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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

Relevant and reliable data that could be used for classification and PNEC for freshwater aquatic plants other than algae were only available for the duckweed, Lemna minor.  A total of seven studies were identified; EC50s ranged from 19.3-127.2 µg Co/L and the EC10s ranged from 4.9–31.2 µg Co/L; variability is attributed to differences in the characteristics of the test waters. Values for the CSA were geometric means of the available data for the common endpoint of frond count (more sensitive endpoint).

Key value for chemical safety assessment

EC50 for freshwater plants:
52 µg/L
EC10 or NOEC for freshwater plants:
10.4 µg/L

Additional information

Freshwater:

 

From the database of cobalt toxicity to freshwater plants, high quality NOEC and EC10 values are reported for the duckweed, Lemna minor. The following table indicates the high quality EC10 values used for the HC5 and aquatic freshwater PNEC derivation:

 

Table 6.1.5 -3. High quality studies used for derivation of the HC5 and aquatic freshwater PNEC

Key Study

Selected values for the most sensitive endpoints used for derivation of the freshwater HC5

Species

Endpoint

Value (µg Co/L)

Heijerick et al, 2007

Lemna minor (duckweed)

Growth rate

EC50: 90.1

EC10: 4.9

OSU 2017a

 Lemna minor (duckweed)

 frond count

EC50: 127.16

EC10: 31.2

EC50: 19.3

EC10: 5.4

EC50 : 51.6

EC10: 7.3

EC50: 43.0

EC10: 7.9

EC50: 106.4

EC10: 15.0

 OSU 2017b

  Lemna minor (duckweed)

 frond count

EC50: 34.3

EC10: 8.7