Toxicity of metalaxyl,azoxystrobin, dimethomorph,cymoxanil, zoxamide and mancozeb to Phytophthora infestans isolates from Serbia

A study of the in vitro sensitivity of 12 isolates of Phytophthora infestans to metalaxyl, azoxystrobin, dimethomorph, cymoxanil, zoxamide and mancozeb, was conducted. The isolates derived from infected potato leaves collected at eight different localities in Serbia during 2005–2007. The widest range of EC₅₀ values for mycelial growth of the isolates was recorded for metalaxyl. They varied from 0.3 to 3.9 μg mL^?1 and were higher than those expected in a susceptible population of P. infestans. The EC₅₀ values of the isolates were 0.16–0.30 μg mL^?1 for dimethomorph, 0.27–0.57 μg mL^?1 for cymoxanil, 0.0026–0.0049 μg mL^?1 for zoxamide and 2.9–5.0 μg mL^?1 for mancozeb. The results indicated that according to effective concentration (EC₅₀) the 12 isolates of P. infestans were sensitive to azoxystrobin (0.019–0.074 μg mL^?1), and intermediate resistant to metalaxyl, dimethomorph and cymoxanil. According to resistance factor, all P. infestans isolates were sensitive to dimethomorph, cymoxanil, mancozeb and zoxamide, 58.3% of isolates were sensitive to azoxystrobin and 50% to metalaxyl. Gout's scale indicated that 41.7% isolates were moderately sensitive to azoxystrobin and 50% to metalaxyl.     

Toxicity of mancozeb,chlorothalonil, captan,fluopyram, boscalid,and difenoconazole to Didymella applanata isolates from Serbia

Field isolates of Didymella applanata, the causal agent of spur blight of raspberry, were evaluated in vitro for their sensitivity to mancozeb, chlorothalonil, captan, fluopyram, boscalid and difenoconazole. A total of 10 isolates, collected during 2013 at five localities in the major raspberry growing region in Serbia, and characterized as copper hydroxide, dithianon, and tebuconazole (sensitive), pyraclostrobin (sensitive or highly resistant) and fluazinam (sensitive or moderately resistant), were used in this study. The EC₅₀ values for the isolates ranged from 1.33 to 2.88 mg L^?1 for mancozeb, from 3.18 to 6.65 mg L^?1 for chlorothalonil, from 15.75 to 24.69 mg L^?1 for captan and from 1.80 to 8.20 mg L^?1 for fluopyram. The narrowest range of EC₅₀ values was recorded for difenoconazole (0.23–0.49 mg L^?1), whereas the widest range was obtained for boscalid (4.49–49.25 mg L^?1). The calculated resistance factors showed that all D. applanata isolates were sensitive to mancozeb, chlorothalonil, captan, and difenoconazole. Four isolates were moderately resistant to boscalid, while three of them were also moderately resistant to fluopyram. This finding of moderately resistant isolates to these SDHI fungicides indicates a possible cross-resistance which should be clarified in further investigations.     

In vitro toxicity of fungicides with different modes of action to alfalfa anthracnose fungus,Colletotrichum destructivum

Abstract

Sensitivity of 24 isolates of Colletotrichum destructivum O’Gara, collected from alfalfa plants in Serbia, to eight selected fungicides, was investigated in this study. Molecular identification and pathogenicity test of isolates tested were also performed. Fungicide sensitivity was evaluated in vitro, using mycelial growth assay method. All isolates exhibited significant pathogenicity, causing necrosis at the alfalfa seedling root tips two days after inoculation. Using the primer pair GSF1-SR1 and by comparing the amplified fragments of the tested isolates with the marker (M), the presence of the amplicon of the expected size of about 900?bp was determined for all isolates. The isolates tested in this study showed different sensitivity towards fungicides in vitro. Mycelial growth was highly inhibited by QoI (quinone outside inhibitors) fungicide pyraclostrobin (mean EC₅₀=0.39?µg mL^?1) and by DMI (demethylation-inhibiting) fungicide tebuconazole (mean EC₅₀=0.61?µg mL^?1), followed by azoxystrobin (mean EC₅₀=2.83?µg mL^?1) and flutriafol (mean EC₅₀=2.11?µg mL^?1). Multi-site fungicide chlorothalonil and MBC (methyl benzimidazole carbamate) fungicide thiophanate-methyl evinced moderate inhibition with mean EC₅₀=35.31 and 62.83?µg mL^?1, respectively. Thirteen isolates were sensitive to SDHI (succinate dehydrogenase inhibitors) fungicide boscalid and fluxapyroxad, (mean EC₅₀=0.49 and 0.19?µg mL^?1, respectively), while the rest of isolates were highly resistant.     

