Ecotoxicity and genotoxicity of a binary combination of triclosan and carbendazim to Daphnia magna.
In the environment, chemical substances appear as complex mixtures and consequently organisms are exposed to a variety of chemicals from different sources (e.g. wastewater treatment plants, agriculture runoffs). When studying chemical mixtures, there are two conceptual models usually used to predict toxicity: the Independent Action (IA) and Concentration Addition (CA) models. However, deviations from these reference models can occur as synergism or antagonism, dose ratio or dose level dependency. The aim of the present study was to investigate the effects of triclosan and carbendazim, and their binary mixture to Daphnia magna. With this purpose, immobilisation, feeding inhibition, and reproduction were assessed as main ecotoxicity endpoints. In addition, in vivo genotoxicity of both chemicals was investigated using the comet assay. In the single exposure, carbendazim was more toxic to D. magna than triclosan. When daphnids were exposed to both single compounds, DNA damage was observed. Concerning mixture exposures, different endpoints followed different patterns of response, from additivity: IA model (feeding inhibition and reproduction data), to deviations that indicate interaction between chemicals inside the organism: dose level dependency (immobilisation data) and dose ratio dependency (DNA damage). This study showed that additivity does not rule the dose-effect relation in chemical mixtures of carbendazim and triclosan and interactions between both chemicals might induce generally higher toxicity than predicted based on single chemical exposures.
Department of Biology & CESAM, University of Aveiro, 3810-193, Portugal. Electronic address: ritas@ua.pt.
Ana Rita R
AR
Silva
Department of Biology & CESAM, University of Aveiro, 3810-193, Portugal.
Diogo N
DN
Cardoso
Department of Biology & CESAM, University of Aveiro, 3810-193, Portugal.
Andreia
A
Cruz
Department of Biology & CESAM, University of Aveiro, 3810-193, Portugal.
Joana
J
Lourenço
Department of Biology & CESAM, University of Aveiro, 3810-193, Portugal.
Sónia
S
Mendo
Department of Biology & CESAM, University of Aveiro, 3810-193, Portugal.
Amadeu M V M
AM
Soares
Department of Biology & CESAM, University of Aveiro, 3810-193, Portugal. Electronic address: sloureiro@ua.pt.
Susana
S
Loureiro
D000818:Animals; D001562:Benzimidazoles / Q000633:toxicity*; D002219:Carbamates / Q000633:toxicity*; D004249:DNA Damage; D003621:Daphnia / Q000187:drug effects; D004347:Drug Interactions; D012098:Reproduction / Q000187:drug effects; D014260:Triclosan / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D001562:Benzimidazoles; D002219:Carbamates; D014874:Water Pollutants, Chemical; D014260:Triclosan; C006698:carbendazim
DNA damage; Feeding inhibition; Reproduction; Single/mixture toxicity; Synergism/antagonism