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Short-term toxicity to aquatic invertebrates

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Description of key information

 The 48 hour EC50 for toxicity to aquatic invertebrates is 0.823 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.823 mg/L

Additional information

The acute toxicity of DCPD to Daphnia magna was determined in a GLP-compliant study following OECD guideline 202. Based on geometric mean measured concentrations, the 48 hour EC50 was 0.823 mg/L, with 95% confidence limits of 0.740 to 0.909 mg/L. The test material was prepared as a saturated solution (nominal 10 mg/L) and diluted to give test concentrations of 6.25, 12.5, 25, 50 and 100% saturated solution (corresponding geometric mean measured concentrations were 0.3, 0.57, 1.11, 2.39 and 5.09 mg/L). The study followed a semi-static design, with renewal at 24 hours, and was conducted in a sealed vessel with no headspace.

In the Safepharm Laboratories (1995) study it identified a 48 hour median effect concentration (EC50) of DCPD to Daphnia magna. This was calculated to be 0.62 mg/L with 95% confidence limits of 0.52-0.72 mg/L. The test material was prepared as a solvent stock solution, though the concentration and stability of the test material was not determined.

The MITI study reviewed in the OECD SIDS showed an EC50 of 8 mg/L. The study, which follows OECD 202, with a solubiliser control, was unavailable for review so could not be assessed for reliability. However, as it has been through the regulatory review process, it has been included here as a supporting study. Passino-Reader (1997) is a near guideline study which provides an EC50 of 4.2 mg/L for Daphnia pulex. The study follows ASTM (1980) E728-80 with a solvent control and, though there are restrictions in design and/or reporting, the study is considered adequate as a supporting study. A QSAR result has also been included as a supporting study, which used the ECOSAR program to derive a 48 hour LC50 of 6.4 mg/L.

As a new proprietary study conducted under GLP and to guideline is available for the acute toxicity of DCPD to aquatic invertebrates, this value has been used as the key study for this endpoint. Although a lower result is available, this is taken from a study with no analytical confirmation of the test concentrations and therefore the new proprietary study is considered more robust. The use of the lower result would not change the classification applied or the exposure assessment.