Kijlstra A, Traag W A, Hoogenboom L A P
Animal Sciences Group, Wageningen University and Research Centre, 3219 PH Lelystad, the Netherlands.
Poult Sci. 2007 Sep;86(9):2042-8. doi: 10.1093/ps/86.9.2042.
To decrease dioxin uptake by the general population the European Union (EU) has set limits to the dioxin content of many foodstuffs including eggs. Eggs from free foraging chickens are known to have a higher dioxin content compared with confined laying hens, and the question is whether these eggs can adhere to current EU regulations. The aim of the study was to investigate parameters that are involved in the contamination of eggs from chickens raised under organic conditions. Samples from 34 organic farms including soil and earthworm samples were collected between September and December of the year 2003. Dioxin levels were assayed by gas chromatography-mass spectrometry. Various parameters were collected by on farm interviews. Egg dioxin content varied between 0.4 and 8.1 pg of toxic equivalents (TEQ)/g of egg fat with a mean of 2.2 pg of TEQ/g of egg fat. Nine out of 34 farms exceeded the EU limit of 3 pg of TEQ/g of egg fat. In addition, dioxin-like polychlorinated biphenyls (DL-PCB) were measured, and 8 samples exceeded the limit for the sum of dioxins and DL-PCB. Overall, egg samples from 10 farms were noncompliant with the dioxin or total TEQ limits. No statistically significant relation could be observed between egg dioxin levels and the concentration observed in soil or earthworms. A statistically significant association was observed between flock size and egg dioxin and DL-PCB content. This effect is most likely attributable to the fact that flock size is related to the time chickens spend outside. Restricting outdoor run use on one of the farms resulted in a decrease of the egg dioxin content to a level that was within the EU limits. This demonstrates that the most likely contamination source is the soil or soil organisms but that the behavior of the hens determines the extent of the contamination. Following the completion of this study, a dioxin monitoring protocol has been set up in the Netherlands to prevent marketing of eggs with raised dioxin levels.
为降低普通人群对二恶英的摄入量，欧盟对包括鸡蛋在内的多种食品的二恶英含量设定了限制。与笼养产蛋母鸡相比，自由觅食鸡所产鸡蛋的二恶英含量更高，问题在于这些鸡蛋是否能符合欧盟现行法规。本研究的目的是调查有机饲养条件下鸡所产鸡蛋受污染涉及的参数。2003年9月至12月期间，从34个有机农场采集了包括土壤和蚯蚓样本在内的样品。采用气相色谱 - 质谱法测定二恶英水平。通过农场访谈收集了各种参数。鸡蛋二恶英含量在0.4至8.1皮克毒性当量（TEQ）/克蛋黄脂肪之间，平均为2.2皮克TEQ/克蛋黄脂肪。34个农场中有9个超过了欧盟规定的3皮克TEQ/克蛋黄脂肪的限值。此外，还测定了二恶英类多氯联苯（DL - PCB），8个样品超过了二恶英和DL - PCB总量的限值。总体而言，10个农场的鸡蛋样品不符合二恶英或总TEQ限值。在鸡蛋二恶英水平与土壤或蚯蚓中观察到的浓度之间未发现统计学上的显著关系。在鸡群规模与鸡蛋二恶英和DL - PCB含量之间观察到统计学上的显著关联。这种影响很可能归因于鸡群规模与鸡在户外停留时间有关这一事实。在其中一个农场限制户外活动区域的使用，导致鸡蛋二恶英含量降至欧盟限值以内。这表明最可能的污染源是土壤或土壤生物，但母鸡的行为决定了污染程度。本研究完成后，荷兰已制定了二恶英监测方案，以防止销售二恶英含量升高的鸡蛋。
