Coal tar dyes are artificial colouring agents used in foods, cosmetics and personal care products like hair dyes, shampoo and deodorants and much more.
Nothing is as mouth-watering as a brightly iced birthday cake or a lemon popsicle on a hot day. Those intense colours stimulate our appetites and trick our brains into believing they’re healthy. But those intense colours are created from “coal tar dyes.” (The term dates back to when colouring agents were byproducts of the coal industry. Although the original name prevails, today they’re synthesized from petroleum.)
Not just food contains coal tar dyes. Cosmetics and hair dyes do too. P-phenylenediamine is the organic compound found in hair dye. Food dyes contain compounds like erythrosine, xanthene or triphenylmethane. The letters CI (for “colour index”) on a product’s ingredient list followed by a set of numbers means coal tar dyes are present.
Health and environmental hazards of coal tar dyes
Human health risks and concerns
Food dyes
Food dyes are generally classified according to numbers such as Red No. 40, Yellow No. 5, Yellow No. 6, Blue No. 1 and Blue No. 2. The most common are Red 40, Yellow 5 and Yellow 6. Studies on Blue 1, Red 40, Yellow 5 and Yellow 6 have found no cancer link. The most controversial is Red No. 3, or erythrosine. The United States Food and Drug Administration banned its use in cosmetics after research showed high doses could cause cancer in laboratory animals. It’s been mainly replaced by Red 40. It may still be present in some foods such as lollipops, sausages, imitation bacon bits, candy and strawberry milk.
Food dyes brighten breakfast cereals, candy and snacks. Studies show food dyes linked to an increase in hyperactivity. This is most often seen in children with attention deficit hyperactivity disorder. Red 40 and Yellow 5 have the strongest links.
P-phenylenediamine
Laboratory testing on this hair dye links it to the development of tumours in mice, according to the U.S National Toxicology Program and the National Cancer Institute. PPD is used in permanent and some semi-permanent hair dyes and can be an irritant and allergen. It may cause dry, itchy bumps, blisters and dermatitis in sensitive individuals. (Patch test before using any hair dye containing PPD.) The FDA doesn’t allow hair dyes for eyelashes and eyebrows, as it may hurt the eyes and even cause blindness.
Environmental risks and concerns
Synthetic dyes used in textile processing and the pharmaceutical sector evoke environmental concerns. An estimated 80 per cent of dye-containing wastewater gets released into waterways. That affects human health and ecosystems. Untreated synthetic dyes can be toxic to plants, animals and humans.
Regulatory status of coal tar dyes
Current regulatory status of coal tar dyes in Canada
Canadian law requires permanent and semi-permanent hair dyes that use coal tar dye bases and intermediates be labelled for possible skin irritation and suggest a patch test before use. Health Canada’s review of current scientific data shows there’s no hazard associated with the proper use of hair dyes.
Canada’s Cosmetic Regulations sets out the prohibitions and restrictions for coal tar dyes. Most are safe for use in cosmetics. Those found unsafe are prohibited or restricted.
The Government of Canada reviews many colourants under the Chemicals Management Plan. The Cosmetic Ingredients Hotlist is regularly updated with ingredients found to be unsafe for human health. Canada’s Food Inspection Agency provides a list of coal tar dyes considered safe as food additives.
Current regulatory status of coal tar dyes in other countries
The regulatory status of coal tar dyes in other countries is complicated. Some are approved in some countries, but banned in others.
- United States. The Food and Drug Administration must approve all colour additives used in foods. In 2023, California became the first state to ban Red No. 3 in food. This supersedes the FDA’s rule allowing small amounts in foods.
- The European Union, United Kingdom, Australia, China, Japan and New Zealand. All have banned Red No. 3 (listed on labels as “FD&C Red Dye No. 3”) in foods. As of 2010, the U.K. requires a warning on labels of food containing artificial food dyes. The U.K. and EU do not ban p-Phenylenediamine in hair dyes. The maximum concentration of PPD must not exceed two per cent.
Function of coal tar dyes
Colour greatly enhances our daily lives. Coal tar dyes are artificial colouring agents used in foods, over-the-counter and prescription drugs, textiles, cosmetics and personal care products like hair dyes, shampoo and deodorants.
Colours play an important gourmet role. Brightly coloured foods are considered more palatable and healthy, stimulating the senses and increasing the appetite. People will eat more brightly coloured cuisine than they will bland appearing foods.
Hair care that cares for the planet
Commercial hair care products often contain a cocktail of synthetic chemicals such as sulfates and parabens. These can harm your health and the environment. Adopt sustainable, Earth-friendly washing, styling and maintenance habits.
How to avoid coal tar dyes
What to look for on labels
Coal tar-derived colours are used extensively in cosmetics. They’re generally identified by a five-digit colour index number. The U.S. colour name may also be listed as “FD&C” or “D&C,” followed by a colour name and number.
Substitutes and alternative methods
Companies that prioritize customer health and safety steer clear of coal tar dyes. Organic and vegan alternatives exist for lipsticks and other cosmetics.
P-phenylenediamine can be replaced with henna, vegetable-based hair dyes and DIY tints. Always patch test before trying something new.
Limit food dyes in a child’s diet whenever possible.
- Choose whole (not processed) nutritious foods low in food dyes.
- Avoiding Red Dye 3. Replace artificially coloured drinks with fruit-infused water. Substitute roasted pumpkin seeds for imitation bacon bits. Make homemade trail mix with nuts, chocolate and raisins instead of artificially coloured candy.
