| dc.description | Surface water samples from S??o Paulo state were collected to perform Bioluminescent
Yeast Estrogen Screen (BLYES) and chemical analyses (LC-MS/MS). Results
showed environmental concentrations of atrazine from 2 to 43 ng L-1 on chemical
analyses. Some studies have been performed to evaluate toxic effects on non-target
organisms (fish) using herbicides such as Atrazine, a moderately toxic compound
classified as an endocrine disrupting chemical (EDC) that can affect reproduction of
several aquatic organisms with a compromise of vitellogenin production. To determine
toxicity on embryonic stages of fish to different environmental chemicals and waste
water, Fish Embryo Toxicity Test (FET) was designed using Danio rerio as model
specie on this test, according to OECD 236 or ISO 15088 protocols, however these
protocols observe only acute toxicity based on endpoints such as coagulated eggs, nondetachment
of the tail, lack of heart beating and lack of somite formation. Some
abnormalities can be recorded after the exposure on FET test but they are not
considered as endpoint, neither any other compromised biomarker by EDC action. In
order to evaluate the possibility of using these chronic endpoints and to verify if those
environmental concentrations of atrazine are ecologically relevant, compromising
reproductive aspects, FET test using Danio rerio were performed to assess lethal
concentrations, sublethal concentrations and vitellogenin quantification after atrazine
exposure. Occurrence of morphological abnormalities (microcephaly, spine curvature,
edema, reduced size) and mortality of the embryos were determined exposing 20
fertilized eggs to atrazine concentrations from 2 to 64 mg L-1. The LC50 and EC50
were obtained after 96 hours of exposure. Organisms that survived each concentration
were frozen to further vitellogenin quantification. Preliminary average concentrations
obtained (LC 50; 96h= 48.15 mg L-1 and EC 50; 96h= 27 mg L-1) were considerably
higher than concentrations observed on environmental samples. Therefore, surface
water concentrations would not cause mortality or deformity in fish emphasizing the
necessity to observe possible effect on vitellogenin concentration. Data will be
analyzed and compared with the environmental concentration of atrazine to stablish
the potential application of vitellogenin as endpoint on FET test. | |
