Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

5. Environmental fate and pathways

n-Butyraldehyde is a naturally occurring substance which is emitted by plants, animal waste, microbes and insects. n-Butyraldehyde is readily biodegradable in water and rapidly decomposed in the air by photodegradation. The substance does absorb on soil however, the degradation and decomposition is rapid therefore bioaccumulation is unlikely.

5.1 Phototransformation

Calculated half-lives of photo-degradation in air (indirect photolysis by OH radicals) ranged from 5 - 16.4 h at 25 °C; one estimate for direct photodegradation was 2 h. This indicates that n-butyraldehyde will rapidly decompose in the environment.

5.2 Biodegradation

n-Butyraldehyde was tested for biodegradability in several studies proved to be readily biodegradable. No verifiable data have been located in water/sediment systems as well as in soil. Based on the inherent properties and ready biodegradability of n-butyraldehyde in water, rapid elimination of the substance can also be predicted in compartments in sediment and soil by analogy. According to the REACH regulation no further studies are required when the substance is proven to be readily biodegradable.

5.3 Bioaccumulation

n-Butyraldehyde is not expected to have a bioaccumulating potential, based on inherent substance properties. No empirical results are avaliable. Using a Henry's Law constant of 1.2 x 10-4 atm*m3/mole, a log Kow of 0.88, and a regression-derived equation, an estimated bioconcentration factor (BCF) of 3.0 has been determined (US EPA 1988). The BCF programme in EPIWIN v.3.10 predicts a BCF of 3.16, indicating that bioaccumulation is unlikely (Vinken, R., 2007). In addition, the bioconcentration factor was found to be between 1.13-2.75. These values suggest that the potential for bioconcentration of n-butyraldehyde in aquatic organisms is low.

5.4 Transport and distribution

  • Water, soil - air

The Henry's Law constant for n-butyraldehyde, as predicted by EPIWIN v.3.10 ranges from 1.20 to 1.48 x 10-4atm*m3/mole, indicating that volatilization from water will occur.

A measured Henry's Law constant is reported to be 1.15x 10-4atm*m3/mole.

Based on the Henry’s law constant(1.2 x 10-4atm*m3/mole), vapor pressure, and water solubility, the estimated volatilization half-life for n-butyraldehyde from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec) is estimated as approximately 5 to 9 h. The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec) is estimated as approximately 5.3 d.Volatilization half-life from a model environmental pond (2 m deep) can be estimated to be about 4 d.

Volatilization of n-butyraldehyde from dry soil surfaces is likely to exist, based upon a vapor pressure of 111 mm Hg.

  • Soil - water

Estimated of Koc values of 5, 9 and 71 indicate high to very high soil mobility.

.