Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

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In a GLP study according to OECD guideline 301C, IBDU was degraded by 78% after 28 days (NITE 2002). The OECD criteria: 10 -day window and pass level >= 60% were fulfilled. Therefore, IBDU can be classified as readily biodegradable.

 

Due to the ready biodegradability of IBDU, no further testing on biodegradation in water and sediment (simulation tests) and biodegradation testing in soil needs to be conducted for a registration under REACh (EC No. 1907/2006). However, the biodegradability of IBDU in soil, was also studied in several tests (e.g. Hughes 1976, Markova 1978). Through its use as slow-release fertilizer, IBDU granules are directly applied on soil. In soil, dissolved IBDU is hydrolyzed to urea and isobutyraldehyde (Hamamoto, 1966). Urea is decomposed by urease into NH3 and CO2 (ammonification) and NH3 then protonated into the ammonium ion. The latter volatilizes or isoxidized via nitrite into nitrate (nitrification). Low pH (pH 6), high temperatures, high soil moisture and small granular size increase solubilisation of IBDU and, hence, mineralization (Hamamoto, 1966; Hughes, 1976; Markova, 1978). Within 24 weeks, the total amount of mineralized nitrogen in 4 different soil types with pH values of 4.8 to 8.3 was between 88 and 99 % of the introduced IBDU (Markova, 1978)