Cytochrome P4501A induction and testosterone hydroxylation in cultured hepatocytes of four fish species

Primary hepatocytes of the rainbow trout (Oncorhynchus mykiss), flounder (Platychthis flesus), dab (Limanda limanda) and lemon sole (Microstomus kitt) were exposed to 3,3'4,4'5 pentachlorobiphenyl (PCB 126) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for two days. This resulted in a dose-dependent induction of cytochrome P4501A (CYP1A) activity, measured as ethoxyresorufin O-deethylase (EROD), or methoxyresorufin O-deethylase (MROD) activity. In all species, a linear relationship was observed between EROD and MROD activities, suggesting that the same CYP1A enzyme metabolizes the two alkoxy-resorufin substrates. Exposures of hepatocytes of flounder or dab to TCDD, resulted in a 59-fold and 8.2-fold induction of EROD activity, respectively. This did not concur with a change in the in vitro testosterone hydroxylation profiles of both species. These and other in vitro data indicate that TCDD exposure does not influence monooxygenase activities involved in testosterone hydroxylation. Furthermore, CYP1A is of minor importance for testosterone hydroxylation in these fish species.     

Loch fleet: liming to restore a brown trout fishery

This project has been successful in meeting its objectives in terms of demonstrating that catchment liming techniques can restore acidified waters to conditions suitable for fish populations for relatively long periods. This improvement in conditions has extended to the inlet stream, which provides vital fish spawning and nursery areas, which are difficult to treat effectively be other means in remote locations. The project has also provided an assessment of the effectiveness of differing rates and modes of lime application, which suggest that only quite restricted parts of a catchment require treatment. This not only maximizes the cost-effectiveness of the treatments, but also helps to minimize any side-effects on, for example, moorland vegetation. The biological monitoring programme at Loch Fleet has also provided an assessment of the overall ecological consequences of adding limestone to naturally acidic and calcium-deficient ecosystems.     

Cytochrome P4501A, genotoxic and stress responses in golden grey mullet (Liza aurata) following short-term exposure to phenanthrene

This study represents a first approach to short-term effects of phenanthrene (Phe) in fish. The teleost Liza aurata was exposed to 0.1-2.7microM Phe during 16h. CYP1A induction was assessed as liver ethoxyresorufin-O-deethylase (EROD) activity. Genotoxicity was evaluated in gill and liver as DNA integrity (by alkaline unwinding), whereas in blood the erythrocytic nuclear abnormalities (ENA) frequency was determined. Stress responses were determined as cortisol, glucose and lactate plasma levels. Liver EROD activity was significantly increased by Phe 0.3-2.7microM. Phe genotoxicity in gill was not found, whereas liver DNA integrity significantly decreased after exposure to Phe 0.1 and 0.9microM demonstrating its genotoxicity which did not correlate with liver CYP1A induction. Phe genotoxicity in blood was demonstrated by a significant ENA increase from 0.1 up to 2.7microM. In terms of stress responses, plasma cortisol was significantly increased by Phe 0.3-2.7microM, though plasma glucose was only significantly increased by Phe 0.9 and 2.7microM. The Phe observed effects on L. aurata detected at different levels demonstrate a physiological unbalance and a probable ecological risk to ichthyofauna.     

Survival of brown trout during spring flood in DOC-rich streams in northern Sweden: the effect of present acid deposition and modelled pre-industrial water quality

Mortality and physiological responses in brown trout (Salmo trutta) were studied during spring snow melt in six streams in northern Sweden that differed in concentrations of dissolved organic carbon (DOC) and pH declines. Data from these streams were used to create an empirical model for predicting fish responses (mortality and physiological disturbances) in DOC-rich streams using readily accessible water chemistry parameters. The results suggest that fish in these systems can tolerate higher acidity and inorganic aluminium levels than fish in low DOC streams. But even with the relatively low contemporary deposition load, anthropogenic deposition can cause fish mortality in the most acid-sensitive surface waters in northern Sweden during spring flood. However, the results suggests that it is only in streams with high levels of organically complexed aluminium in combination with a natural pH decline to below 5.0 during the spring where current sulphur deposition can cause irreversible damage to brown trout in the region. This study support earlier studies suggesting that DOC has an ameliorating effect on physiological disturbances in humic waters but the study also shows that surviving fish recover physiologically when the water quality returns to less toxic conditions following a toxic high flow period. The physiological response under natural, pre-industrial conditions was also estimated.     

