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The eggs from my own chickens are different to the ones they sell in the stores. They are much smaller, have a whiter shell, have less egg white, and the yolk is lighter yellow. They also taste different.

People from the chicken egg industry argue this is due to the fact that because of the battery they use their chicken can't eat each others droppings. Furthermore they claim that eggs from industrial origin contain less dioxin than the ones that 'privately held' chicken produce.

Is this really true? Is it unhealthy to eat non-industrial eggs?

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    Skeptics - Stack Exchange is for challenging unreferenced notable claims, pseudoscience and biased results. Skeptics is about applying skepticism — it is for researching the evidence behind claims you encounter. It is not for speculation, philosophical discussions or investigating original claims. – johanvdw Sep 20 '11 at 13:25
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    @Johanvdw Claim: the industry claims that the battery they use prevents their chickens from eating each other's droppings, which results in less dioxin in the eggs, making the eggs healthier than non-industrial eggs. The skeptical question: is there any real health benefit to eating industrial eggs over privately raised (or, contrarily, is there any increased health risk for eating privately raised versus industrial)? Seems valid to me. – Beofett Sep 20 '11 at 13:34
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    @johanvdw: I want to know if this is true or not, from a scientifical point of view. If statistically proven that industrial eggs are healthier I also want to understand how this is caused. I do not see how you regard this question to be speculation or a philosophical discussion. I also do not understand the difference between "original claims" and "notable claims". I thought it was quite notable. – BaGi Sep 20 '11 at 13:34
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    @Beofett: exactly. Maybe I should rephrase my question to make it more clear. I don't want to know if the eggs from MY particular chickens are healthier of unhealthier, I want to know in general if this is true or not. – BaGi Sep 20 '11 at 13:38
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    @johanvdw: Are you referring to the actual claim of the industry, or the fact that they make this claim? I believe even if a claim is speculation it is still worthwhile to investigate that claim. – BaGi Sep 20 '11 at 14:13
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This post currently has several different claims:

  • The OP claims the taste, size and appearance of the eggs are different. I'm not addressing that claim.

  • "People from the chicken industry" claim that this is because of chickens eating eat others droppings. I'm not addressing that claim because even if it is true (i.e. caged chickens eat less droppings and also that that leads to changes in the egg), I don't see any claim that this makes the eggs dangerous.

  • Finally, there is the main claim: free-range chickens have higher dioxin contamination, which is a safety issue. This is the claim I am addressing.

The dioxin claim is reproduced in this article:

Contamination of free-range chicken eggs with dioxins and dioxin-like polychlorinated biphenyls, Greet Schoeters, Ron Hoogenboom, Molecular Nutrition & Food Research (Special Issue: Dioxins), Volume 50, Issue 10, pages 908–914, October 2006 DOI: 10.1002/mnfr.200500201

In their abstract, first they argue the need for care:

Dioxins and dioxin-like (DL) polychlorinated biphenyls (PCB) are persistent organic pollutants that enter the body mainly by food intake. A small margin exists between current exposure levels in the human population and the levels causing biological effects. Therefore, stringent control of concentrations of these contaminants in food and feed is needed.

Then they claim that free-range chickens are a concern:

Eggs from free-range chicken are increasingly becoming an important part of the diet. These eggs have a higher risk of being contaminated with increased levels of dioxins and DL-PCB than barn or cage eggs. Ingestion of soil particles from environmentally contaminated areas may contribute to elevated dioxin levels in free-range chicken eggs. Available data show that current soil levels of dioxins and DL-PCB in residential and agricultural areas in Europe often appear to be too high to produce free-range eggs with dioxin levels below the current limit values in the EU.

Then they admit that it might not be a concern for the eggs:

On the other hand, polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans concentrations in eggs from free-range chicken are not necessarily above the limit values.

Finally they urge caution:

Contamination levels in soil should be kept low and should be controlled in areas with free foraging chicken although all modifying factors that influence uptake of dioxins and PCB from the environment and transfer into eggs are yet not well understood.

The article is behind a firewall, and the abstract provides no way of seeing how they reached their conclusions. How do we know they are not egg-industry shills?

Well, this paper supports their claims about eggs picking up contaminants from the soil:

F. Schuler, P. Schmid, Ch. Schlatter, The transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans from soil into eggs of foraging chicken, Chemosphere, Volume 34, Issue 4, February 1997, Pages 711-718, ISSN 0045-6535, 10.1016/S0045-6535(97)00463-3

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