Elevated PCDD/F Levels and Distinctive PCDD/F Congener Profiles in Free Range Eggs

For the purposes of this research, scientists collected 6 free-range and 12 regular eggs from farms and markets throughout Taiwan. After testing the eggs for dioxins, researchers found that all of the free-range egg samples had higher PCDD/F levels than the caged egg samples. In fact, the free-range eggs contained 5.7 times higher levels of PCDD/Fs than regular eggs.

Reports suggest that the hens may be the source of the PCDD/Fs and that they may transfer these compounds to their eggs. PCDD/Fs likely enter the eggs after oral ingestion by the adult hens, and then accumulate in the egg fat.

The free-range samples collected from farms close to the seaboard may have increased levels of PCDD/Fs which come from emissions from incinerators and factories with combustive processes. In mountain areas, the likely source of the PCDD/Fs could be from the farm-related activities and the uncontrolled burning of grass. Free-range chickens have a greater chance to run outside and ingest soil containing PCDD/Fs, which is at least party responsible for the higher levels detected.