Skittles motto of "taste the rainbow" is getting a dark new meaning in the wake of a lawsuit about the dangers of titanium dioxide, an artificial chemical added to the candy.

The complaint was filed last week in the US District Court for the Northern District of California.

A reasonable consumer would expect that the product can be safely purchased and consumed as marketed and sold, according to the complaint. The products are not safe and pose a health risk to the public.

Mars said it would remove artificial colors from food products over the course of five years. Mars stated that titanium dioxide would be among the artificial colorants removed from its human food products. Studies show that titanium dioxide can cause damage to the body's organs, even in small amounts.

Skittles have titanium dioxide. It is listed as an active ingredient for Skittles in the US. Skittles are made with an alternative recipe in Europe because of the European Commission's phase-out of TiO2 as a colorant.

Titanium dioxide can be used as a color enhancer if the toxin doesn't exceed 1% of a food's total mass. According to the lawsuit filed against Mars, other brightly colored candy, like Sour Patch Kids, are made without use of the chemical.

Skittles products are compliant according to Mars. A company spokesman told Fast Company that titanium dioxide complies with FDA regulations.

Coffee creamers, baking and cake decorations, milk products, and pastries are some of the products that use titanium dioxide as a whitener. The toxin can be found in over-the-counter products and cosmetics as a color enhancer.

While the FDA allows the use of TiO2 in human-ingested products, pet retailers are banning the toxin. Titanium dioxide is listed as one of the artificial colorings that do not meet its nutrition standards by Petco.