Determination of sixteen pesticides in peppers using high-performance liquid chromatography/mass spectrometry

A method for the detection and quantification of 16 pesticides: flufenoxuron, fenoxycarb, dimethomorph, acetamiprid, imidacloprid, lufenuron, thiacloprid, thiabendazole, thiophanate-methyl, spinosad, fenbutatin oxide, methoxyfenozide, oxamyl, clothianidin, thiamethoxam and carbendazim has been developed based on high-performance liquid chromatography-mass spectrometry. Pesticide residues were extracted from the samples according to the QuEChERS method which stands for quick, essay, cheap, effective, rugged and safe. Homogenised analytical portions (10 g ± 0.1) of samples of peppers were spiked at two levels (10 and 100 μg kg?1) with a small volume of an appropriate standard mixture solution containing each pesticide. Analyses were performed using electrospray ionization (ESI) and a MSD trap system. Chromatography separation was achieved using a ZORBAX SB-C18 3.5 μm particle size analytical column, 2.1 × 50 mm from Agilent, with gradient elution at a flow-rate of 0.4 mL/min with mobile phases: waters-0.1 % HCOOH-5 mM HCOONH? and MeOH-5 mM HCOONH?. The method has been validated based on the SANCO European Guidelines. Under the optimized conditions the recoveries (n = 7) were in the range 70-110 % with satisfactory precision (CV ≤ 20 %). A linear dynamic range was obtained over a range of concentrations from 10 to 100 μg kg?1 for each of the analytes, with correlation coefficients >0.997.     

Toxicity assessment of 45 pesticides to the epigeic earthworm Eisenia fetida

This study was conducted to investigate comparative toxicity of 45 pesticides, including insecticides, acaricides, fungicides, and herbicides, toward the epigeic earthworm Eisenia fetida. Results from a 48-h filter paper contact test indicated that clothianidin, fenpyroximate, and pyridaben were supertoxic to E. fetida with LC(50) values ranging from 0.28 (0.24-0.35) to 0.72 (0.60-0.94) μg cm(-2), followed by carbaryl, pyridaphenthion, azoxystrobin, cyproconazole, and picoxystrobin with LC(50) values ranging from 2.72 (2.22-0.3.19) to 8.48 (7.38-10.21) μg cm(-2), while the other pesticides ranged from being relatively nontoxic to very toxic to the worms. When tested in artificial soil for 14 d, clothianidin and picoxystrobin showed the highest intrinsic toxicity against E. fetida, and their LC(50) values were 6.06 (5.60-6.77) and 7.22 (5.29-8.68) mg kg(-1), respectively, followed by fenpyroximate with an LC(50) of 75.52 (68.21-86.57) mgkg(-1). However, the herbicides fluoroglycofen, paraquat, and pyraflufen-ethyl exhibited the lowest toxicities with LC(50) values>1000 mg kg(-1). In contrast, the other pesticides exhibited relatively low toxicities with LC(50) values ranging from 133.5 (124.5-150.5) to 895.2 (754.2-1198.0) mg kg(-1). The data presented in this paper provided useful information for evaluating the potential risk of these chemicals to soil invertebrates.     

