Key Concerns
Data are available on the toxicity of cobalt to freshwater algae, invertebrates and fish. Seventy two hour EC50 values for growth of an alga (Selanstrum capricornutum) exposed to cobalt in the absence of EDTA range form 0.02 to 0.27 mg/l (Grimwood et al. 1998). Forty eight hour EC50 values for immobilization of Daphnia magna ranged from 1.1 to 1.5 mg/l (Biesinger and Christensen 1972; Khangarot and Ray 1987). Ninety six hour LC50 values for crayfish (Austropotamobius sp. and Orconectes limosus) were 8.8 and 10.2 mg/l, respectively, with corresponding 30 day LC50 values of 0.8 and 0.9 mg/l (Boutet and Chaisemartin 1973). LC50 values for various species of fly larvae (Ephemere lla subvaria, Acroneuria lycorias and Hydropsyche betteni) exposed to cobalt for 4 to 8 days range from 16 to 32 mg/l (Warnick and Bell 1969). Ninety six hour LC50 values for fathead minnow (Pimephales promelasi) and a teleost (Colisa fascialatus) were 12.7 to 24.8, and 102 mg/l, respectively (Srivaastiva and Agrawal 1979; Curtis and Ward 1981). No effects on the growth or survival of zebrafish (Brachydanio rerio) were reported following exposure to a cobalt concentration of 2 mg/l for 96 hours (Grimwood et al. 1998).
| Habitat/ Ecosystem Type | Critical Load/ Level | Status | Reliability | Indication of exceedance | Reference |
|---|---|---|---|---|---|
| Freshwaters |
3 µg/l |
Provisional Environmental Quality Standard (EQS) | reliable i.e. a number of published papers of various studies show comparable results |
Guideline value for the protection of freshwater life, expressed as an annual mean. The corresponding provisional Maximum Acceptable Concentration (MAC) was 100 µg/l. |
1169 |