Lack of genotoxic potential of permethrin in mice evaluated by the comet assay and micronucleus test

Permethrin is a common insecticide that does not show genotoxic potential in standard in vitro and in vivo assays. To investigate the genotoxic potential of permethrin in more detail, two in vivo studies were conducted on female mice to assess DNA damage in tumor target organs by the comet assay and micronucleus test. For this, mice were administered permethrin at doses of 150, 300, or 600 mg/kg/day by gavage for 2 days, and their lung, liver, glandular stomach, peripheral blood, and bone marrow cells were examined for DNA damage. There were no significant increases in % tail DNA in the organs examined and no increase in micronuclei in peripheral blood by flow cytometry. Taken together, the present findings provide evidence that permethrin has no genotoxic, aneugenic, or clastogenic potential.     

Genotoxic effects of Ag2S and CdS nanoparticles in blue mussel (Mytilus edulis) haemocytes

The use of functionalised metal sulphide nanoparticles (NPs) for nanoremediation and biomedical application is rapidly increasing, which could lead to significant inputs into the marine environment. The potential impact of some NPs on marine organisms is still poorly understood. In the present paper the genotoxic potential of Ag₂S and CdS NPs on Mytilus edulis haemocytes was assessed. MPEG-SH (thiol-terminated methyl polyethylene glycol), was used as capping agent to avoid NPs agglomeration. TEM analysis showed that the Ag₂S NPs size was 13±7 nm, whereas CdS quantum dots had an average diameter of 4±1 nm. DNA integrity was evaluated by Comet assay following exposure to increasing concentration series (0.01–10 mg/L). Both silver and cadmium NPs showed genotoxic effects at the highest dose. MPEG-SH was also found to exert a weak genotoxic activity, suggesting that at least part of the genotoxic potential of functionalised NPs on mussel cells might be attributable to the capping agent. These results confirm the genotoxic potential of Ag₂S NPs for mussel cells and demonstrated, for the first time, that CdS NPs is genotoxic in a marine organism.     

Indium tin oxide nanoparticles-mediated DNA fragmentation and cell death by apoptosis in human lung epithelial cells

Indium tin oxide (ITO) nanoparticles (NP) have extensive applications in industrial fields, and concerns regarding their potential toxicity in humans and environmental impact have increased. Since exposure to ITO NP is mainly via skin and inhalation, this study was conducted utilizing human lung epithelial (A549) cell line. Cells were exposed to different concentrations of the ITO NP for 24 and 48 hr. A severe cytotoxic response of ITO NP was observed as evident by the (3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and neutral red uptake assays after 48 hr exposure. ITO NP significantly reduced glutathione levels with a concomitant increase in lipid hydroperoxide levels, superoxide activity, and reactive oxygen species (ROS) generation after exposure. A significant induction in caspase activity and formation of condensed chromosomal bodies was also observed after ITO NP (10 or 25 µg/ml) exposure. Furthermore, a significant induction in DNA damage was observed by the Comet assay in cells exposed to ITO NP. Our data demonstrate that ITO NP display cytotoxic and genotoxic potential. However, increase in ROS levels and oxidative stress leading to oxidative DNA damage and condensed chromosomal bodies formation, suggests involvement of apotosis. Thus, ITO NP-mediated effects on cell viability indicate cytotoxicity, and therefore, exposures need to be carefully monitored in the industrial sector.     

Transport of the insecticides chlorpyrifos,chlorfenvinphos, carbofuran,carbosulfan, and furathiocarb from soil into the foliage of cauliflower and Brussels sprouts plants grown in the field

