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EC number: 204-506-4 | CAS number: 121-91-5
Short-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
Description of key information
No studies are available on the short-term toxicity of the free acid form of isophthalic acid to freshwater invertebrates, however a reliable (Klimisch 1, guideline- and GLP- compliant) study addresses the short-term toxicity of its structural analogue terephthalic acid.
In this study (Government of Japan, Ministry of the Environment, 2003b), Daphnia magna were exposed to high purity TPA (free acid), dosed from a stock solution prepared with DMSO, at a concentration intended to approximate to TPA's aqueous solubility limit (ca. 17 mg/L at 25 degrees C):
D. magna 48 -h EC50 (semi-static): >20.1 mg TPA/L, 96 -h NOEC: 20.1 mg TPA/L.
This endpoint is a mean measured value and represents the maximum limit concentration achievable under the test conditions. It demonstrates an absence of toxicity at concentrations up to the solubility limit of TPA in water. Based on read-across, the same is considered to apply to IPA, at the corresponding, higher solubility limit of ca. 120 mg/L at 25 degrees C.
Support for this proposition is provided by another study (Knacker et al., 1993b, Klimisch 1) in which D. magna were exposed to IPA following conversion to its sodium salt(s). Daphnia were exposed to IPA following its treatment with NaOH solution, and exposure in this study was consequently to sodium isophthalate. No toxicity was observed under these conditions:
D. magna 48 -h EC50 (static): >952 mg IPA-equiv/L, 96 -h NOEC: 952 mg IPA-equiv/L.
These endpoints are mean measured values that represent the highest concentration applied and demonstrate the low intrinsic toxicity of the isophthalate moiety.
Isophthalic acid and its more environmentally relevant isophthalate sodium salt exhibit very low short-term toxicity to freshwater invertebrates.
Key value for chemical safety assessment
Additional information
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