Registration Dossier
Registration Dossier
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EC number: 201-195-7 | CAS number: 79-31-2
Endpoint summary
Administrative data
Description of key information
Additional information
Stability
Phototransformation in air
For the indirect photodegradation of isobutyric acid in air by the reaction with OH-radicals, a half-life of approx. 167 hours (6.9 days) was calculated (ECT, 2009).
Hydrolysis
Due to its chemical structure and reactivity, isobutyric acid will not hydrolyze under environmental conditions. The structure of the molecule does not contain hydrolysable constituents (GUBDH, 2008).
Biodegradation
Biodegradation in water: screening test
Isobutyric acid has been shown to be readily biodegradable as combined evidence from two biodegradation tests
1. - test similar to OECD TG 302 B (Hoechst AG, undated; RL2; KS)
2. - test similar to OECD TG 301 E (Henkel KGaA, 1983; RL3; WoE)
Biodegradation in water and sediment: simulation test
In accordance with column 2 of REACH Annex IX Nr. 9.2, the study does not need to be conducted as the substance is readily biodegradable.
Biodegradation in soil
In accordance with column 2 of REACH Annex IX Nr. 9.2, the study does not need to be conducted as the substance is readily biodegradable.
Bioaccumulation
Bioaccumulation: aquatic/sediment
In accordance with column 2 of Annex IX, the study does not need to be conducted if the substance has a low potential for bioaccumulation. The log Kow of 1.1 for isobutyric acid (OXEA, 2009) indicates a low potential for bioaccumulation. Therefore and for reasons of animal welfare a fish study is not performed.
Based on an experimental log Kow of 0.94, the log BCF of isobutyric acid was estimated to be 0.5 (BCF = 3.162). In addition, a log BAF (upper trophic)of 0.31 (BAF = 2.06) was calculated using the method of Arnot-Gobas (ECT, 2010). The low BCF/BAF values indicate a low potential of isobutyric acid for bioaccumulation in aquatic and benthic organisms.
Transport and Distribution
Adsorption/Desorption
In accordance with column 2 of REACH Annex IX Nr. 9.3.3, the study does not need to be conducted as the substance has a low potential for adsorption (log Kow < 3) and is readily biodegradable.
As additional information, the Koc of isobutyric acid was estimated to be 44.7 (log Koc = 1.65; charged molecule) (OXEA, 2010) indicating high mobility in soil.
Henry’s Law constant
For isobutyric acid, a Henry's law constant of 8.85E-7 atm m³/mol was determined in an experimental study using equilibrium partial pressure measurements over aqueous solutions at 298.15 K (25°C) (Khan, 1992).
Calculations (ECT, 2009) (US EPA EPI Suite v4.00) resulted in
Bond contribution method: HCL (25°C) = 9.65E-007 atm*m3/mol
Group contribution method: HCL (25°C) = 9.09E-007 atm*m3/mol
Isobutyric acid volatilizes only to a low degree from water.
Additional testing according to ANNEX X
Further testing on the environmental fate and behavior of the substance and/or degradation products will be proposed if the chemical safety assessment according to Annex X indicates the need to investigate further the fate and behavior of the substance.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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