Bis(ethyl acetoacetato-O1',O3)bis(2-methylpropan-1-olato)titanium

Biodegradation in water: screening tests

Description of key information

Testing is not scientifically justified as substance is hydrolytically unstable. Based on the rapid hydrolysis, and the ready biodegradability and low aquatic toxicity of the known decomposition products, this substance can be considered as readily degradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Biodegradability testing of this substance is not scientifically justified as it is hydrolytically unstable. When this substance comes in contact with water or moisture, a complete hydrolysis will take place with no significant reaction products other than 2 -methylpropanol, ethyl acetoacetate and hydrated titanium dioxides (half-life less than 10 minutes, Brekelmans 2013). In addition, biodegradability testing is not necessary as all the decomposition products have been identified.

The organic degradation products (2 -methylpropanol and ethyl acetoacetate) are also readily biodegradable. TiO₂ is inorganic and insoluble and therefore not relevant to be considered for this endpoint.

Several studies have been conducted to assess the biodegradation of 2 -methylpropanol. Biodegradation of 2-methylpropanol in 20-d BOD test was 72 % of ThOD and 74 % at 28-d OECD 301 D closed bottle test (Waggy et al. 1994).Based on the study by Price et al. (1974), 20-d biodegradation of 2-methylpropanol using non-adapted settled domestic wastewater was 72 % in freshwater at nominal test concentrations of 3, 7 and 10 mg/l. According to the study by Dias and Alexander (1971), a 30-day BOD test at 30°C reported 42 % bio-oxidation by day 2, 61 % by day 5, 75 % by day 10 and 55 % by day 30 for 2-methyl-1-propanol. Values were corrected for oxygen consumption in bottles with no test substance present, which accounted for the lower rate on day 30. Aerobic biodegradation in adapted sludge was measured to be 44 % of theoretical oxygen required for complete oxidation of 500 ppm test solution after 23 hours (McKinney and Jeris 1955). Aerobic biodegradation in unadapted sludge was found to be 10.4 % of ThOD after 24 hours (Gerhold and Malaney 1966). All the studies show the 2 -methylpropanol is readily biodegradable.

Ethyl acetoacetate is also classified as readily biodegradable based on the closed bottle test results (European Chemicals Bureau 2002). The biodegradation after 28-d was 66 %. After 7 days , 65 % ethyl acetoacetate was degraded and 10-day window was fulfilled.

Based on the information on aquatic toxicity and biodegradation of the decomposition products, and the rapid hydrolysis of the target substance, the abiotic degradation can be used to demonstrate fast degradation of this substance for the purposes of C&L.