title: Evaluation of the aquatic toxicity of two veterinary sulfonamides using five test organisms.
abstract: The aquatic toxicity of sulfaquinoxaline (SQO) and sulfaguanidine (SGD) was evaluated on the following test organisms: Daphnia magna (reproduction test), Pseudokirchneriella subcapitata, Scenedesmus dimorphus, Synecococcus leopoliensis (algal growth inhibition test) and Lemna gibba (duckweed growth inhibition test). Furthermore, the additivity of the two compounds was measured on D. magna (acute immobilisation test) and P. subcapitata (algal growth inhibition test) using the isobologram method. Results show that SQO and SGD are more toxic to green algae and daphnids, respectively, than other veterinary sulfonamides (SAs) and that their mixtures have a less then additive interaction. Taking into account the highest concentrations detected so far in surface waters for SQO (0.112 μg L(-1)) and for SGD (0.145 μg L(-1)) and the lowest NOECs obtained with the five test organisms, divided by an assessment factor of 10, the following PNECs and risk quotients (RQs) were calculated. SQO: PNEC 2 μg L(-1); RQ 0.056. SGD: PNEC 39.5 μg L(-1); RQ 0.004. Consequently, at the concentrations actually detected in the aquatic environment, the two SAs alone should not harm the freshwater organisms. However, it seems advisable, for veterinary mass treatments, the use of other SAs that have a lesser impact on the aquatic environment. Furthermore, considering the high probability of having complex mixtures of different SAs residues in water, each individual contamination should be evaluated by applying to the SAs mixtures the conservative criteria of additivity.
authors.affiliation: Dipartimento di Sanità Pubblica, Patologia Comparata e Igiene Veterinaria, Facoltà di Medicina Veterinaria, Università degli Studi di Padova, Agripolis, I-35020 Legnaro, PD, Italy. marco.deliguoro@unipd.it
authors.forename: Marco
authors.initials: M
authors.lastname: De Liguoro
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Di Leva
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Gallina
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Faccio
authors.forename: Gabriele
authors.initials: G
authors.lastname: Pinto
authors.forename: Antonino
authors.initials: A
authors.lastname: Pollio
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000633:toxicity*; D029064:Araceae / Q000187:drug effects; D000460:Chlorophyta / Q000187:drug effects; D003621:Daphnia / Q000187:drug effects; D013414:Sulfaguanidine / Q000633:toxicity*; D013428:Sulfaquinoxaline / Q000633:toxicity*; D046940:Synechococcus / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000890:Anti-Infective Agents; D014874:Water Pollutants, Chemical; D013414:Sulfaguanidine; D013428:Sulfaquinoxaline