Determination of the insecticide diflubenzuron in mushrooms by kinetic method and high-performance liquid chromatographic method

In the present study, a new sensitive and simple kinetic-spectrophotometric method for the determination of the insecticide diflubenzuron [1-(4-chlorophenyl)-3-(2,6-diflubenzoil)urea] is proposed. The method is based on the inhibited effect of diflubenzuron on the oxidation of sulphanilic acid (SA) by hydrogen peroxide in phosphate buffer in presence Cu(II) ion. Diflubenzuron was determined with linear calibration graph in the interval from 0.31 to 3.1 μg mL?1 and from 3.1 to 31.0 μg mL?1. The optimized conditions yielded a theoretical detection limit of 0.18 μg mL?1 corresponding to 0.036 mg kg(-1)mushroom sample based on the 3S(b) criterion. The RSD is 5.03-1.83 % and 2.81-0.71 % for the concentration interval of diflubenzuron 0.31-3.1 μg mL?1 and 3.1-31.0 μg mL?1, respectively. The reaction was followed spectrophotometrically at 370 nm. The kinetic parameters of the reaction are reported, and the rate equations are suggested. The developed procedure was successfully applied to the rapid determination of diflubenzuron in spiked mushroom samples of different mushroom species. The HPLC method was used like a comparative method to verify results.     

Simultaneous analysis of free and sulfo-conjugated steroid estrogens in artificial urine solution and agricultural soils by high-performance liquid chromatography

A simple and robust analytical method was developed to simultaneously detect and quantify 17β-estradiol (E2), estrone (E1), 17β-estradiol-3-sulphate (E2-3S), and estrone-3-sulphate (E1-3S) in aqueous solutions (calcium chloride and artificial urine solutions) and agricultural soils using high performance liquid chromatography and UV detection. The standards for all four compounds were linear in the range of 0.01 to 1.0 μg mL(-1) (n = 6) and 1.0 to 20 μg mL(-1) (n = 6), respectively, with correlation coefficients > 0.999. The on-column limits of detection at an injection volume of 50 μL and S/N (signal: noise) ratio of 3 were: 9.0 ng mL(-1), 10 ng mL(-1), 5.0 ng mL(-1), and 7.0 ng mL(-1) for E2-3S, E1-3S, E2 and E1, respectively. The limit of detection and quantification in artificial urine solution and CaCl(2) solution was 1.0 ng mL(-1) for all four compounds. Method detection limits for the compounds in the 3 soils ranged from 2 to 2.4 ng g(-1) (E2-3S and E1-3S), and 1.0 to 2.9 ng g(-1) (E2 and E1), respectively.     

Residues behavior of some fungicides applied on two greenhouse tomato varieties different in shape and weight

The degradation of 12 fungicides (azoxystrobin, cymoxanil, cyproconazole, cyprodinil, fenarimol, fludioxonil, iprovalicarb, mepanipyrim, penconazole, pyrimethanil, tolclofos-methyl, triadimenol), commonly used in pest management strategies on Sardinian greenhouse tomato crops was studied. A different residue behaviour was observed between the studied cultivar. On the smaller, a “cherry” type tomato, field data showed an initial residue mostly higher than the “beefsteak” tomato. In any case, except for penconazole, all pesticide residues were below their maximum residue levels (MRLs) reaching the pre-harvest interval (PHI). On both cultivar, triadimenol and cymoxanil residues completely disappeared reaching their PHI, while iprovalicarb, fenarimol, and fludioxonil disappeared in a time of 17 to 24 days. On the contrary, azoxystrobin, cyproconazole, cyprodinil, penconazole, tolclofos-methyl, mepanipyrim, and pyrimethanil showed a long persistence on both tested cultivar and may have residual problems due to an accumulation effect if repeated field treatments will be performed. The first group of molecules according to their rapid degradation could be used in low pesticide-input management in order to obtain tomatoes with low or no detectable residues.     

Residues behavior of some fungicides applied on two greenhouse tomato varieties different in shape and weight

The degradation of 12 fungicides (azoxystrobin, cymoxanil, cyproconazole, cyprodinil, fenarimol, fludioxonil, iprovalicarb, mepanipyrim, penconazole, pyrimethanil, tolclofos-methyl, triadimenol), commonly used in pest management strategies on Sardinian greenhouse tomato crops was studied. A different residue behaviour was observed between the studied cultivar. On the smaller, a "cherry" type tomato, field data showed an initial residue mostly higher than the "beefsteak" tomato. In any case, except for penconazole, all pesticide residues were below their maximum residue levels (MRLs) reaching the pre-harvest interval (PHI). On both cultivar, triadimenol and cymoxanil residues completely disappeared reaching their PHI, while iprovalicarb, fenarimol, and fludioxonil disappeared in a time of 17 to 24 days. On the contrary, azoxystrobin, cyproconazole, cyprodinil, penconazole, tolclofos-methyl, mepanipyrim, and pyrimethanil showed a long persistence on both tested cultivar and may have residual problems due to an accumulation effect if repeated field treatments will be performed. The first group of molecules according to their rapid degradation could be used in low pesticide-input management in order to obtain tomatoes with low or no detectable residues.     

