Fipronil is a broad-spectrum insecticide for control of external parasites, used to combat and prevent fleas and ticks e.g. on dogs and cats also in Finland. Fipronil can also be used in biocidal products for pest control in specifically restricted applications. It is not authorised in Finland or anywhere else in the EU for use on production animals, such as egg laying hens.

Fipronil was in the summer of 2017 found in Central Europe in eggs. It is suspected that companies specialising in pest control have added it in an anti-tick product used on egg laying hens to improve the effectiveness of the product.

The German risk assessment authority, Bundesinstitut für Risikobewertung (BfR), has assessed the effects of fipronil on health when it is found in foods of animal origin. The highest fipronil concentration measured in eggs in connection with this incident could cause acute adverse health effects to children. This does not necessarily mean, however, that adverse effects will occur. In practice there is no risk for other consumer groups.

The properties of fipronil and its metabolic and decomposition products have been assessed on the basis of e.g. animal tests. The adverse effects found in animal tests have only occurred with considerably higher fipronil levels and after longer exposure than in this incident. Fipronil has not been shown to be carcinogenic to humans. In case of a high intake of fipronil or prolonged exposure, harmful effects can be caused to the central nervous system and the liver, for example.