Accumulation pattern and biotransformation enzyme induction in rainbow trout embryos exposed to sublethal aqueous concentrations of 3,3',4,4'-tetrachlorobiphenyl

Accumulation pattern of 3,3',4,4'-tetrachlorobiphenyl (PCB 77) and the exposure time needed to activate the monooxygenase (EROD) and conjugation (GST) enzyme systems of fish at the advanced embryonic stage were studied. Eyed stage embryos of rainbow trout (Oncorhynchus mykiss) were exposed to sublethal doses (0, 1, 10, and 100 micrograms/l) of PCB 77. Results indicated direct accumulation of the chemical into the eggs, but the exposure time was not long enough for PCB 77 to reach constant steady state. However, at the two lowest test concentrations (1 microgram/l and 10 micrograms/l) a temporary plateau at chemical accumulation was reached at the third exposure day (185 and 1221 ng PCB/g egg w.w). At the highest concentration (100 micrograms/l) the decrease in the accumulation rate was already evident after the first day (2182 ng PCB/g egg w.w). The chemical uptake increased again at day 7 in all the exposure groups. That event could have been caused by the increased metabolic rate of the embryos in preparation for the upcoming hatching event. The microsomal CYP1A monooxygenase system (EROD) was shown to be a sensitive indicator of embryonic exposure, being induced at the low (1 microgram/l, 182 ng/g egg) PCB concentration and after a short (3 day) exposure time. The conjugation enzyme system (GST) was shown to be functioning already at the advanced embryonic stage, although no response to the studied chemical stress was detected.     

Toxicity of waters from two streams to early life stages of brown trout (Salmo trutta f. fario L.), tested under semi-field conditions.

The development of brown trout (Salmo trutta f. fario L.) in water of two differently polluted streams and in a control situation was monitored in order to get insights into the impact of anthropogenic chemical stressors on the reproductive success of this fish species indigenous to both streams. The test streams, situated in the south of Stuttgart, Germany, were the complexly polluted K?rsch stream and the less polluted Kr?henbach stream. Bypass systems connected to the streams and a laboratory control system were used for continuous exposure of early brown trout stages shortly after fertilisation up to the end of the embryonic development. Temperature and oxygen conditions were standardised in all test series in order to minimise unspecific effects. The examined endpoints were: (1) mortality, (2) developmental rate, (3) time course of hatching, (4) malformations, and (5) growth. A retarded development, reduced growth rates and higher mortality rates of K?rsch stream water exposed embryos indicated an embryotoxic potential for the more polluted stream. High infection-related mortality rates of embryos suggested the presence of confounding factors also in the less polluted Kr?henbach stream. In parallel to the exposure experiment, physicochemical and limnochemical parameters as well as concentrations of organic contaminants and heavy metals were monitored. Analytical data confirm the different degrees of pollution of both streams.     

Assessment of insecticide contamination in runoff and stream water of small agricultural streams in the main soybean area of Argentina

