the impression food makes on us is a melange of sensations, and colour and surface appearance are amongst the most important…Colour is one of the greatest life enhancers we have.”

Secretary Richard Ratcliffe explained to that the source of the molecule which creates a food additive is irrelevant; it is the molecule itself which is important. Consequently, it does not matter that the source used to be coal tar and is now the petrochemical industry.

“It’s old-fashioned and old chemistry,” he said. “Most of these things can now be derived from oil. Coal-tar is old-fashioned emotive stuff.”

As for saccharin, the International Sweeteners Association told “The synthesis of saccharin was traditionally based on toluene, which was originally obtained from coal-tar but would nowadays be obtained by petrochemistry.

“It would be very far-fetched and over-simplified to claim that food additives are made of coal tar or of petrol. There are many steps in the synthesis of food additives like in the synthesis of other substances.”

Tartrazine linked to hyperactive kids

But of course this is not the whole story. Just because there is a lack of understanding over what ‘coal tar derivative’ means, it does not mean that everybody is in agreement over whether such additives are safe for human consumption. Tartrazine in particular has had a bad press, linked as it is with hyperactivity in children, and the rest of the azo dyes are regarded as equally culpable.

The FAIA’s Ratcliffe said: “The link between tartrazine and hyperactivity is not fully proven.” He is looking for future testing to look at the effect of a child’s entire diet and not just the additives he or she consumes.

But charities across the world disagree with him. Jane Hersey, National Director of the Feingold Association in America, believes that a range of behavioural problems can be put down to food, and the Association runs a programme which helps parents eliminate certain foods from their child’s diet.

Food ‘purity’ an unhelpful concept?

She questions the idea of purity being a good thing. “The word is relative,” she told “You can have pure arsenic, it doesn’t mean it is necessarily advisable for people to eat it. Purity is not the issue.”

Hersey believes there is sufficient independent scientific research to back up her contention that food colourings cause health problems. “In some, their chemical structure is similar to one of the brain’s neurotransmitters.

“Doctor have said these additives get into the brain and because their structure is similar to the neurotransmitter, they can act as neurotoxins. The brain thinks it has received a real molecule but instead a synthetic molecule has taken its place and the brain reacts to the false one.”

Hersey agrees that it is largely irrelevant where such molecules are derived from, but said she refers to the petrochemical industry to give people an understanding of the sources of their food and “just to get people to sit up and take notice. It is bizarre that people have no idea where the things that they consume come from.”

Sally Bundy, who founded the Hyperactive Children’s Support Group in the UK agrees that colourings should be banned and feels that the arguments about adding colour to food are spurious. “From a nutritional point of view, the addition of colours is not necessary,” she told

She added that the decision by a company like Bird’s Eye to stop including additives in their products showed that change is possible from major manufacturers.

Jury out on the relation of food to ADHD

Not everybody agrees with this viewpoint, even those involved in helping people suffering from similar problems. The US-based Children and Adults with Attention-Deficit/Hyperactivity Disorder believes that eliminating certain types of food is not the answer, and says that the science which supports the Feingold Programme does not stand up to scrutiny. “Research has also shown that the simple elimination of sugar or candy does not affect AD/HD symptoms, despite a few encouraging reports,” it says on its website. There is clearly much work to do in this area.

Is it important for the public to be educated as to where their food additives are coming from? In terms of the unregulated information in the public domain, then yes. In terms of how much the public are paying attention to that information, probably not. Despite the extensive coverage of the coloured curry story this year, the UK’s Food Standards Agency had not been asked about coal tar until contacted it while researching this article. Entirely separate is the issue of just how healthy such additives are. And time may be the only thing which conclusively settles that debate.

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