The toxicity testing of double-walled nanotubes-contaminated food to Eisenia veneta earthworms.

Nanotechnology is playing an increasing role in the society, but very little is known about the environmental toxicity of nanotechnological products. Few previous studies have been published with regard to the effect of nanoparticles on soil organisms. The present paper deals with the toxicity of carbon double-walled nanotubes (DWNT) and C60 fullerenes to the soil-dwelling earthworm Eisenia veneta, with the aim of evaluating the lethal and sub-lethal toxicity. Reproduction of E. veneta was affected by DWNT administered through food at concentrations above 37 mg DWNT/kg food. The most sensitive toxicological parameter was reproduction (cocoon production), with no effect on hatchability, survival or mortality at up to 495 mg DWNT/kg and 1000 mg C60/kg.

Ochratoxin A carcinogenesis in the (C57BL/6J X C3H)F1 mouse.

The potential carcinogenic effects of the mycotoxin ochratoxin A [(OA); CAS: 303-47-9] were assessed in a 24-month feeding study in male and female (C57BL/6J X C3H)F1 (B6C3F1) mice. The mice were assigned to 3 groups of 50 males and 50 females each; group 1 mice were the controls, group 2 mice were fed 1 ppm OA, and group 3 mice were fed 40 ppm OA. Renal neoplasms, both carcinomas and adenomas, were found only in male mice of the 40-ppm dose group. Fourteen of 49 animals that survived at least 20 months had neoplasms morphologically consistent with renal carcinoma. Renal adenomas were present in some of these mice and in other 40-ppm-group males, making a total of 26 mice with renal adenomas. All male mice of the 40-ppm dose group had nephropathy characterized by varying degrees of renal tubular dilation, attenuation and hyperplasia of lining epithelium, and proliferation of regenerative tubules. Females of the 40-ppm dose group had similar but less severe renal changes but no carcinomas or adenomas. Compound-related renal lesions were absent in the 1-ppm dose group. The incidence of hepatocellular neoplasms was slightly increased in male and female mice fed diets containing OA. These results indicate that OA is a renal carcinogen in male B6C3F1 mice and a hepatic carcinogen in female mice of this strain.

Establishing a community-wide DNA barcode library as a new tool for arctic research.

DNA sequences offer powerful tools for describing the members and interactions of natural communities. In this study, we establish the to-date most comprehensive library of DNA barcodes for a terrestrial site, including all known macroscopic animals and vascular plants of an intensively studied area of the High Arctic, the Zackenberg Valley in Northeast Greenland. To demonstrate its utility, we apply the library to identify nearly 20 000 arthropod individuals from two Malaise traps, each operated for two summers. Drawing on this material, we estimate the coverage of previous morphology-based species inventories, derive a snapshot of faunal turnover in space and time and describe the abundance and phenology of species in the rapidly changing arctic environment. Overall, 403 terrestrial animal and 160 vascular plant species were recorded by morphology-based techniques. DNA barcodes (CO1) offered high resolution in discriminating among the local animal taxa, with 92% of morphologically distinguishable taxa assigned to unique Barcode Index Numbers (BINs) and 93% to monophyletic clusters. For vascular plants, resolution was lower, with 54% of species forming monophyletic clusters based on barcode regions rbcLa and ITS2. Malaise catches revealed 122 BINs not detected by previous sampling and DNA barcoding. The insect community was dominated by a few highly abundant taxa. Even closely related taxa differed in phenology, emphasizing the need for species-level resolution when describing ongoing shifts in arctic communities and ecosystems. The DNA barcode library now established for Zackenberg offers new scope for such explorations, and for the detailed dissection of interspecific interactions throughout the community.

Time-dependent disappearance of ochratoxin A residues in tissues of bacon pigs.

Crystalline ochratoxin A was administered to bacon pigs for one month. After termination of toxin exposure the pigs were slaughtered at different intervals and analyses for ochratoxin A residues in four tissues were conducted. Kidneys contained the highest concentrations, and fat the lowest, at each interval. Ochratoxin A disappeared from muscles and fat after 2 weeks, from liver after 3 weeks, and from the kidneys after 4 weeks. The toxin disappeared from tissues exponentially. All the pigs would have passed the meat inspection because no pathologic lesions were developed although tissues contained mycotoxin residues. The results of this study indicate that contamination of meat by ochratoxin A may be avoided by feeding pigs ochratoxin-free feed during the last 4 weeks before slaughter.

