A new study finds the levels of chemicals in some brands of e-cigarette flavoring exceed recommended limits. Some of the chemicals could be respiratory irritants, HealthDay reports.

The flavorings used in e-cigarette fluids are generally the same as those used in food and candy. The difference is that when they are used in e-cigarette fluids, they are inhaled, not eaten, the researchers note in Tobacco Control. They point out the chemicals used for flavoring are usually not included on ingredient labels.

The study included 30 e-cigarette fluids. The flavors tested included cherry, cotton candy, bubble gum and grape. The researchers looked at the types and levels of chemicals. They did not investigate whether the chemicals were safe. They calculated that a person using a typical amount of e-cigarette fluid a day would be exposed to twice the recommended occupational exposure limits of the chemicals benzaldehyde and vanillin.

The results are “likely to be similar to what a broad survey would have revealed, and in any case strongly suggest that very high levels of some flavor chemicals are undoubtedly present in a great number of the thousands of products currently available,” wrote researcher James Pankow of Portland State University in Oregon.

Pankow and colleagues called for new regulations on e-cigarettes, including requiring a listing of ingredients, limits on the levels of certain flavorings, and limits on the total levels of flavoring, “particularly as there is some concern that flavored products might make e-cigarettes more attractive to young people.”