Toxicity of abamectin and doramectin to soil invertebrates

This study aimed at determining the toxicity of avermectins to soil invertebrates in soil and in faeces from recently treated sheep. Abamectin was more toxic than doramectin. In soil, earthworms (Eisenia andrei) were most affected with LC50s of 18 and 228 mg/kg dry soil, respectively, while LC50s were 67-111 and >300 mg/kg for springtails (Folsomia candida), isopods (Porcellio scaber) and enchytraeids (Enchytraeus crypticus). EC50s for the effect on reproduction of springtails and enchytraeids were 13 and 38 mg/kg, respectively for abamectin, and 42 and 170 mg/kg for doramectin. For earthworms, NOEC was 10 and 8.4 mg/kg for abamectin and doramectin effects on body weight. When exposed in faeces, springtails and enchytraeids gave LC50s and EC50s of 1.0-1.4 and 0.94-1.1 mg/kg dry faeces for abamectin and 2.2->2.4 mg/kg for doramectin. Earthworm reproduction was not affected. This study indicates a potential risk of avermectins for soil invertebrates colonizing faeces from recently treated sheep.     

Sub-lethal toxicity of the antiparasitic abamectin on earthworms and the application of neutral red retention time as a biomarker

The antiparasitic abamectin has been proven effective against both endo- and ectoparasites of farm animals and hence used widely in animal husbandry. It may enter the soil environment with the excreta of treated animals. Very little information is available with regard to the sub-lethal effects of abamectin on soil invertebrates, such as earthworms. The objective of this study was to evaluate the toxic effect of abamectin on earthworms, using Eisenia fetida, by analyzing changes in the survival, growth, reproduction and cocoon hatchability of exposed earthworms. Furthermore, a biomarker of the lysosomal membrane stability, measured by neutral red retention time (NRR-time), was also applied. Abamectin showed significant toxicity on the growth of earthworms with increasing concentrations up to 5mg/kg. The most sensitive parameter was reproduction (cocoons production and hatchability) and NRR-time. The number of cocoons was reduced at concentrations above 0.25mg/kg and no cocoons were present at the highest concentration of 5mg/kg. Cocoons exposed to abamectin exhibited a reduced hatching success at concentrations above 1.5mg/kg. The NRR-time was reduced significantly at exposure concentrations of abamectin above 0.25mg/kg. The change in lysosomal membrane stability showed a good correlation with reproduction and may hence be a potential predicator of the effects on earthworm populations.     

Effects of the antibacterial agents tiamulin,olanquindox and metronidazole and the anthelmintic ivermectin on the soil invertebrate species Folsomia fimetaria (Collembola) and Enchytraeus crypticus (Enchytraeidae)

Veterinary pharmaceutical products such as antibacterial agents and antiparasitics are widely used to control diseases and promote production in the agricultural sector. Exposure of non-target organisms are a likely result of using manure from treated live stocks or from dung dropped on the field by grazing animals. The aim of this study was to determine the toxic threshold levels of three antibacterial agents (tiamulin, olanquindox and metronidazole) and one anthelmintic (ivermectin) to two species of soil dwelling organisms (springtails and enchytraeids), that are often found in bio-solids such as manure or dung. The antibacterial agents were not toxic to adults and effects on reproduction occurred generally above concentrations normally found in soil or dung. The threshold values for toxicity (10% reduced reproduction or EC10 values) were in the range of 61-111 mg kg(-1) dry soil for springtails and 83-722 mg kg(-1) dry soil for enchytraeids. Ivermectin was significantly more toxic with EC10 values of 0.26 mg kg(-1) dry soil for the springtails and 14 mg kg(-1) dry soil for the enchytraeids. A comparison of these results with rough estimates of likely and worse case environmental concentrations indicates a potential risk of ivermectin to non-target species such as springtails and enchytraeids, whereas direct toxic effect of antibacterial agents is very unlikely to occur at environmental realistic concentrations. However, indirect effects of antibacterial agents driven through changes in the food web cannot be abolished at this stage.     