The effect of initial concentration, co-application and repeated applications on pesticide degradation in a biobed mixture

A 180 d laboratory experiment was conducted to investigate the degradation rates of chlorpyrifos (10 and 50 mg kg(-1)) and metalaxyl (100 mg kg(-1)) separately and co-applied in a biomix constituted by topsoil, vine-branches and urban-waste-garden compost. The effect of repeated application of metalaxyl was also investigated. Microbial biomass-C (MBC) content and metabolic quotient (qCO(2)) were measured to evaluate changes in microbial biomass size and activity induced by the presence of the two pesticides. Degradation rate decreased with increasing concentration of chlorpyrifos in all treatments. Metalaxyl half-life was significantly reduced in co-application with chlorpyrifos indicating a synergic interaction between the two pesticides in favour of enhanced degradation rate for metalaxyl but not for chlorpyrifos. Furthermore, repeated application resulted in a sharp reduction of metalaxyl half-life from 37 d after first application to 4 d after third application. MBC content was negatively influenced by the addition of pesticides but it started to recover immediately, in both separate and co-applied treatments, reaching the control value when pesticide residues were about 50% of the initial concentration. The qCO(2) reached a steady-state after about 20 d in separately applied and 40 d in co-applied treatments, indicating a tendency to arrive at a new metabolic equilibrium. In conclusion, the biomix tested has been shown to degrade pesticides relatively fast and to have a microbial community that is varied enough to allow selection of those microorganisms able to degrade metalaxyl and chlorpyrifos.     

Genotoxic potential of selected cytostatic drugs in human and zebrafish cells

Due to their increasing use, the residues of anti-neoplastic drugs have become emerging pollutants in aquatic environments. Most of them directly or indirectly interfere with the cell’s genome, which classifies them into a group of particularly dangerous compounds. The aim of the present study was to conduct a comparative in vitro toxicological characterisation of three commonly used cytostatics with different mechanisms of action (5-fluorouracil [5-FU], cisplatin [CDDP] and etoposide [ET]) towards zebrafish liver (ZFL) cell line, human hepatoma (HepG2) cells and human peripheral blood lymphocytes (HPBLs). Cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and acridine orange/ethidium bromide staining. All three drugs induced time- and dose-dependent decreases in cell viability. The sensitivity of ZFL and HepG2 cells towards the cytotoxicity of 5-FU was comparable (half maximal inhibitory concentration (IC₅₀) 5.3 to 10.4 μg/mL). ZFL cells were more sensitive towards ET- (IC₅₀ 0.4 μg/mL) and HepG2 towards CDDP- (IC₅₀ 1.4 μg/mL) induced cytotoxicity. Genotoxicity was determined by comet assay and cytokinesis block micronucleus (CBMN) assay. ZFL cells were the most sensitive, and HPBLs were the least sensitive. In ZFL cells, induction of DNA strand breaks was a more sensitive genotoxicity endpoint than micronuclei (MNi) induction; the lowest effective concentration (LOEC) for DNA strand break induction was 0.001 μg/mL for ET, 0.01 μg/mL for 5-FU and 0.1 μg/mL for CDDP. In HepG2 cells, MNi induction was a more sensitive genotoxicity endpoint. The LOEC values were 0.01 μg/mL for ET, 0.1 μg/mL for 5-FU and 1 μg/mL for CDDP. The higher sensitivity of ZFL cells to cytostatic drugs raises the question of the impact of such compounds in aquatic ecosystem. Since little is known on the effect of such drugs on aquatic organisms, our results demonstrate that ZFL cells provide a relevant and sensitive tool to screen genotoxic potential of environmental pollutant in the frame of hazard assessment.     

