The mutagenic hazards of aquatic sediments: a review

Increase in developmental instability in a field-collected Chironomus population maintained under laboratory conditions

In order to be a relevant indicator of exposure towards teratogenic stressors, morphological defects should not be passed on to the next generation. In this study, we compare morphological variations in Chironomids collected from a contaminated river stretch with those of their progeny, reared in uncontaminated sediment under laboratory conditions. We focused on mentum defects (deformities, fluctuating asymmetry and mean shape change), measured by geometric morphometrics. We observed no significant variation in deformity rate between the parental generation and its progeny. On the contrary, we observed a significant increase in fluctuating asymmetry and a significant decrease in mentum centroid size in the offspring. Our results suggest that shape defects are not caused by direct exposure to teratogenic stressors alone. We propose four hypotheses to explain this: (a) teratogenic contaminants are present in egg-clutches, (b) contaminants at the sampling site have mutagenic effects, (c) costs of tolerance, and (d) contamination-induced genetic impoverishment.

Survey of the mutagenicity of surface water, sediments, and drinking water from the Penobscot Indian Nation

U.S. Environmental Protection Agency (US EPA) Regional Applied Research Effort (RARE) projects address the effects of environmental pollutants in a particular region on the health of the population in that region. This report is part of a RARE project that addresses this for the Penobscot Indian Nation (PIN), Penobscot Island, Maine, U.S., where the Penobscot River has had fish advisories for many years due to high levels of mercury. We used the Salmonella mutagenicity assay with strains TA100, TA98, YG1041, and YG1042 with and without metabolic activation to assess the mutagenic potencies of organic extracts of the Penobscot River water and sediment, as well as drinking-water samples, all collected by the PIN Department of Natural Resources. The source water for the PIN drinking water is gravel-packed groundwater wells adjacent to the Penobscot River. Most samples of all extracts were either not mutagenic or had low to moderate mutagenic potencies. The average mutagenic potencies (revertants/L-equivalent) were 337 for the drinking-water extracts and 177 for the river-water extracts; the average mutagenic potency for the river-sediment extracts was 244 revertants(g-equivalent)(-1). This part of the RARE project showed that extracts of the Penobscot River water and sediments and Penobscot drinking water have little to no mutagenic activity that might be due to the classes of compounds that the Salmonella mutagenicity assay detects, such as polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (nitroarenes), and aromatic amines. This study is the first to examine the mutagenicity of environmental samples from a tribal nation in the U.S.

Cytogenetic index and functional genome alterations in Chironomus piger Strenzke (Diptera, Chironomidae) in the assessment of sediment pollution: a case study of Bulgarian and UK rivers

The genotoxicity of trace metals in the sediments from a number of polluted sites on UK and Bulgarian rivers to Chironomus piger was assessed by an examination of genome instability as demonstrated by structural and functional changes to the salivary glands chromosomes. Based on the metal assays, the sediments were characterized to range from 'extremely' to 'strongly contaminated'. The cytogenetic index calculated on the basis of somatic structural chromosome alterations in the polytene chromosomes indicates a high level of pollution (0.07-0.06 in Bulgarian and 0.10-0.13 in UK stations). Exposure of C. piger to contaminated sediments resulted in a high level of chromosome damage as indicated by a somatic index of between 1.96 and 4.0. The transcription mechanism of the Balbiani rings and nucleolar organizer was damaged as their activity was either partially or completely suppressed. We have demonstrated that the C. piger genome is a sensitive sublethal indicator of sediment contamination, and is a highly suitable candidate for ecotoxicological monitoring of running waters.

Exploring the potential interference of estuarine sediment contaminants with the DNA repair capacity of human hepatoma cells

Estuaries may be reservoirs of a wide variety of pollutants, including mutagenic and carcinogenic substances that may impact on the ecosystem and human health. A previous study showed that exposure of human hepatoma (HepG2) cells to extracts from sediment samples collected in two areas (urban/industrial and riverine/agricultural) of an impacted estuary (Sado, Portugal), produced differential cytotoxic and genotoxic effects. Those effects were found to be consistent with levels and nature of sediment contamination. The present study aimed at evaluating whether the mixtures of contaminants contained in those extracts were able to modulate DNA repair capacity of HepG2 cells. The residual level of DNA damage was measured by the comet assay in cells exposed for 24 or 48 h to different extracts, after a short preexposure to a challenging concentration range of ethyl methanesulfonate (EMS), as a model alkylating agent. The results suggested that the mixture of contaminants present in the tested samples, besides a potential direct effect on the DNA molecule, may also interfere with DNA repair mechanisms in HepG2 cells, thus impairing their ability to deal with genotoxic stress and, possibly, facilitating accumulation of mutations. Humans are environmentally/occupationally exposed to mixtures rather than to single chemicals. Thus, the observation that estuarine contaminants induce direct and indirect DNA strand breakage in human cells, the latter through the impairment of DNA repair, raises additional concerns regarding potential hazards from exposure and the need to further explore these endpoints in the context of environmental risk assessment.

An integrative assessment to determine the genotoxic hazard of estuarine sediments: combining cell and whole-organism responses

The application of the Comet assay in environmental monitoring remains challenging in face of the complexity of environmental stressors, e.g., when dealing with estuarine sediments, that hampers the drawing of cause-effect relationships. Although the in vitro Comet assay may circumvent confounding factors, its application in environmental risk assessment (ERA) still needs validation. As such, the present work aims at integrating genotoxicity and oxidative DNA damage induced by sediment-bound toxicants in HepG2 cells with oxidative stress-related effects observed in three species collected from an impacted estuary. Distinct patterns were observed in cells exposed to crude mixtures of sediment contaminants from the urban/industrial area comparatively to the ones from the rural/riverine area of the estuary, with respect to oxidative DNA damage and oxidative DNA damage. The extracts obtained with the most polar solvent and the crude extracts caused the most significant oxidative DNA damage in HepG2 cells, as measured by the formamidopyrimidine-DNA glycosylase (FPG)-modified Comet assay. This observation suggests that metals and unknown toxicants more hydrophilic than polycyclic aromatic hydrocarbons may be important causative agents, especially in samples from the rural part of the estuary, where oxidative DNA damage was the most significant. Clams, sole, and cuttlefish responded differentially to environmental agents triggering oxidative stress, albeit yielding results accordant with the oxidative DNA damage observed in HepG2 cells. Overall, the integration of in vivo biomarker responses and Comet assay data in HepG2 cells yielded a comparable pattern, indicating that the in vitro FPG-modified Comet assay may be an effective and complementary line-of-evidence in ERA even in particularly challenging, natural, scenarios such as estuarine environments.