Ecotoxicity of nickel to Eisenia fetida, Enchytraeus albidus and Folsomia candida

Despite growing concern about the potential adverse effects of elevated nickel concentrations in the environment, only a few toxicity data are available for terrestrial invertebrates. Therefore, chronic toxicity of nickel was assessed for Eisenia fetida, Enchytraeus albidus and Folsomia candida, the three invertebrates for which standard test protocols are available. The 21 d EC50 for the cocoon production of E. fetida was 362 (241-508) mg Ni/kg dry wt. For the reproduction of E. albidus, a 42 d EC50 of 275 (217-346) mg Ni/kg dry wt was observed. The 28 d EC50 for the reproduction of F. candida was 476 (347-671) mg Ni/kg dry wt. The obtained toxicity data were very similar to those of related species reported in literature. Although the presented data can be considered as a step forward in the assessment of the potential risks of nickel in terrestrial environments, further research is needed to evaluate the influence of soil parameters on the toxicity of nickel and to quantify the effect of ageing on bioavailability.     

Risk assessment of linear alkylbenzene sulphonates, LAS, in agricultural soil revisited: robust chronic toxicity tests for Folsomia candida (Collembola), Aporrectodea caliginosa (Oligochaeta) and Enchytraeus crypticus (Enchytraeidae)

To obtain robust data on the toxicity of LAS, tests with the collembolan Folsomia candida L., the oligochaetes Aporrectodea caliginosa Savigny (earthworm) and Enchytraeus crypticus Westheide and Graefe (enchytraeid) were performed in a sandy loam soil. Additionally limited tests with LAS spiked to sewage sludge, and subsequently mixed into soil, were performed. For the endpoint of interest, reproduction in soil, we found an EC10 of 205 mg LAS kg(-1) soil [8.6-401] [95% confidence limits] for F. candida and an EC10 of 46 mg LAS kg(-1) soil [13-80] for A. caliginosa after 28 days. E. crypticus was not affected by concentrations up to 120 mg LAS kg(-1) soil. When adding (low contaminated) non-spiked sludge to soil, high stimulation of reproduction was observed for E. crypticus and A. caliginosa but not for F. candida. We argue that this difference in stimulative response between the tested species is related to the difference in feeding behaviour. Sludge spiked with LAS did not significantly affect the reproduction of F. candida (fertility: number of juvenile offspring) and A. caliginosa (fecundity: number of cocoons) (dose equivalent to 181 g and 91 g LAS kg(-1) sludge, respectively). Significantly reduced reproduction was observed for E. crypticus (at 120 mg LAS kg(-1) soil+sludge corresponding to 72 g LAS kg(-1) sludge) compared to non-spiked sludge. The reproduction by E. crypticus was, however, comparable to the reproduction observed in the control soil without sludge. Compared to LAS directly spiked to soil, the reproductive output of organisms exposed to spiked sludge was either not significantly different (F. candida, E. crypticus) or significantly improved (A. caliginosa). More studies are needed in order to make firm conclusions on the potential effect of artificially contaminated sludge in soil systems.     

The toxicity of soil samples containing TNT and other ammunition derived compounds in the enchytraeid and collembola-biotest

The effect of ammunition-like compounds and armament waste on the mortality and reproduction of terrestrial invertebrates was assayed by using two biotests: the enchytraeid-biotest withEnchytraeus crypticus and the collembola-biotest withFolsomia Candida. Toxicity was investigated by using standard soil (Lufa 2.2) spiked with 2,4,6-trinitrotoluene (TNT), hexahydro-l,3,5-trinitro-l,3,5-triazine (hexogen, RDX), octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazocine (octogen, HMX) and 2,4,6-triaminotoluene (TAT). Ecotoxicity was investigated with ammunition-contaminated soil material from the former ammunition plant “Tanne” at Clausthal-Zellerfeld (CTNTla) and the Brandplatz (incineration site) in Torgau-Elsnig (TETNT1a), Germany. TNT increased mortality and reduced reproduction of both test organisms corresponding to the concentrations used, whereas hexogen, octogen and TAT had no effect in the tested concentrations (1000-2000 mg/kg). From the two soil materials, TETNT1a was much more toxic than CTNT1a. The LC50(7d) in the enchytraeid-biotest was 570 mg TNT/kg and the EC50(28d) 369 mg TNT/kg soil material (dw). In the collembola-biotest the LC50(7d) was 185 mg TNT/kg and the EC50(28d) 110 mg TNT/kg soil matter (dw).     

