Tricobalt tetraoxide

Long-term toxicity to aquatic invertebrates

Description of key information

Relevant and reliable data used for the determination of a PNEC for the freshwater and marine environments were retrieved for 13 different species: Aeolosoma sp. (oligochaete), Daphnia magna (cladoceran), Hyalella azteca (isopod), Lymnaea stagnalis (snail), Ceriodaphnia dubia (cladoceran), Chironomus tentans (midge), Brachionus calyciflorus (rotifer), Mytilus edulis (mussel), Mysidopsis bahia (mysid), Neanthes arenaceodentata (marine annelid), Dendraster excentricus (sand dollar), Stronglyocentrotus purpuratus (sea urchin), and Crassostrea sp. (pacific oyster). Tests followed international accepted guidance and were based on measured levels of dissolved cobalt as cobalt dichloride. Values ranged from 1.4 to 6314 µg Co/L for the freshwater species and 206 to 2763 µg Co/L for the marine species.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

7.55 µg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

206 µg/L

Additional information

Freshwater:

 

From the database of chronic cobalt toxicity to freshwater invertebrates, 84 individual EC₁₀ or NOEC values for 7 different individual species were reported. The NOEC/L(E)C10 ranged from 1.4 µg/L to 45 µg/L for Ceriodaphnia dubia exposed to a range of water types (CDI 2010i).

 

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

	Species	Endpoint	Value (mg Co/L)
Heijerick et al. 2007;	Hyalella azteca	Growth rate	7.55
CD1 2005; OSU 2020; OSU 2013; OSU 2016; OSU 2017	Ceriodaphnia dubia	Reproduction	14.3 (Geomean)
Heijerick et al. 2007; OSU 2017	Lymnaea stagnalis	Growth rate	EC10: 39.4 EC10: 14.6 EC10: 24.8 EC10: 16.8 EC10: 9.61
Heijerick et al. 2007; Stubblefield and de Schamphelaere 2014	Daphnia magna	Reproduction	59.1 (Geomean)
CDI 2008	Aeolosoma sp.	Population	155
Pacific EcoRisk 2005	Chironomus tentans	Survival	167
OSU 2017	Brachionus calyciflorus	Growth rate	857 (Geomean)

Marine:

From the database of chronic cobalt toxicity to marine invertebrates, NOEC or EC10 values are reported for 6 species. The NOEC/L(E)C10 values range from 206 µg Co/L for reproductive effects with the marine annelid, Neanthes arenaceodentata (CDI 2010j) to 2763 µg Co/L for the developmental endpoint with the oyster, Crassostrea sp (CDI 2010e). 

The table below represents the EC10 values of high quality studies used for the derivation of HC5 and aquatic marine PNEC

 

Table X. High quality studies used for derivation of the aquatic marine HC₅and PNEC

	Species	Endpoint	Value (mg Co/L)
Lehman, 2010	Mysidopsis bahia (mysid)	neonatal total young	219
CDI, 2010j	Neanthes arenaceodentata (marine annelid)	reproduction	206
CDI, 2010d	Mytillus sp. (mussel)	proportion normal	1656
CDI, 2010f	Dendraster excentricus (sand dollar)	proportion normal	968
CDI, 2010g	Stronglyocentrotus purpuratus (sea urchin)	proportion normal	1786
CDI, 2010e	Crassostrea sp (pacific oyster)	proportion normal	2763

Efforts have been ongoing to characterize the influence of fresh water quality parameters on the toxicity of cobalt to the cladoceran, Ceriodaphnia dubia. Because water quality parameters (e.g., hardness, pH, dissolved organic carbon, etc.) have effects on the bioavailability and subsequent toxicity of metals to aquatic organisms, Biotic Ligand Models (BLMs) have been developed for certain organisms. NOEC/EC10 values for Ceriodaphnia dubia were used to develop these models.