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Ecotoxicological information

Endpoint summary

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Description of key information

The following ecotoxicity data for aquatic organisms isavailable for OBSH (m = measured concentration). It should be noted that these values may reflect toxic effects of degradation products as well as the parent compound.

Short-term toxicity

Fish [Oryzias latipes]: LC50(96 hrs) > 6.6 mg/L (m, semi-static)

Invertebrates [Daphnia magna]: EC50(48 hrs) = 2.9 mg/L (m, semi-static)

Algae [Pseudokirchneriella subcapitata]: EC50(72 hrs) = 0.35 mg/L (growth rate) (m, static)


Long-term toxicity:

NOEC for freshwater fish (Oryzias latipes, Early-Life Stage Toxicity Test, 45d): 0.09 mg/L (m, flow-through)

NOEC for freshwater invertebrates (Daphnia magna, 21 d reproduction study): 2.13 mg/L (m, semi-static)

NOEC for fresh water algae (Pseudokirchnerella subcapitata, 3 d, growth rate): 0.059 mg/L (m, static)

Additional information

Furthermore, the hydrolysis studies showed quite short hydrolysis half-lives of 5.9 hr (pH=9), 7.9 (pH=7), 11.7 (pH=4). The pH range of the toxicity studies were in the range of 7.3 – 9.0. At these pH-ranges, a large percentage of the mother substance is degraded (>65% after 12 hours, >88% after 24 hours, >98% after 48 hours) during the test, if no water exchange has been carried out. The main degradation products from the hydrolysis have been identified to be hydrazine (CAS No. 302-01-2) and 4,4’-oxybis(benzenesulfonic acid) (SIDS Initial Assessment Profile, It is very likely that especially hydrazine has contributed to the observed toxicity.

Therefore, the environmental safety assessment must be performed for OBSH degradation products. Hydrazine monohydrate was used as a worst-case scenario, because it is very toxic to environmental organisms and is classified as hazardous to the aquatic environment H400, Acute Hazard, Category 1 and H 410, Chronic Hazard, Category 1 according to the CLP Regulation.

No literature toxicity data can be found for the other main degradation product, namely 4,4’-oxybis(benzenesulfonic acid, but data for similar substances such as Disodium oxybis(methylbenzenesulfonate, 4-hydroxybenzenesulphonic acid, Benzene sulfonic acids and Hydropes were less toxic compared to hydrazine monohydrate.