Studies On The Time Toxicities Of Some Drugs And Their Mixtures Towards Two Kinds Of Test Organisms

A large number of drugs has been used in human health and aquaculture, and mostly are discharged with its prototype or metabolites in excreta into the environment, which become a new kind of pollutants. Drugs discarded into the environment not only pose a threat to the survival of aquatic organisms, but also induce microorganisms to produce tolerance. Therefore, the environmental pollutant of drugs gradually has become a widespread concern by the academia and the public. Survey has indicated that some antibiotics are highly toxic and different antibiotics have different time variations of toxicity to aquatic organisms. However, studies on the ecotoxicological effects of drugs haven’t been fully carried out. It is necessary to study the ecotoxicological effects of drugs expecially their time-dependent toxicity, which has a important practical significance in assessing ecological risk.In the paper, Vibrio-qinghaiensis sp.-Q67（Q67） and Chlorella pyrenoidosa（CP） were taken as indicators and 96-well microplate was chosed as exposure experiment carrier, four kinds of aminoglycosides（dihydrostreptomycin, sulfuric acid chains chlortetracycline, neomycin sulfate and apramycin sulfate）, one kind of broad-spectrum antibiotics（chloramphenicol）, five kinds of beta antibiotics（penicillin G potassium, sodium piperacillin, sulbactam sodium, sodium carboxymethyl benzyl penicillin and cloxacillin sodium）, five kinds of sulfa antibiotics（sulfamethazine, sulfamethoxazole, sulfasalazine, sulfadiazine, and sulfa-chloro pyridazine） and five kinds of insoluble drugs（carbamazepine, oxcarbazepine, oxytetracycline, norfloxacin and enrofloxacin） were choosed as the research object. Direct equipartition ray design（Equ Ray） and uniform design（UD-ray） methods were employed to design the binary mixtures and five mixtures, respectively. In each binary mixture, five rays with different concentration ratios, and In each pentanary mixture, seven rays with different concentration ratios were designed. The toxicity of each mixture ray was detemined by the time-dependent microplate toxicity analysis（t-MTA） The obtained toxicity data at different exposure time was fitted by non-linear least squares method. Taking concentration addition（CA） as the reference model, the toxicity interaction within designed mixtures were evaluated, and the toxicity interaction strength were further characterized by using of fitting to zero index. The main results obtained in this thesis are summarized in detail as follows:（1） It was shown the four kinds of aminoglycoside antibiotics apramycin sulfate（APR）, streptomycin sulfate（STS）, Dihydrostreptomycin Sulphate（DIS）, neomycin sulfate（NEO）, one broad-spectrum antibiotic chloramphenicol（CHL）, and their mixtures had time-dependent toxicity towards CP. The toxictity changing with time lengthening of four aminoglycoside antibiotics were basicly similar. CHL also showed time-dependent toxicity, but its toxicity was mainly located in the high concentration range and low concentration basically did not show any toxicity. The negative logarithm of mean effect concentration(p EC₅₀) was selected as toxicity index for the comparison of individual substances. In the group of ten mixed system in addition to the CRCs of the STS-CHL and DIS-CHL mixture system falling outside the observed CRC’s 95% confidence interval, the remaining eight groups of fourty mixtures of the forecast CRC falled within the observed CRC’s 95% confidence intervals, diplaying a classic additive effect. With the concentration ratio of CHL increasing, the interaction of DIS-CHL mixture system varied gradually from additive effect of R1 and R2 to the synergic effect of R3, R4 and R5. As for the STS-CHL system, the antagonism of R1 to R5 gradually decreased in intensity, and R5 was close to additive effect.（2） In the five kinds of insoluble drugs and their mixtures, four kinds of insoluble drugs enrofloxacin（ENR）, norfloxacin（NOR）, carbamazepine（CMP） and oxcarbazepine（OCP） indicated time-dependent toxicity with Q67. The former two drugs showed hormesis in the last two tested timepoint, the other timepoints was Signoid shape and the last two drugs were S shape effect in each timepoint. TER exhibited acute toxicity, and with time lengthening, the intensity of toxcity decreased. Wheher the appearance of hormesis depended on the content of ENR or NOR in the mixture. TER-OCP and TER-CMP mixture systems, antagonism in the high concentration region of the first three timepoints transformed to additive effect of the last two timepoint. And the strength of interaction were characterized by the fitting to zero index. In the seven rays of five mixture system, the CRCs of R3 and R6 showed time-dependent hormesis, the remained were all Signoid shape.（3）The toxcities of five kinds of beta antibiotics penicillin G potassium（BLP）, piperacillin sodium（PSS）, sulbactam sodium（SBS）, carbenicillin sodium（CBD） and cloxacillin sodium（CLS） to Q67 and CP were tested. The effect of them on the Q67 showed a significant time-dependent toxicity, while they show low toxicity and no obvious time-dependency to CP. The toxicity order of the timepoint of 12 h followed by CLS <SBS <PSS <CBD <BLP.（4） The toxcities of five kinds of sulfa antibiotics sulfa-chloro pyridazine（SCP） sulfadiazine（SD） sulfapyridine（SPY） sulfamethoxazole（SMX） and sulfamethazine（SM2） and mixtures to Q67 and CP were tested respectively. The effect of them on the Q67 showed a significant time-dependent toxicity, while they show low toxicity and no obvious time-dependency to CP. The toxicity order of the timepoint of 20 h followed by: SM2 <SD <SMX <SCP <SPY; The toxicity of binary mixture was similar to the single. Taking concentration addition（CA） as the reference model. As for the five substances to CP only the sulfamethoxazole（SMX） and sulfamethazine（SM2） showed a low time-dependent toxicity, the others basicly have no toxic effects; the mixture toxcities towards CP also showed a low time-dependent or had no toxic effects.