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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Description of key information

The 18-day NOEC for reproduction in Daphnia carinata was 50 mg/L DTPA.

Key value for chemical safety assessment

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

Additional information

Two chronic freshwater studies with DTPA (free acid) were conducted with Daphnia carinata. Both studies were well documented, however neither exposure with DTPA (free acid) was conducted such that trace elements were supplemented in the test water. Therefore, the observed toxicity of DTPA (free acid) in both studies was likely due to the limitation of essential metals in the test media and not inherent toxicity of the DTPA molecule. In the 1996 study, Daphnia carinatawas also exposed to Fe(III)-DTPA (disodium salt dihydrate) in the same study design, and the observed toxicity was much less as compared to DTPA (free acid). The authors concluded that this was likely due to the fact that when bound to Fe3+, DTPA was less likely to bind up other essential metals in the test media. Upon stoichiometric conversion, the NOEC of 67 mg/L Fe(III)-DTPA disodium salt dihydrate equates to 50 mg/L DTPA (free acid), and this value was used as the chronic value for invertebrate toxicity, since the observed toxicity (based on reproduction inD. carinata) was likely due to inherent toxicity of the molecule and not the chelation of essential metals.