This article was first published in聽
In the late 19th century, Germany was at the forefront of chemical research and it was an ideal place for Purdue University chemistry professor Dr. Harvey Washington Wiley to spend a sabbatical to broaden his horizons.
After attending lectures by August Wilhelm Hoffman, under whose tutelage young William Henry Perkin had discovered mauve, the first synthetic dye, Wiley himself developed an interest in 鈥渃oal tar dyes.鈥� This would come in handy when, in 1882, he accepted the position of chief chemist at the U.S. Department of Agriculture. He was charged with looking into the safety of chemicals added to the food supply, a totally unregulated process at the time.
Wiley became concerned with the safety of some of the 80 food colourants being used and decided that testing was in order. Based on the somewhat primitive tests available, these were trimmed down to seven, one of which was erythrosine, a compound that was first synthesized in 1876 by Swiss chemist Karl Kussmaul. When the 1906 Pure Foods and Drugs Act, Wiley鈥檚 handiwork, erythrosine was christened Red Dye #3 and was deemed to be safe for use in foods.
The dye cruised along under the radar until the 1970s, when the Food and Drug Administration became concerned that erythrosine, with four iodine atoms in its molecular structure, might somehow affect the thyroid gland that relied on iodine to produce its hormones. A study was designed in which rats and mice were fed varying amounts of erythrosine and their thyroids examined. No effect was seen in mice or in female rats, but 16 of 69 male rats fed the highest dose of erythrosine every day over their lifetime developed thyroid tumours. That dose was 2.5 grams per kg of body weight, which for a child of 20 kg would mean 50 grams. Given that the estimated amount of erythrosine in the daily human diet is about 2 milligrams, the dose given to the male rats was 25,000 times greater than human exposure.
A follow-up study of male rats in 1990, often quoted as evidence that the dye causes cancer, did not even check for cancer.
What the study found was that at the same high dose as used in the previous trial, and only at that dose, the level of thyroid stimulating hormone (TSH) in the rats鈥� bloodstream was increased. Since increased activity of the thyroid gland is believed to be associated with cancer, the researchers hypothesized that 鈥渓ifetime feeding of a four-per-cent erythrosine diet to rats promotes the formation of thyroid tumours indirectly via chronic stimulation of the thyroid by TSH.鈥�
That information was enough for the FDA to ban the use of erythrosine in cosmetics, where it was deemed non-essential, but it saw no reason to ban it in food, stating that the risk to humans was negligible and suitable replacements were not available.
Indeed, the risk is negligible when considering the animal data that shows no evidence of carcinogenicity at any dose approaching human exposure. Yet, judging by effusive recent media reports, one would be led to think that a heavy yoke has been lifted from the neck of Americans with the banning of Red Dye #3 by the FDA.
The ban is not the result of some new research that implicates this dye as a felon lurking in the food supply. It is the result of years of legal wrangling about the application of an amendment to the 1938 Food, Drugs and Cosmetic Act known as the 鈥淒elaney Clause.鈥�
Sponsored by Congressman James Delaney of New York, the amendment states 鈥渢hat the Food and Drug Administration shall not approve for use in food any chemical additive found to induce cancer in man, or, after tests, found to induce cancer in animals.鈥�
That sounds like motherhood and apple pie, since it seems obvious that a carcinogen should not be purposefully added to the food supply. However, the Delaney Clause presents carcinogenesis as a white or black issue when science is hardly ever white or black, it is shades of gray. The Delaney Clause ignores the cornerstone of toxicology first voiced by the sage Paracelsus in the 16th century: Only the dose makes the poison.
In 2022, The Center for Science in the Public Interest, an organization that has produced a great deal of useful information for consumers, petitioned the Food and Drug Association to ban Red Dye #3 based on the Delaney Clause. The petition, while on firm legal footing but amounting to no more than baying at the moon, led to the ban. The clause clearly states that any substance that in any dose causes cancer in any animal, cannot be allowed in the food supply. Although this sounds reasonable, the law is based on 鈥渉azard鈥� analysis, only considering whether a substance has carcinogenic potential, as opposed to the more realistic 鈥渞isk鈥� analysis that takes into account the type and extent of exposure.
Health Canada has determined that while Red Dye #3 could be hazardous, it poses no risk, which I think is the correct evidence-based decision.
Another concern, namely the possible role food dyes may play in triggering behavioural problems in children, has also been raised. The issue was first broached in the 1970s by American pediatric allergist Benjamin Feingold, who found that hyperactive children given a diet free of artificial food additives and dyes experienced a reduction in symptoms. Interest in this effect waned when studies failed to reproduce the results. It was revived when a 2008 study carried out at Southampton University in England found that some dyes and preservatives can affect behaviour in children, although erythrosine was not one of the dyes tested.
As a result of the Southampton study, in Europe, foods that contain any of six synthetic dyes must have a warning that the dyes 鈥渕ay have an adverse effect on activity and attention in children.鈥�
In my view, the evidence for erythrosine causing behavioural problems is very thin, and for cancer in people nonexistent. That being said, I am certainly no fan of food dyes.
They serve only a cosmetic purpose without imparting any nutritional value and generally attract consumers to highly processed foods that should be limited, not because of any perceived toxicity of food dyes, but because numerous studies have shown such foods to be detrimental to health. The toxicity issue has no practical relevance, and replacing synthetic dyes with natural ones extracted from beets or berries does not make processed foods 鈥渉ealthier.鈥� Red Dye #3 being synthesized from petroleum, as reported by fear-mongering bloggers, is a moot point.
When it comes to food safety, banning Red Dye #3 amounts to flicking a flea off the back of an elephant.