Development of zinc bioavailability and toxicity for the springtail Folsomia candida in an experimentally contaminated field plot

The influence of outdoor exposure conditions and ageing of contamination on the toxicity of zinc was investigated for the springtail Folsomia candida to evaluate the validity of a standardised soil toxicity test. In three successive years, animals were incubated in an experimentally contaminated field plot. During the first months after construction of the test field, total zine concentrations of the soil decreased rapidly due to leaching of excess zinc with rainwater, while increased sorption of the remaining residues resulted in a reduced bioavailability of the metal. Although variation between replicates was substantial, the EC50s for the effect of zinc on reproduction of F. candida determined in the field experiments differed by less than a factor of two from effect concentrations obtained in laboratory tests in which the same soil was used. Expression of the EC50s on the basis of water soluble zinc allowed for a comparison with effect concentrations estimated for other soil types. EC50s were comparable with literature data, which indicates that bioavailability of zinc is the main factor determining toxicity for F. candida. It is concluded that laboratory based toxicity data are suitable to predict effects of zinc for F. candida under outdoor conditions, provided that the bioavailability of zinc is determined accurately using water soluble concentrations.     

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.     

Ecotoxicological assessment of metal-polluted urban soils using bioassays with three soil invertebrates

This study aimed at assessing the quality of urban soils by integrating chemical and ecotoxicological approaches. Soils from five sites in downtown Naples, Italy, were sampled and characterized for physical-chemical properties and total and water-extractable metal concentrations. Bioassays with Eisenia andrei, Enchytraeus crypticus and Folsomia candida were performed to assess toxicity of the soils, using survival, reproduction and growth as the endpoints. Metal bioaccumulation in the animals was also measured. The properties and metal concentrations of the soils strongly differed. Metal bioaccumulation was related with total metal concentrations in soil and was highest in E. crypticus, which was more sensitive than E. andrei and F. candida. Responses of the three species to the investigated soils seemed due to both metal contamination and soil properties.     

The fate of herbicide acetochlor and its toxicity to Eisenia fetida under laboratory conditions

To assess the toxic effects of the herbicide acetochlor on earthworms, we exposed Eisenia fetida (Savigny) to artificial soils (OECD soil) supplemented with different concentrations (5, 10, 20, 40 and 80 mg kg-1 soil) of acetochlor. The residues of acetochlor in soil and the effect of the herbicide on growth, reproduction, glutathione-S-transferases (GST) activity and cellulase activity of earthworms were determined. The degradation half-life of acetochlor in soil of acetochlor was between 9.3 and 15.6 days under laboratory condition; the degradation rate with low concentrations was faster than it was with higher concentrations. At 5 and 10 mg kg-1, acetochlor had not significant effect on growth of E. fetida except after 15 and 30 days of exposure. When concentration>20 mg kg-1, growth rates and numbers of juveniles per cocoon decreased significantly compared to the control in all treatments. However, cellulase activity decreased significantly in all treatments (5-80 mg kg-1). This study showed that acetochlor had no long-term effect on the growth and reproduction of E. fetida at field dose (5-10 mg kg-1). At higher concentrations of acetochlor (20-80 mg kg-1), acetochlor revealed sublethal toxicity to E. fetida. Growth, numbers of juveniles per cocoon and cellulase activity can be regarded as sensitive parameters to evaluate the toxicity of acetochlor on earthworms.     