Chromium(VI) resistance and removal by actinomycete strains isolated from sediments

Forty-one isolated actinomycetes were used to study qualitative and semi-quantitative screening of chromium(VI) resistance. Chromate-removing activity was estimated using the Cr(VI) specific colorimetric reagent 1,5-diphenylcarbazide. Twenty percent of the isolates from El Cadillal (EC) and 14% of isolates from a copper filter plant (CFP) were able to grow at 13 mM of Cr(VI). All isolates from sugar cane (SCP) could grow up to Cr(VI) concentration of 17 mM. EC, CFP and SCP strains were able to remove 24%, 30% and more than 40% of Cr(VI), respectively. The highest and lowest Cr(VI) specific removal values were 75.5 mg g(-1) cell by M3 (CFP), and 1.5 mg g(-1) cell by C35 (EC) strains. Eleven Cr(VI) resistant strains were characterized and identified as species of the genera Streptomyces (10) and Amycolatopsis (1). Differences on actinomycete community composition between contaminated and non-contaminated soil were found. This study showed the potential capacity of actinomycetes as tools for Cr(VI) bioremediation.     

Toxicity and removal of pesticides by selected aquatic plants

Pesticides are being detected in water bodies on an increasingly frequent basis. The present study focused on the phytoremediation potential of selected aquatic plants to remove phytosanitary products from contaminated water. We investigated the uptake capacity of Lemna minor (L. minor), Elodea canadensis (E. canadensis) and Cabomba aquatica (C. aquatica) on three pesticides: copper sulphate (fungicide), flazasulfuron (herbicide) and dimethomorph (fungicide). Pesticide toxicity was evaluated by exposing plants to five concentrations (0-1 mg L(-1)) in culture media for 7d using chlorophyll fluorescence as a biomarker. The toxicity of the contaminants was the same for all the aquatic plants studied and occurred in this descending order of toxicity: flazasulfuron>copper>dimethomorph. We found that L. minor had the most efficient uptake capacity, followed by E. canadensis and then C. aquatica. The maximum removal rate (microg g(-1)fresh weight d(-1)) of copper, flazasulfuron and dimethomorph was 30, 27 and 11, respectively.     

Toxicity of fungicides with different modes of action to Cladobotryum dendroides and Agaricus bisporus

Isolates of Cladobotryum dendroides from Serbian mushroom farms and Agaricus bisporus F56 were tested for sensitivity to selected fungicides in vitro. Chlorothalonil was the most toxic fungicide to C. dendroides isolates (EC₅₀ values were below 1.68 mg L^{? 1}). Trifloxystrobin and kresoxim-methyl were not effective in growth inhibition of C. dendroides isolates (EC₅₀ values exceeded 300 mg L^{? 1}). Metalaxyl-M+mancozeb was the most toxic fungicide to strain F56 of A. bisporus, and iprodione the least toxic. The fungicide selectivity indexes for both C. dendroides and A. bisporus indicated that iprodione, chlorothalonil, captan and metalaxyl-M+mancozeb had satisfactory selective fungitoxicity. Iprodione had the best selectivity to both the pathogen and the host, although inferior than prochloraz manganese and carbendazim, fungicides officially recommended for mushroom cultivation in European Union (EU) countries.     

HCI in Rocket Exhaust Clouds: Atmospheric Dispersion,Acid Aerosol Characteristics,and Acid Rain Deposition

NASA is examining Space Shuttle launch impacts. Solid rocket exhaust includes ?60 tons HCL and ?87 tons alumina particles emitted below 2.5 km, of which 50-80% forms an altitude stabilized exhaust cloud (EC). Several 60% smaller Titan-Ill EC were sampled by aircraft for this study. Three distinct features are presented: (a) An analysis of HCL (gaseous plus aqueous) data traces. Total range of peak HCL was 25-0.5 ppm (3-300 min) for 8 EC. Power-law decays of peak HCL applied. Calculated HCL dispersions for 7 standard meteorologies are also shown, (b) An analysis of simultaneous HCL (g), HCL (g + aq) data for 2 EC. Vapor-liquid HCL/H₂O equilibria were calculated for a flat surface aqueous aerosol. HCL partitioning varied with EC dilution and H₂O content. HCL (aq) and aqueous mass fraction maximized early at >3 molal and >0.1 mg/g air. Calculated H₂O (g + aq) compared favorably with independent EC measurements, (c) An analysis of wet deposition after EC interception at ?30 min by a convective storm. A 28 km² acid chloride (1 < pH < 3) footprint was defined. In conclusion, (a) HCL dispersion in large EC tends to follow power-law decay, but HCL concentration may vary widely (100 times after 1 h) with meteorology, (b) HCL (g/aq) and H₂O (g/aq) partitioning is consistent with equilibrated acid aerosol compositions, and (c) localized deposition of highly acidic rain may occur sometimes.     

