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Long-term toxicity to aquatic invertebrates

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Description of key information

No toxic effects occur at the range of solubility.
NOEC(overall effects) >=1 mg/L ( which is far above the water solubility)

Key value for chemical safety assessment

Additional information

Assessment of the parent compound Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-,C7-9-branched alkyl esters (CAS: 125643 -61 -0)

The chronic effects of Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-,C7-9- branched alkyl esters towards Daphnia magna were tested in two GLP-guideline studies according to OECD guideline 211.

In the first study (RCC 2000) a filtrate of supersaturated emulsion with a loading rate of 100mg/L test item was prepared. The undiluted filtrate and the dilutions 1:3.2, 1:10, 1:32 and 1:100 were tested. No auxiliary solvent or emulsifier was used.

At the start of the test medium renewal periods, the test item concentration in the analyzed test medium (the undiluted filtrate of the supersaturated emulsion) was below the limit of quantification of 0.03 mg/l.  


Taking into account the survival rates and the reproduction rates of the test animals, the dilution 1:3.2 was the highest treatment of Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-,C7-9-branched alkyl ester tested without toxic effects after the exposure period of 21 days (21 -day NOEC). The undiluted filtrate with a loading rate of 100mg/L was the lowest treatment tested with toxic effects (21 -day LOEC) due to the significant mortality rate and due to the statistically significantly reduced mean reproduction rate of Daphnia magna.

A NOEC equal to a dilution of 1 : 3.2 of the undiluted filtrate (loading rate 100mg/L) was derived from this study.


As the substance is a liquid uvcb substance consisting of homologous structures with a very low water solubility of 0.0005 mg/L no details could be given on the concentration of the substance causing no effects besidesdilution 1:3.2 of filtrate with a loading rate of 100mg/L.

For this reason a second test with a similar study design and lower loading rate of 1mg/L was performed (BASF SE 2012).

A saturated test solution with a loading rate of 1 mg/L was prepared. No vehicle was used and no analytical monitoring was conducted.

No significant mortality (21 d EC01 mg/L) or any adverse effects on reproduction or additional endpoints (i.e. growth, immobile young, time to first brood, or aborted eggs) were observed.

The 21-day effect concentrations in Daphnia magna were obtained based on loading rate (nominal concentration):

LOEC / LOELR                  >         1mg/L          

NOEC / NOELR                 >=        1mg/L          

From these tests it can be concluded that the NOEC Daphnia 21 days is above the solubility. No toxic effects occur in the range of solubility.

Supporting assessment of the impurity Metilox (CAS 6386-38-5)

In a long-term toxicity to aquatic invertebrates test with Daphnia under semi-static conditions, the NOEC based on reproduction was 0.123 mg/L based on measured concentration and 0.16 mg/L based on nominal concentrations. The test concentrations were achieved by dilution of a stock solution mixed with Methanol. Measured concentrations taken at > 1mg/L nominal differed > 20% from nominal concentrations. It can be assumed that the stock solutions and test concentrations > 1mg/L were prepared above the solubility limit.