Acute and chronic toxicity of veterinary antibiotics to Daphnia magna

The acute and chronic toxicity of nine antibiotics used both therapeutically and as growth promoters in intensive farming was investigated on the freshwater crustacean Daphnia magna. The effect of the antibiotics metronidazole (M), olaquindox (OL), oxolinic acid (OA), oxytetracycline (OTC), streptomycin (ST), sulfadiazine (SU), tetracycline (TC), tiamulin (TI) and tylosin (TY) was tested in accordance to the ISO (1989) and OECD (1996) standard procedures. The acute toxicities (48-h EC50 value, mg/l) in decreasing order were OA (4.6), TI (40), SU (221), ST (487), TY (680) and OTC (approximately 1000). NOECs were 340 mg/l for TC and 1000 mg/l for M and OL. Toxic effect on reproduction occurred generally at concentrations, which were one order of magnitude below the acute toxic levels. The chronic toxicity (EC50 values, mg/l) in the D. magna reproduction test in decreasing order were TI (5.4), SU (13.7), TC (44.8) and OTC (46.2). The NOECs (mg/l) obtained in the reproduction test with OA, ST, TY and M were 0.38 for OA, 32 for ST, 45 for TY and 250 for M. The observed toxicity of OA to D. magna indicates that this substance, which is a commonly used feed additive in fish farms, has a potential to cause adverse effects on the aquatic environment.     

Detection of organic pollutants in sandy soils via TDR and eigendecomposition

In this study, organic pollutants in sandy soils are detected using a time domain relectrometry (TDR) probe system and eigendecomposition technique. As a demonstration, four types of organic fluids (motor oil, diesel oil, methanol and ethanol) were examined. Samples were prepared with different combinations of deionized water and organic fluid contents. For each experiment, reflected signals were captured by an oscilloscope, and their characteristics were identified using eigendecomposition technique. Autoregressive modeling and singular value decomposition methods were utilized for calculating the eigenvalues. The most significant eigenvalues were then identified based on their relative magnitude. Experimental results indicated that the presented system is sensitive to both water and pore fluid organic contents. For saturated conditions, signature curves were determined for identification of organic and/or water contents in soil pore fluids.     

Anaerobic incorporation of the radiolabeled explosive TNT and metabolites into the organic soil matrix of contaminated soil after different treatment procedures

Four bioreactor designs were performed to evaluate the level of incorporation of 14C-labeled 2,4,6-trinitrotoluene (TNT) and metabolites into the organic soil matrix of different anaerobically treated contaminated soils. The contaminated soils were amended with molasses slivers (80:20% per weight) as auxiliary substrate to enhance microbial activity. After 5 weeks (bioreactors 1 and 2), 8 weeks (bioreactor 3) and 12 weeks (bioreactor 4) of anaerobic incubation, we determined 41%, 58%, 72%, and 54%, respectively, of the initially applied radioactivity immobilized in various soil fractions. After alkaline hydrolyses of the solvent-extracted soils, low quantities of radiolabel were found in the humic and fulvic acid fractions, whereas the bulk of 14C activity was found to be strongly bound to the humin fraction (solid soil residues). The amounts of solvent extractable radioactivity were 53%, 40%, 16%, and 29% for bioreactors 1, 2, 3, and 4, respectively. The level of TNT transformation at the end of the experiments was within 90-94%. Regarding the results presented in this study, we can assume that there is the possibility of high incorporation levels of TNT metabolites into the soil organic matrix mediated by microbial cometabolism under strictly anoxic conditions.     

Clearance of PCDD/Fs via the gastrointestinal tract in occupationally exposed persons.

A digestive tract mass balance was performed on six men with high body burdens of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Intake via food was measured by analyzing duplicate portions of the food consumed by the volunteers and excretion via feces was determined by quantitative collection and analysis of the feces. Blood samples were taken to determine the current body burden. The results showed that the quantity of non-metabolized chemical excreted in the feces clearly exceeded the uptake via food for all of the 2,3,7,8-substituted PCDDs and some of the PCDFs, indicating a significant clearance across the gastrointestinal tract. The concentrations of these PCDD/F congeners in blood and feces were highly correlated (r > 0.8), demonstrating that the fecal PCDD/F content was determined by the body burden. The half lives in the test persons due to fecal clearance of non-metabolized chemical were estimated from the excretion rate and the current body burden and ranged between 10 years (Cl8DD) and 33 years (2,3,4,7,8-Cl5DF). These were compared with the overall contaminant half-lives due to all clearance processes which were calculated from the body burden and the decrease in blood concentrations measured over several years. The fecal clearance of non-metabolized PCDD/F contributed on average between 37% (2,3,7,8-Cl4DD) and 90% (Cl8DD) to the total elimination. This indicates that the gastrointestinal pathway plays a decisive role in the clearance of most 2,3,7,8-subsituted PCDD/F congeners.     