Evaluation of the ecotoxicity of sediments from Yangtze river estuary and contribution of priority PAHs to ah receptor--mediated activities

In this study, in vitro bioassays were performed to assess the ecotoxicological potential of sediments from Yangtze River estuary. The cytotoxicity and aryl hydrocarbon receptor (AhR)-mediated toxicity of sediment extracts with rainbow trout (Oncorhynchus mykiss) liver cells were determined by neutral red retention and 7-ethoxyresorufin-O-deethylase assays. The cytotoxicity and AhR-mediated activity of sediments from the Yangtze River estuary ranged from low level to moderate level compared with the ecotoxicity of sediments from other river systems. However, Yangtze River releases approximately 14 times greater water discharge compared with Rhine, a major river in Europe. Thus, the absolute pollution mass transfer of Yangtze River may be detrimental to the environmental quality of estuary and East China Sea. Effect-directed analysis was applied to identify substances causing high dioxin-like activities. To identify unknown substances contributing to dioxin-like potencies of whole extracts, we fractionated crude extracts by open column chromatography. Non-polar paraffinic components (F1), weakly and moderately polar components (F2), and highly polar substances (F3) were separated from each crude extract of sediments. F2 showed the highest dioxin-like activities. Based on the results of mass balance calculation of chemical toxic equivalent concentrations (TEQs), our conclusion is that priority polycyclic aromatic hydrocarbons indicated a low portion of bio-TEQs ranging from 1% to 10% of crude extracts. Further studies should be conducted to identify unknown pollutants.

Evaluation of impairment of DNA in marine gastropod, Morula granulata as a biomarker of marine pollution

The impairment of DNA in marine gastropod Morula granulata was evaluated in terms of the loss of DNA integrity in the species as a measure of the impact of genotoxic contaminants prevalent in the marine environment along the coast of Goa, India. The extent of DNA damage occurred in the marine gastropods collected from different sampling sites such as Arambol, Anjuna, Sinquerim, Dona Paula, Bogmalo, Hollant, Velsao, Betul and Palolem along the coast of Goa was measured following the technique of partial alkaline unwinding as well as comet assays. The highest DNA integrity was observed at Arambol (F, 0.75), identified as the reference site, whereas the lowest DNA integrity at Hollant (F, 0.33) situated between the two most contaminated sites at Bogmalo and Velsao. The impact of genotoxic contaminants on marine gastropods was pronounced by their low DNA integrity at Sinquerim (F, 0.40) followed by Betul (F, 0.47), Velsao (F, 0.51), Anjuna (F, 0.54), Bogmalo (F, 0.55), Dona Paula (F, 0.67) and Palolem (F, 0.70). The extent of DNA damage occurred in M. granulata due to ecotoxicological impact of the prevailing marine pollutants along the coast of Goa was further substantiated by comet assay and expressed in terms of %head-DNA, %tail DNA, tail length and Olive tail moment. The single cell gel electrophoresis of M. granulata clearly showed relatively higher olive tail moment in the marine gastropod from the contaminated sites, Anjuna, Hollant, Velsao and Betul. The variation in the mean %head DNA at different sampling sites clearly indicated that the extent of DNA damage in marine gastropod increases with the increase in the levels of contamination at different sampling sites along the coast. The stepwise multiple regression analysis of the water quality parameters showed significant correlation between the variation in DNA integrity and PAH in combination with NO3, salinity and PO4 (R¯(2), 0.90). The measurement of DNA integrity in M. granulata thus provides an early warning signal of contamination of the coastal ecosystem of Goa by genotoxic contaminants.

Determining oxidative and non-oxidative genotoxic effects driven by estuarine sediment contaminants on a human hepatoma cell line

Estuarine sediments may be reservoirs of hydrophilic and hydrophobic pollutants, many of which are acknowledged genotoxicants, pro-mutagens and even potential carcinogens for humans. Still, studies aiming at narrowing the gap between ecological and human health risk of sediment-bound contaminant mixtures are scarce. Taking an impacted estuary as a case study (the Sado, SW Portugal), HepG2 (human hepatoma) cells were exposed in vitro for 48 h to extracts of sediments collected from two areas (urban/industrial and Triverine/agricultural), both contaminated by distinct mixtures of organic and inorganic toxicants, among which are found priority mutagens such as benzo[a]pyrene. Comparatively to a control test, extracts of sediments from both impacted areas produced deleterious effects in a dose-response manner. However, sediment extracts from the industrial area caused lower replication index plus higher cytotoxicity and genotoxicity (concerning total DNA strand breakage and clastogenesis), with emphasis on micronucleus induction. On the other hand, extracts from the rural area induced the highest oxidative damage to DNA, as revealed by the FPG (formamidopyrimidine-DNA glycosylase) enzyme in the Comet assay. Although the estuary, on its whole, has been classified as moderately contaminated, the results suggest that the sediments from the industrial area are significantly genotoxic and, furthermore, elicit permanent chromosome damage, thus potentially being more mutagenic than those from the rural area. The results are consistent with contamination by pro-mutagens like polycyclic aromatic hydrocarbons (PAHs), potentiated by metals. The sediments from the agriculture-influenced area likely owe their genotoxic effects to metals and other toxicants, probably pesticides and fertilizers, and able to induce reactive oxygen species without the formation of DNA strand breakage. The findings suggest that the mixtures of contaminants present in the assayed sediments are genotoxic to HepG2 cells, ultimately providing a useful approach to hazard identification and an effective line-of-evidence in the environmental monitoring of anthropogenically-impacted coastal ecosystems.

Organic contamination of surface sediments in the metropolitan coastal zone of Athens, Greece: sources, degree, and ecological risk

Bottom sediments represent a crucial component of the marine environment, since they constitute a habitat, a trophic resource, and a spawning place for various organisms. Unfortunately, the sediments of urban coastal areas are deeply impacted by anthropogenic activities that degrade their quality. In the Drapetsona-Keratsini metropolitan coastal zone of Athens, current industrial and shipping activities together with the effluents from a sewage outfall, which was in operation in the past, have resulted in one of the most contaminated sedimentary environments, in terms of organic compound loads, in Mediterranean. Exceptionally high concentrations of aliphatic hydrocarbons (up to 4457 μg g⁻¹), carcinogenic PAHs (up to 7284 ng g⁻¹), and organochlorines (up to 544 ng g⁻¹ for PCBs; up to 208 ng g⁻¹ for DDTs) constitute a major threat to the marine life of the associated Saronikos Gulf.

