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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The following studies have been submitted for the biodegradation in water: screening tests endpoint:
Errécalde et al (1995). Biotransformation of Butyltin Compounds Using Pure Strains of Microorganisms. APPLIED ORGANOMETALLIC CHEMISTRY, VOL. 9, 23-28 (1995).
Günzel P et al (1991). Study on the biodegradability of Di-n-butyltin dichloride in the modified Sturm test. Testing laboratory: Schering AG, Experimentelle Toxicologie, Berlin, FRG. Report no.: IC 4/92. Owner company: Atochem, North America, Philadelphia, USA. Report date: 1993-07-09.
Günzel et al (1991) has been allocated a Klimisch score of 1 and is considered to be the key study for this endpoint. Errécalde et al (1995) has been allocated a Klimisch score of 4 and is provided for information purposes only.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Günzel P et al (1991) was assigned as the key study to fulfil this data requirement. The study was performed to the guideline OECD 301 B, and in compliance with GLP, as such the study was considered to be of high reliability and accordingly assigned a reliability score of 1 (reliable without restrictions) and considered adequate to assess the ready biodegradability of the test material. The study was performed using the modified Sturm test (Schering AG report number: IC 4/92). The test material can be described as not readily biodegradable under the conditions of the test, according to the stringent test criteria. The test product di-n-butyltin dichloride was degraded within 28 days to approx. 6 % in the saturated solution of 4 mg/l, and to approx. 1% in the concentration of 20 mg/l (suspension). The data indicated that inhibition of the microbial population occurred to a certain extent during an adaption period of approx. 20 days, because the CO2 produced by the test solutions was lower than that of the blank. This was, however, not concentration-dependent. Therefore, it can be suggested that the particles of the suspension were not bioavailable for the microbes.


Errécalde et al (1995) was provided as supporting information. The study was assigned a reliability score of 4 (not assignable) due to deficiencies within the reporting. The debutylation of tributyltin chloride by several strains of fungi, yeasts and bacteria is described.Under standard conditions and with low initial concentration of substrate, significant bioticdegradation of tributyltin (6-32%) was detected after five days at 28 °C. Dibutyltin and monobutyltin were formed in all cases, with higher yields ofthe latter.For DBTC, most of the degradation to MBT was abiotic, and fungi biodegraded DBT to MBT to extent of 10-26% (of tin).