Human exposure to ochratoxin A in areas of Yugoslavia with endemic nephropathy.

Ochratoxin A is a mycotoxin with pronounced nephrotoxic potency in all species of single-stomach animals studied; it is a major disease determinant of porcine nephropathy and a disease occurring endemically in several countries. This disease is comparable with Balkan (endemic) nephropathy, suggesting a common causal relationship. Ochratoxin A has been found in foodstuffs in many countries, but the highest frequency of ochratoxin A contamination in foods (10.3% of 1,553 samples of foodstuffs) was encountered in an area of Yugoslavia, where Balkan (endemic) nephropathy is prevalent. Detection of ochratoxin A in human blood samples confirmed the prevalent exposure to this food contaminant. Relative risk calculations indicated a tendency to an association between this mycotoxin and Balkan (endemic) nephropathy, supporting the hypothesis of a causal role of ochratoxin A in this disease.

Role of ochratoxin in disease causation.

Under experimental conditions renal damage has been induced by alimentary exposure to ochratoxin A in all single-stomach animals tested so far, including rodents, dogs, pigs and birds, and even in young ruminants still functioning as single-stomach animals. Most information on ochratoxin-induced nephropathy has been obtained in pigs during experimental studies comprising structural as well as functional changes. The renal damage is characterized morphologically by atrophy of the proximal tubules, interstitial cortical fibrosis and sclerotized glomeruli, and functionally by impairment of tubular function indicated by a decrease in TmPAH/Cin and reduced ability to produce concentrated urine. The renal effect has been observed using exposure levels of ochratoxin A in the range 200 to 4000 micrograms/kg feed. Field cases of ochratoxin-induced nephropathy in pigs have been encountered in many countries, and the disease mycotoxic porcine nephropathy (MPN) is recognized as an endemic disease entity in several northern and central European countries. Epidemics of MPN have been reported, closely related to excessive climatic conditions in periods preceding harvest. Ochratoxin A is a recognized renal carcinogen in the mouse. In female pigs exposed to alimentary ochratoxin A for 2 years, no renal cancer was observed. Ochratoxin A is metabolized and excreted relatively fast in animals, with an RL50 (residue elimination) in the pig of a few days for various tissues. Past exposure data is a requirement in retrospective epidemiological studies, but because of the short RL50 values tissue analysis for ochratoxin A is unlikely to provide that kind of data, in animals or in humans. In order to meet this demand a procedure has been developed, using renal biopsy material for activity analysis of two renal tubular enzymes, phosphoenolpyruvate carboxykinase and gamma-glutamyl transpeptidase. In pigs exposed to ochratoxin A for 1 week a 40% reduction of the enzyme activity was observed. The dose-related activity decrease of the two enzymes was accompanied by a dose-related aggravation of renal impairment, as measured by a reduction of TmPAH/Cin, suggesting that these enzymes are sensitive indicators of ochratoxin A-induced nephropathy.

St Georg modular knee prosthesis. A two-and-a-half to six-year follow-up.

The St Georg modular knee replacement has been studied in 59 cases with an observation period ranging from 28 to 73 months. In 47% of the knees both compartments were replaced; five of the six poor results were in this group. These were revised to a hinge arthroplasty or, in one case, to an arthrodesis. Other complications were few and insignificant. There were no infections. We concluded that unicompartmental knee arthroplasty can be recommended when joint involvement is localised to one compartment only. With more generalised joint disease we prefer a semiconstrained total condylar prosthesis.

Reye's syndrome in a child on long-term salicylate medication.

A case of Reye's syndrome in a four-year-old child on long-term salicylate medication for rheumatoid arthritis is reported. Severe fatty changes of the liver, lipid vacuolation in the renal proximal tubules, and severe brain oedema were the prominent postmortem findings. Symptoms of a trivial infection and vomiting just before death added to the resemblance of this case to Reye's syndrome.

Bending overload and implant fracture: a retrospective clinical analysis.

