Ecotoxicological Effects Of Combined Pollution Between Di-n-butyl Phthalates And Cadmium On Earthworms

As a kind of environmental endocrine disrupting chemicals, potential toxicity of phthalic acid esters(PAEs) on environmental organisms has been paid considerable attentions. The aim of the study mainly focused on di-n-butyl phthalates(DBP) widely used in the production of plastic products. We performed the acute tests of singal DBP on earthworms(Eisenia fetida) in individual level. Besides genotoxic effects and the activity of enzymes of combined pollution between DBP and Cd in biochemical and molecular level were also performed by a comprehensive mixture with methods of ecotoxicology, biochemistry and molecular biology in this study. The information of ecotoxicological effects of DBP and Cd on earthworm will be a useful tool for drug risk assessment and risk prediction early. DBP was considered to be potential risk on soil environmental safety. Main results of the research were presented as follows:(1)Acute toxic tests of DBP on earthworm were done by contact filter and artificial soil test(OECD,1984). Results showed that the 24h-LC50 and the 48h-LC50 of DBP on the earthworms were 9.78mg/cm2 and 6.8mg/cm2, respectively, in filter paper contact test. In the artificial soil test, the 14d-LC50 was 2364.8mg/kg. Acute toxic tests of DBP on earthworm were low toxicity.(2)Results of single DBP on the activity of enzymes showed that the single effect of DBP on the activity of SOD, POD, and AChE was inhibitory effect. With the increase of exposure time and concentration of DBP, the effect of DBP presented more obvious inhibitory effect. When the concentration of DBP was 100mg/kg, the inhibition of SOD, POD, and AChE reached the hightest degree. CAT activity increased first and then decreased when the earthworms were exposed to 100mg/kg of DBP. DBP markedly inhibited the activity of CAT and GST at the post-exposure time. With the increase of exposure time, MDA content in DBP treatment groups significantly increased. And there was a dose-response relationship between the exposure concentration of DBP and the inhibition rate of earthworm enzymes.(3)Results of single DBP on DNA damage showed that there exsited DNA damage inearthworm coelomocyte after exposure of different concentration of DBP. The inceasing concentration of DBP resulted in a gradual increase in the OTM, which suggested that there was a significant dose-response relationship between the exposure concentration of DNA damage and DBP.(4)Results of combined effect of DBP and Cd on the activity of enzymes showed that after early exposure time the combined effect of low concentration(5mg/kg) of DBP and Cd on SOD and POD showed antagonistic effect to some degree and that when high concentration of DBP combined with Cd, the effect presented synergistic effect. With the increase of exposure time and DBP concentration, the combined effect of DBP and Cd showed synergistic effect. The combined effect of high concentration of DBP and Cd on GST,AChE, and MDA showed synergistic effect as well. At the entire exposure time, the effect combined with high concentration of DBP and Cd on earthworm enzymes showed obvious synergistic effect.(5)Results of combined effect of DBP and Cd on DNA damage showed that when low concentration(5mg/kg) of DBP combined with Cd, the effect of DBP and Cd showed mild antagonism. Nevertheless the combined effect of high concentration of DBP and Cd presented synergistic effect. With the increase of exposure time and DBP concentration, the effect of DBP and Cd showed synergistic effect, which cause severe DNA damage.