Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability

 

Phototransformation in air

For the indirect photodegradation of butyric acid in air by the reaction with OH-radicals, a half-life of approx. 188 hours (7.8 days) was calculated (ECT, 2009).

 

Hydrolysis

Due to its chemical structure and reactivity, butyric acid will not hydrolyze under environmental conditions. The structure of the molecule does not contain hydrolizable constituents (GUBDH, 2008).

 

Biodegradation

 

Biodegradation in water: screening test

Butyric acid has been demonstrated to be readily biodegradable in a valid biodegradation test according to OECD TG 301 E (Hüls, 1996).

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.

Biodegradtation 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 butyric acid (OXEA, 2009) indicates a low potential for bioaccumulation. In addition the substance is readily biodegradable (Hüls, 1996). Therefore and for reasons of animal welfare a fish study is not performed.

Based on an experimental log Kow of 1.1, the log BCF of butyric 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 butyric 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 absorption (log Kow < 3) and is readily biodegradable.

As additional information, the Koc of butyric acid was estimated to be 45.5 at pH 7 (log Koc = 1.66) (OXEA, 2010) indicating high mobility in soil.

 

Henry’s Law constant

For butyric acid, a Henry's law constant of 2.20E-7 atm m³/mol was determined in a 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

Group contribution method: HCL (25°C) = 5.87E-007 atm*m3/mol

Bond contribution method: HCL (25°C) = 9.65E-007 atm*m3/mol

 

Butyric acid volatilizes only to a low degree from water.