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Long-term toxicity to aquatic invertebrates

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Description of key information

This information will be submitted later based on ECHA communication number CCH-D-2114483442-48-01/D.

Key value for chemical safety assessment

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Data directly evaluating the long-term adverse effects of mono-, and di-(sec-hexadecyl)naphthalene to the freshwater invertebrate, Daphnia magna, are not available. However, there are data for a structurally related alkylnaphthalene, MCP 2395 (i.e, C20 -alkylated naphthalene analog) for read-across assessment. Justification for read-across stems from the fact that MCP 2395 (naphthalene, 1-methylnonadecyl) is a related C20 alkylnaphthalene structural analog of the study substance (mono-, and di-(sec-hexadecyl)naphthalene) and because of their close structural similarities (C16- versus C20- alkyl group) and expected similar properties. Physical-chemical properties like water solubility are expected to be very low for both these two long-chain alkylated naphthalene substances. Read-across effects on Daphnia magna are expected to be similar owing to the expected very low water-solubility and bioavailability for these related alkylated naphthalene materials (four carbon difference between the two materials).


The chronic toxicity of MCP 2395 as measured by the reproductive capacity of the water flea , Daphnia magna, was evaluated in freshwater. Relative to controls, the test material did not cause adverse effects to the survival/immobilization and reproduction of Daphnia magna under the WAF conditions of the 21-day test and such effects are not expected at its maximum water solubility. The 21-day LL50 (survival/immobilization) and the 21-day EL50 (reproduction) was estimated to be greater than 103 mg/L (limit test). The 21-day NOEL loading for reproduction was greater than 103 mg/L WAF.


Hence, based on the read-across data for the structurally related alkylated naphthalene surrogate, the study substance, namely, mono-, and di-(sec-hexadecyl)naphthalene, is not expected to cause chronic toxicity to invertebrates at its maximum water solubility limits (if tested under WAF conditions). 

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