Human hepatoma cells exposed to estuarine sediment contaminant extracts permitted the differentiation between cytotoxic and pro-mutagenic fractions

Complex toxicant mixtures present in estuarine sediments often render contaminant screening unfeasible and compromise determining causation. HepG2 cells were subjected to bioassays with sediment extracts obtained with a series of progressively polar solvents plus a crude extract. The sediments were collected from an impacted area of an estuary otherwise regarded as pristine, whose stressors result mostly from aquaculture effluents and hydrodynamic shifts that enhance particle deposition. Compared to a reference scenario, the most polar extracts yielded highest cytotoxicity while higher genotoxicity (including oxidative damage) was elicited by non-polar solvents. While the former caused effects similar to those expected from biocides, the latter triggered effects compatible with known pro-mutagens like PAHs, even though the overall levels of toxicants were considered of low risk. The results indicate that the approach may constitute an effective line-of-evidence to infer on the predominant set of hazardous contaminants present in complex environmental mixtures.

Sources, trends and ecotoxicological risks of PAH pollution in surface sediments from the northern Adriatic Sea (Croatia)

In this study, the levels, sources and historical trends (2007-2012) of PAH pollution in surface sediments in the northern Adriatic Sea (Croatia) have been assessed. In addition, ecotoxicological risks have been estimated by evaluating the PAH dataset against Sediment Quality Guidelines (SQGs). The results indicate that PAH in surface sediments are of pyrolitic origin with no clear positive or negative trend in PAH concentration over the investigated period. Evaluations against SQG and mSQGq indicate that surface sediments at all sampling sites have a low to medium ecotoxicological risk. In order to improve trend analysis and characterization of PAH pollution in surface sediments in this region an increase in spatial resolution of sampling points is recommended.

Hazard assessment of sediments from a wetland system for treatment of landfill leachate using bioassays

Four bioassays were used in this study for the hazard assessment of sediments from sediment traps and several ponds in a treatment wetland for landfill leachate at Atleverket, Sweden. In the 6-day solid phase microbiotest with the sediment-dwelling crustacean Heterocypris incongruens both acute and chronic effects were observed with a gradual decrease and loss of toxicity with treatment in the wetland system. Some samples showed a low toxicity in porewater and only one sample was weakly toxic in the whole sediment test when assessed with Aliivibrio fischeri (Vibro fischeri). No genotoxicity was detected in the umu test. The toxicity response in the H4IIE- luc test evaluating the presence of dioxin-like compounds was considerably higher in the samples from the sediment traps. The hazard of the sediment therefore appears to be highest in the sediment traps and pond 1 with the methods employed. The result indicates that the wetland system has a design supporting the concentration and sequestration of toxic substances in the first part of the wetland. Based upon the results we suggest that hazard assessment of sediments from other treatment wetlands for landfill leachate should be conducted.

Mutagenicity, genotoxicity, and estrogenic activity of river porewaters

We investigated mutagenicity, genotoxicity, and estrogenic activity in the porewaters of two river basins in southern Italy that had different features. Three samples from each site were collected in different seasons from 7 sites for a total of 21 samples. Mutagenicity was measured with the Ames test with and without metabolic activation (S9) using Salmonella typhimurium TA98 and TA100 strains. Genotoxicity was measured with two tests: one involved a chromophore that detected DNA damage in Escherichia coli PQ37 (SOS chromotest), and the other measured micronuclei formation in the root cells of Vicia faba. Estrogenic activity was measured with a yeast-based estrogen receptor assay and an MCF-7 cell-based, estrogen-sensitive proliferation assay. We also applied chemical analyses to detect alkylphenols, pesticides, natural and synthetic hormones, and heavy metals. The porewaters of both river sediments showed mutagenic/genotoxic activity on V. faba test and Ames test, the latter both with and without S9 liver fraction. The SOS chromotest without metabolic activation was not sufficiently sensitive to detect genotoxicity of the porewaters, but the SOS DNA repair system in E. coli PQ37 was activated in the presence of S9 mix. Good correlations were found between mutagenicity/genotoxicity and the concentration of cadmium and between estrogenic activity and the presence of copper. This study assessed the chemical concentrations of some bioavailable pollutants in porewater and detected the overall effects of multiple pollutants that contributed to mutagenicity, genotoxicity, and estrogenic activity of these two basin porewaters, thus increasing our understanding of the environmental consequences of polluted aquatic ecosystems.

Solution by dilution?--A review on the pollution status of the Yangtze River

The Yangtze River has been a source of life and prosperity for the Chinese people for centuries and is a habitat for a remarkable variety of aquatic species. But the river suffers from huge amounts of urban sewage, agricultural effluents, and industrial wastewater as well as ship navigation wastes along its course. With respect to the vast amounts of water and sediments discharged by the Yangtze River, it is reasonable to ask whether the pollution problem may be solved by simple dilution. This article reviews the past two decades of published research on organic pollutants in the Yangtze River and several adjacent water bodies connected to the main stream, according to a holistic approach. Organic pollutant levels and potential effects of water and sediments on wildlife and humans, measured in vitro, in vivo, and in situ, were critically reviewed. The contamination with organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans, polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and others, of water and sediment along the river was described. Especially Wuhan section and the Yangtze Estuary exhibited stronger pollution than other sections. Bioassays, displaying predominantly the endpoints mutagenicity and endocrine disruption, applied at sediments, drinking water, and surface water indicated a potential health risk in several areas. Aquatic organisms exhibited detectable concentrations of toxic compounds like PCBs, OCPs, PBDEs, and PFCs. Genotoxic effects could also be assessed in situ in fish. To summarize, it can be stated that dilution reduces the ecotoxicological risk in the Yangtze River, but does not eliminate it. Keeping in mind an approximately 14 times greater water discharge compared to the major European river Rhine, the absolute pollution mass transfer of the Yangtze River is of severe concern for the environmental quality of its estuary and the East China Sea. Based on the review, further research needs have been identified.

Uptake and retention of metallic nanoparticles in the Mediterranean mussel (Mytilus galloprovincialis)

We measured the uptake, distribution and elimination of two types of metallic nanoparticles (MetNPs) by the aquatic mussel Mytilus galloprovincialis in static seawater column exposures. Test MetNPs included polyethylene glycol (PEG) functionalized Fe3O4 nanoparticles (PEG-FeOxNP) and PEG-functionalized cadmium-selenide quantum dots (PEG-Qdot). Exposure water was sampled at various times to assess MetNP clearance, and mussels were serially euthanized to assess uptake of MetNPs into the hemolymph, digestive gland, and remaining carcass. Results indicated that >90% of both types of MetNPs were taken up by mussels within 8h of initial exposure. Nearly the entire retained dose of FeOxNPs and PEG-Qdots was deposited in the digestive gland. Our results provide important insights on the uptake and elimination kinetics of MetNPs in filter-feeding marine bivalves, and will be useful for subsequent development of toxicokinetic models to predict the kinetics of these processes.

