The eggs do not pose a threat to human health, unless consumed in excessive quantities [GALLO/GETTY]

Thousands of farms across Germany have been ordered closed by the authorities after it emerged that they produced eggs that may be contaminated with dioxin, a toxic chemical.

Operations at about 4,700 farms, mostly in Lower Saxony, have now been halted until it can be proven that the products do not present any danger of contamination.

The decision came amid revelations by Frederic Vincent, a European Commission health spokesman, on Thursday that the affected German products had entered Britain in the form of 14 tonnes of processed products (egg fluid) that are to be used in the preparation of human food.

There is as no evidence, however, that the eggs exported to the UK contain dioxin, he said.

Tests on other eggs produced by the affected farms in Germany have, however, been found to contain up to five times the legal EU limit for dioxin, he said.

He also said that the levels detected do not pose a risk to human health, unless an excessive quantity of eggs or processed egg products are consumed.

Al Jazeera's Paul Brennan, reporting from London, said that given the way in which the food is processed, and the fact that the eggs suspected of being contaminated will have been mixed with uncontaminated eggs, "the risk to the public is actually believed to be rather low".

He said that the egg fluid would likely be used in pastries, custards and other egg-based foods.

Oil mix-up

Earlier this week, German authorities said that up to 3,000 tonnes of animal feed were contaminated with highly toxic dioxin, and then sent to poultry and hog farms. Eggs from the poultry farms were then exported for processing to the Netherlands.

Dioxins are toxins formed by burning waste and by other industrial processes. They have been shown to contribute to higher cancer rates and to affect pregnant women.

The origin of the contamination has been traced to a distributor of oils for animal feed production in the northern German state of Schleswig-Holstein. Oils meant for industrial use in biofuels were distributed instead for animal feed at the site.

German officials are due to brief their EU counterparts in Brussels next week on the status of the contamination. The incident could lead to new EU rules to avoid the mixing of industrial and animal feed oils, Vincent said.

Our correspondent said that the discovery on December 23 of the contamination appears to be "belated", and that questions are being asked of whether the authorities should have been quicker in realising the mix-up had taken place.

Source: Al Jazeera and agencies