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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

There are no experimental/literature available data on tert-butyl bromoacetate, thus the environmental fate and pathway has been investigated using data calculated by estimation tools.

Endpoint Value / result Reference
Biodegradation in water
Ready biodegradable: NO Data estimated by the US Environmental Protection Agency’s EPISuite™ (BIOWIN v4.10). 
Ready biodegradable: NO Data predicted using VEGA Qsar model (IRFMN). (a)
Endpoint Value / result Reference
Bioconcentration BCF
BCF = 16.7 at pH 5.5 and 7.4) Data predicted by ACD/Labs platform.
BCF = 10.9 Data predicted by the US Environmental Protection Agency’s EPISuite™ (regression-based method).
BCF = 5.7 Data predicted using VEGA Qsar model (CAESAR). (b)
BCF = 11.9 Data predicted using VEGA Qsar model (Meylan). (c)
BCF = 2.1 Data predicted using VEGA Qsar model (Read-across). (d)
Endpoint Value / result Reference
Adsorption / desorption (Koc)
261 (at pH 5.5 and 7.4) Data predicted by ACD/Labs platform.
102 Data predicted by the US Environmental Protection Agency’s EPISuite™ (Kow method).
Henry's Law constant at 25 °C 0.0000473 atm m3/mol Data predicted by the US Environmental Protection Agency’s EPISuite™ (Bond SAR method).
logKoa 4.79 Data predicted by the US Environmental Protection Agency’s EPISuite™.

Details on VEGA predictions

Applicability domain comparison Model
Predicted compound is outside the AD of the model. (a)
Similar molecules in the training set have experimental values that disagree with the predicted value. (a)

Details on EPISuite prediction

Rapid Probability Models Expert Survey Biodegradation Results MITI Biodegradation probability Anaerobic Biodegradation Probability
Biowin1 (linear): 0.5988 Biowin3 (ultimate): 2.7252 (weeks - months) Biowin5 (linear): 0.6906 Biowin7 (linear): 0.82
Biowin2 (non-linear): 0.1361 Biowin4 (primary): 3.66772 (days - weeks) Biowin6 (non-linear): 0.4186

Both EPISuite and VEGA reports that the substance is not readily biodegradable, but the predictions have low reliability. However, according to the work of Hiromatsu et al. (2000), the substance presents functional groups which are associated to a negative biodegradability potential, i.e. the presence of an halogen and a quaternary carbon.

Considering both the sources, it can be concluded that the subtance should not be readily biodegradable.

Regarding the hydrolysis, despite the chemical contains an alkyl ester functional group, which is potentially hydrolizable, the presence of a steric bulky substituent (in this case a tert-butyl) significantly decrease the neutral and base hydrolysis rate constants. The presence of an halogen on the other hand generally increases the reaction kinetics, however this effect is typical only for very high electronegative halogen (e.g. chlorine), due to their high electronegativity (Larson and Weber, 1994). The EPISuite software calculated a Kb half-life value of 2 and 20 days at pH 8 and 7, respectively.

The substance does not have an high affinity to the non-polar phase, presents a good water solubility and a low vapor pressure. For this reason, the water environmental compartment should be the main in which the substance will show the highest partitioning, based on its physicochemical properties.

The penetration by passive diffusion across biological membranes is facilitated by its low molecular weight; however, due to the low octanol/water partition coefficient (and consequently the bioaccumulation factor BCF), the chemical should not show an high bioaccumulation potential. BCF predictions are rather in agreement between the assessed models and shows acceptable reliability.

REFERENCE

Hiromatsu K. et al., Prediction for biodegradability of chemicals by an empirical flowchart, Chemosphere, 2000.

Larson R.A. and Weber E.J., Reaction mechanisms in environmental organic chemistry, Lewis Publishers, 1994.