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Short-term toxicity to aquatic invertebrates

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Description of key information

Short-term toxicity to aquatic invertebrates: 
- EC50 (48h) & LC50 (48h) = 4.13 mg/L for Daphnia magna (OECD TG 202)
- NOEC = 1.86 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
4.13 mg/L

Additional information

Two reliable studies are available for this endpoint:

(1) WARD T.J., WYSKIEL D.C. and BOERI R.L. (2003)

(2) STEPHENSON R.R. (1982)

The first study was conducted in accordance with OECD test guidelines 202 and in compliance with OECD (1997) Good Laboratory Practice standards. OECD validity criteria were fulfilled. The concentration of the substance being tested has been recorded and maintained throughout the test; the mean measured concentrations were used to calculate median effective concentration (EC50s).

 

The second study didn’t satisfy all these conditions: GLP compliance is not mentioned in the study report and no analytical monitoring has been performed. Therefore, it was not possible to check that the concentration of the substance has been satisfactorily maintained during the test. 

Based on these observations, the first study is considered as the key study. The second one less reliable can't be considered as supporting study because the EC50 value determined in this study led to a less severe classification (i.e. EC50 = 54 mg/L).

So, only the key study summary is developed below:

The study was performed in 2003 at T.R. Wilbury Laboratories, Inc. to assess the acute toxicity of heptanal to the daphnid, Daphnia magna.

The test was performed for 48 hours under flow-through conditions with five concentrations of test substance at a temperature of 20 ± 1°C. Nominal concentrations of heptanal were: 0 mg/L (control and solvent control), 2.6, 4.4, 7.2, 12, and 20 mg/L. Mean measured concentrations of heptanal were: ND (none detected at or above the limit of quantification; control and solvent control), 1.86, 3.12, 5.10, 9.78, and 13.8 mg/L. These mean measured concentrations, which ranged from 69 to 82% of nominal concentrations, were used in this study to calculate median effective concentration (EC50). Insoluble material was not observed at any tested concentration during the definitive test.

Twenty daphnids (less than 24 hours old) were equally distributed among two replicates of each treatment. During the toxicity test, the numbers of surviving organisms, the occurrence of immobility and sublethal effects, and the presence of insoluble material were determined visually and recorded after 0, 24, and 48 hours.

Exposure of daphnids to heptanal resulted in a 48 hour median effective concentration (EC50) of 4.13 mg/L (95% confidence interval = 3.41 to 4.96 mg/L). The 48 hour no observed effect concentration (NOEC) was 1.86 mg/L. Based on the results of this study, Heptanal is considered as toxic to aquatic organisms tested in accordance with the Directive 67/548/EC.

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