Studies of the behaviour and fate of the polymer-additives octadecyl-3-(3.5-di-t-butyl-4-hydroxyphenyl)propionate and tri-(2.4-di-t-butylphenyl)phosphite in the environment

In order to evaluate the environmental risk potential of the polymer-additi ves octadecyl-3-(3.5-di-t-butyl-4-hydroxyphenyl)propionate (additive 1) and tri-(2.4-di-t-butylphenyl)phosphite (additive 2) we have studied the degra dation of the C-14-labelled single components and their release from a poly propylene matrix in abiotic and biotic test systems as well as their transp ort behaviour in soil. The biotic degradation in waste compost, activated s ludge and in soil was studied. In order to conduct release tests, waste dis posal material were used as well. The abiotic degradation was effectuated b y photooxidation at a catalytic surface. The highest mineralisation rates w ere obtained by photooxidative degradation of the two test substances. The maximum content of bounded residues was found for additive 1 in soil and fo r additive 2 in waste compost. In the extracts of soil and compost, the pri ncipal metabolites could be identified in the case of additive 1 as 7.9-di- t-butyl-1 -oxaspiro[4.5]deca-6.9-dien-2.8-dion and in activated sludge as t he methyl ester of 3-(3.5-dit-butyl-4-hydroxyphenyl) propionic acid. Additi ve 2 metabolised in all degradation tests nearly completely under formation of two products. The main component was identified as tri-(2.4-di-t-butylp henyl)phosphate. Both polymer-additives were eluated from the chosen soil t ypes. The transport behaviour of additive 1 was independent from the soil t ype. In all test matrices additive 1 as well as additive 2 were released fr om polypropylene. Because the amounts of additive 1 and 2 adsorbed onto soi l particles were taken into account, the highest liberation rates were foun d in the soil test. (C) 1999 Elsevier Science Ltd. All rights reserved.