The taste of Skittles’ rainbow includes toxic titanium, according to a lawsuit filed Thursday against candymaker Mars Inc.

Consumer Jenile Thames filed a class-action lawsuit in a federal court in Oakland, California, alleging that Mars was not forthcoming about its use of titanium dioxide to give Skittles shells their flavorful hue. 

The suit charges that titanium dioxide, which also is used in adhesives, coatings, paints, printer ink and roofing material, can cause “DNA and chromosomal damage, organ damage, inflammation, and other health effects,” as reported by Bloomberg Law. 

Ms. Thames’ complaint argues that Mars lied about titanium dioxide being safe for consumption. The complaint argues that the company “claimed that ‘artificial colors pose no known risks to human health or safety …’ Defendant concealed from consumers … scientific research showing that the toxin is unsafe for consumption,” according to UniCourt.

While Skittles does list titanium dioxide in its ingredients list, Ms. Thames’ complaint alleges that the list is “provided in minuscule print on the back of the Products … made even more challenging by the lack of contrast in color between the font and packaging,” as cited by UniCourt.

Titanium dioxide is still approved by the Food and Drug Administration, but European regulators have implemented a ban on the additive that goes into effect on Aug. 7.

Mars Inc. earlier this year issued a recall of certain types of candies, including Skittles, because thin metal strands were found in some bags and in the candy itself.