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Toxicity to aquatic algae and cyanobacteria

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Description of key information

The substance is acutely toxic to aquatic algae.

Key value for chemical safety assessment

Additional information

In order to determine the effects of Hydrogenation products of 4-[(4-amino-3-methyl-phenyl)methyl]-2-methyl-aniline (CAS 6864-37-5, DMDC) on aquatic algae, there are data from two studies available:

1.) In a non-GLP study according to OECD Guideline 201, conducted with Desmodesmus subspicatus (BASF AG, 1989), the 72-h ErC50 was determined to be >5.0 mg/L (nominal; analytically not verified; 72-h ErC10 = 1.25 mg/L).

2.) In an additional GLP-study (NITE Japan, 2002), performed according to OECD 201 (Alga, Growth Inhibition Test) with Pseudokirchneriella subcapitata, the test concentrations were analytically verified. The results were recalculated with Toxrat v2.10; the mean measured concentrations for the relevant concentration were within ±20% of the nominal values. As analytical monitoring was only performed for this study by NITE (2002), these values are selected as key data.The 72-h ErC50 was estimated to be 7.9 mg/L. The 72-h ErC10 was determined to be 4.1 mg/L and the 72-h NOEC was 0.13 mg/L. All validity criteria were fulfilled in this study.

According to the Guidance on information and safety assessment Chapter R.10: Characterisation of dose [concentration]-response for environment “an EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis) will be used preferentially. […] There has been a recommendation within OECD in 1996 to phase out the use of NOEC, in particular as it can correspond to large and potentially biologically important magnitudes of effect. The advantage of regression method for the estimation of ECx is that information from the whole concentration-effect relationship is taken into account and that confidence intervals can be calculated. These methods result in an ECx, where x is a low effect percentile (e.g. 5-20%). It makes results from different experiments more comparable than NOECS”.

Therefore, the ErC10 (4.1 mg/L; 95% CL: 3.5 - 4.7 mg/L; NITE, 2002) instead of the NOEC has been used for the assessment.