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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Link to relevant study record(s)

Description of key information

acute toxicity to freshwater algae: lowest IC50 0.136 mg Zn/l (Selenastrum capricornutum; single value) (neutral/high pH)
chronic toxictiy to freshwater algae: lowest NOEC 0.019 mg Zn/l (Pseudokircherniella subcapitata =Selenastrum capricornutum; geomean of 27 data)
chronic toxicity to marine algae: 12 species available which NOECs range between 0.0078 and 0.67 mg/l (dissolved concentrations)

Key value for chemical safety assessment

Additional information

Acute freshwater toxicity tests of high quality and relevancy performed according to standard protocol. Information is on 1 species which is in both the acute and chronic aquatic database on zinc the most sensitive. The lowest IC50 value is taken as reference value for classification for acute effect at neutral/high pH.

Chronic freshwater toxicity tests of high quality and relevancy according to standard protocol or equivalent. Data on 2 species, one of which the most sensitive of all freshwater organisms, second species is less sensitive.

Chronic seawater tests of high quality and relevancy according to standard protocol or equivalent. Data on 12 species, for which 3 species are in the low part of the species sensitivity distribution. One species of macro-algae is the second most sensitive of all seawater organisms.

ZnO nano

There are a very limited number of studies that could be used for algae because most studies did not compare the nanoform with bulk or other zinc compound. The lowest values are:

-         Acute toxicity freshwater: 0.042 mgZn/l for Pseudokircherniella subcapitata

-         Chronic toxicity freshwater: 0.17 mgZn/l forPseudokircherniella subcapitata

Only one study is present for marine chronic toxicity (Dunaliella tertiolecta) with a value of 0.08 mgZn/l

We can see that values for the nano ZnO are again in the range of those of the bulk or other zinc compounds.