In several field assays made in different locations in 1988 and 1989, cauliflower and Brussels sprouts plants were treated some days after plantation by pouring onto soil around the stem of the plant one of the insecticides chlorpyrifos, chlorfenvinphos, carbofuran, carbosulfan, or furathiocarb, for protection against the root fly. During plant growth, each of the insecticides (and their soil metabolites) was transported from soil into the plant foliage, where it could give—during a certain period of time—a secondary plant protection against the foliage insects. The foliage concentrations of the non systemic chlorpyrifos and chlorfenvinphos were equal or greater than 1 mg/kg fresh weight during a period of about 44 days after soil treatment in Brussels sprouts crops, and 35 days in cauliflower crops. Comparison of 1988 and 1989 however showed that these periods of time changed according to the weather conditions, especially rainfall. These periods of time were greater when the insecticide soil concentrations were greater—and thus when the rates of insecticide soil metabolism were smaller— and when the rainfall were greater—water transporting the insecticides from soil to the foliage. Similar relationships were observed with the systemic insecticides carbofuran, carbosulfan and furathiocarb; the weights per plant of insecticide compounds transported from soil into the foliage however were greater with these systemic insecticides than they were with the non systemic chlorpyrifos and chlorfenvinphos. The extreme values observed for the periods of time of insecticide foliage concentrations equal or greater than 1 mg/kg fresh weight thus were: 1. in cauliflower crops: 21 to 36 days for chlorpyrifos, and 23 to 39 days for chlorpyrifos + oxon; 24 to 37 days for chlorfenvinphos; 20 to 48 days for carbofuran; 2. in Brussels sprouts crops: 43 to 49 days for chlorpyrifos; 47 to 53 days for chlorpyrifos + oxon; 41 to 45 days for chlorfenvinphos; between 2 to 3 months for carbofuran, carbofuran + carbosulfan, and carbofuran + furathiocarb in the fields treated respectively with either carbofuran, carbosulfan, or furathiocarb. Moreover, in the spring and summer cauliflower crops made on fields onto which continuous cauliflower crops—with their soil insecticide treatments—had been made since a greater number of years (greater soil “history”), the insecticide compounds soil and foliage concentrations generally were lower.     

Acephate-induced shortening of developmental duration and early adult emergence in a nontarget insect Drosophila melanogaster

Similar to several environmental monitoring studies, the present study used Drosophila melanogaster as a model nontarget organism to explore the interfering effects of an organophosphate (OP) insecticide acephate on insect life cycle parameters. Acephate, a common OP, is readily available in nature from agricultural sources as an environmental contaminant. Along with target pests, nontarget fruit flies also suffer exposure to such environmental chemical. To evaluate the effects of such exposure, initially, acute LC₅₀ of acephate for third instar larvae was investigated and found to be between 14 and 16 μg/ml. This information yielded the following experimental concentrations (0.5, 1.5, 2.5, 3.5, 4.5, and 5.5 μg/ml) of test chemical for evaluation of effect, if any, on the insect model. Results showed that mean larval duration of insect significantly decreased on treatment with acephate, whereas the mean pupal duration remained unaffected. Interestingly the decreasing trend was seen to persist in case of mean adult emergence, where treated flies emerged significantly earlier in comparison to controls. Thus, the study demonstrated that acephate-induced shortening of developmental time and early emergence in Drosophila melanogaster.     

In situ evaluation of the genotoxic potential of the river Nile: I. Micronucleus and nuclear lesion tests of erythrocytes of Oreochromis niloticus niloticus (Linnaeus, 1758) and Clarias gariepinus (Burchell, 1822)

This study aimed to investigate the genotoxic potential of chemicals present along the course of the river Nile using frequencies of micronuclei (MN) and nuclear lesions (NL) in erythrocytes of Nile tilapia Oreochromis niloticus niloticus and African catfish Clarias gariepinus, as biomarkers. Results showed that most of the physicochemical parameters detected and heavy metal concentrations were significantly higher in the water collected from the estuaries of the river Nile compared to other sites of the upper Nile. The frequencies of MN and NL in peripheral blood erythrocytes of Nile tilapia and African catfish were significantly higher in estuary sites in Damietta and Rosetta compared to upper sites. The lowest level of genotoxicity was observed at two sites (Aswan and Kena), considered to be less contaminated. Our results suggested that higher frequencies of MN and NL determined at Damietta and Rosetta sites may be indicative of damage produced by pollutants in these areas. The most remarkable result was that MN and NL frequencies appear to be strongly related to water quality at different sites examined, indicating that MN frequencies may serve as a reliable biomarker for testing genotoxicity in situ. The positive correlation between MN and NL induction suggested that NL may be a useful complementary assay for genotoxicity analyses when fish are used as experimental animals. It was also found that seasonal variations in MN and NL frequencies might contribute to a better understanding of genotoxic responses in the field. The use of fish as indicator organisms for monitoring the presence of genotoxic-inducing contaminants in the environment seemed justified because the effects of exposure to a “complex mixture” such as river water were obtained. Nile tilapia appears to be a more suitable bioindicator species than African catfish in studying genotoxic chemical pollution in the river Nile attributed to a higher sensitivity.     

