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Long-term toxicity to fish

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Description of key information

The lowest reliable NOEC for chronic toxicity to freshwater fish is 1.13 mg Sb/L for Pimephales promelas. (Kimball, 1978). No valid chronic studies with marine fish have been identified.

Key value for chemical safety assessment

Additional information

Two studies are considered to be valid (Kimball, 1978 and LeBlanc and Dean, 1984). However, only Kimball can be used to derive a PNEC since the NOECs reported by LeBlanc and Dean are unbounded.

LeBlanc and Dean (1984) exposed eggs from Pimephales promelas in a flow-through system, using two replicates, with five concentrations (range: 0.6 - 7.5 µg Sb/L) and two controls (one regular and one vehicle control (HCl)), with each replicate comprising 55 eggs. The tests were performed in well water with a hardness of 28-40 mg CaCO3/L. Since there were no statistically different effects (endpoints: mortality, larvae lengths and weights) when compared to the control, even at the highest concentration used (7.5 µg Sb/L), the resulting unbounded NOEC value was > 7.5 µg Sb/L.

A chronic test performed by Kimball (1978) used embryo-larvae of Pimephales promelas in a flow-through system, with four replicates and six concentrations (range: 0.52 – 19.11 mg Sb/L) and a control, with each group comprising 20 eggs. The tests were performed with hard well water. The lowest resulting NOEC from this study, using reduction of length as an indicator of toxicity, is 1.13 mg Sb/L. This value is also the lowest valid NOEC for freshwater fish from long-term toxicity tests.

There are studies by Birge and co-workers (Birge, 1978; Birge et al., 1980), which report NOECs below 1.13 mg Sb/L. However, even though these studies are well performed, with measured test concentrations etc., neither of them are considered to be valid. The reason for this is that the test concentrations used are never reported, which makes it impossible to determine whether the calculated NOEC values are included in the tested concentration range.

The rationale for discarding the results from Doe et al.(1987) on Oncorhynchus mykiss is already provided in the section on acute fish toxicity.