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Long-term toxicity to aquatic invertebrates

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Description of key information

The following toxicity values were obtained in a 21d-reproduction toxicity study with tetrahydromethylphthalic anhydride (MTHPA) to daphnia magna:
ErC50(21d) >40mg/L
NOECr(21d) = 20mg/L
LOECr(21d) = 40mg/L

Key value for chemical safety assessment

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

Additional information

The 21-day-chronic toxicity of tetrahydromethylphthalic anhydride (MTHPA) to Daphnia Magna was studied under semi-static conditions in two Daphnia magna reproduction tests (OCED 211).

In a new key study (2010, report no. 556.826.2254), Daphnids were exposed to control and test chemical at nominal concentrations of 1.25; 2.5; 5; 10; 20 and 40 mg test item/L. The performed parallel running analytical determinations confirmed that the test item concentrations remained within the range of ±20 % of the nominal and of the initial concentrations (varied between 94 and 105 % of the nominal concentration). The NOEC was determined as 20 mg test item/L, consequently the LOEC was 40 mg test item/L.

One supporting study (1997, report no. EDR96007) was considered as not assignable (Klimisch 4) as the available study report does not give enough experimental details and analytical measurements are equivocal. In this study Daphnids were exposed to control and test chemical at nominal concentrations of 1.3, 4.1, 13, 41 and 130 mg/L. The 21 day LC50 for parenteral animals was >110 mg/L and the EC50 based on mortality/sublethal effects was 9.2 mg/L.

Both studies revealed comparable LC50 values (> 110 mg/L and > 40 mg/L) and in high concentrations a reduced number of Juveniles. As one study is not assignable (see “rationale for reliability”) and one study (2010, report no. 556.826.2254) satisfies the guideline requirements for a chronic toxicity study with freshwater invertebrates with a state of the art analytics, weight of evidence justifies a NOEC of 20 mg/L for chronic Daphnia toxicity.