Compartmentation and effects of lead (Pb) in the collembolan,Folsomia candida

Environmental Science and Pollution Research - The impact of soil lead (Pb) pollution on survival, growth, and reproduction of the collembolan, Folsomia candida, and Pb compartmentation in its gut...     

Chronic exposure to chlorpyrifos reveals two modes of action in the springtail Folsomia candida

Organophosphates are popular insecticides, but relatively little is known about their chronic effects on ecologically relevant endpoints. In this paper, we examine a life-cycle experiment with the springtail Folsomia candida, exposed via food to chlorpyrifos (CPF). The results for all endpoints (survival, growth and reproduction) were analyzed using the DEBtox model. Growth was unaffected by CPF, even at concentrations causing severe effects on survival and reproduction. Model analysis suggests that CPF directly affects the process of egg production. For the short-term response (45 days), this single mode of action accurately agreed with the data. However, the full data set (120 days) revealed a dose-related decrease in reproduction at low concentrations after prolonged exposure, not covered by the same mechanism. It appears that CPF interacts with senescence by increasing oxidative damage. This assumption fits the data well, but has little consequences for the predicted response at the population level.     

QSAR development and bioavailability determination: The toxicity of chloroanilines to the soil dwelling springtail Folsomia candida

Quantitative structure–activity relationships (QSARs) are an established tool in environmental risk assessment and a valuable alternative to the exhaustive use of test animals under REACH. In this study a QSAR was developed for the toxicity of a series of six chloroanilines to the soil-dwelling collembolan Folsomia candida in standardized natural LUFA2.2 soil. Toxicity endpoints incorporated in the QSAR were the concentrations causing 10% (EC10) and 50% (EC50) reduction in reproduction of F. candida. Toxicity was based on concentrations in interstitial water estimated from nominal concentrations in the soil and published soil–water partition coefficients. Estimated effect concentrations were negatively correlated with the lipophilicity of the compounds. Interstitial water concentrations for both the EC10 and EC50 for four compounds were determined by using solid-phase microextraction (SPME). Measured and estimated concentrations were comparable only for tetra- and pentachloroaniline. With decreasing chlorination the disparity between modelled and actual concentrations increased. Optimisation of the QSAR therefore could not be accomplished, showing the necessity to move from total soil to (bio)available concentration measurements.     

Does monensin in chicken manure from poultry farms pose a threat to soil invertebrates?

Monensin is a carboxylic polyether ionophore used in the poultry industry as a coccidiostat. It enters the environment via manure from broiler farms. In spite of its potential presence in the environment, information concerning monensin residues in manure and soil and its toxicity to soil organisms are insufficient. In the present study, two beneficial soil invertebrate species, earthworms (Eisenia andrei) and woodlice (Porcellio scaber), were used to assess the toxicity of monensin. Animals were exposed to a range of monensin concentrations via soil or food. Earthworm reproduction was found to be the most susceptible endpoint (NOEC=3.5 mg kg(-1) dry soil; EC(50)=12.7 mg kg(-1) dry soil), while no adverse effects were recorded in isopods (NOEC?849mgkg(-1) dry soil, NOEC?357mgkg(-1) dry food). The obtained toxicity data were compared with potential concentrations of monensin in soil. In view of this, manure from broiler chickens treated with monensin at a poultry farm was sampled. According to monensin and nitrogen concentrations in the chicken manure and the degradation time of monensin, the predicted environmental concentration (PEC) was calculated. PEC of monensin is around 0.013 mg kg(-1) soil if manure is used after 3 months of composting and 0.05 mg kg(-1) soil if used without storage. Data for earthworm reproduction was used to estimate the predicted no-effect concentration (PNEC). If fresh chicken manure is applied to terrestrial ecosystems, the risk quotient (PEC/PNEC ratio) is above 1, which indicates that monensin might pose an environmental risk under certain conditions. To prevent this, it is strongly recommended to compost chicken manure for several months before using it as fertiliser.     

