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EC number: 200-909-4 | CAS number: 75-86-5
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
Description of key information
As indicated in the hydrolysis study acetone cyanhydrin hydrolyses rapidly within minutes to acetone and cyanide. The study was performed over 96 hours. Therefore the toxic principle is the cyanide ion. The hydrolysis product cyanide of acetone cyanhydrin is very toxic against the green algae Desmodesmus subspicatus.
Key value for chemical safety assessment
Additional information
As
2-hydroxy-2-methylpropanenitril (CAS-Nr. 75-86-5) hydrolyses within
minutes to form acetone and HCN, the active toxic principle is the
cyanide ion. Therefore it can be extrapolated that
2-hydroxy-2-methylpropanenitril (CAS-Nr. 75-86-5) would exhibit the same
toxicity as potassium cyanide against green algae Desmodesmus
subspicatus. The study classified as acceptable and satisfies the
information needs for toxicity against green algae.The LOEC value based
on cell density (turbidity of the test cultures) was 160 mg
a.i./L. Potassium cyanide (CAS-No. 151-50-8) is very toxic against the
green algae Desmodesmus subspicatus.
These finding are in compliance with the AEGL committee (US-NAC,
Acetone
Cyanohydrin, Interim Acute Exposure Guideline Levels (AEGLs), Interim
final draft, 2005) and ECETOC (JACC report No. 53, Volume I, 2007),
where the toxic effects of acetone cyanhydrin are attributed to the
toxic action of the free cyanide. The principle of cyanide toxicity is
similar in all organisms including micro-organisms. The cyanide ion
reacts with the central metal ion of metallo-enzymes to form cyanide
complexes thus rendering those enzymes non-functional.
Following ECETOC JACC report No. 53, Volume I, 2007 there are only a few
studies providing EC50 values for effects of cyanide on algae. None of
them seems to have been conducted to current or Good Laboratory Practice
(GLP) guidelines. Exposure was static in all tests. Most of the values
are higher than 200 μg/l,
but Krebs (1991) reported an EC50 of 45 μg/l
for oxygen production of Chlorococcales (green algae) and Pablo et
al (1997a) determined an EC50 of 57 μg/l
for the saltwater diatom Nitzschia closterium (Both
not assignable).
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