Reproductive and genotoxic effects in zebrafish after chronic exposure to methyl methanesulfonate in a multigeneration study

There is still controversy whether adverse effects by genotoxic anthropogenic pollutants are linked to the decline of fish populations. Further investigations into the relationship between genotoxic stress and detrimental effects on development and reproduction in fish are required. For this end, zebrafish (F0 generation) were exposed in vivo to the alkylating model genotoxin methyl methanesulfonate (MMS) from fertilization to the age of 1 year. F0 fish were mated over 6 months to check for reproductive capacities. F1 fish grew up without exposure in order to allow for regeneration. Mortality of F0 fish depended on MMS concentrations. In MMS-exposed F0 fish, times of first spawning were delayed and fertility was reduced. Using the alkaline comet assay and the micronucleus test, significant genotoxic effects were found in the livers, gills and gonads of either sex in the F0 generation. No detrimental effects on growth were found. In F1 fish with parental exposure, teratogenic effects were increased, and larval survival was reduced. However, fertility capacities of the non-exposed F1 generation had recovered. Development and survival rates further recovered in the F2 generation. Anthropogenic genotoxicants may thus play a considerable role in the decline of wild fish populations.

Do UK coastal and estuarine water samples pose a phototoxic threat?

Many studies have investigated phototoxicity under controlled laboratory conditions, however, few have actually demonstrated it occurring in environmental samples. Here we report on the potential for UK marine coastal waters to demonstrate phototoxicity when tested using the oyster embryo (Crassostrea gigas) bioassay in the presence UV light. Subsurface water, sea surface microlayer samples and subsurface water samples that had been extracted through solid phase extraction (SPE) columns were analysed. Results demonstrated that the majority of samples failed to display any phototoxic potential. However, those collected from Belfast Lough did display an increase in toxicity when bioassays were performed in the presence of UV light when compared to identical samples assayed in the absence of UV light. Analysis of water samples at this location identified known phototoxic PAHs, pyrene and fluoranthene. These findings suggest the need to consider the potential UV light has when determining the toxicity of environmental samples.

Global and local chemical reactivities of mutagen X and simple derivatives

Registered by the World Health Organization (WHO), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) is one of the strongest bacterial mutagens ever tested, as highlighted by the Ames Salmonella typhimurium TA100 assay. We provide new insights concerning this mutagenic activity on the basis of global and local theoretically defined electrophilicity indices. Our results further support the idea that mutagenicity of MX and its analogues is related more closely to one-electron transfer processes from the electron-rich biological environment than to adduct formation processes. We also stress that, although the Z-open tautomers are intrinsically more electrophilic than furanone ring analogues, the observed mutagenic activity is significantly correlated only to the electrophilicity response of the ring forms. In that context, we also emphasize that it is electrophilicity at the C α in the α-β unsaturated carbonyl moiety that exhibits a strong correlation with the observed mutagenic activity.

Evaluation of removal efficiency for acute toxicity and genotoxicity on zebrafish in anoxic-oxic process from selected municipal wastewater treatment plants

The anoxic-oxic (A/O) process has been extensively applied for simultaneous removal of organic contaminants and nitrogen in wastewater treatment. However, very little is known about its ability to remove toxic materials. Municipal wastewater contains various kinds of pollutants, some of which have recalcitrant genotoxicity and may cause potential threat to environment, and even can lead to extinction of many species. In this study, we have selected three municipal wastewater treatment plants (WWTPs) employing anoxic-oxic (A/O) process to evaluate their ability to remove acute toxicity and genotoxicity of wastewater. Mortality rate of zebrafish (Danio rerio) was used to evaluate acute toxicity, while micronucleus (MN) and comet assays were used to detect genotoxicity. Results showed that in this process the acute toxicity was completely removed as the treatment proceeded along with decrease in chemical oxygen demand (COD) (<50 mgL(-1)) in the effluent. However, in these treatment processes the genotoxicity was not significantly reduced, but an increase in genotoxicity was observed. Both MN and comet assays showed similar results. The eliminated effluent may pose genotoxic threaten although its COD level has met the Chinese Sewage Discharge Standard. This study suggests that further treatment of the wastewater is required after the A/O process to remove the genotoxicity and minimize the ecotoxicological risk.

Bioaccumulation-depuration kinetics and effects of phenanthrene on Mediterranean mussel (Mytilus galloprovincialis)

In this study, Mediterranean mussel species, Mytilus galloprovincialis, were exposed to phenanthrene (PHE) due to its ubiquitousness and bioavailability in the aquatic environment. Kinetic parameters of the PHE bioaccumulation and depuration were calculated for an 11-day uptake and subsequent 11-day depuration periods. Those values of kinetic rate constants for uptake and depuration of PHE were calculated as varying between 93-177 and 0.18-0.25, respectively. Negative correlation was observed between the PHE concentrations and kinetic rate constants. Bioaccumulation Factors (BAFs) for the mussels exposed to different PHE concentrations were calculated from both kinetic rate constants and from the experimental data and found between 509-701 and 441-658, respectively. Experimental quantitative structure activity relationship (QSAR) values for PHE were found comparable to the calculated QSARs reported in literature. Two sub-lethal biomarker methods (filtration rate and lysosomal stability) were applied to observe the responses of the mussels throughout the experimental period. Results of both biomarkers show that PHE negatively affects mussels during the uptake of PHE, and mussels were able to recover physiologically at the end of depuration period according to the filtration rate results.

The comet assay in marine animals

Comet assay is a quick and versatile technique for assessing DNA damage in individual cells. It allows the detection of DNA single- and double-strand breaks, as well as the presence of alkali-labile sites and cross-links. Here we describe the protocols for the single-cell gel electrophoresis (Comet) assay in its alkaline (pH > 13), mild alkaline (pH = 12.1), and neutral (pH = 8) versions, when applied in marine animals.

