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P H Krogh

Publications and source records attributed to P H Krogh.

At least 19 recordsLinked to original sources
PubMed2006

Nonylphenol stimulates fecundity but not population growth rate (lambda) of Folsomia candida.

The toxicity of nonylphenol (NP) to springtails was pronounced at 40 mg/kg dry weight soil, at which no animals survived. Body length and fecundity were the individual life-history traits significantly stimulated by sublethal concentrations of NP during a 64-day experiment. However, the effects of NP on these traits did not result in a statistically significant increase in population growth rate (lambda). Decomposition analysis indicated that fecundity was the main contributor to the (non-significant) changes observed in lambda. However, since the elasticity of fecundity was very low, large changes in fecundity resulted in a minimal effect on lambda. Juvenile survival had the highest elasticity of all traits, but was not affected by NP, and therefore did not contribute to effects on lambda. This study confirms previous studies showing that effects of chemicals on individual life-history traits are attenuated at the population level and that lambda is an appropriate endpoint for ecotoxicological studies.

Animals↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Agriculture↗
PubMed2001

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.

Agriculture↗
PubMed2001

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.

Agriculture↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Adaptation, Physiological↗
PubMed2000

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.

Animals↗
PubMed1999

Toxicity of nickel to a soil-dwelling springtail, Folsomia fimetaria (Collembola: Isotomidae).

Exposure of the collembolan Folsomia fimetaria L. to nickel via soil caused significant mortality and reduced growth and reproductive output. Nickel may be present in elevated concentrations due to anthropogenic discharge. Although collembolans are very numerous and important organisms in the soil ecosystem, the effect of nickel has not previously been studied on these organisms. The aim of this study was to investigate the toxic effects of high soil nickel concentrations on the collembolan F. fimetaria following a 3-week exposure in a loamy sand spiked with nickel up to 1000 mg Ni/kg. A 10% decrease in adult female numbers at 427 mg Ni/kg and at 645 mg Ni/kg for adult male numbers was observed for nickel-spiked soil. Juvenile numbers were reduced at 701 mg Ni/kg following a 3-week exposure. The corresponding EC50 values were 786 mg Ni/kg for females, 922 mg Ni/kg for males, and 859 mg Ni/kg for juveniles. The reproductive output seems to be the most sensitive parameter being reduced at soil nickel concentrations above 173 mg Ni/kg (EC10). Adult growth was not affected by soil nickel concentrations up to 1000 mg Ni/kg, but juvenile growth was reduced at concentrations above 480 mg Ni/kg (EC10).

Animals↗
PubMed1997

Ecological effects assessment of industrial sludge for microarthropods and decomposition in a spruce plantation.

Effects of dried, granulated industrial sludge-containing residues of organic pesticides and precursors were assessed for microarthropod fauna and the decomposition of a spruce forest floor. The investigation was highly realistic, using large plots of about 1/2 ha, and the application was done with professional equipment. The ecological effects of the sludge were compared with the ecological effects of an inorganic fertilizer. Decreases in abundance of the microarthropods ranged from 20 to 80% of the control level after 1 year. Isotoma notabilis Schäffer was the only species that exhibited stimulation at twice the control level due to the sludge. The least affected collembolan species was Lepidocyrtus cyaneus Tullberg, a member of the surface-dwelling life forms. Sensitive species were Isotoma anglicana Lubbock and Isotomiella minor Schäffer. In subhabitats with almost no application of sludge due to a heterogeneous horizontal distribution, the microarthropods were still affected to the same degree as those in the zones of maximum application. Laboratory tests with Folsomia candida Willem gave results similar to the effects on field populations concerning the sludge but revealed no adverse effects of the fertilizer. Decomposition was stimulated to the same extent in the field by the two types of fertilizer but in the laboratory the sludge caused the largest stimulation. The effects on the microarthropod fauna are suggested to be the result of a combination of direct toxicity and changes in the microbial community due to fertilizers.

