Compounds containing cyanide can be found in some fruit pit kernels and some other foods as well.
Even cabbage, broccoli and cauliflower contain cyanide compounds, but not enough to make them unsafe.
Too many fruit pits can add up to a real risk, however.
Apricot pits, for example, contain a compound called amygdalin, the supposedly active ingredient in laetrile, the discredited cancer drug.
Amygdalin is a member of the class of chemicals called cyanogenic glycosides, meaning that it can be broken down into cyanide, glucose and benzaldehyde by an enzyme.
A study of the toxicity levels of peaches and apricots clearly shows that thirteen to fifteen raw peach pit kernels could be lethal for adults.
For apricots, the toxicity varies widely in a tenfold range, depending on variety.
The wild apricot is highest, and some are quite low, but for a variety in the middle level of toxicity, about seventeen to twenty kernels could be lethal. No one has survived eating more than thirty-eight.
For children, as little as around 15 percent of the adult level could be lethal.
Apple seeds contain some cyanide, about a quarter as much as peach pits for the same weight.
They are very small compared with peach kernels, but eating a cupful of apple seeds has caused cyanide poisoning. The occasional consumption of an apple seed or two is not a problem.
As for toxicity to wildlife, species differences are wide, and it is important not to translate human data to animals, or vice versa.
In a study of rats, for example, they were found to be far more resistant than humans to apricot pits.