Embryotoxic and genotoxic effects of heavy metals and pesticides on early life stages of Pacific oyster (Crassostrea gigas)

This study evaluated embryotoxicity and genotoxicity of two dissolved metals copper and cadmium (Cu and Cd) and two pesticides (metolachlor and irgarol) occurring in Arcachon Bay (SW France) in Pacific oyster (Crassostrea gigas) larvae and investigated the relationship between those two endpoints. Embryotoxicity was measured by calculating the percentage of abnormal D-shaped larvae and genotoxicity was evaluated with DNA strand breaks using the comet assay. After 24h exposure, significant increases of the percentage of abnormal D-larvae and the DNA strand breaks were observed from 0.1 μg L⁻¹ for Cu, 10 μg L⁻¹ for Cd and 0.01 μg L⁻¹ for both irgarol and metolachlor in comparison with the controls. A strong positive relationship between embryotoxicity and genotoxicity was recorded for Cu, Cd and metolachlor. The current study suggests that copper, irgarol and metolachlor can induce larval abnormalities and DNA damage in a population of exposed oysters at environmentally relevant concentrations.

Genotoxicity of the sediments collected from Pearl River in China and their polycyclic aromatic hydrocarbons (PAHs) and heavy metals

The accelerated industrialization and urbanization in the last three decades around the Pearl River Delta within Guangdong Province in China have led to serious concerns about the impacts on the aquatic environment. In the present study, the genotoxicity of the sediments collected from the Pearl River was evaluated by micronucleus (MN) assay with Vicia faba root tip cells, and the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs, including Cr, Cu, As, Se, Cd, Hg, and Pb) in the sediments were determined respectively by GC-MS, inductively coupled plasma mass spectrometry, and inductively coupled plasma atomic emission spectrometry. The results showed that there were significant increases of MN frequencies observed in the sediment-exposed groups, compared with the negative group (P < 0.05, P < 0.01), indicating that the sediments clearly had genotoxicity to the V. faba root cells. The total concentrations of the priority PAHs (250-13,656 ng g(-1), dry weight) and HMs (As, 22,770-36,639 μg kg(-1); Cr, 39,333-133,343 μg kg(-1); Cu, 36,145-159,270 μg kg(-1); Pb, 51,210-166,642 μg kg(-1); Cd, 475.4-1,818.9 μg kg(-1); Hg, 59.9-460.8 μg kg(-1); and Se, 331.7-1,250.4 μg kg(-1), dry weight) were close to those obtained from other urbanized and industrialized areas, which have been considered moderately polluted. There was a clear positive correlation between MN potency and the molar concentrations of Hg and Pb in the sediments (Hg, r = 0.94; Pb, r = 0.91), suggesting that Hg and Pb were the most important factors that posed the sediments higher genotoxicity to V. faba root cells. Our results suggested that both biological and chemical approaches are necessary to be included in a battery of tests to assess the eco-environmental risks of sediments.

Genotoxicity of sediment extracts of the Berre lagoon (France)

To evaluate the genotoxic risk that contaminated sediment could constitute for benthic organisms, three contaminated (VA, VC and VN) and one uncontaminated (RN) sediment samples were collected in the Berre lagoon (France). Potentially bioavailable contaminants in sediments were obtained using sediment extraction with synthetic seawater adjusted to pH 4 or pH 6, simulating the range of pH prevailing in the digestive tract of benthic organisms. The genotoxic activities of these extracts were evaluated by three short-term bioassays: the Salmonella mutagenicity test using the Salmonella typhimurium strain TA102, the alkaline comet assay and the micronucleus assay on the Chinese Hamster Ovary cells CHO-K1. Results of the Salmonella mutagenicity assay detected a mutagenic response for RN extract at pH 6, and for VA extract at pH 4. Results of the comet and micronucleus assays detected low genotoxic/clastogenic activities for VA and VC extracts at pH 6 and higher activities for RN, VA and VC extracts at pH 4. To identify if metals (Al, Fe, Mn, As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were involved in these genotoxic activities, their concentrations were determined in the extracts, and their speciation was assessed by thermodynamic calculations. Results showed that extracts from sites VA, VC and VN generally presented the highest trace metal contents for both extractants, while the site RN presented lower trace metal contents but the highest Fe and Mn contents. Thermodynamic calculations indicated that Fe, Mn, As and in a lower extend Co, Ni and Zn were mainly present under free forms in extracts, and were consequently, more likely able to induce a genotoxic effect. Results globally showed no correspondence between free metal contents and genotoxic activities. They suggested that these positive results could be due to uncharacterized compounds, acting as direct genotoxic agents or enhancing the genotoxic properties of analyzed metals.

Ecotoxicological characterisation of sedimentation in the Kis-Balaton Water Protection System

The main function of the Kis-Balaton Water Protection System is to retain nutrients and total suspended solids, thus protecting the water quality of Lake Balaton. In this paper, the toxic nature of the sediment in the 2nd reservoir of the KBWPS has been characterised, using a battery of tests: Vibrio fischeri acute bioassay on whole sediment samples, and V. fischeri bioassay on pore water and elutriate samples. The latest version of the V. fischeri bioluminescence inhibition was applied, the Flash assay which uses a kinetic mode and is able to detect the toxicity of solid, turbid/coloured samples. Whole sediment toxicity showed a clear spatial distribution of toxicity, in parallel with elutriate toxicity. However, no pore water toxicity was detected, leading to the conclusion that contaminants are not water soluble.

Mutagenicity assessment of contaminated soil in the vicinity of industrial area

In the industrial area of Chinhat, Lucknow (India) wastewater coming from pesticide manufacturing and other industries is used to irrigate the agricultural crops. This practice has been polluting the soil and pollutants might reach the food chain. Gas chromatographic analysis revealed the presence of certain organochlorine pesticides in soil samples. Samples were extracted using different solvents, i.e., hexane, acetonitrile, methanol, chloroform, and acetone (all were HPLC-grade, SRL, India). Soil extracts were assayed for mutagenicity using Ames Salmonella/mammalian microsome test. Mutagenicity was observed in the test samples and TA98 was the most responsive strain for all the soil extracts (irrigated with wastewater) in terms of mutagenic index in the presence (+S9) and absence (-S9) of metabolic activation. In terms of slope (m) of linear dose-response curve for the most responsive strain TA98 exhibited highest sensitivity against the soil extracts in the presence and absence of S9 fraction. Hexane-extracted soil sample (wastewater) exhibited maximum mutagenicity in terms of net revertants per gram of soil in the presence and absence of S9 mix as compared to the other soil extracts. Groundwater-irrigated soil extracts displayed low level of mutagenicity as compared to wastewater-irrigated soil. The soil is accumulating a large number of pollutants due to wastewater irrigation and this practice of accumulation has an adverse impact on soil health.