杀虫剂三唑磷对沼水蛙（Hylarana guentheri）蝌蚪的遗传毒性研究

采用微核试验和单细胞凝胶电泳技术(彗星试验)检测了不同浓度(0、0.2、0.4、1.2、2.0、2.8mg·L-1)的三唑磷溶液对沼水蛙蝌蚪遗传毒性的影响.结果表明,当三唑磷染毒24h(≥1.2mg·L-1)及72h(≥0.2mg·L-1)后,蝌蚪微核率和核异常率比对照组均有极显著的提高.在同一时间下,随着三唑磷浓度的增大,蝌蚪微核率和核异常率总体上随之增加;在同一浓度下,随着染毒时间的增加,低浓度组(≤0.4mg·L-1)微核率出现逐渐升高趋势;高浓度组(≥1.2mg·L-1)微核率则先增加后降低.染毒24h后,彗星试验的各项指标Tail Length、Comet Length、Tail Moment和Olive Tail Moment均随三唑磷浓度的增加而增加,并呈现极显著的剂量-效应关系.当三唑磷浓度达到0.2mg·L-1时,与对照组相比,DNA总体损伤水平(Comet Assay Tail Factor)显著提高.实验表明三唑磷对蛙类蝌蚪会造成一定的遗传损伤,微核试验和彗星试验在检测污染物对蝌蚪的遗传毒性方面具有较大的应用价值.     

Assessment of the in vivo genotoxicity of a new formulation of Bacillus thuringiensis var israelensis SH-14

Biological control agents have become a useful alternative for the reduction of the use of chemical insecticides. LABIOFAM (Cuba) is developing a new formulation of a biolarvicide that possesses as active biological agent Bacillus thuringiensis var israelensis serotype H14. In order to evaluate the genotoxicity of this new formulation, an in vivo battery test was used: micronucleus (MN), chromosome aberrations (CAs), and sperm morphology (SM) assays. A dose of 6.45?×?10⁸ spores was administered per animal via oral administration. Bone marrow cells were collected 24?h after a two day treatment for the MN assay, and 24?h after a unique treatment for the CA assay, using cyclophosphamide as the positive control. Sperm cells were collected at 5 weeks from the first of five administrations for the SM test, using acrylamide as positive control. Bacillus thuringiensis var israelensis serotype H14 failed to show either a significative increase of micronucleated polychromatic erythrocytes, chromosomal aberrations, or sperm abnormalities. Acute oral administration of a high dose of Bacillus thuringiensis var israelensis serotype H14 did not produce mutagenic effects in bone marrow or sperm cells.     

Effect of acute exposure of acephate on hemocyte abundance in a non-target victim Drosophila melanogaster

Organophosphate insecticide acephate was tested to investigate effects on hemocyte abundance in a non-target dipteran insect Drosophila melanogaster. For this purpose, third-instar larvae were fed on four graded concentrations (2, 4, 6, or 8 μg/ml) acephate for a period of 12 and 24 hr (acute treatment). Control groups were simultaneously maintained for comparison. Relative proportions of plasmatocytes in hemolymph smear were found to fall with increasing concentrations of the test chemical. Similar decreasing trend in population of lamellocytes was also noted after 12 and 24 hr chemical exposure. In contrast to plasmatocytes and lamellocytes, crystal cell number was found to rise with increasing pesticide concentration. Several factors like oxidative stress, apoptosis induction, and mitotic failure might be the cause of reduced plasmatocyte and lamellocyte count. The elevated number of crystal cells in hemolymph smears is directly indicative of high melanin synthesis that assists larvae to combat chemical stress, since melanin is well known for its potential to minimize physical, chemical, and pathogenic stress.     

