Editor's note: This is the third in a four-part series covering Moms Across America's testing results for the top U.S. fast food restaurants. Part 1 reported on antibiotics and hormones. Part 2 reported on pesticides. Part 3 reports on heavy metals. The fourth part will address nutrition.

Kids are consuming harmful amounts of heavy metals when they eat fast food, according to the nonprofit Moms Across America's (MAA) report on heavy metals in foods sold by the U.S.' 20 top-selling fast food restaurants.

One hundred percent of the samples tested by MAA contained "alarming" levels of lead and cadmium, and roughly 93% of samples contained detectable levels of arsenic, according to the test results.

The nonprofit tested fast food because many Americans eat fast food and some fast food chains supply school lunches.

The MAA testing found food with lead levels nearly 5 times the U.S. Food and Drug Administration's (FDA) daily maximum for kids. According to the FDA, "Lead is toxic to humans and can affect people of any age or health status.