Animals↗
PubMed1997

Predator-prey relationships in a two-species toxicity test system.

In a two-species toxicity test system survival and reproduction of both the predator Hypoaspis aculeifer (Gamasida) and the prey Folsomia fimetaria (Collembola) were studied after 21 days of residual exposure to a soil contamination of the insecticide dimethoate. Additional experiments were run to analyze which species-species and compound-species relationships determine the outcome of this two-species experiment. Number of adult F. fimetaria were reduced by both predation and dimethoate exposure, whereas mites preyed less efficiently on adults than on juveniles. At 0.357 mg dimethoate/kg soil, numbers of juvenile F. fimetaria were mainly reduced by predation on adults and juveniles. At 0.7 mg/kg, an additional dimethoate effect was found, which was attributed to an effect on the reproduction of F. fimetaria, mainly due to lethality of adults. It was reasoned that lethal effects on juvenile springtails are less important. Adult H. aculeifer was not affected by dimethoate exposure, whereas numbers of juvenile H. aculeifer demonstrated a decline only at the highest concentration of 0.7 mg/kg. It is hypothesized that this latter effect is possibly due to food depletion caused by a decreased availability of prey, rather than to the lethal effects of dimethoate on juvenile mites. Such a secondary effect of a pesticide application could not have been derived from a single-species toxicity experiment and demonstrates the additional value of a two-species toxicity test system.

Animals↗
PubMed1996

Effect of dimethoate on body growth of representatives of the soil living mesofauna.

For the elucidation of effects of a pesticide on life-cycle parameters of arthropods, applicable in the development of ecotoxicological test procedures with soil living animals, attention was drawn to body growth, which has previously been described as a sensitive parameter in Collembola. Body growth of the following three soil-dwelling arthropods was studied under the influence of dimethoate: Folsomia fimetaria (L.), Hypogastrura assimilis Krausbauer, and Hypoaspis aculeifer Canestrini. The effect of this insecticide and acaricide proved to be sex and species specific. Two models were compared for modeling individual body length. The logistic growth model fitted data for all species, whereas the growth model of von Bertalanffy was less applicable for F. fimetaria and H. aculeifer. The growth rate coefficient of the logistic model proved to be a robust parameter useful for predicting effects of dimethoate on juvenile growth of F. fimetaria and H. aculeifer. Adverse effect concentrations on growth for these species were the following: EC10 = 0.11 mg dimethoate/kg dry soil for F. fimetaria and EC10 = 0.59 mg dimethoate/kg dry soil for H. aculeifer. For H. assimilis, no adverse effects on growth were observed at the tested concentrations. The results are compared to other life-cycle parameters (end-points).

Analysis of Variance↗
PubMed1995

Does a heterogeneous distribution of food or pesticide affect the outcome of toxicity tests with Collembola?

The reproduction of two closely related soil microarthropods, Folsomia candida Willem and Folsomia fimetaria L. (Insecta: Collembola), was tested under the influence of the insecticide dimethoate. Dimethoate had an adverse effect on the survival of adults and their reproduction in concentrations of about the recommended field dose, with F. fimetaria being more sensitive than F. candida. The experimental conditions were altered to evaluate the realism in the basic single species/single chemical reproductive test system. The importance of the spatial distribution of dimethoate was studied with food applied to the surface (original procedure), mixed homogeneously in the whole soil profile or only in the top layer, or mixed heterogeneously into the soil preserving the small granula of the yeast originally in the commercial formulation. Toxicity decreased significantly when exposure could be avoided in an uncontaminated bottom layer and even more if food was available in this soil horizon. But the results indicate that Collembola were not able to completely avoid dimethoate when they had the choice. For extrapolation purposes a simple test system may be sufficient as EC50 was changed less than one order of magnitude with the different test designs. In terms of EC50 the outcome of a toxicity test with a heterogeneous distribution of food and dimethoate was changed only slightly but the effects to suboptimally fed populations should be considered because they may be more vulnerable.

Animals↗
PubMed1991

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.

Adult↗