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Long-term toxicity to aquatic invertebrates

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Description of key information

No valid data could be located regarding the long-term toxicity of monoisopropylnaphthalene to aquatic invertebrates.
To compensate for this lack of data, information resulting from diisopropylnaphthalene as supporting substance is used.
Supporting substance diisopropylnaphthalene: in a valid Daphnia magna 21-d reproduction test similar to OECD TG 202, Part II, the NOEC of diisopropylnaphthalene was determined to be 0.013 mg/L (WaBoLu/BGA 1990)
This value is adopted for isopropylnaphthalene and used in assessment of its aquatic toxicity.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
0.013 mg/L

Additional information

For the long-term toxicity assessment of monoisopropylnaphthalene to aquatic invertebrates, valid data could not be identified. Data for diisopropylnaphthalene as supporting substance will be used based on following reasons.

Both substances are closely related. Main structural feature is the two ring polycyclic aromatic hydrocarbon naphthalene. The naphthalene system is substituted with either one or two isopropyl-substituents for mono- and diisopropylnaphthalene, respectively. Chemical properties, metabolism, and toxicological effects will be quite similar. Differences will exist in physico-chemical parameters, as water solubility is somewhat higher and lipophilicity is somewhat lower for the mono-substituted naphthalene. Within their water solubility, the aquatic toxicity of the two substances should not be affected by these differences in a substantial way. Thus, it is justified to use diisopropylnaphthalene as supporting substance in the evaluation of the long-term toxicity of monoisopropylnaphthalene to aquatic invertebrates.

Supporting substance diisopropylnaphthalene

WaBoLu/BGA 1990

Diisopropylnaphthalene was tested on the water flea Daphnia magna in a 21-d acute immobilization test similar to OECD TG 202, Part II (1984) under semi-static conditions at concentrations of 0 (control), 0.002, 0.003, 0.006, 0.013, 0.025, 0.050, 0.100, and 0.200 mg/L. Mortality (immobilisation) and reproductive rate were observed for 21 days and the date evaluated by statistical analysis.

The 21-d NOEC (reproduction rate and mortality) was determined to be 0.013 mg/L (WaBoLu/BGA 1990).

This value is adopted to characterise the aquatic toxicity of isopropylnaphthalene. It will be used in derivation of PNECs.