Endocrine disrupting, mutagenic, and teratogenic effects of upper Danube River sediments using effect-directed analysis

Effect-directed analysis (EDA) can be useful in identifying and evaluating potential toxic chemicals in matrixes. Previous investigations of extracts of sediments from the upper Danube River in Germany revealed acute nonspecific and mechanism-specific toxicity as determined by several bioassays. In the present study, EDA was used to further characterize these sediments and identify groups of potentially toxic chemicals. Four extracts of sediments were subjected to a novel fractionation scheme coupled with identification of chemicals to characterize their ability to disrupt steroidogenesis or cause mutagenic and/or teratogenic effects. All four whole extracts of sediment caused significant alteration of steroidogenesis and were mutagenic as well as teratogenic. The whole extracts of sediments were separated into 18 fractions and these fractions were then subjected to the same bioassays as the whole extracts. Fractions 7 to 15 of all four extracts were consistently more potent in both the Ames fluctuation and H295R assays. Much of this toxicity could be attributed to polycyclic aromatic hydrocarbons, sterols, and in fraction 7-naphthoic acids. Because the fraction containing polychlorinated biphenyls, polychlorodibenzodioxin/furan, dichlorodiphenyltrichloroethane, and several organophosphates did not cause any observable effects on hormone production or a mutagenic response, or were not detected in any of the samples, these compounds could be eliminated as causative agents for the observed effects. These results demonstrate the value of using EDA, which uses multiple bioassays and new fractionation techniques to assess toxicity. Furthermore, to our knowledge this is the first study using the recently developed H295R assay within EDA strategies.

Gene-TEQ--a standardized comparative assessment of effects in the comet assay using genotoxicity equivalents

Existing methods for the comparison of genotoxic effects in the comet assay bear considerable disadvantages such as the problem to link information about concentration dependence and severity of effects. Moreover, given the lack of standardized protocols and the use of various standards, it may be extremely difficult to compare different studies. In order to provide a method for standardized comparative assessment of genotoxic effects, the concept of genotoxicity equivalents (Gene-TEQ) was developed. As potential reference compounds for genotoxic effects, three directly acting (N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), methyl-methanesulfonate, and N-methyl-N-nitrosourea) and three indirectly acting (cyclophosphamide, dimethylnitrosamine, and 4-nitroquinoline-oxide) genotoxic substances were compared with respect to their cytotoxic (neutral red) and genotoxic (comet assay) concentration-response profiles in the permanent fish cell line RTL-W1. For further comparison, two sediment extracts from the upper Danube River were investigated as environmental samples. Based on the results of cytotoxicity and genotoxicity testing, MNNG was selected as the reference compound. At several exposure levels and durations, genotoxic effects of both the other pure substances and the environmental samples were calculated as percentages of the maximum MNNG effect and related to the absolute MNNG effect (EC values). Thus, genotoxicity equivalent factors (Gene-TEQs) relative to MNNG could be calculated. Gene-TEQs can easily be applied to pure substances, mixtures and field samples to provide information about their toxicity relative to the reference compound. Furthermore, the Gene-TEQ concept allows a direct comparison of environmental samples from different laboratories.

International round-robin study on the Ames fluctuation test

An international round-robin study on the Ames fluctuation test [ISO 11350, 2012], a microplate version of the classic plate-incorporation method for the detection of mutagenicity in water, wastewater and chemicals was performed by 18 laboratories from seven countries. Such a round-robin study is a precondition for both the finalization of the ISO standardization process and a possible regulatory implementation in water legislation. The laboratories tested four water samples (spiked/nonspiked) and two chemical mixtures with and without supplementation of a S9-mix. Validity criteria (acceptable spontaneous and positive control-induced mutation counts) were fulfilled by 92-100%, depending on the test conditions. A two-step method for statistical evaluation of the test results is proposed and assessed in terms of specificity and sensitivity. The data were first subjected to powerful analysis of variance (ANOVA) after an arcsine-square-root transformation to detect significant differences between the test samples and the negative control (NC). A threshold (TH) value based on a pooled NC was then calculated to exclude false positive test results. Statistically, positive effects observed by the William's test were considered negative, if the mean of all replicates of a sample did not exceed the calculated TH. By making use of this approach, the overall test sensitivity was 100%, and the test specificity ranged from 80 to 100%.

Assessment of the genotoxicity of quinolone and fluoroquinolones contaminated soil with the Vicia faba micronucleus test

The genotoxicity of quinolone and fluroquinolones was assessed using the micronucleus (MN) test on Vicia faba roots by direct contact exposure to a solid matrix. Plants were exposed to quinolones (nalidixic acid) and fluoroquinolones (ciprofloxacin and enrofloxacin) alone or mixed with artificially contaminated soils. Four different concentrations of each of these antibiotics were tested (0.01, 0.1, 1 and 10 mg/Kg) for nalidixic acid and (0.005, 0.05, 0.5 and 5 mg/Kg) for ciprofloxacin and enrofloxacin. These antibiotics were also used in mixture. Exposure of Vicia faba plants to each antibiotic at the highest two concentrations showed significant MN induction. The lowest two concentrations had no significant genotoxic effect. The mixture of the three compounds induced a significant MN induction whatever the mixture tested, from 0.02 to 20 mg/Kg. The results indicated that a similar genotoxic effect was obtained with the mixture at 0.2 mg/Kg in comparison with each molecule alone at 5-10 mg/Kg. Data revealed a clear synergism of these molecules on Vicia faba genotoxicity.

Can the integration of multiple biomarkers and sediment geochemistry aid solving the complexity of sediment risk assessment? A case study with a benthic fish

Surveying toxicity of complex geochemical media as aquatic sediments often yields results that are either difficult to interpret or even contradictory to acknowledged theory. Multi-level biomarkers were investigated in a benthic fish exposed to estuarine sediments through laboratory and in situ bioassays, to evaluate their employment either in ecological risk assessment or in more mechanistic approaches to assess sediment-bound toxicity. Biomarkers reflecting lesions (such as genotoxicity or histopathology), regardless of their low or absent specificity to contaminants, are efficient in segregating exposure to contaminated from uncontaminated sediments even when classical biomarkers like CYP1A and metallothionein induction are inconclusive. Conversely, proteomics and gene transcription analyses provided information on the mechanics of toxicity and aided explaining response variation as a function of metabolic imbalance and impairment of defences against insult. In situ bioassays, although less expedite and more affected by confounding factors, produced data better correlated to overall sediment contamination.