Metabolic responses of Azolla pinnata to cadmium stress: photosynthesis,antioxidative system and phytoremediation

This present study deals with the growth, photosynthesis, oxidative stress and phytoremediation character of Azolla pinnata L. exposed to different levels (0.05, 0.1, 0.5, 1.0, 1.5 and 2.0 mg·L^?1) of cadmium (Cd). Significant accumulation of Cd in Azolla fronds was noticed after 24 and 96 h of exposure and the accumulation rate was dose and time dependent. Growth of A. pinnata increased significantly after both exposure times with and without metal. At lower Cd doses (0.05 and 0.1 mg·L^?1), growth and photosynthesis of A. pinnata showed a marginal increase over the respective control, however, at higher Cd doses (0.5, 1.0, 1.5 and 2.0 mg·L^?1), a decreasing trend was noticed. At lower doses, Azolla fronds could counterbalance the negative effect of enhanced levels of superoxide radicals (SOR) and hydrogen peroxide (H₂O₂) through the greater activity of antioxidative enzymes. The decaresing trends in catalase and peroxidase activity at higher Cd doses suggest that Azolla fronds were not able to mitigate the negative effects of H₂O₂, hence an increase in malondialdehyde content was noticed. The study concludes that up to 0.1 ,mg·L^?1 Cd, A. pinnata can flourish and be used as biofertiliser and for phytoremedial purposes in Cd-contaminated fields; beyond this concentration poor growth may restrict its application.     

Residues and dissipation of the pesticide emamectin benzoate under Egyptian field condition: a case study

A simple, rapid analytical procedure for the quantification of emamectin benzoate in tomato was developed using high performance liquid chromatography with fluorescence detector (HPLC-FLD). Emamectin benzoate residues were extracted from tomato samples with n-hexane:ethyl acetate (1:1, v/v). The method involved derivatization using trifluoroacetic anhydride and 1-methylimidazole, prior to analysis by HPLC-FLD. Limit of quantification of this method was found to be 0.01 mg/kg, while limit of detection was 0.005 mg/kg. The dissipation of emamectin benzoate on tomato was studied, and half-life (t_1/2) was estimated in a field study carried out at three different locations. Emamectin benzoate was sprayed on tomato at recommended dosage. Samples of tomato were collected at 0, 1, 3, 7, 10, and 15 days after treatment. The t_1/2 of emamectin benzoate when applied at the recommended doses in tomato was approximately 2.5 days. The residue of emamectin benzoate reached below the maximal residue limit (MRL) 10 days after spraying at the tested dosage. Hence, a safe pre-harvest interval of 10 days is suggested before harvesting of tomato. This study would also be helpful for the Egypt government to establish the MRL of emamectin benzoate in tomatoes and provide guidance on the proper and safe use of this insecticide.     

Effects of paclobutrazol (PP333) on lead and zinc accumulations in Pseudostellaria maximowicziana

Paclobutrazol (PP333) can enhance the resistance capabilities of plants to stress conditions. In this study, PP333 were sprayed on the lead (Pb) and zinc (Zn) accumulator plant Pseudostellaria maximowicziana, which was planted in Pb–Zn contaminated soil, and the effects of PP333 on Pb and Zn accumulation levels in P. maximowicziana were studied. Spraying 10?mg/L PP333 increased, while 20, 30 and 50?mg/L PP333 decreased, the biomass of P. maximowicziana compared with the control. The 10?mg/L PP333 had no significant effects on the photosynthetic pigment contents of P. maximowicziana compared with the control, while the other doses increased the contents. The activities of antioxidant enzymes (superoxide dismutase, peroxidase and catalase) and the Pb and Zn concentrations in P. maximowicziana were increased by PP333 compared with the control. These items had the increase trend with the increase of PP333 concentrations. Only 10 and 20?mg/L PP333 increased the amount of Pb extracted by P. maximowicziana shoots, while all of the doses increased the amount of Zn extracted by P. maximowicziana shoots. Thus, low concentration of PP333 could promote the growth and heavy metal extraction ability of P. maximowicziana shoots, with the 10?mg/L being the best.     

