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Toxicity to aquatic algae and cyanobacteria

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Description of key information

The lowest effect values from the whole familiy of PPDs and their degradation products was found fo p-hydroquinone (EC50 0.335 mg/L) and for 44PD (NOEC 0.0958 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.335 mg/L
EC10 or NOEC for freshwater algae:
0.096 mg/L

Additional information

Algae studies:

p-Hydroquinone is the (secondary) hydrolysis product of 77PD. The effect concentration of this substance was used as a key value as it represents the worst case. The lowest NOEC for algae was found in a study for 44PD. Supporting information from experimental and from calculated data is given for the degradation products of 77PD, 1,4 -Dimethylpentylamine as well as from 4 -hydroxydiphenylamine used as a similar substance to 1,4 -dimethylpentylamino-p-phenol. The results of these studies are effect levels higher than those stated for the key studies.

The read-across justification is attached in a separate document in chapter 13 IUCLID.

Toxicity of Tyre wear particles (TWP) to algae:

TWPs are produced containing antioxidants like 77PD in a concentration of about 1%. The toxicities of the TWP elutriates to P. subcapitata were determined in 72-h static toxicity tests performed according to OECD Test Method 201. In this study the toxicity of such particles mixed in sediment was evaluated. Water-sediment systems are considered the likely reservoir of tire wear particles in the environment.

Under standard test temperature conditions, no response in the tested concentration range (100, 500, 1,000 or 10,000 mg/l TWP) was observed. EC/LC50 values were greater than 10,000 mg/l. Based on the high EC50 values and the limited conditions under which toxicity was observed TWP should be considered as posing a low risk to aquatic algae.