If you're prepared to pay a premium for free-range eggs because you think they're healthier, check where they come from. It could be that they carry more toxins than the cheaper, regular egg, as researchers have discovered. Researchers tested free-range and regular eggs from Taiwan, and discovered that the free-range ones had nearly six times the levels of dioxins such as PCDDS and PCDFs, which are by-products of burning waste. The researchers suspect that the chickens being raised in the open air are also picking up more pollutants in the air and in the soil. They point out that Taiwan is a heavily populated and industrialized island that uses municipal incinerators for industrial and domestic waste. Similar levels of toxins may not be seen in free-range eggs from less polluted areas. (Source: Journal of Agricultural and Food Chemistry, 2010; doi: 10.1021/jf100456b).