Runoff of genotoxic compounds in river basin sediment under the influence of contaminated soils

Contaminated sites must be analyzed as a source of hazardous compounds in the ecosystem. Contaminant mobility in the environment may affect sources of surface and groundwater, elevating potential risks. This study looked at the genotoxic potential of samples from a contaminated site on the banks of the Taquari River, RS, Brazil, where potential environmental problems had been identified (pentachlorophenol, creosote and hydrosalt CCA). Samplers were installed at the site to investigate the drainage material (water and particulate soil matter) collected after significant rainfall events. Organic extracts of this drained material, sediment river samples of the Taquari River (interstitial water and sediment organic extracts) were evaluated by the Salmonella/microsome assay to detect mutagenicity and by Allium cepa bioassays (interstitial water and whole sediment samples) to detect chromosomal alterations. Positive mutagenicity results in the Salmonella/microsome assay of the material exported from the area indicate that contaminant mixtures may have drained into the Taquari River. This was confirmed by the similarity of mutagenic responses (frameshift indirect mutagens) of organic extracts from soil and river sediment exported from the main area under the influence of the contaminated site. The Allium cepa test showed significant results of cytotoxicity, mutagenic index and chromosome aberration in the area under the same influence. However, it also showed the same similarity in positive results at an upstream site, which probably meant different contaminants. Chemical compounds such as PAHs, PCF and chromium, copper and arsenic were present in the runoff of pollutants characteristically found in the area. The strategy employed using the Salmonella/microsome assay to evaluate effects of complex contaminant mixtures, together with information about the main groups of compounds present, allowed the detection of pollutant dispersion routes from the contaminated site to the Taquari River sediment.

Cytotoxicity and genotoxicity evaluation of urban surface waters using freshwater luminescent bacteria Vibrio-qinghaiensis sp.-Q67 and Vicia faba root tip

The freshwater luminescent bacteria Vibrio-qinghaiensis sp.-Q67 test and the Vicia faba root tip test associated with solid-phase extraction were applied for cytotoxicity and genotoxicity assessment of organic substances in three rivers, two lakes and effluent flows from two wastewater treatment plants (WWTPs) in Xi'an, China. Although the most seriously polluted river with high chemical oxygen demand (COD) and total organic carbon (TOC) showed high cytotoxicity (expressed as TII50, the toxicity impact index) and genotoxicity (expressed as RMCN, the relative frequency of micronucleus), no correlative relation was found between the ecotoxicity and organic content of the water samples. However, there was a linear correlative relation between TII50 and RMCN for most water samples except that from the Zaohe River, which receives discharge from WWTP and untreated industrial wastewaters. The ecotoxicity of the organic toxicants in the Chanhe River and Zaohe River indicated that cytotoxic and genotoxic effects were related to the pollutant source. The TII50 and RMCN were also found to correlate roughly to the dissolved oxygen concentration of the water. Sufficient dissolved oxygen in surface water is thus proved to be an indicator of a healthy water environmental condition.

Sediment-contact fish embryo toxicity assay with Danio rerio to assess particle-bound pollutants in the Tietê River Basin (São Paulo, Brazil)

The Tietê River and its tributary Pinheiros River receive a highly complex organic and inorganic pollutants load from sanitary sewage and industrial sources, as well as agricultural and agroindustrial activities. The aim of the present study was to evaluate the embryotoxic and teratogenic effects of sediments from selected locations in the Tietê River Basin by means of the sediment contact embryo toxicity assay with Danio rerio, in order to provide a comprehensive and realistic insight into the bioavailable hazard potential of these sediment samples. Lethal and sub-lethal effects were recorded, and high embryo toxicity could be found in the samples not only in the vicinity of the megacity São Paulo (Billings reservoir and Pinheiros River samples), but also downstream (in the reservoirs Barra Bonita, Promissão and Três Irmãos). Results confirm that most toxicity is due to the discharges of the metropolitan area of São Paulo. However, they also indicate additional sources of pollutants along the river course, probably from industrial, agricultural and agroindustrial residues, which contribute to the degradation of each area. The sediment contact fish embryo test showed to be powerful tool to detect embryo toxicity in sediments, not only by being a sensitive method, but also for taking into account bioavailability. This test provides an ecological highly realistic and relevant exposure scenario, and should therefore be added in ecotoxicological sediment quality assessments.

Polycyclic aromatic hydrocarbons and hydroxylated metabolites in the muscle tissue of Eurasian perch (Perca fluviatilis) through dietary exposure during a 56-day period

Eurasian perch (Perca fluviatilis) was exposed trophically to phenanthrene, pyrene and benzo[a]pyrene. Accumulation kinetics in the muscle tissue of parent PAHs and hydroxylated metabolites were established for 56 days at 3 levels of exposure (0, 100 and 500 μg/kg BW). Benzo[a]pyrene and 3-hydroxy-benzo[a]pyrene were not detected in the muscles. During exposure, there was an increase in phenanthrene, pyrene and their hydroxylated metabolites in the muscle tissue. Low transfer to muscle tissue was observed at equilibrium for phenanthrene (4.4±0.6% and 2.7±0.8%) and pyrene (1.0±0.2% and 0.33±0.09%), depending on the concentrations in the spiked feed.

Association between mutation spectra and stable and unstable DNA adduct profiles in Salmonella for benzo[a]pyrene and dibenzo[a,l]pyrene

Benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP) are two polycyclic aromatic hydrocarbons (PAHs) that exhibit distinctly different mutagenicity and carcinogenicity profiles. Although some studies show that these PAHs produce unstable DNA adducts, conflicting data and arguments have been presented regarding the relative roles of these unstable adducts versus stable adducts, as well as oxidative damage, in the mutagenesis and tumor-mutation spectra of these PAHs. However, no study has determined the mutation spectra along with the stable and unstable DNA adducts in the same system with both PAHs. Thus, we determined the mutagenic potencies and mutation spectra of BP and DBP in strains TA98, TA100 and TA104 of Salmonella, and we also measured the levels of abasic sites (aldehydic-site assay) and characterized the stable DNA adducts ((32)P-postlabeling/HPLC) induced by these PAHs in TA104. Our results for the mutation spectra and site specificity of stable adducts were consistent with those from other systems, showing that DBP was more mutagenic than BP in TA98 and TA100. The mutation spectra of DBP and BP were significantly different in TA98 and TA104, with 24% of the mutations induced by BP in TA98 being complex frameshifts, whereas DBP produced hardly any of these mutations. In TA104, BP produced primarily GC to TA transversions, whereas DBP produced primarily AT to TA transversions. The majority (96%) of stable adducts induced by BP were at guanine, whereas the majority (80%) induced by DBP were at adenine. Although BP induced abasic sites, DBP did not. Most importantly, the proportion of mutations induced by DBP at adenine and guanine paralleled the proportion of stable DNA adducts induced by DBP at adenine and guanine; however, this was not the case for BP. Our results leave open a possible role for unstable DNA adducts in the mutational specificity of BP but not for DBP.