Thirty-nine patients with implant fractures treated by three of the authors have been analyzed as to probable causes. Thirty-five (90%) of the fractures occurred in the posterior region. Thirty (77%) of the prostheses were supported by one or two implants, which were exposed to a combination of cantilever load magnification and bruxism or heavy occlusal forces. It was concluded that prostheses supported by one or two implants and replacing missing posterior teeth are subjected to an increased risk of bending overload. The literature review indicates that the fracture frequency is low in these situations and this study demonstrates that with appropriate treatment planning, such overload situations can essentially be prevented.

The reverse-torque test: a clinical report.

Reverse torque to failure on implants has been studied in animals. Three implants were reverse torqued to failure in a human volunteer, with failure rates between 45 and 58 Ncm. Clinical data are presented on 404 implants examined after reverse-torque testing and loading, with no increase in failure rates. Reverse-torque testing at 20 Ncm appears to be a safe, reliable method for verifying osseointegration with pure titanium screw-shaped implants.

Osseointegrated implants for single tooth replacement: a 1-year report from a multicenter prospective study.

One hundred seven dental implants were inserted to support single tooth restorations in 92 patients participating in a prospective multicenter investigation. Only three implants (2.8%) were lost after 1 year of clinical function. Most of the remaining restorations were esthetically successful by using modified components. The gingival condition was healthy around the single crowns and coincided well with the clinical situation around the permanent teeth. The most obvious problem experienced during the first year was related to loose abutment screws. Twenty-six percent of the screws retaining crowns were retightened during the observation period, but the frequency of loose screws had a tendency to decrease as the study progressed.

Osseointegrated implants for single-tooth replacement: progress report from a multicenter prospective study after 3 years.

After 3 years, 82 of the original 92 patients remain in this prospective multicenter study of single-tooth restorations supported by Brånemark implants. Since the 1-year follow-up, 6 more patients have been lost, but no additional implants have failed in those patients examined at the 3-year follow-up visit. After 1 year of function, 97.2% of the implants survived in 88 patients, and between the 1- and 3-year follow-up, 100% survived in 82 patients, giving a 3-year cumulative success rate of 97.2%. No changes were observed in the status of gingivitis, pocket depth, periodontal pocket bleeding index, and tooth and implant mobility from those reported after 1 year. Marginal bone resorption remained at a low level--less than 0.1 mm annually during the second and third years. Abutment screw loosening continued, but at a significantly reduced rate from that reported after 1 year. When used, gold rather than titanium abutment screws remained secure.

Osseointegrated implants for single-tooth replacement: a prospective 5-year multicenter study.

One hundred seven Brånemark implants were placed in 92 patients participating in an international multicenter trial on single-implant restorations at seven centers. The patients were followed for 5 years in a prospective study focusing on implant success and crown function. Plaque and gingival indexes, as well as probing depths, were recorded around teeth and implants. The marginal bone level at implants was determined from intraoral radiographs. Only three implants (2.8%) had been lost at the final annual checkup. During the follow-up period, a total of 17 patients dropped out or were excluded because of nonconformity with the protocol. Based on the remaining patients, a total of 86 implants were clinically and radiographically evaluated at the 5-year follow-up period, resulting in a cumulative success rate of 96.6% (71 implants) in the maxillae and 100% (15 implants) in the mandibles. Plaque and gingival indexes showed a similar pattern of good health around both natural teeth and titanium abutments. The marginal bone loss during the 5-year period did not exceed 1 mm as a mean for all implants analyzed. The most frequent complication recorded during the follow-up was loosening of the abutment fixation screw. The outcome of this study indicated that safe and highly predictable results can be obtained for 5 years when Brånemark implants are used to support single-tooth restorations.

Effects of the antibiotics oxytetracycline and tylosin on soil fauna.

Antibiotics may enter the terrestrial environment when amending soils with manure. A Note of Guidance on ecological risk assessment of veterinary medicines was issued in January 1998. Hardly any information about ecotoxicological effects of already existing substances are available. This study has tested the effects of two widely used antibiotics, tylosin and oxytetracycline, on three species of soil fauna: Earthworms, springtails and enchytraeids. Neither of the substances had any effect at environmentally relevant concentrations. The lowest observed effect concentration was 3000 mg kg-1 and in many cases no effect was seen even at the highest test concentration of 5000 mg kg-1.

