Millions of eggs are being recalled from shops and warehouses in Germany, the Netherlands and Belgium after they were found to contain high levels of a toxic insecticide banned from use in the production of food for human consumption.

In large quantities, the substance is considered to be “moderately hazardous” according to the World Health Organisation, and can have risky effects on people’s kidneys, liver and thyroid glands.

Dutch food safety watchdog NVWA published a list this week of the serial numbers of eggs that were deemed unsafe, with one specific range of eggs labelled as an acute health hazard.

The insecticide, manufactured by Germany’s BASF among other companies, is commonly used in veterinary products to get rid of fleas, lice and ticks.

“Affected farms must have all eggs destroyed by a specialist firm and submit to the NVWA a plan to evacuate the birds’ droppings to preserve the environment”, a spokesman said.

Late Monday, the NWVA sent out a warning to consumers that eggs with X-NL-4015XX stamped on them had dangerously high levels of the insecticide.

The origin of the case, the breeders of poultry in the netherlands have appealed to Chickfriend, a company specialized to eradicate the proliferation of sea lice red, a parasite that is very harmful for the chickens.

Chickens can remain contaminated for between six to eight weeks.

The night before, the grocery store chain Rewe and its discount subsidiary Penny had announced that they would be removing all eggs from the Netherlands from supermarket shelves.

Erik Hubers from the Dutch agricultural and horticultural association said a suspect company linked to the scandal may have mixed the illegal substance with a legal one to improve its effectiveness.

Amid fears the Dutch poultry industry could be facing millions of euros in losses, the country’s biggest supermarket chain Albert Heijn said it was pulling 14 types of eggs from its shelves.

Chickfriend could not be reached for comment on Tuesday, with all calls from AFP going to an answering machine with a message saying the company was closed “for professional reasons”.

Over the weekend it was reported that contaminated eggs had been confirmed at 28 packing centers in the Netherlands, as well as at one center over the border in the western German state of North Rhine-Westphalia. “We won’t sell Dutch eggs until they are proven free of fipronil”, REWE said.

“The contaminated eggs have been traced and withdrawn from the market and the situation is under control”, EU Commission Spokeswoman Anna-Kaisa Itkonen said.

The Dutch daily newspaper De Volkskrant reported that the illegal mix had been used on farms in the Netherlands for over a year.