'Fowl' news: Hints from Taiwan that free-range eggs may be less healthy than regular eggs

Contrary to popular belief, paying a premium price for free-range eggs may not be healthier than eating regular eggs, a new study reports. Scientists found that free-range eggs in Taiwan contain at least five times higher levels of certain pollutants than regular eggs. Their findings appear in ACS' Journal of Agricultural and Food Chemistry.

In the new study, Pao-Chi Liao and colleagues note that free-range chickens are those that have continuous access to fresh air, sunshine, and exercise, in contrast to chickens that are confined to cages. Demand for eggs from free-range chickens has increased steadily due to their supposed better nutrition qualities, including higher levels of certain healthy fats. But scientists suspect that free-range chickens may risk getting higher levels of exposure to environmental pollutants, particularly PCDDs and PCDFs, potentially toxic substances that are produced as by-products of burning waste. Also known as dioxins, these substances may cause a wide range of health problems in humans, including reproductive and developmental problems and cancer.

The scientists collected six free-range eggs and 12 regular eggs from farms and markets in Taiwan and analyzed the eggs for their content of dioxins. Taiwan, they note, is a heavily populated, industrialized island with many of the municipal incinerators that release PCDDs and PCDFs. They found that the free-range eggs contained 5.7 times higher levels of PCDDs and PCDFs than the regular eggs. The scientists suggest that the findings raise concern about the safety of eating free-range chicken eggs.