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 3. Sublethal effects on soil invertebrates.

Sewage sludge applied to agricultural soils often contains considerable amounts of linear alkylbenzene sulfonates (LAS). Toxic effects of LAS on soil organisms should, therefore. be evaluated to ensure safe use of sewage sludge as a fertilizer. In this study, dose-response relationships for the toxicity of Na-LAS to six species of soil invertebrates (survival, reproduction, and growth) were established using a sandy, agricultural soil as test substrate. In general, toxic effects on reproduction and growth appeared when the concentration in soil exceeded 40 to 60 mg/kg. Reproduction was approximately fourfold more sensitive in earthworms and enchytracids than in springtails and mites. It is argued that this difference in sensitivity is related to the dependency of soil pore water, which is high in the annelids but comparatively low in the arthropods.

Effects of polycyclic aromatic compounds on the drought tolerance of Folsomia fimetaria (Collembola, Isotomidae).

Drought tolerance (survival at 98.2% relative humidity and 20 degress C) was investigated for adult individuals of the springtail Folsomia fimetaria after three weeks of exposure to different polycyclic aromatic compounds (PACs). Seven PACs were investigated (acridine, dibenzofuran, carbazole, fluorene, dibenzothiophene, fluoranthene, and pyrene), with each substance used at several exposure concentrations. Sublethal concentrations of dibenzothiophene, fluorene, fluoranthene, and pyrene caused a dose-related decrease in drought tolerance in exposed adults, whereas no such relationship was found for acridine, dibenzofuran, and carbazole. The organisms used in the drought tolerance study were taken directly from standard ecotoxicity tests that had just been completed, hence the concentrations causing subsequent effects on drought tolerance and those affecting survival and reproduction in the ecotoxicity tests could be compared. Some of the tested substances significantly reduced the drought tolerance of F. fimetaria at concentrations that had little effect on survival, indicating a synergistic effect of the two stressors. However, drought tolerance was affected at concentrations below the threshold value for toxicity in standard tests (no-observed-effect concentration for reproduction) only for dibenzothiophene. In the field, soil organisms exposed to contaminants also face multiple environmental stressors such as drought and cold. Because the reduced drought tolerance is a side effect of chemical exposure, such effects should be considered when extrapolating from laboratory to field conditions.

Effects of di(2-ethylhexyl) phthalate and dibutyl phthalate on the collembolan Folsomia fimetaria.

Lethal and sublethal effects of di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) on adult individuals of the collembolan Folsomia fimetaria were investigated in the laboratory by the use of small microcosms. Effects of DEHP and DBP were also tested on newly hatched collembolans in a multidish system. The endpoints were juvenile mortality, growth, and development. When exposed to DEHP, adults and juveniles were unaffected at all test concentrations, that is, up to 5,000 mg/kg. However, DBP caused increased adult mortality at 250 mg/kg and juvenile mortality at 25 mg/kg. For DBP, adult reproduction was a more sensitive endpoint than was survival, with an EC10 and EC50 of 14 and 68 mg/kg, respectively. Juvenile molting frequency seems to be a sensitive parameter, because number of cuticles produced by young springtails was reduced at 1 mg/kg. Toxicity was reduced when soil spiked with DBP was stored at 20 degrees C for a period of up to 28 d before adding the animals. Reduction in toxicity of DBP may be due a combination of degradation, evaporation, and adsorption of DBP to soil material. This was confirmed by chemical analyses, which showed a rapid initial disappearance followed by a much slower disappearance. Our results lead to the overall conclusion that significant adverse effects of phthalates on collembolans are not likely to occur as a result of normal sewage sludge application.

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 5. Probabilistic risk assessment of linear alkylbenzene sulfonates in sludge-amended soils.

