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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Table 3.4: Degradation of PTBBA in natural surface waters (EU risk assessment report, p. 15-16 (2009))
Ground water River water Harbour water
Biodegradation rate constant 1/d (a) NC (b) 0.027 0.073 (c)
Half-life (d) / 26 9.5 (c)
Initial microbe cell count of the unfiltered water (cells / ml) 55 420 310
These values are not used for the CSA (see discussion).

Key value for chemical safety assessment

Additional information

Under consideration of the lack of ready biodegradability and for estimating concentrations in surface water, it is assumed that the substance is not biodegradable (kbiowater = 0 d-1). The results of Table 3.4 are not used in modelling as the concentrations of PTBBA employed in the study were much higher than what can be expected to be found in the environment.

For soil and sediment no studies were available and thus on the basis of the results from tests on ready biodegradability, degradation is assumed to be zero for these compartments.