Direct and indirect effects of pesticides on a benthic grazer during its life cycle

Background

Macroinvertebrates in aquatic ecosystems are repeatedly exposed to pesticides during their life cycle. Effects of consecutive exposure during different life stages and possible synergistic effects are not addressed in the standardized hazard assessment. The present study investigated two environmentally relevant exposure scenarios in batch (microcosm) and artificial indoor stream (mesocosm) experiments using the larvae of the mayfly Rhithrogena semicolorata (grazer) and natural aufwuchs. Grazers were analysed regarding growth, physiological condition, and drift behaviour, while the aufwuchs was analysed in terms of biomass using the particulate organic carbon as well as the chlorophyll a content. The aim was to reveal direct and indirect effects of an herbicide exposure during autumn on juvenile grazers and an insecticide exposure during spring on semi-juvenile grazers.

Results

Direct and indirect effects were found in both exposure scenarios at environmentally relevant concentrations. In the herbicide exposure scenario with terbutryn, clear direct effects on the aufwuchs community with a LOEC of 0.38 µg L^?1 were found. Effect levels of grazers due to indirect effects were equal, with the overnight drift being the most sensitive grazer endpoint. In the insecticide exposure scenario, clear lethal and sub lethal effects of lambda-cyhalothrin were evident. Derived LC₅₀ values for the artificial indoor stream and batch experiment were 2.42 µg g^?1 OC (69 days) and 1.2 µg g^?1 OC (28 days), respectively. Sub lethal effects in terms of increased drift as well-reduced growth and triglyceride levels were found at concentrations of 1.4 and 0.09 µg g^?1 OC (LOECs). These results were confirmed by the batch experiment, which revealed effect values in the similar range. Finally, a clear indirect effect of the insecticide on the aufwuchs was evident in the batch experiment with an LOEC at 0.9 µg g^?1 OC.

Conclusion

Toxicity Exposure Ratios calculated with the derived effect values indicate a risk for the investigated grazer by both pesticides. Moreover, observed indirect effects during the herbicide exposure seem to be able to affect the grazers during a second exposure with an insecticide, due to reduced physiological conditions. We suggest further research with time-shifted exposure scenarios to gain a better understanding of the complex interactions of pesticides with the life cycle and the food webs of macroinvertebrates.

     

Size at maturity,fecundity and reproductive potential of a protected population of the spiny lobster<Emphasis Type="Italic"> Palinurus elephas</Emphasis> (Fabricius, 1787) from the western Mediterranean

Protected lobster populations are expected to contribute to the replenishment of fished populations through increased egg production. We studied the reproductive biology and egg production potential of a population of the spiny lobster Palinurus elephas protected from fishing since 1990 in the Columbretes Islands Marine Reserve (western Mediterranean). An index of spawning potential was derived to compare egg production potential in the Reserve and in western Mediterranean exploited populations. Females' physiological maturity (ability to reproduce) and functional maturity (ability to mate and bear eggs) occurred at a carapace length (CL) of 76–77 mm. Males' physiological maturity occurred at a slightly larger size, 82.5 mm CL. In the Reserve, P. elephas' individual fecundity increases linearly with body size up to the females' maximum size, although maximum reproductive yield (eggs per body gram) was reached at intermediate sizes. Size-specific fecundity in the protected population was similar to that of lightly fished populations off Ireland and greater than that of western Mediterranean exploited populations. The female size class of 105–110 mm CL contributed most to egg production in the protected population and is well above the minimum landing size (MLS) for western Mediterranean fisheries. Newly mature females (below MLS) generate a very small fraction (1%) of the egg production from the Reserve. Given the pattern of exploitation in western Mediterranean fisheries, egg production potential depends more on the quantity than on the mean size and fecundity of the available females. The role of the greater availability of large males for mating in unfished populations is discussed in terms of the females' individual fecundity and mating success.     

