Hazard identification of phthalates based on hepatotoxicity of zebrafish larvae

ObjectiveThe risk assessment model of fatty liver accumulation in zebrafish larvae was established to identify the hepatotoxicity hazards of plasticizer butyl benzyl phthalate （BBP） using Di （2-ethylhexyl） phthalate （DEHP） and dibutyl phthalate （DBP） as positive control samples. This model was used to identify hepatotoxicity of butyl benzyl phthalate （BBP）.MethodsThe fatty liver signal intensity and expression of peroxisome proliferator activated receptor （PPAR） target gene CD36 in zebrafish liver after DEHP and DBP exposure were analyzed， and the hepatotoxicity model of zebrafish larvae was preliminarily constructed， which was used to evaluated the hepatotoxicity of BBP. In addition， liver density analysis， TG quantitative detection of zebrafish larvae and liver pathological examination of adult zebrafish were used to further verify the reliability of the model. The benchmark dose method （BMD） was used to derive the point of departure.ResultsDEHP and DBP showed significant risk of fatty liver induction （both P<0.01）， and the relative expression level of CD36 was significantly higher （P<0.001 and P<0.05）， indicating the success of modeling. BBP （0.000 012 5%， 0.000 025%， 0.000 05%） induced significant lipid deposition （P<0.05， P<0.001， P<0.001）， significantly affected liver parenchyma （P<0.05， P<0.01， P<0.01）， increased TG accumulation significantly （P<0.05， P<0.05， P<0.01）， and up-regulated CD36 gene expression. Furthermore， BBP （≥0.000 012 5%） induced the formation of lipid vacuoles in the liver of adult zebrafish， as well as the reduction of vacuolar space and number， suggesting that BBP had significant hepatotoxicity. The key effect was fatty liver signal intensity （S） and the benchmark dose lower-bound confidence limit （BMDL） value was 0.013 mg/L.ConclusionThis study successfully established a model of liver fat signal intensity to identify the hepatotoxicity of phthalates in zebrafish larvae， and preliminarily clarified the PPAR target gene CD36 involved in hepatotoxicity， and further provided a scientific basis for the risk assessment of phthalates combined with the BMD.