Methods for the analysis of PCBs in human food, faeces and serum.

A method was developed to determine trace concentrations of a range of individual PCB congeners in biological samples (serum, food and faeces) using GC-MS, to prepare a mass balance of PCBs in humans. A simple method for the analysis of PCBs in human serum, which excluded an extraction step, was first employed. Results indicated that the recoveries of 13C12 PCB spikes were variable. A soxhlet extraction step was added and was found to be efficient and reproducible. A quality control routine and method validation results are presented. In batch tests of the methods presented it was found that the serum analysis method gave within batch mean 13C12 spike recoveries of 98-120% and standard deviations between 6 and 20%. The food/faeces analysis method gave within-batch mean 13C12 spike recoveries of 88-100%, and within batch standard deviations between 4 and 12%. The batch to batch mean recovery for serum analysis was 100%, with an RSD of 9% for high spikes and 10% for low spikes. For food/faeces analysis the batch to batch average recovery was 110%, with an RSD of 5% for high spikes and 9% for low spikes.     

Metabolism and body-burden of PCBs in lactating dairy cows.

This paper uses data from a detailed 4 month PCB mass balance study on lactating cows fed a naturally contaminated background diet to quantify the metabolism and body-burdens of a range of PCB congeners. Dietary intake fluxes and milk and faecal output fluxes reported previously are combined with subcutaneous fat and blood PCB concentrations and with data from tissue/organ samples from a slaughtered animal to estimate the degree of metabolism within the cow. A total body burden is derived, showing that fat deposits account for approximately 98% of total PCB present in the lactating cow. The daily intake through feed (ng day-1) accounted for between 0.9 and 1.5% of the total body burden for persistent congeners (e.g. PCB 153) and up to 43% for those congeners which are readily metabolised (e.g. PCB 52). Detailed balances for a range of tri- to octa-chlorinated PCBs are presented and clearly demonstrate that many congeners are metabolised effectively by lactating dairy cows (e.g. PCB 149) whilst others are efficiently transferred to human dairy food products. An approach to predicting the degree of metabolism for individual PCB congeners is presented which gives good agreement with observations.     

A laboratory study of the mineralization and binding of 14C-labeled herbicide rimsulfuron in a rendzina soil.

The fate of pyrimidine-2-14C-rimsulfuron in a rendzina soil was investigated using a laboratory microcosm approach. Measurement of CO2 evolution suggested that rimsulfuron applied at 5 times the recommended dose did not affect soil respiration. Under abiotic conditions, no mineralization of 14C-rimsulfuron into 14C-CO2 occurred and under biotic ones it was very low reaching 0.75% of the applied 14C-rimsulfuron after 246 days of incubation. The analysis of data showed that a three-half order model provided the best fit for the mineralization curve. Extractable 14C-residues decreased over time to 70-80% of the applied 14C-rimsulfuron at the end of the incubation. After 246 days of incubation, non extractable residues (NER) accounted for up to 24.7% of the applied 14C-rimsulfuron and were distributed according to organic carbon in soil size fractions, suggesting a progressive incorporation process of NER to soil humus.     

Airborne pollutants along a roadside: assessment using snow analyses and moss bags

Vertical snow sampling and moss bag transplants were used to estimate the local inorganic and organic pollutant load deposited from traffic along a major highway in Finland. The pH and concentrations of Cl(-), NO(3)(-), SO(4)(2-), Ca(2+), Na(+) and polyaromatic hydrocarbons (PAHs) were determined from snow samples collected in winter at different sites along the highway. In summer, moss bags containing 20 g of fresh red-stemmed feather moss (Pleurozium schreberi) were transplanted at the same sites. The moss bag transplants remained exposed to roadside traffic for a period of one month following which the samples were collected and the PAH profiles and concentrations were analysed. The deposition of inorganic and organic pollutants from road traffic was observed up to 60 m from the road. The prevailing winds had a significant effect on the dispersion of pollutants. Snow appears to be a good collector of inorganic pollutants from the atmosphere and can be used to monitor local airborne pollution from road traffic. Snow packs can also be used as passive collectors of organic pollutant loads from road traffic on a local scale. To monitor organic PAH deposition from the road traffic, moss bags appeared to be better indicators compared to snow sampling. The efficiency of moss bags in accumulating PAH compounds indicate that vegetation may be an important sink for traffic pollution.