Induction of micronuclei in tadpoles of Odontophrynus americanus (Amphibia: Leptodactylidae) by the pyrethroid insecticide cypermethrin

Cypermethrin (CY) is an active cyano pyrethroid effective against a wide range of pests encountered in agriculture and forestry. Although CY is not mutagenic in in vitro assays for gene mutation, in vivo assays showed conflicting results. In vivo genotoxicity of the synthetic pyrethroid CY in erythrocytes of Odontophrynus americanus tadpoles was examined. The frequency of micronuclei (MN) was recorded in blood smears obtained from tadpoles exposed in vivo to four different nominal concentrations 5, 10, 20 or 40?µg?L^?1 of the compound and fixed at two sampling times 48 and 96?h. As a positive control larvae were exposed to 40?mg?L^?1 of cyclophosphamide (CP). Tadpoles exposed to all CY treatments showed a significant increase in single small MN compared to the negative control group after 48?h and at 5 and 10?µg?L^?1 of CY at 96?h. Results obtained here demonstrated the genotoxic effects of the commercial formulation CY in the anuran larvae analyzed. Thus, data suggest that measurements of MN and other erythrocytes morphological aberrations performed in circulating blood samples of O. americanus tadpoles is a method for detecting cytogenetic damage in other native species.     

Potential toxicity of flubendiamide in Drosophila melanogaster and associated structural alterations of its compound eye

Flubendiamide, a comparatively new insecticide, is used against lepidopteran insect pests and presumed safe for non-target Drosophila melanogaster (D. melanogaster). In this study, treatment concentrations (0.5, 1, 2 5, 10, and 20 μg/ml) of flubendiamide, lower than agricultural concentrations (rice 50μg/ml or cotton 100 μg/ml), were able to inhibit acetylcholinesterase activity in third instar larvae of D. melanogaster indicating a neurotoxic potential. In addition, larvae exposed to flubendiamide also manifested increased amounts of stress protein hsp70. The larvae expressing such stress response when allowed to emerge as adults displayed severe eye structure deformities found by scanning electron microscopy. These findings indicate a toxic potential for flubendiamide in D. melanogaster.     

Carbofuran-induced effects on acetylcholinesterase (AChE) in erythrocytes and liver of Cyprinus carpio

A study was conducted to determine the effects of long-term exposure to carbofuran on erythrocyte and liver acetylcholinesterase (AChE) activity in Cyprinus carpio, and assess which tissue was more sensitive to pesticide exposure examining this enzyme. Fish were allowed to accilimatize in toxicant-free water for 24 days after 60-day exposure. AChE activity was determined with a spectrophotometer using acetylthiocholine iodide as a substrate in erythrocytes and liver. Enzymic activity of erythrocytes and liver decreased over time. A higher degree of enzyme inhibition was observed in erythrocyte compared to liver. The degree of enzyme inhibition was positively correlated with exposure time. When exposed fish were transferred to clean water, recovery was greater in erythrocytes than liver. Erythrocyte AChE activity recovered after 18 days, while it required 21 days in liver. The findings of this study indicate that erythrocyte AChE is more sensitive to carbofuran than liver. The greater sensitivity of erythrocyte AChE suggests that it may be more useful as a biomarker for monitoring status of pollution in freshwater bodies.     

