June 21, 2010


Taiwan study shows that free-range eggs contain more dioxins


A recent study from Taiwan found that eggs from free-range chickens contained nearly six times higher levels of dioxins than conventional eggs.


Dioxins, a typical by-product of burning waste, have been linked to cancer and reproductive issues in humans. The diet of caged chickens can be tightly controlled, providing a perfect balance of nutrients and supplements. More freedom, on the other hand, appears to expose chickens to more environmental pollutants. 


The researchers in Taiwan cautioned that their study sample was small and conducted in a heavily populated area, near municipal incinerators. Even so, it is clear that care should be taken to raise animals on toxin-free land. Otherwise, these toxins can be magnified through the food chain. Chickens do not roam far from their roosting area either, so the ground can quickly become depleted of nutrients, mud-packed and covered in faeces. Some farmers solve this problem by periodically moving enclosures from one pasture to another.


Maintaining genetic diversity may also help. In 2008, researchers from the UK found a link between healthy chickens and a diverse population. They concluded that a free-range lifestyle is not a major source of infection, contrary to the concerns of non-organic poultry farmers.


Previous studies have found no difference between free-range and caged chickens in terms of infectious disease. In 2004, a USDA study found salmonella in a quarter of all chickens in the market - caged, free-range and organic alike. The researchers also found no difference in nutritional value between free-range eggs and conventional eggs.