The first- and second-order streams, Brown and Horqueta, respectively, which are located in the main area of soybean production in Argentina were examined for insecticide contamination caused by runoff from nearby soybean fields. The insecticides most widely used in Argentina (chlorpyrifos, cypermethrin and endosulfan) were detected in sediments, suspended particles and water. Highest concentrations in suspended particles were 318 microg/kg for endosulfan in the stream Horqueta, while 226 microg/kg chlorpyrifos and 13.2 microg/kg cypermethrin were measured in the stream Brown. In the Horqueta stream 150 and 53 microg/kg chlorpyrifos and cypermethrin were detected in runoff sediments, respectively. Whereas cypermethrin concentrations in the suspended particles were relatively low, levels in the floodwater of Brown reached 0.7 microg/l. The highest chlorpyrifos concentration in floodwater was 0.45 microg/l in Brown. However, endosulfan was not detected in the water phase. In runoff water the highest concentrations measured were 0.3 microg/l for chlorpyrifos in Horqueta and 0.49 microg/l for cypermethrin in the Brown stream. On five sampling dates during the pesticide application period in Brown stream (2002/2003) the concentration of chlorpyrifos and cypermethrin in runoff and/or floodwater exceeded the water quality criteria for freshwater mentioned in this study. In three cases this insecticide concentration was measured in stream water, indicating an acute risk to aquatic life. The acute toxicity-exposure-ratio (TER) for chlorpyrifos and cypermethrin also shows an acute risk for aquatic invertebrates in the Brown stream. In the Horqueta chlorpyrifos concentrations in the runoff exceeded the safety levels three times during the application period (2001/2002), potentially endangering the aquatic fauna. Effects on aquatic macroinvertebrates after insecticide contamination were reported in earlier studies in Horqueta stream.     

A comparison of predicted and measured levels of runoff-related pesticide concentrations in small lowland streams on a landscape level

Short-term pollution events via runoff are typical of streams in agricultural areas. Existing runoff models that simulate pesticide loss from agricultural fields require extensive input of information. There is thus a need for a simple model that can predict runoff-related pesticide concentrations in many streams on a landscape level when only limited data are available. To validate such a model, the runoff-related pesticide load of 18 small lowland streams was predicted with an extended version of the model "simplified formula for indirect loadings caused by runoff" (available from the Organisation for Economic Cooperation and Development, OECD). The authors suggest that the model presented here is suitable for use in routine exposure assessment of pesticides on a landscape level, as all input data (soil, slope, precipitation, pesticide application) are readily available from public authorities or could be generated by simple regional flood hydrograph curves. The predicted concentrations were compared with measured concentrations obtained by runoff-triggered sampling. Fungicides, insecticides and herbicides were detected in 17 streams, with max. concentrations measuring up to 29.7 microg/l for the fungicide azoxystrobin and 0.3 microg/l for the insecticide parathion-ethyl. Herbicides were detected in 16 streams, with max. concentrations between 13.7 and 1.2 microg/l. The linear regression between the predicted and measured concentrations (log-values) shows significant correlations for the following pesticides: azoxystrobin: r2=0.43; p=0.03; epoxiconazole: r2=0.71; por=0.5 microg/l).     

Greenhouse gas emission from small clinics solid waste management scenarios in an urban area of an underdeveloping country: A life cycle perspective

This study aimed to investigate the effects on the environment of small clinics solid waste management by applying a life cycle analysis approach. Samples were collected from 371 private clinics situated in densely populated areas of Hyderabad, Pakistan. The solid waste from surveyed clinics was categorically quantified on daily basis for 30 consecutive days. The functional unit for waste was defined as 1 tonne. System limitations were defined as landfilling, incineration, composting, material recovery, and transportation of solid waste. The treatment and disposal methods were assessed according to their greenhouse gas emission rate. For the evaluation, three different scenarios were designed. The second scenario resulted in the highest emission value of 1491.78 kg CO₂ eq/tonne of solid waste due to mixed waste incineration, whereas the first scenario could not offer any saving because of uncovered landfilling and 67.5% higher transport fuel consumption than the proposed network. The proposed third scenario was found to be a better solution for urban clinics solid waste management, as it resulted in savings of 951.38 kg CO₂ eq/tonne of solid waste. This integrated design is practicable by resource-constrained economy. This system consists of composting, material recovery, and incineration of hazardous waste. The proposed system also includes a feasible transportation method for urban area collection networks. The findings of the present study can play a vital role in documenting evidence and for policymakers to plan the solid waste management of clinics, as previously no studies have been conducted on this particular case.

