- Kees van Ginkel, Akzo Nobel Technology & Engineering, Arnhem, The Netherlands

Registration within REACH requires data on the biodegradability of chemicals. When carried out properly, read-across is a strong tool for assessing biodegradability (non-persistence) of chemicals. Read-across improves the assessment of the biodegradability and reduces testing.

The most important step for a valid read-across is defining a family of chemicals. The existence of a family should be based on evidence showing that one organism (isolate) is capable of degrading all the members of a family using, for instance, information on the substrate specificity or intermediates in the biodegradation pathway. Available information on the biodegradability (persistence) of one member (extrapolation) or preferably more members (might allow interpolation) of the family on the persistence allows assessment of the whole family accordingly.

The substrate specificity of alkylamine-degrading microorganisms and the biodegradation pathway of primary alkylamines have been studied recently (van Ginkel et al, 2007a). To this end, a Pseudomonas sp. which utilizes primary long-chain alkylamines as nitrogen, carbon and energy source, was isolated. The substrate spectrum of this Pseudomonas includes primary alkylamines with alkyl chains ranging from C3 to C18. The degradation of alkylamines is initiated by an enzyme which produces ammonium and the respective alkanals. The proposed pathway for the oxidation of alkylamine proceeds from alkylamine to alkanal, and then to the fatty acid. This information allows treating alkylamines as a family. Adequate ready biodegradability test results already available lead to the conclusion that all alkylamines should be classified as readily biodegradable (non persistent). The same approach has been used for other surfactants (van Ginkel, 2007b).

CG van Ginkel, A Louwerse and B van der Togt (2007a) Biodegradation PMID: 17492358 CG van Ginkel (2007b) Ultimate biodegradation of ingredients of cleaning agents In; Handbook of Cleaning Agents/Decontamination of Surfaces, Eds. I Johansson and P Somasundaran, Elsevier Amsterdam The Netherlands Elsevier Amsterdam The Netherlands Volume 2 pp 655-694