Linear alkylbenzene sulfonates (LAS) can be found in high concentrations in sewage sludge and, hence, may enter the soil compartment as a result of sludge application. Here, LAS may pose a risk for soil-dwelling organisms. In the present probabilistic risk assessment, statistical extrapolation has been used to assess the risk of LAS to soil ecosystems. By use of a log-normal distribution model, the predicted no-effect concentration (PNEC) was estimated for soil fauna, plants, and a combination of these. Due to the heterogeneous endpoints for microorganisms, including functional as well as structural parameters, the use of sensitivity distributions is not considered to be applicable to this group of organisms, and a direct, expert evaluation of toxicity data was used instead. The soil concentration after sludge application was predicted for a number of scenarios and used as the predicted environmental concentration (PEC) in the risk characterization and calculation of risk quotients (RQ = PEC/PNEC). A LAS concentration of 4.6 mg/kg was used as the current best estimate of PNEC in all RQ calculations. Three levels of LAS contamination (530, 2,600, and 16,100 mg/kg), three half-lives (10, 25, and 40 d), and five different sludge loads (2, 4, 6, 8, and 10 t/ha) were included in the risk scenarios. In Denmark, the initial risk ratio would reach 1.5 in a realistic worst-case consideration. For countries not having similar sludge regulations, the estimated risk ratio may initially be considerably higher. However, even in the most extreme scenarios, the level of LAS is expected to be well beyond the estimated PNEC one year after application. The present risk assessment, therefore, concludes that LAS does not pose a significant risk to fauna, plants, and essential functions of agricultural soils as a result of normal sewage sludge amendment. However, risks have been identified in worst-case scenarios.

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 4. The influence of salt speciation, soil type, and sewage sludge on toxicity using the collembolan Folsomia fimetaria and the earthworm Aporrectodea caliginosa as test organisms.

Sewage sludge applied to agricultural soils often contains linear alkylbenzene sulfonates (LAS) in the range of 1 to 10 g/kg dry weight, and their toxicity to relevant soil organisms should, therefore, be assessed to ensure safe use of sewage sludge as a fertilizer. Studies of LAS toxicity to soil organisms are few, and to our knowledge, factors that may influence the toxicity in the field have not been studied in detail. In this paper, we report on the influence of speciation of LAS in the test solution added to soil (soluble Na-LAS vs poorly soluble Ca-LAS or Mg-LAS), the influence of soil type, and the modifying effects of sludge amendment on the toxicity of LAS. These issues were investigated using reproduction of Collembola and growth of juvenile earthworms as test parameters. Speciation of the LAS added to test soil did not have any influence on toxicity for any of the test species. Likewise, in three different agricultural soils (sand, loam, and clay), we found almost equal toxicities. The LAS added to test soil in a sludge-water suspension was equally toxic as when it was added in an aqueous solution. However, anaerobic incubation for 7 and 14 d of the LAS-sludge suspension (with no decay of LAS) caused the toxicity to increase almost threefold in both collembolan and earthworm. The relationships between soil constituents, bioavailability, and toxicity are also discussed.

Effects of eight polycyclic aromatic compounds on the survival and reproduction of the springtail Folsomia fimetaria L. (Collembola, isotomidae).

The effects of eight polycyclic aromatic compounds on the survival and reproduction of the collembolan Folsomia fimetaria L. were investigated in a well-characterized Danish agricultural soil. With the exception of acridine, polycyclic aromatic hydrocarbons (PAHs) and neutral N-, S-, and O-monosubstituted analogues showed similar toxicities to soil collembolans when the results were expressed in relation to total soil concentrations (mg/kg). The estimated concentrations resulting in a 10% reduction of reproductive output (EC10 values) were based on measured initial concentrations and were for acridine 290 mg/kg, carbazole 10 mg/kg, dibenzofuran 19 mg/kg, dibenzothiophene 7.8 mg/kg, fluoranthene 37 mg/kg, fluorene 7.7 mg/kg, phenantrene 23 mg/kg, and pyrene 10 mg/kg. When the EC10 values were converted to soil pore-water concentrations, they showed a highly significant correlation (r2 = 0.71, p < 0.01) to no-observed-effect concentrations for the freshwater crustacean Daphnia magna, as estimated by a quantitative structure activity relation (QSAR) for baseline toxicity (nonpolar narcosis). Only carbazole and acridine were more than two times more toxic (4.9 and 3.1, respectively) than expected from the Daphnia QSAR data. The latter result indicates that the toxicity of the tested substances is close to that expected for compounds with nonpolar narcosis as the mode of action. However, the relatively large uncertainties in the extrapolation method prevent final conclusions from being drawn.