Implications: This study aims to highlight the impact of small clinics solid waste management scenarios on the environment in a developing country’s urban area. Life cycle analysis is used for comparison of greenhouse gase emission from different scenarios, including the purposed integrated method. Small clinics play a very important role in health care, and their waste management is a very serious issue; however, there are no previous studies on this particular case to the best knowledge of the authors. This study can be considered as forerunner effort to quantify the environmental footprint of small clinics solid waste in urban areas of a developing country.     

Toxicity of silver nanoparticles to rainbow trout: A toxicogenomic approach

Silver (Ag) nanoparticles are used as antimicrobial adjuvant in various products such as clothes and medical devices where the release of nano-Ag could contaminate the environment and harm wildlife. The purpose of this study was to examine the sublethal effects of nano-Ag and dissolved Ag on Oncorhynchus mykiss rainbow trout. Hepatic Ag contents and changes in gene expression were monitored to provide insights on bioavailability and mode of action of both forms of silver. Fish were exposed to increasing concentrations (0.06, 0.6 and 6 μg L⁻¹) of nano-Ag (20 nm) and silver nitrate (AgNO₃) for 96 h at 15 °C. A gene expression analysis was performed in the liver using a DNA microarray of 207 stress-related genes followed by a quantitative polymerase chain reaction on a selection of genes for validation. The biochemical markers consisted of the determination of labile zinc, metallothioneins, DNA strand breaks, lipid peroxidation (LPO) and vitellogenin-like proteins. The analysis of total Ag in the aquarium water revealed that nano-Ag was mostly aggregated, with 1% of the total Ag being dissolved. Nevertheless, hepatic Ag content was significantly increased in exposed fish. Indeed, dissolved Ag was significantly more bioavailable than nano-Ag only at the highest concentration with 38 ± 10 and 11 ± 3 ng Ag mg⁻¹ proteins for dissolved and nano-Ag respectively. Exposure to both forms of Ag led to significant changes in gene expression for 13% of tested gene targets. About 12% of genes responded specifically to nano-Ag, while 10% of total gene targets responded specifically to dissolved Ag. The levels of vitellogenin-like proteins and DNA strand breaks were significantly reduced by both forms of Ag, but DNA break levels were lower with nano-Ag and could not be explained by the presence of ionic Ag. Labile zinc and the oxidized fraction of metallothioneins were increased by both forms of Ag, but LPO was significantly induced by nano-Ag only. A discriminant function analysis revealed that the responses obtained by biochemical markers and a selection of ten target genes were able to discriminate completely (100%) the effects of both forms of Ag. Exposure to nano-Ag involved genes in inflammation and dissolved Ag involved oxidative stress and protein stability. Hence, the toxicity of Ag will differ depending on the presence of Ag nanoparticles and aggregates.     

Endocrine modulation, inhibition of ovarian development and hepatic alterations in rainbow trout exposed to polluted river water

Under laboratory conditions, female rainbow trout were exposed to graded concentrations of water from the River Lambro, a polluted tributary of the River Po, and to the effluent of a large wastewater treatment plant which flows into the River Lambro. In field exposures, trout were held in cages in the River Po upstream and downstream from the confluence of the River Lambro. After 10-day (laboratory) and 30-day (laboratory and field) exposures, trout were examined for several chemical, biochemical and histological endpoints. The results indicated that exposure to complex mixtures of chemicals, including estrogen receptor agonists, aryl-hydrocarbon receptor agonists, and probably antiandrogens, had occurred. Exposure altered the plasma levels of 17β-estradiol and testosterone, and some treatments also enhanced the activity of hepatic ethoxyresorufin O-deethylase. Gonadal histology showed varying levels of degenerative processes characterised by oocyte atresia, haemorrhages, melano-macrophage centres (MMCs), and oogonia proliferation. Liver histology showed less severe effects.     