Toxicological and biochemical responses of the earthworm Lumbricus rubellus to pyrene, a non-carcinogenic polycyclic aromatic hydrocarbon

The effects of the polycyclic aromatic hydrocarbon (PAH) pyrene on earthworms were investigated in contact and soil tests. In addition to measuring toxic effects on survival and reproduction, Ethoxyresorufin-o-deethylase (EROD) activity and catalase activity were also studied as possible biomarkers of toxic stress. The survival data indicated that LC₅₀ values were 0.0068 mg/ml for the contact test, and 283 mg/kg in the soil test. Cocoon production rate was significantly reduced compared to controls at 160, 640 and 2560 mg/kg in the soil test. No EROD activity could be detected in preliminary studies using control and exposed animals from the contact test, so this assay was not used to the soil test. Catalase activity was shown to be significantly lower at 640 mg/kg in the soil test compared to all other treatments and the control. When compared to toxicological data for other soil invertebrates, Lumbricus rubellus has an intermediate sensitivity in respects of survival and a lower sensitivity for reproductive effects, although the soil used in this study had a higher organic content than previous studies, meaning that the sensitivity of this species may be underestimated in comparison to previous published data for other soil invertebrates.     

Avoidance of low doses of naphthalene by Collembola

The introduction of behavioural aspects of soil animals in ecological risk assessment would allow us to better assess soil quality, all the more if a range of animal populations are considered. We compared the avoidance behaviour of several strains of springtails (Arthropoda: Collembola) obtained from different soils. Naphthalene, a polycyclic aromatic hydrocarbon (PAH), widely represented in soils polluted with hydrocarbons, was tested in aqueous solutions on nine springtail species issuing from four sites. Fine quartz sand saturated with an aqueous solution of naphthalene was avoided by most of the tested species, avoidance being, however, detected down to a concentration of 0.030 mg L(-1). Folsomia candida (Isotomidae) was shown to be relatively tolerant to pollutants compared to other Collembola such as Mesaphorura macrochaeta, Mesaphorura yosii (Onychiuridae), Parisotoma notabilis (Isotomidae) and Arrhopalites caecus (Arrhopalitidae). Differences between strains could not be explained by properties of the original soils.     

Survival, Pb-uptake and behaviour of three species of earthworm in Pb treated soils determined using an OECD-style toxicity test and a soil avoidance test

Mature (clitellate) Eisenia andrei Bouché (ultra epigeic), Lumbricus rubellus Hoffmeister (epigeic), and Aporrectodea caliginosa (Savigny) (endogeic) earthworms were placed in soils treated with Pb(NO(3))(2) to have concentrations in the range 1,000 to 10,000 mg Pb kg(-1). After 28 days LC50(-95%confidence limit)(+95%confidence limit) values were E. andrei 5824(-361)(+898) mg Pb kg(-1), L. rubellus 2867(-193)(+145) mg Pb kg(-1) and A. caliginosa2747(-304)(+239) mg Pb kg(-1) and EC50s for weight change were E. andrei2841(-68)(+150) mg Pb kg(-1), L. rubellus1303(-201)(+240) mg Pb kg(-1) and A. caliginosa1208(-206)(+212) mg Pb kg(-1). At any given soil Pb concentration, Pb tissue concentrations after 28 days were the same for all three earthworm species. In a soil avoidance test there was no difference between the behaviour of the different species. The lower sensitivity to Pb exhibited by E. andrei is most likely due to physiological adaptations associated with the modes of life of the earthworms, and could have serious implications for the use of this earthworm as the species of choice in standard toxicological testing.     

