[5] Authorities in the Netherlands were alerted by an anonymous source in November 2016 that fipronil was being used in poultry farms, but failed to communicate the findings.

[6][7] In July/August 2017 millions of chicken eggs were blocked from sale or withdrawn from the market in the Netherlands, Belgium, Germany and France after elevated levels of fipronil were discovered by the Dutch food and product safety board.

[4][9] Early investigation led to two companies: ChickFriend, a provider of pest control services in the Netherlands, suspected of knowingly using and selling DEGA-16 mixed with fipronil to hundreds of chicken farmers, and Poultry Vision in Belgium, accused of selling DEGA-16 mixed with fipronil to ChickFriend.

[10][11] The first results of an investigation by Belgian police led to the discovery of 6 cubic metres (210 cu ft) of fipronil that Poultry Vision had imported from a chemical manufacturing company in Romania.

The Dutch food and product safety board (NVWA) reported that the test results of one batch of eggs originating from one poultry farm in the Netherlands exceeded the threshold of 0.72 mg/kg.