Mycobiota and mycotoxins in bee pollen collected from different areas of Slovakia

Contamination by microscopic fungi and mycotoxins in different bee pollen samples, which were stored under three different ways of storing as freezing, drying and UV radiation, was investigated. During spring 2009, 45 samples of bee-collected pollen were gathered from beekeepers who placed their bee colonies on monocultures of sunflower, rape and poppy fields within their flying distance. Bee pollen was collected from bees' legs by special devices placed at the entrance to hives. Samples were examined for the concentration and identification of microscopic fungi able to grow on Malt and Czapek-Dox agar and mycotoxins content [deoxynivalenol (DON), T-2 toxin (T-2), zearalenone (ZON) and total aflatoxins (AFL), fumonisins (FUM), ochratoxins (OTA)] by direct competitive enzyme-linked immunosorbent assays (ELISA). The total number of microscopic fungi in this study ranged from 2.98 ± 0.02 in frozen sunflower bee pollen to 4.06 ± 0.10 log cfu.g(-1) in sunflower bee pollen after UV radiation. In this study, 449 isolates belonging to 21 fungal species representing 9 genera were found in 45 samples of bee pollen. The total isolates were detected in frozen poppy pollen 29, rape pollen 40, sunflower pollen 80, in dried poppy pollen 12, rape pollen 36, sunflower 78, in poppy pollen after UV radiation treatment 54, rape 59 and sunflower 58. The most frequent isolates of microscopic fungi found in bee pollen samples of all prevalent species were Mucor mucedo (49 isolates), Alternaria alternata (40 isolates), Mucor hiemalis (40 isolates), Aspergillus fumigatus (33 isolates) and Cladosporium cladosporioides (31 isolates). The most frequently found isolates were detected in sunflower bee pollen frozen (80 isolates) and the lowest number of isolates was observed in poppy bee pollen dried (12 isolates). The most prevalent mycotoxin of poppy bee pollen was ZON (361.55 ± 0.26 μg.kg(-1)), in rape bee pollen T-2 toxin (265.40 ± 0.18 μg.kg(-1)) and in sunflower bee pollen T-2 toxin (364.72 ± 0.13 μg.kg(-1)) in all cases in frozen samples.     

Comparative acute toxicity of two phytosanitary molecules,lambda-cyhalothrin and acetamiprid,on Nile Tilapia (Oreochromis Niloticus) juveniles

Abstract

This study aimed to compare the toxicity for fish of two active ingredients (lambda-cyhalothrin-20?g L^?1, a pyrethroid, and acetamiprid-15?g L^?1, a neonicotinoid) which are components of a commercial insecticide (Acer 35 EC) used in cotton crop in many West African countries. The juveniles of Oreochromis niloticus (4.01?±?0.34?g, mean body weight) were exposed for 96?h to increasing concentrations of active ingredients (lambda-cyhalothrin and acetamiprid) or a mixture similar to Acer 35 EC (composed by 20?g of chemical compound lambda-cyhalothrin and 15?g of acetamiprid dissolved in 1?L of acetone). The experiments were carried out under controlled conditions in aquaria according to OECD Guidelines. During the experiments, the behavioral responses (loss of balance, color change, hyperactivity, etc.) that usually precede death were observed in exposed fish. Mortalities were recorded in each aquarium and the LC₅₀-96h of each chemical was determined. The LC₅₀-96h obtained were respectively 0.1268, 0.0029, 182.9 and 0.5685?ppm for Acer 35 EC, lambda-cyhalothrin, acetamiprid and mixture. All insecticides used in this study had profound impact on Nile tilapia behavior which may confirm the neurotoxicity of each single active compound as well as of their mixture.     