Evaluation of results of a numerical simulation of dispersion in an idealised urban area for emergency response modelling

WinMISKAM is evaluated from an emergency response perspective. Comparisons are made between ground level concentrations observed during selected Mock Urban Setting Test (MUST) field trials and predictions generated by the model. The model was driven by 5 min averaged on-site meteorological data, and used minimum grid spacing of 0.5 m in both the horizontal and vertical. The code was found to perform well, with 46% of all predictions (paired in time and space) and 83% of arc maxima predictions within a factor of two of observed concentrations. The model was found to perform better for neutral cases than stable cases with 27% of stable case predictions and 57% of neutral case predictions within a factor of two when compared in time and space.     

A hybrid modeling approach to resolve pollutant concentrations in an urban area

A modeling tool that can resolve contributions from individual sources to the urban environment is critical for air-toxics exposure assessments. Air toxics are often chemically reactive and may have background concentrations originated from distant sources. Grid models are the best-suited tools to handle the regional features of these chemicals. However, these models are not designed to resolve pollutant concentrations on local scales. Moreover, for many species of interest, having reaction time scales that are longer than the travel time across an urban area, chemical reactions can be ignored in describing local dispersion from strong individual sources making Lagrangian and plume-dispersion models practical. In this study, we test the feasibility of developing an urban hybrid simulation system. In this combination, the Community Multi-scale Air Quality model (CMAQ) provides the regional background concentrations and urban-scale photochemistry, and local models such as Hybrid Single Particle Lagrangian Integrated Trajectory model (HYSPLIT) and AMS/EPA Regulatory Model (AERMOD) provide the more spatially resolved concentrations due to local emission sources. In the initial application, the HYSPLIT, AERMOD, and CMAQ models are used in combination to calculate high-resolution benzene concentrations in the Houston area. The study period is from 18 August to 4 September of 2000. The Mesoscale Model 5 (MM5) is used to create meteorological fields with a horizontal resolution of 1×1 km². In another variation to this approach, multiple HYSPLIT simulations are used to create a concentration ensemble to estimate the contribution to the concentration variability from point sources. HYSPLIT simulations are used to model two sources of concentration variability; one due to variability created by different particle trajectory pathways in the turbulent atmosphere and the other due to different flow regimes that might be introduced when using gridded data to represent meteorological data fields. The ensemble mean concentrations determined by HYSPLIT plus the concentrations estimated by AERMOD are added to the CMAQ calculated background to estimate the total mean benzene concentration. These estimated hourly mean concentrations are also compared with available field measurements.     

Effects of a fire-retardant chemical to fathead minnows in experimental streams

BACKGROUND: Each year millions of liters of fire-retardant chemicals are applied to wildfires across the nation. Recent laboratory studies with long-term fire-retardant chemicals indicate a significant photoenhanced toxicity of products containing sodium ferrocyanide corrosion inhibitors. Our objective of this study was to determine the toxicity of fire-retardant chemicals to fathead minnows during exposure in experimental outdoor streams. METHODS: Stream tests were conducted to determine the potential toxicity of a pulse of exposure as might occur when fire retardant chemical is rinsed from the watershed by rainfall. Two artificial 55-meter experimental streams were dosed with different concentrations of Fire-Trol GTS-R, or uncontaminated for a control. Replicate groups of fathead minnows were added to screened containers (10 fish per container) and exposed to retardant chemicals in the recirculating flow of the stream for up to 6 hours. RESULTS AND DISCUSSION: Under field conditions toxicity of GTS-R only occurred in the presence of sunlight. When GTS-R was tested on sunny days, 100% mortality occurred. However, when tested during heavily overcast conditions, no mortality occurred. CONCLUSIONS: Lethal concentrations of cyanide were measured when GTS-R with YPS exposures were conducted under sunny conditions, but not under cloudy conditions, indicating that a minimum UV level is necessary to induce toxicity as well as the release of cyanide from YPS. The toxicity observed with GTS-R was likely associated with lethal concentrations of cyanide. Rainwater runoff following applications of this fire-retardant at the recommended rate could result in lethal concentrations in small ponds and streams receiving limited water flow under sunny conditions. RECOMMENDATIONS AND OUTLOOK: In addition to avoiding application to aquatic habitats, it is important to consider characteristics of the treated site including soil binding affinity and erosive properties.     