Toxicity of three halogenated flame retardants to nitrifying bacteria, red clover (Trifolium pratense), and a soil invertebrate (Enchytraeus crypticus)

Halogenated flame retardants have a high sorption affinity to particles, making soils and sediments important sinks. Here, three of the most commonly used flame retardants have been tested for sub-lethal toxicity towards soil nitrifying bacteria, a terrestrial plant (seed emergence and growth of the red clover, Trifolium pratense), and a soil invertebrate (survival and reproduction of Enchytraeus crypticus). Tetrabromobisphenol A (TBBPA) was quite toxic to enchytraeids, with significant effects on reproduction detected already at the 10 mgkg(-1) exposure level (EC(10)=2.7 mgkg(-1)). In contrast, decabromodiphenyl ether (DeBDE) was not toxic at all, and short-chain chloroparaffins (CP(10-13)) only affected soil nitrifying bacteria at the highest test concentration (EC(10)=570 mgkg(-1)). Exposure concentrations were verified by chemical analysis for TBBPA and DeBDE, but not for CP(10-13), as a reliable method was not available. Based on the generated data, a PNEC for soil organisms can be estimated at 0.3 mgkg(-1) for TBBPA and 57 mgkg(-1) for short-chain chloroparaffins. No PNEC could be estimated for DeBDE. Measurements of TBBPA in soil are not available, but measured concentrations in Swedish sludge are all lower than the estimated threshold value for biological effects in soil.     

Genotoxicity of two novel pesticides for the earthworm, Eisenia fetida

In this paper, several studies were conducted to evaluate the genotoxicity of two pesticides, Imidacloprid and RH-5849, for earthworm (Eisenia fetida). Earthworms were exposed in different exposure systems to evaluate their acute toxicity and the genotoxicity of the two pesticides was evaluated by using the method of sperm deformity assessment, micronucleus test of root tip cells in Vicia faba, a mouse bone-marrow micronucleus test, and comet assay. LC(50) (interpolated concentration at which 50% mortality of test population occurs) for earthworms varied in different exposure systems. The results indicated that Imidacloprid was consistently more toxic than RH-5849 in all exposure systems. In this study, sperm deformity test was used to detect the potential adverse influences of pesticides on the reproduction of earthworms. The results demonstrated that significant induction of sperm deformity (p<0.01) and a dose-effect relationship displayed at Imidacloprid concentrations higher than 0.5 mg/kg dry soil. However, the sperm deformity frequency of groups exposed to RH-5849 did not show significant difference (p>0.05) from the control until the dose reached 100 mg/kg dry soil. The results of the V. faba micronucleus tests showed that micronuclei frequency of the exposed group did not show significant difference (p>0.05) from the control until the concentration of Imidacloprid and RH-5849 reached 100 mg/ml. The results of the mouse bone-marrow micronuclei test also indicate that two pesticides did not show significant effects (p>0.05) on the micronuclei frequency in mice bone-marrow cells until the dose reached 100 mg/kg for Imidacloprid and 300 mg/kg for RH-5849 (2/3 LD(50)). Although no genotoxicity was detected by using the micronucleus tests, the results of the comet assay showed that the two pesticides induce significant DNA damage (p<0.01) in earthworms and dose-effect relationships were displayed. The 'earthworm comet assay' is a rapid and sensitive way to screen chemicals or terrestrial environments for their DNA-damaging properties.     

Effect of two major N-nitroso hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) metabolites on earthworm reproductive success

Soil and topical tests were employed to investigate the effect of two N-nitroso metabolites of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) on earthworm reproduction. The lowest observed effect concentration (LOEC) for cocoon production and hatching was 50mg/kg for both hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) in soil. MNX and TNX also significantly affected cocoon hatching in soil (p<0.001) and in topical tests (p=0.001). The LOECs for cocoon hatching were 1 and 10mg/kg for MNX and TNX in soil, respectively, and 10mg/L in the topical test. Greater than 100mg/kg MNX and TNX completely inhibited cocoon hatching. In soil, the EC20 values for MNX were 8.7 and 8.8mg/kg for cocoon and juvenile production, respectively, compared to 9.2 and 9.1mg/kg for TNX, respectively. The EC20 values for the total number of cocoon hatchlings were 3.1 and 4.7mg/kg for MNX and TNX, respectively, in soil and 4.5 and 3.1mg/L in the topical test. Both MNX and TNX inhibited cocoon production and hatching, suggesting that they may have a negative affect on soil ecosystems at contaminated sites.