Determination of detoxification to Daphnia magna of four pharmaceuticals and seven surfactants by activated sludge

Pharmaceuticals are bioactive compounds generally resistant to biodegradation, which can make them problematic when they are released into nature. The use pattern for pharmaceuticals means that they are discharged into water via sewage treatment plants. Also surfactants are discharged through sewage treatment plants, primarily due to their use in detergents and shampoos and other cleaners. In this study the acute toxicity to Daphnia magna of four pharmaceuticals (ciprofloxacin, ibuprofen, paracetamol and zinc pyrithione) and seven surfactants (C8 alkyl glucoside, C6 alkyl glucoside, sodium caprylimidiopropionate, tallow-trimethyl-ammonium chloride, potassium decylphosphate, propylheptanol ethoxylate and alkylmonoethanolamide ethoxylate) was determined. Abiotic (without activated sludge bacteria) and biotic (with activated sludge bacteria) detoxification was also determined. The 24-h EC50s ranged from 2 μg L(-1) for the most toxic substance (zinc pyrithione) to 2 g L(-1) for the least toxic compound (C6 alkyl glucoside). Detoxification rates determined as the ratio between initial EC50 and EC50 after 1 week in water with activated sludge bacteria ranged from 0.4 (paracetamol) to 13 (zinc pyrithione). For most of these chemicals detoxification rate decreased after 1 week, but for one (alkylmonoethanolamide ethoxylate) it increased from about 2 to 30 times after 2 weeks. Many of these chemicals were "detoxified" also abiotically at about the same rate as biotically. Further studies are needed to determine the degradation products that were precipitated (aggregated) for some of the tested chemicals. Altogether, this study has shown that there are large differences in toxicity among chemicals entering sewage treatment plants, but also that the detoxification of them can differ. Therefore, the detoxification should receive more attention in the hazard and risk assessment of chemicals entering sewage treatment plants.     

Is the OECD acute worm toxicity test environmentally relevant? The effect of mineral form on calculated lead toxicity

In a series of experiments the toxicity of lead to worms in soil was determined following the draft OECD earthworm reproduction toxicity protocol except that lead was added as solid lead nitrate, carbonate and sulphide rather than as lead nitrate solution as would normally be the case. The compounds were added to the test soil to give lead concentrations of 625-12 500 microg Pb g(-1) of soil. Calculated toxicities of the lead decreased in the order nitrate> carbonate> sulphide, the same order as the decrease in the solubility of the metal compounds used. The 7-day LC50 (lethal concentration when 50% of the population is killed) for the nitrate was 5321+/-275 microg Pb g(-1) of soil and this did not change with time. The LC50 values for carbonate and sulphide could not be determined at the concentration ranges used. The only parameter sensitive enough to distinguish the toxicities of the three compounds was cocoon (egg) production. The EC50s for cocoon production (the concentration to produce a 50% reduction in cocoon production) were 993, 8604 and 10246 pg Pb g(-1) of soil for lead nitrate, carbonate and sulphide, respectively. Standard toxicity tests need to take into account the form in which the contaminant is present in the soil to be of environmental relevance.     

Spore release by the green alga Ulva: a quantitative assay to evaluate aquatic toxicants

A toxicity test using spore release of the aquatic green alga, Ulva, was developed and evaluated by assessing the toxicity of different organic and inorganic chemicals and elutriates of sewage or waste sludge. The toxic ranking of four metals was: Cu (EC50 of 0.040mgL(-1))>Cd (0.095mgL(-1))>Pb (0.489mgL(-1))>Zn (0.572mgL(-1)). The EC50 for TBTO ranged from 24 to 63microgL(-1). The most toxic VOC was formalin (EC50 of 0.788microlL(-1)) and the least toxic was acetone. Spore release was significantly inhibited in all elutriates; the greatest and least toxic effects were for industrial sewage (3.29%) and filtration bed (10.08%), respectively. The bioassay is simple, inexpensive and sensitive. The cosmopolitan distribution of Ulva means that the test would have a potential application worldwide.