Fate and transformation products of amine-terminated PAMAM dendrimers under ozonation and irradiation.

This article deals with the degradation of a third-generation (G3) poly(amidoamine) (PAMAM) dendrimer under ozonation and irradiation. The identification and quantification of G3 PAMAM dendrimer and its transformation products has been performed by liquid chromatography-electrospray ionization-hybrid quadrupole time-of-flight-mass spectrometry. The dendrimer was completely depleted by ozone in less than 1 min. The effect of ultraviolet irradiation was attributed to hydroxyl-mediated oxidation. The transformation products were attributed to the oxidation of amines, which resulted in highly oxidized structures with abundance of carboxylic acids, which started from the formation of amine oxide and the scission of the CN bond of the amide group. We studied the toxicity of treated mixtures for six different organisms: the acute toxicity for the bacterium Vibrio fischeri and the microcrustacean Daphnia magna, the multigenerational growth inhibition of the alga Pseudokirchneriella subcapitata, and the seed germination phytotoxicity of Licopersicon esculentum, Lactuca sativa and Lolium perenne. Ozonation and irradiation originated transformation products are more toxic than the parent dendrimer. The toxicity of the dendrimer for the green alga was linked to a strong increase of intracellular reactive oxygen species with intense lipid peroxidation.

Integrated approach to PBT and POP prioritization and risk assessment.

This article summarizes discussions at the SETAC Pellston Workshop on "Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs" and provides an overview of other articles from that workshop that are also published in this issue. Identification of persistent, bioaccumulative, and toxic substances (PBTs) and persistent organic pollutants (POPs) and evaluation of their impact are more complicated than those for other chemicals and remain a challenge. The main reason for this is that PBT substance and POP assessment is associated with higher uncertainty and generally requires more data. However, for some data-rich PBTs and POPs, that identification and assessment of impact are feasible has been clearly demonstrated. New scientific developments and techniques are able to significantly increase the certainty of the various elements of PBT and POP assessment, and the current scientific literature provides many successful and illustrative examples that can be used as methodologies to build on. Applying multiple approaches for assessment is advisable, because it will reduce uncertainty and may increase confidence and improve the quality of decision-making.