Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

The acute toxicity to fish (Oncorhynchus mykiss) of CYDI ((1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide) was evaluated.

The results indicate that none of the tested concentrations (0.1, 1 and 10 mg/L) in test substance cause mortality to fish after 96 hours exposure.

The LC50,96hof (1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide to fish was therefore determined to be > 10mg/L.

This result indicates that (1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide should not be classified for Aquatic Acute Toxicity according to CLP ( Regulation (EC) No 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures).

The value of 10mg/L is mentionned to be the solubility limit of the test item and no death was observed so no LC50 value higher than 10 mg/L can be derived, meaning that (1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide should not be classified for Aquatic Chronic Toxicity according to CLP.

However, considering the the not rapidely biodegradability of the test item and 96h LC50 for fish >10 mg/L, it is classified as Aquatic chronic 3 according to CLP.

Additional information

Respiration inhibition of (1,4,5,6-tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide on activated sludge has been studied. The activated sludge was subjected to various concentrations of test substance for 3 consecutive hours.

A preliminary study has been carried out with test substance concentrations of 1, 10, 100 and 1000 mg/L.

Based on the results obtained in this preliminary test, it was decided to make new measurements on 100 mg/L replicates.

The average respiration inhibition based on the 100 mg/L replicates was found to be 4%.

The EC50 for respiration inhibition of activated sludge by (1,4,5,6-tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide after 3 hours of exposure was therefore determined to be > 100 mg/L.