The European Food Safety Authority (EFSA) has said it is unlikely that there is a health risk from cyanogenic glycosides in foods other than raw apricot kernels.

Traces of naturally-occurring compounds called cyanogenic glycosides can be present in some foods and be converted into cyanide after eating.

EFSA’s panel on Contaminants in the Food Chain (CONTAM) launched a public comment period on the draft scientific opinion. This is open until Jan. 25, 2019.

The work is a follow-up to the 2016 scientific opinion on the acute health risks from cyanogenic glycosides in raw apricot kernels which established an acute reference dose (ARfD) of 20 µg/kg body weight (bw) for cyanide.

In the latest opinion, the ConTAM panel concluded this ARfD was applicable for acute effects of cyanide regardless the dietary source.

Cyanogenic glycosides contain chemically bound cyanide and are present in almonds, linseed and cassava. When plant cells are damaged, by grinding or chewing, these compounds and their degrading enzymes are brought into contact and cyanide is released.

The panel said for foods other than raw apricot kernels, bitter almonds and cassava roots, this ARfD is likely to be over-conservative but different doses for other types of food was not appropriate.

The acute lethal oral dose of cyanide in humans is reported to be between 0.5 and 3.5 mg/kg bw. Signs of acute cyanide poisoning include headache, vertigo, agitation, respiratory depression, metabolic acidosis, confusion, coma, convulsions and death. Poisoning cases, some fatal, have resulted from ingestion of amygdalin preparations, bitter almonds and cassava.

As many as 2,586 analytical results on total cyanide in foods were available in the EFSA database – of which about 89 percent came from Germany – to estimate acute and chronic dietary exposure.

Highest occurrence values were in bitter almonds (mean concentration 1,437 mg/kg) and in linseed (mean concentration 192.1 mg/kg). No occurrence data was available for cassava and derived products.

Estimated acute and chronic exposures to cyanide from foods containing cyanogenic glycosides across different dietary surveys and all age groups ranged from 0.0 to 13.5 µg/kg bw per day.

The highest acute and chronic exposures were estimated for infants, toddlers and other children and the main contributors to acute and chronic exposure to cyanide in all age groups were biscuits (cookies), Juice or nectar from fruits, and Pastries and cakes.

For raw cassava root, containing 235 mg total cyanide/kg, the ARfD is reached by consumption of 0.7 gram – 8.5 gram depending on the body weight of the individual. For cassava flour back-calculations show that, depending on body weight, consumption of 17 gram – 200 gram leads to an exposure equivalent to the ARfD.

Depending on body weight of the individual, consumption of 1.3 gram – 14.7 gram of ground, linseed containing cyanide at the highest level found in the database, reaches the ARfD. Depending on body weight of the individual, consumption of 0.1 – 1.4 g bitter almonds, containing the highest level found, hits the ARfD.

Assuming that marzipan or persipan contain the maximum limit (ML) of 50 mg CN/kg and depending on body weight, consumption of 42 gram – 480 gram could reach the ARfD. Depending on body weight, consumption of 35 gram – 400 gram canned stone fruits, with the ML of 5 mg CN/kg, leads to an exposure equivalent to ARfD. For stone-fruit marc spirits and stone-fruit spirits, containing 35 mg total CN/kg, the ARfD is reached by consumption of 26 gram – 57 gram, depending on body weight of the individual.

The panel made a number of recommendations including the need for occurrence data for cyanide for raw and processed food commodities CNGs or cyanide; consumption data for foods from cyanogenic plants, such as cassava root and leaf products on the EU market and validated methods to quantify cyanogenic glycosides; and total cyanide in different foods.

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