Running to the store to get the latest iPhone? Not so fast, if scientists at the Ecology Center have their way. Scientists recently tested 36 of the most popular smartphones currently on the market -- including the new Apple iPhone 5 -- and found significant levels of lead, mercury, cadmium and other hazardous ingredients linked to brain damage, thyroid problems and learning disabilities. The good news? The iPhone 4 had fewer chemicals than the newest model, which means if your older phone is in good working order, it is a greener and healthier choice.