https://www.bbc.com/news/business-64123157
But the lawsuit refers to recent findings by US magazine Consumer Reports (CR), which tested 28 dark chocolate bars for lead and cadmium.
The magazine alleged that 23 of them, including chocolate from Hershey, Godiva and Lindt, contained "comparatively higher levels" of the metals.
"For 23 of the bars, eating just an ounce (28g) a day would put an adult over a level that public health authorities and CR's experts say may be harmful for at least one of those heavy metals," it claimed.
In particular, Hershey's Special Dark bar and Lily's 70% bar were high in lead, while Lily's 85% bar was high in lead and cadmium.
"Any food can contain heavy metals if they are present in the soil in high concentration," nutritionist Sheeba Majmudar told the BBC.