Just in time for Valentine's Day, a California consumer watchdog group filed legal notices last week demanding that many of the big chocolate firms post warnings on packages showing their products contain high levels of lead and cadmium.

As You Sow, an Oakland nonprofit, says single servings of 26 products it tested (three times) had more of the two harmful heavy metals than allowed under the Golden State's Proposition 65 toxic-chemical warning law.

Overexposure to lead can cause health problems, including lowering children's IQ. Cadmium, a carcinogen, can cause kidney damage.

The chocolate companies, and the association that represents them, dispute all this, saying there are, at worst, trace amounts of lead and cadmium in chocolate from natural sources and that regulators have rejected this argument before.

However, in a 2005 study, Russ Flegal and colleagues concluded the lead in chocolate was not from natural sources, but from the manufacturing. They believed the beans might be collecting lead pumped into the atmosphere by the use of leaded gasoline in Nigeria, whose beans they tested.

Surveys have repeatedly listed lead concentrations in chocolate products among the highest of all foods, he said. - Washington Post