Testing commissioned by As You Sow, and conducted at independent laboratories, indicates that the chocolate products contain lead and/or cadmium, and they fail to provide the legally required warning to consumers.

“Lead exposure is associated with neurological impairment, such as learning disabilities and decreased IQ, even at very low levels. In fact, there is no safe level of lead for children," said Eleanne van Vliet, MPH, As You Sow's environmental health consultant.

As You Sow has filed legal notices against chocolate manufacturers, including Trader Joe's, Hershey's, Green and Black's, Lindt, Whole Foods, Kroger, Godiva, See's Candies, Mars, Theo Chocolate, Equal Exchange, Ghirardelli, Earth Circle Organics and more, for failure to warn of lead and/or cadmium in their chocolate products.

Recent revelations of lead contamination in water in Flint, Michigan raised awareness that lead is irrefutably linked to neurological impacts in children. Since 1992, As You Sow has led enforcement actions resulting in removal of lead from children's jewelry and formaldehyde from portable classrooms.

“Lead and cadmium accumulate in the body, so avoiding exposure is important, especially for children," explained Danielle Fugere, As You Sow president. “Our goal is to work with chocolate manufacturers to find ways to avoid these metals in their products."

As You Sow, a California-based consumer advocacy group, believes that some chocolate has more lead than necessary. An updated survey released by the group this week found levels of lead in chocolate at nine times the daily amount that California considers safe to avoid reproductive harm. In addition, the group also found cadmium up to seven times the state's maximum daily exposure.

The group had multiple samples of 50 different cocoa products analyzed by an independent lab and found more than half contained lead and cadmium levels above the state's limits, which are more strict than federal guidelines. As You Sow won't disclose the exact amounts of metals found in the products, in hopes of working directly with the manufacturers to help target sources of these metals, it said.

"Our goal is to work with chocolate manufacturers to find ways to avoid these metals in their products," said Danielle Fugere, president of As You Sow.

Eleanne Van Vliet, a consultant on testing for As You Sow, said that lead and cadmium can enter the products a variety of ways.

"It depends on the growing, processing, manufacturing, shipping. So there are a few possible sources, from our research," she said. "We would really like to have the chocolate industry come together and determine the sources."

She says consumer groups and advocates like As You Sow have become more powerful and political with the help of social media. Last March, As You Sow was active in helping remove titanium dioxide nanoparticles from Dunkin Donuts' powdered sugar. Recently, Mars, the maker of M&M's and Snickers, announced that it will begin to include genetically modified food labeling on its products in order to comply with a 2014 Vermont law that requires food with genetically modified products to be labeled.