Occupational exposure to formaldehyde in an institute of morphology in Brazil: a comparison of area and personal sampling

Background, aims, and scope

Formaldehyde (FA) is a harmful chemical, which is classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. Solutions of FA that are used to preserve cadavers in research and education morphological institutes represent a risk to occupational health of professionals and students. During the dissection of cadavers in the anatomy laboratories, FA vapors are emitted, resulting in the exposure of students and their instructors to elevated levels of FA. The World Health Organization recommends an air quality guideline value of 0.1 mg m^?3 for exposure to FA. The limit of occupational exposure adopted by the Brazilian legislation (2.3 mg m^?3) is markedly higher than those adopted by institutions of other countries around the world. The purpose of this study was to determine the levels of personal exposure and the area concentration of FA in the morphology department of the Federal Fluminense University, Brazil, and investigate and compare the relationship between them.

Methods

Four rooms distributed in the three floors of the Morphology Department were evaluated: the embalming laboratory, the anatomy laboratories, the corridor of the teachers?? rooms, and the entrance hall. Thirty-six samples in total were collected in the second semester of 2010 and first semester of 2011. The air sampling and FA analysis were performed according to the EPA TO-11A Protocol, using a diffusive sampling device for carbonyl compounds. Personal samples were collected from monitors using a sampling device pinned on each person??s lapel. The samples were analyzed using rapid resolution liquid chromatography with UV-DAD detection at 360 nm.

Results and discussion

The concentrations of FA ranged from 0.20 and 0.18 mg m^?3 in the corridor between the teachers?? rooms, 0.03 to 0.37 mg m^?3 in the entrance hall, 0.22 to 2.07 mg m^?3 in the anatomy laboratory, 2.21 to 2.52 mg m^?3, in the embalming room. The levels found in the corridor between the teachers?? rooms and in the entrance hall were lower than in other compartments because of their large distances to the sources of FA and better ventilation. The other rooms presented higher levels of FA because of the activities carried there (embalming and dissection procedures). Even in the rooms that showed the lowest levels of FA, the values found were higher than those established by all international guideline limits, except the Brazilian legislation limit, although, the concentration level in the embalming room was even greater than the Brazilian guideline. These concentrations are 100?C1,000-fold higher than those reported in an FA outdoor study. The exposure levels of monitors and students ranged from 1.89 to 4.82 mg m^?3, indicating that current practices at the Morphology Department at the university would represent a health risk. The simultaneous monitoring of area concentrations and personal exposure showed that the characteristics of classes and of cadavers?? parts, the number of students in the room and even the activities of the monitors influence the FA concentrations.

Conclusion

This study revealed that the concentration of FA was low in the ventilated areas of the Morphology Department, and that the personal exposure when the person was close to the cadavers during the dissection procedure was higher than the mean FA concentration. This should be considered in the risk assessment of FA during these activities without effective protection equipment. It is suggested that the Brazilian legislation of exposure to formaldehyde requires an urgent update considering international legislation.     

Distribution of antidepressants and their metabolites in brook trout exposed to municipal wastewaters before and after ozone treatment--evidence of biological effects

This study examined the tissues distribution of selected serotonin reuptake inhibitors (SSRIs) in brook trout exposed for 3 months to continuous flow-through primary-treated effluent before and after ozone treatment. A reliable analytical method was developed for the quantification of trace amounts of antidepressants in small tissue homogenate extracts. Levels of six antidepressants and four of their N-desmethyl metabolites were determined using liquid chromatography-tandem mass spectrometry. Significant amounts of the SSRIs were found in fish tissue-in decreasing order: liver>brain>muscle. Sertraline and its metabolite desmethylsertraline were the predominant substances observed in most tissues (0.04-10.3 ng g(-1)). However, less SSRIs (0.08-1.17 ng g(-1)) were bioaccumulated in the ozonated effluent. The early molecular effects of these SSRIs on the Na/K-dependent ATPase pump activity in brain synaptosomes where also investigated in vitro and in fish exposed to the municipal effluents. With respect to their potential biological effects, in vitro exposure to selected SSRIs induced a reduction of the brain Na/K-ATPase activity in synaptosomes in a dose-dependent manner. Results showed that Na/K-ATPase activity was readily inhibited by exposure to municipal effluent before and, to a lesser extent, after ozone treatment. Moreover, the Na/K-ATPase activity was significantly and negatively correlated with brain tissue concentrations of fluoxetine (r=-0.57; p<0.03), desmethylsertraline (r=-0.84; p<0.001), and sertraline (r=-0.82; p<0.001). The present study reveals that SSRIs are readily available in fish, biologically active and corroborates previous findings on the serotonergic properties of municipal effluents to aquatic organisms.     

