contrary to popular belief, paying a 1 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 2（污染物） than regular eggs. their findings appear in acs' bi-weekly 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（限制，禁闭） cages. demand for eggs from free-range chickens has increased 3 due to their supposed better nutrition（营养） 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 4 substances（有毒物质） that are produced as by-products of burning waste. also known as dioxins（二恶英） , 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 5 the eggs for their content of dioxins. taiwan, they note, is a heavily populated, industrialized island with many of the municipal（市政的） incinerators（焚化炉） 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.
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