Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Experimental data show that tetradonium bromide is readily biodegradable under conditions where tetradonium bromide does not exert toxicity to the microorganisms.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Experimental data show that tetradonium bromide is readily biodegradable at conditions where the substance does not exert toxicity to the microorganisms.

In a weight of evidence approach, data on cetrimonium chloride are included to support the data on biodegradability of tetradonium and cetrimonium bromide. Read across between homologues of this type of substances can be done, as the degradability is determined by the alkyl structure and not by the counter ion. Therefore the degradability of cetrimonium chloride is considered to represent that of cetrimonium bromide. The biodegradability decreases with the length of the alkyl chain (according to studies by Garcia et al, 2001 and Yamane et al 2008), thus the biodegradability of tetradonium bromide (C14) can be described by the biodegradability of the cetrimonium halides (C16).

Studies on cetrimonium chloride indicate that the substance is biodegradable, but not necessarily passing the criteria for readily biodegradability (FeF, 1993; Madsen et al, 2001; van Ginkel, 1996). This is especially observed when tested at concentrations above a certain level approximately 10-20 mg/L, which is considered to have a toxic effect on the microorganisms in the test system. When toxicity has been removed by the addition of silica gel or SIO2 to the test system, cetrimonium chloride has proven to pass the criteria for readily biodegradability (van Ginkel, 2004; OECD, 1996). When silica or SiO2 particles are present in the test system, the substance will enter equilibrium between adsorbed and dissolved phase. When the dissolved part of the substance biodegrades, the substance is gradually released from the adsorbed phase, and a low concentration not exerting toxicity is maintained in the test system.

Supporting studies with tetradonium bromide show that tetradonium bromide passed the criteria for ready biodegradation at 5 mg/L (Garcia et al, 2001). Note on the weight of evidence approach taken on the biodegradability of tetradonium bromide is attached to the endpoint summary.