Atrazine induction of a family 4 cytochrome P450 gene in Chironomus tentans (Diptera: Chironomidae)

Cytochrome P450-dependent microsomal monooxygenase (P450) activity was measured in control and atrazine-exposed third instar midge larvae, Chironomus tentans. Significantly elevated O-demethylase activity was observed in gut homogenates taken from midges exposed to atrazine concentrations from 1 to 10 ppm for 90 h. No significant induction was observed at atrazine concentrations below 1 ppm. A region of a cytochrome P450 family 4 gene was amplified and sequenced from C. tentans larvae. Alignments of inferred amino acid sequences with other insect CYP4 gene homologues indicate a high degree of similarity. Northern blot analysis employing the CYP4 gene fragment as a probe showed an over-expression in C. tentans exposed to atrazine. The results support the previously identified inducibility of cytochrome P450-dependent activity and provide insight into the potential consequences of atrazine exposure to aquatic organisms.     

Residues in fish exposed to sublethal doses of endosulfan and fish collected from cotton growing area

A one step extraction and cleanup procedure for determining endosulfan in fish was investigated. Minced Fish was mixed with trisodium citrate, disodium hydrogen orthophosphate and sodium sulphate into a dry powdery mixture, which was eluted through silicic acid and alumina with a mixture of dichloromethane and hexane. The eluate was concentrated and chromatographed on GLC using an EC detector without further cleanup. Three species of fresh water fish exposed to 0.7-16 micrograms/litre-1 technical grade endosulfan in tanks for various periods of time were found to concentrate both alpha and beta endosulfan and metabolise them to sulfate, diol, ether and lactone. Fish collected from Gwydir River in the cotton growing area in summer (Dec. 1986-Feb. 1987) were found to contain endosulfan residues suggesting endosulfan is quite stable in the environment and can cause residues.     

The impact of acidification on macroinvertebrate assemblages in welsh streams: towards an empirical model

The acidification of surface waters has profound ecological consequences. There is a need to predict the effects of possible future patterns of acid deposition on the biological components of fresh waters. This paper describes a model of the relationships between water chemistry and macroinvertebrate assemblages in eighteen streams in the upper Tywi whose catchments are subject to different land uses. Using established statistical techniques on data sets derived from riffle and margin samples taken in spring and summer, the macroinvertebrate assemblages were classified into three groups, which corresponded with streams draining conifer afforested catchments, acidic moorland streams and circumneutral moorland streams. Following principal components analysis to select key environmental variables, the application of multiple discriminant analysis generated two discriminant functions which were related most strongly to mean filterable aluminium concentration and mean total hardness, respectively. The discriminant functions were used to assign site-group membership with 100% success in the case of the spring data set with combined habitats. In addition, multiple regression of the primary ordination axis of each data set on mean aluminium concentration and mean hardness or pH, produced equations which explained 62.0%-87.2% of the variance. We conclude that the methods used here provide an effective analytical and potentially predictive tool for use in the understanding and management of the impact of acidification on freshwater ecosystems.     

Spontaneous abortion in women occupationally exposed to inhalational anesthetics: a critical systematic review

Environmental Science and Pollution Research - Occupational exposure to inhalational anesthetics has been associated with health problems, including reproductive issues. Considering the scarcity...