Eggs are the most important part of our Easter menu. Not so long ago they were considered a little bit unhealthy (generally due to the cholesterol content), nowadays we can finally appreciate their nutritional value, especially complete protein. Not everyone, however, is aware that eggs can contain heavy metals. On the occasion of Easter we decided to test various sorts of eggs and check if we can find something unusual in them.
First question we could ask is obviously: where do heavy metals in eggs come from? In spite of appearances it is no surprise. Eggs can be laid by hens which are kept near roads. More likely to contain heavy metal are eggs from free-range hens than those from deep litter indoor housing or battery cage farming (although it is believed that the former ones are more tasty and healthy).
Why these are the free-range hens which lay eggs containing more heavy metal?
Because since they walk along roads or live near factories, they are exposed to eating plants polluted by heavy metal compounds. In turn, heavy metals in plants come from the soil, in which they, for instance lead, accumulate. It is enough to exceed the norm of heavy metals in eggs and meat of such hens.
To perform the test we used three types of eggs: the first ones come from a well-known supermarket (deep liter housing), the other ones from Subcarpathia region and the last ones from Opole Voivodeship.
The results are not surprising: eggs from free-range hens contain an amount of heavy metal which exceed the norm.
In the eggs from Subcarpathia there was observed an increased concentration of tin and iodine. The amount of both elements, however, is not harmful for human health.
Subcarpathian eggs contained also trace amount of tungsten and lead. Concentration of lead was slightly increased.
As we know, lead is poisonous and the effects of poisoning appear usually after body accumulates a significant amount of it. Lead on the roads and in the soil near roads is a result of exhaust fumes. Nowadays, despite unleaded petrol being widely used, it is generally lead which has been being accumulated in the soil for years. It will stay in the soil for a long time.
Fortunately, the amount of tungsten and lead in Subcarpathian eggs should not cause damage neither to our health nor to well-being. Concentration of the elements does not exceed the norms, thus, there is no need to worry unless we plan to eat an enormous number of eggs during Easter.
In eggs from Opole Voivodeship we observed also an increased concentration of iodine, as well as lead and thallium. As in the case of Subcarpathian eggs, the possible cause is free-range farming close to the roads, where soil contains accumulated lead.
It is interesting that deep litter indor housing eggs from supermarket do not contain an increased concentration of any of the given elements. Therefore we can be almost certain that the presence of heavy metals in the eggs is cause by the place where hens live and eat.
COMPARING THE EGGS
Subcarpathian eggs contain the highest level of tin, whereas the highest level of iodine can be observed in supermarket eggs. The eggs marked red are from the supermarket, the eggs marked green – from Subcarpathia, and the eggs marked blue are from Opole Voivodeship.
One should remember that tin isn’t very toxic and that it does not accumulate – on the contrary to other metals – in human body, thus, it does not affect health. Obviously, excessive intake of tin may cause side-effects (for instance, changes in the nervous system). However, we should have intaken really much of the element to make it affect our health. The same applies to iodine: it should not affect our health and well-being in any way.
As for the concentration of lead, the highest level of it has been observed in Opole Voivodeship eggs, the lowest – in the supermarket eggs. The latter ones do not contain also thallium. An increased concentration of lead in Opole Voivodeship eggs suggests that those eggs were grazing probably too close to a road.
In turn, Subcarpathian eggs contain the highest level of tungsten and a trace amount of rhenium. The lowest level of tungsten was observed in the eggs from Opole Voivodeship.
Mercury has not been observed in any of the tested eggs.
HEAVY METALS IN EGGS
The presence of heavy metal in eggs is caused mainly by the manner of feeding and breeding the hens. As we can see, eggs from deep litter indoor housing contain the lowest amount of such elements, whereas free-range eggs contains more heavy metals. However, we must remember that amount of such metals contained by egg is not dangerous for our health and should not lead to overdose or poisoning. Thus, we have no reason to worry.