Biodegradability testing and Toxicity

Biodegradatietoetsen dienen met een niet-toxische concentratie van de te onderzoeken stof te worden uitgevoerd. Omdat blijkt dat in de voorschriften van, door de OESO en EG erkende en aanbevolen, biodegradatietoetsmethoden, onjuiste aanbevelingen worden gedaan t.a.v. controle-experimenten m.b.t. eventueel toxische effecten, werd een onderzoek verricht naar de bacterietoxiciteit van p-chloorfenol en p- nitrofenol. De NOEC-waarden werden bepaald m.b.v. manometrische respirometrie, remming van het respiratietempo van actief slib (NEN 6512) en ATP-afname als toetscriterium voor acute toxiciteit. De laatste methode bleek het meest geschikt als prealabele toets voor een biodegradatieonderzoek.Abstract not availableDGMH/BWS-S / KonemannW.H

Standaardmethoden voor het bepalen van de biologische afbreekbaarheid van industriele chemicalien in water ; huidige status en toekomstige ontwikkelingen

Abstract niet beschikbaarThis report contains an appraisal of the OECD hierarchy for testing the biodegradability of industrial chemicals. A more pragmatic system is proposed which encompasses (1) selecting both the "soft" and the "hard" chemicals, (2) screening chemicals for potential biodegradability in a specified environmental compartment and (3) simulation methods. Methods of level 91) should be applicable to all chemicals, irrespective of their physico-chemical and biological properties. "Soft" chemicals can be recognized by a positive result in a Ready Biodegradability Test (RBT), wheras a negative result in a so-called Inherent Biodegradability Test (IBT) is an indication for persistence of a compound. Although RBT's have been update in 1990, they still suffer from some shortcomings. In this report simple modifications of existing methods are discussed to overcome these shortcomings together with more satisfactory methods, which have been developed the last decade. The limitations of Inherent Biodegradability Tests are evaluated and alternative techniques are proposed to make IBT's applicable to a wider range of physico-chemical properties. Recently developed useful methods, such as test for sea-water and the anaerobic compartment, proved problematic to place in the current OECD test hierachy but fitt easily in level (2) of the proposed test system.DGM/S

Anaerobe afbreekbaarheid: Resultaten van een Nederlands ringonderzoek

Abstract niet beschikbaarIn 1990/1991 a round-robin test was carried out in the Netherlands to investigate s simple serum bottle technique for anaerobic biodegradability, organized by the RIVM. Six laboratories participated in this inter-laboratory exercise and tested four chemicals, according to methods published earlier by the RIVM (1987) and ECETOC (1988). The most satisfactory and simple procedure to evaluate the degree of anaerobic mineralization is to combine two parameters that can easily be measured, i.e. the net gas production and the increase of dissolved inorganic carbon. This approach is more succesful than monitoring the evolved methane. Both procedures to wash the anaerobic sludge are effective in reducing the blank gas production due to the sludge. The blank values are all in the surprisingly small range of 20 and 100 ml per g sludge. Polyethyleneglycol-400 is a suitable positive reference compound. Aniline was most persistent but it also showed toxic effects. 2-Propanol was mineralized in most laboratories after a lag varying from 1 to 4 months. 2-Aminophenol is an erratic compound: participants reported persistence during the test period, toxic effects and (partial and ultimate) biodegradation.DGM/SV