Some curry houses in South Yorkshire are putting dangerous amounts of food colouring in their meals, according to food safety experts.
Trading standards officers bought 49 chicken masalas and rice from takeaways and restaurants across the county.
They said a "significant number" had more than the permitted amount of colouring in the sauces.
Owners of business that failed the test have been contacted and reminded that too much colouring could be harmful.
A number of the chemicals commonly found in curries have been linked to hyperactivity in children, certain allergies and migraines.
Failure to comply with the regulations can lead to a fine of up to £5,000 under the Colours in Food Regulation Act of 1995.
Sue Ellis, a member of Rotherham Borough Council, said: "It is essential that restaurants and takeaways are aware of how much colours they can safely use.
"If they do not comply with the national regulations then local authorities will take legal action."