2-hydroxy-2-methylpropionitrile

Toxicity to terrestrial arthropods

Description of key information

As indicated in the hydrolysis study acetone cyanhydrin hydrolyses in contact with water rapidly within minutes to acetone and cyanide. In this study the arthopods were exposed via the gas phase. Therefore hydrolysis is depending on the air humidity.
The results indicate that the toxic action of the cyanohydrin in insects is due to the combined effects of cyanide ion, the ketone produced by the decomposition of the cyanohydrin, and possibly the intact cyanohydrin molecule. 

Additional information

In a study house flies (Musca domestica) and lesser grain borer (Rhyzopertha dominica) and were fumigated with acetone cyanohydrin. The 24h LC50 for house flies is reported to be 0.07 mg acetone cyanhydrin /L (nominal), for the lesser grain borer 0.40 mg acetone cyanhydrin/L (nominal).
In further studies the concentration of the cyanide ion in the insects after fumigation with acetone cyanhydrin and hydrogen cyanide, respectively at the LC99 effect concentration was determined.
The concentration of cyanide ion was much higher in the house flies exposed to HCN fumigation (680 mgCN^-/g insect body) than in the flies that were exposed to acetone cyanohydrin fumigation (48 mgCN^-/g insect body) or to topical application of acetone cyanohydrin. The concentration of cyanide ion in lesser grain borer was 43 mgCN^-/g insect body after fumigation.
The results indicate that the toxic action of the cyanohydrin in insects is due to the combined effects of cyanide ion, the ketone produced by the decomposition of the cyanohydrin, and possibly the intact cyanohydrin molecule.

According to ECETOC (JACC report No. 53, Volume I, 2007), reportedly 7.1 ppm HCN was the 4h LC50 of Sitophilus grenarius. Another work addressed cyanide metabolism (detoxification) in Sitophilus grenarius and Schistocerca gregaria. Several adults and Larvae of arthropods were exposed to 8.00 mg HCN/m3 in air. Paralysis occurred within 1 – 120 minutes depending on species and stages of development.

Second instar larvae of dengue mosquito (Aedes aegypti) were exposed to concentrations of 0.1, 1.0 and 10 mg NaCN/l in water (0.053, 0.53, 5.3 mg CN^-/l). While 0.053 and 0.53 mg/l did not have visible effects within5 hours, 5.3 mg/l immobilised 50% of the larvae within 43 minutes.