Exposure assessment,chemical characterization and source identification of PM2.5 for school children and industrial downwind residents in Guangzhou,China

To assess the exposure doses of PM_2.5 and to investigate its chemical components for the subpopulation (i.e., school children and industrial downwind residents), simultaneous sampling of indoor and outdoor PM_2.5 was conducted at an elementary school close to traffic arteries and a residence located in the downwind area of a steel plant in metropolitan Guangzhou in 2010. Chemical components, i.e., organic carbon, elemental carbon and 6 water soluble ions were analyzed in PM_2.5. A survey was also conducted to investigate the time-activity patterns of the school children and the industrial downwind residents. Indoor and outdoor PM_2.5 were 63.2 ± 20.1 and (76.7 ± 35.8) μg/m³ at the school, and 118.8 ± 44.7 and 125.7 ± 57.1 μg/m³ in the community, respectively. Indoor PM_2.5 was found to be highly related to outdoor sources, and stationary sources were the significant contributors to PM_2.5 at both sites. The daily average doses of PM_2.5 for the school children at the school (D _children) and the industrial downwind residents in the community (D _residents) were (7.6 ± 1.9) and (36.1 ± 36.8) μg/kg-day, respectively. The daily average doses of particulate organic mass and SO₄ ^2? were the two most abundant chemical components in PM_2.5. PM_2.5 exposure for the school children was contributed by indoor and outdoor environments by 48.8 and 51.2 %, respectively; for the industrial downwind residents, the contributions were 66.0 and 34.0 %, respectively. Age and body weight were significantly and negatively correlated with D _children, while age, body weight and education level were significantly and negatively correlated with D _residents; gender was not a significant factor at both cases.     

Short-term effects of sucralose on Calanus finmarchicus and Calanus glacialis in Disko Bay,Greenland

The potential effects of sucralose on the Arctic copepods Calanus finmarchicus and Calanus glacialis were studied in Disko Bay, Greenland. Sucralose is a non-calorie sweetener and chlorine derivate of sucrose containing three chlorine atoms. Scandinavian screening studies of sucralose in 2007, revealed sucralose in all effluent samples. To investigate whether sucralose is harmful to the Arctic aquatic ecosystems, possible short-term effects were investigated on egg production, hatching rate, food intake and mortality of two species of Arctic copepods. The copepods were exposed to six different concentrations (0–50,000 ng · L^?1) of sucralose, which spans the range of concentrations found in the screening studies. Exposure led to no mortality among the copepods. Food intake by C. glacialis increased with increasing concentrations of sucralose. In C. finmarchicus, food intake did not differ with increasing concentrations. No effect of sucralose was observed on egg production of C. finmarchicus. Despite increased food intake with increasing concentrations of sucralose, C. glacialis did not increase its egg production. The results show that both species responded weakly to sucralose, but with C. glacialis being possibly slightly more sensitive to sucralose than C. finmarchicus.     

Assessment of the role of thymol in combating chromium (VI)-induced oxidative stress in isolated rat erythrocytes in vitro

Thymol, the main phenolic compound in Thymus vulgaris, has been shown to have various biological effects. The main objective of this study was to investigate the efficacy of thymol on counteracting hexavalent chromium-induced oxidative damage in rat erythrocytes in vitro. The radical scavenging activity of thymol was examined using the 1, 1-diphenyl-2-picrylhydrazyl assay. Erythrocytes resistance to oxidative damage, lipid peroxidation, osmotic pressure, hemolysis as well as morphological alterations were evaluated in the presence of 2.5 µg thymol mL^?1 with or without 5 µmol hexavalent chromium mL^?1 of the incubation media. Results from the 1,1-diphenyl-2-picrylhydrazyl assay denoted good radical scavenging activity of thymol. Thymol caused a significant increase in superoxide dismutase and catalase activities and reduced glutathione content in erythrocytes intoxicated with hexavalent chromium. In contrast, the presence of thymol resulted in markedly less-elevated malondialdehyde levels, hemolysis, and destabilization of erythrocytes exposed to hexavalent chromium. Microscopically, thymol markedly reduced hexavalent chromium-induced morphological alterations in rat red blood cells. Conclusively, thymol counteracted hexavalent chromium-induced oxidative damage in rat erythrocytes.