These undesirable substances are chemicals such as nitrite, the substance addressed in the last of the 30 opinions just published; they can occur naturally, or result from environmental or other contamination in the feed and food chain. The elimination of undesirable substances in feed is not always possible, but it is important to reduce their presence in order to avoid endangering animal health, human health or the environment.

Maximum levels of undesirable substances in animal feed are listed in Annex I of the EU Directive 2002/32/EC and are being updated based on EFSA’s individual assessments. Feed containing amounts of undesirable substances above the maximum levels may be unsafe and must be withdrawn from the food chain.

The 30 opinions published over the last 5 years covered natural plant products (such as gossypol and theobromine), persistent organic pollutants (such as DDT and hexachlorobenzene), heavy metals (such as arsenic and mercury), fluorine and mycotoxins (such as aflatoxin B1).

In most cases, the CONTAM Panel identified no risks to animal health resulting from feed intakes at the maximum authorised levels, provided good animal feeding practices are followed. However, adverse effects on animal health could not be excluded for some substances, such as deoxynivalenol in pigs, mercury in cats, gossypol in sheep and theobromine in dogs and horses.

The risks of adverse human health effects due to the presence of undesirable substances in products of animal origin – such as fresh meat, eggs and milk – were generally found to be low but in some cases EFSA recommended reducing their presence, in particular for persistent organic pollutants such as camphechlor.

The need for further research was identified for several substances, and in particular regarding the extent to which the presence of these substances in feed may lead to the contamination of foods of animal origin.

EFSA’s work on undesirable substances has supported the European Commission in several ways. For example, the Commission implemented a recommendation setting out guidance values for the monitoring of mycotoxins in feed, which took into account the opinions on deoxynivalenol, zearalenone, ochratoxin A and fumonisins. Furthermore, based on the conclusions of EFSA’s opinions, the Commission has lowered the maximum levels of certain substances in feed (e.g. lead), increased some levels to take into account new processing techniques – for example to improve nutritional quality (e.g. fluorine) – and introduced maximum levels for other products intended for animal feed, previously not covered (e.g. cadmium in trace elements). Some plant species have been deleted from the list of undesirable substances in feed (e.g. apricots and bitter almonds containing cyanogenic glycosides). Changes in the legislation to take account of the most recent scientific opinions i.e. gossypol, mercury and theobromine, are currently ongoing.