Acrylaldehyde

Endpoint summary

Additional information

The stability of acrolein in the atmosphere is limited by the rapid gas-phase reactions with the hydroxyl radical and ozone. The calculated half-life of acrolein for the reaction with the OH-radical in the troposphere (*OH concentration 5 x 10⁵ molecules/cm³, 24 hours) is less than one day and is in accordance with the half-life values derived from experiments. Unlike to the US ATSDR Report and the EU RAR the WHO Report stated the calculated atmospheric half-life of acrolein, based on rate constants for hydroxyl radical reaction, to be between 3.4 and 33.7 h. Other degradation routes, such as the reaction with nitrate radical (night-time; half-life: 16 days) and ozone (half-life: 59 days) as well as photolysis (daytime; half-life: 10 days in the lower troposphere and less than 5 days in the upper troposphere), are considered to be less significant. Based on the short estimated half-lives, acrolein is not a candidate for long-range atmospheric transport. The estimated reaction rate constant for the reaction of OH radicals with acrolein in water is k(OH) =6.52 x 10E9 (1/(M x s). Assuming a OH radical concentration in water in the range between 1 x 10E-15 and 1 x 10E-18 M and taking into account the calculated reaction rate constant the half-lives can be calculated using the equation t1/2=0.69/k(OH) x OH concentration. The calculations yielded half-lives t1/2 in the range between 30 and 30000 h. Photolysis in water is low. No information is available with respect to the phototransformation in soil.

Acrolein does not contain any hydrolysable groups, but it does react with water in a reversible hydration reaction to 3-hydroxypropanal (HPA). The half-life for this reaction was found to be 15 hours in sewage water, 45 hours in drinking water and up to 11 days in de-ionised water. Besides this reaction step HPA reacts in a secondary reaction with acrolein to 3,3’-oxydipropionaldehyde, which further reacts to other secondary products. In field studies (irrigation canals) half-life values for the elimination of acrolein between 3 and 7 hours were calculated. Apparently, processes other than hydration, e. g. volatilisation, also contribute to acrolein dissipation in the aquatic environment.