Study On Ecotoxicity Effects Of A Typical Anti-cancer Drug—5-fluorouracil

During recent years, great concideration has been given to the issue of occupationalexposure and ecotoxicological risks to the environment by pharmaceuticals. Anti-cancer drugs,which have been widely used for chemotherapy, were shown to have cytotoxic, genotoxic,mutagenic, carcinogenic or teratogenic effects. Due to their molecular mode of action, non targetorganisms in general might be susceptible to their toxicity as they had been released into theenvironment. It’s necessary to study the ecotoxicity of anti-cancer drugs. The present study wasfocused on the acute and chronic toxicity on wheat, Chinese cabbage and rice, and the acutetoxicity on Chlorella pyrenoidosa, Selenastrum capricornutum and Daphnia magna. Therefore,the assessment of ecological risks was considered. The results obtained were summarized asfo1lows:(1) In the seed germination experiments, the results demonstrated that the inhibition rate ofroot and shoot elongation of wheat, Chinese cabbage and rice significantly correlated with theconcentrations of5-fluorouracil (P<0.05), and the root elongation inhibition rate was moresensitive to the contamination of5-fluorouracil than the shoot elongation inhibition rate. Themedian inhibition concentration (IC50) of the three crops5-fluorouracil to the root elongation ofwere212.80mg·L-1,102.53mg·L-1, and13.30mg·L-1, respectively. The sensitivity of the threecrops to5-fluorouracil was in sequence as follows: rice> Chinese cabbage> wheat.(2) The long-term stress of5-fluorouracil have ecological toxicity effects on the growth ofwheat, Chinese cabbage and rice seedlings. With the concentration of2.5~100mg·L-1treatmentof5-fluorouracil for21days, the chlorophyll content and soluble protein content in the leaves ofthe three crops decreased. The activity of SOD, POD and CAT was subdued in varying degrees.Chronic toxicity effects have been observed.(3) The96-hour algal growth-inhibition test showed that the inhibition rates of populationcell density of Chlorella pyrenoidos and Selenastrum capricornutum were positively correlatedwith the concentration of5-fluorouracil. And the algal growth-inhibition-rates showedconcentration-dose relationship with5-fluorouracil. The96-hour median effect concentration(EC50) value of two kinds of algae were450.36mg·L-1,692.30mg·L-1.5-fluorouracil was lowtoxic to Chlorella pyrenoidos and Selenastrum capricornutum according to the acute toxicity ofalgae classification criteria, and Selenastrum capricornutum resistant to5-fluorouracil moregreatly than Chlorella pyrenoidos. Having been treated96hours by5-fluorouracil, thechlorophyll content of two kinds of algae increased in low concentration5-fluorouracil, whiledecreased in high concentration5-fluorouracil. Compared with the chlorophyll b content, thechlorophyll a content was a more sensitive indicator to the contamination of5-fluorouracil.(4) In the aute immobilization test with Daphnia magna of5-fluorouracil, the EC50were243.25mg·L-1and46.05mg·L-1in the treatments for24h and48h. The trendlines ofimmobilization rates in24h and48h represented "S" type increase, and the immobilization rates were related with logarithm of concentrations (R224h=0.9960, R248h=0.9960, p＜0.05).5-fluorouracil was medium toxic substance according to the acute toxicity of Daphnia magnaclassification criteria.