Biological effects of marine contaminated sediments on Sparus aurata juveniles

Chemical analysis of the compounds present in sediment, although informative, often is not indicative of the downstream biological effects that these contaminants exert on resident aquatic organisms. More direct molecular methods are needed to determine if marine life is affected by exposure to sediments. In this study, we used an aquatic multi-species microarray and q-PCR to investigate the effects on gene expression in juvenile sea bream (Sparus aurata) of two contaminated sediments defined as sediment 1 and 2, respectively, from marine areas in Northern Italy. Both sediments affected gene expression as evidenced by aquatic multi-species microarray analysis and q-PCR. Exposure of S. aurata juveniles to sediment 1 and sediment 2 altered expression of genes that are biomarkers for endocrine disruption. There were differences between the effects of sediment 1 and sediment 2 on gene expression in S. aurata juveniles indicating that the chemicals in the two sediments had different physiological targets. These results suggest that the classification of sediment solely on the basis of specific chemical profiles is inadequate, and not a true indicator of its potential to cause harmful effects. Our data also indicate that integration of physiochemical analysis and bioassays for monitoring the downstream harmful effects on aquatic organisms are required to gain a complete understanding of the effects of sediment on aquatic life.

Comparison of two extraction procedures for the assessment of sediment genotoxicity: implication of polar organic compounds

Four sediment samples (Vaïne Airport VA, Vaïne Center VC, Vaïne North VN and Reference North RN) were collected in the Berre lagoon (France). Sediments were analyzed for polycyclic aromatic hydrocarbons (PAHs) by use of pressurized fluid extraction with a mixture of hexane/dichloromethane followed by HPLC with fluorescence detection analysis. Organic pollutants were also extracted with two solvents for subsequent evaluation of their genotoxicity: a hexane/dichloromethane mixture intended to select non-polar compounds such as PAHs, and 2-propanol intended to select polar contaminants. Sediment extracts were assessed by the Salmonella/microsome mutagenicity test with Salmonella typhimurium TA98+S9 mix and YG1041±S9 mix. Extracts were also assessed for their DNA-damaging activity and their clastogenic/aneugenic properties by the comet assay and the micronucleus test with Chinese Hamster ovary (CHO) cells. The PAH concentrations were 611ngg(-1)dw, 1341ngg(-1) dw, 613ngg(-1)dw and 482ngg(-1)dw for VA, VC, VN and RN, respectively. Two genotoxic profiles were observed, depending on the extraction procedure. All the non-polar extracts were mutagenic for TA98+S9 mix, and VA, VC, VN sediment samples exerted a significant DNA-damaging and clastogenic activity in the presence of S9 mix. All the polar extracts appeared mutagenic for TA98+S9 mix and YG104±S9 mix, and VA, VC, VN were genotoxic and clastogenic both with and without S9 mix. These results indicate that the genotoxic and mutagenic activities mainly originated from PAHs in the non-polar extracts, while these activities came from other genotoxic contaminants, such as aromatic amines and nitroarenes, in the polar extracts. This study focused on the important role of uncharacterized polar contaminants such as nitro-PAHs or aromatic amines in the global mutagenicity of sediments. The necessity to use appropriate extraction solvents to accurately evaluate the genotoxic hazard of aquatic sediments is also highlighted.

Use of three bivalve species for biomonitoring a polluted estuarine environment

Estuaries are marine areas at great contamination risk due to their hydrodynamic features. PAH are wide and ubiquitous contaminants with a high presence in these marine environments. Chemical analysis of sediments can provide information, although it does not give a direct measure of the toxicological effect of such contaminants in the biota. Samples of Venerupis pullastra, Cerastoderma edule, and Mytilus galloprovincialis were collected from two locations in Corcubión estuary (Norhwest of Spain). The level of PAH in sediment and biota, and its possible origin were assessed. A moderate level of contamination was observed with a predominance of PAH of a pyrogenic origin. Genotoxic damage, measured as single-strand DNA breaks with the comet assay, was evaluated in gill tissue and in hemolymph. The values of DNA damage obtained showed a higher sensitivity of clams and cockles to the pollution load level. These differences among species make us suggest the use of some other species coupled with mussels as an optimal tool for biomonitoring estuarine environments.

Identification of mutagens in freshwater sediments by the Ames-fluctuation assay using nitroreductase and acetyltransferase overproducing test strains

Extracts of sediments from an area of concern in the Elbe river basins (Spittelwasser creek) were analyzed with the Ames-fluctuation test and in parallel with gas chromatography/mass spectrometry for compound identification. The standard test strains TA 98 and TA 100 showed mutagenicity mainly in medium-polar fractions of the sediment extracts. PAHs contribute to the overall mutagenic potential of the sample. Especially, cyclopenta[c,d]pyrene that was previously not defined as a priority hazardous substance has to be considered as well. The addition of metabolically competent test strains, which overexpress nitroreductase and acetyltransferase (e.g., YG1041 and YG1042) to the test battery, increased significantly the sensitivity of the Ames test for medium polar to polar genotoxins. The increased mutagenicity that was found in these bacterial strains indicates the presence of nitroarenes and/or aromatic amines. In fact, a number of heterocyclic and nitrogen-substituted aromatic compounds were identified in the sediments of the Spittelwasser creek of which methyl parathion, 1-naphthylamine, and N-phenyl-2-naphthylamine are mutagenic.

Isolation and characterization of a novel pyrene-degrading Bacillus vallismortis strain JY3A

The PAHs-degrading bacterium strain JY3A was newly isolated from the polluted soil in the Jinan Oil Refinery Factory, Shandong Province of China. The isolate was identified as Bacillus vallismortis with respect to its 16S rDNA sequence, DNA-DNA relatedness and fatty acid profiles, as well as various physiological characteristics. The strain was Gram-positive, motile, endospore forming, aerobic, oxidase and catalase-positive. The cells were 0.8-1.0μm wide and 2.0-2.5μm long, single or in pairs and sometimes in chains. Bacillus vallismortis strain JY3A could utilize naphthalene, phenanthrene, anthracene, pyrene, fluorene, benzene, toluene, phenol, methanol, ethanol, Tween 80, cyclohexane or catechol as sole carbon source. The strain alone removed 90.5% of pyrene at an initial concentration of 150ppm in 15days in the presence of 0.5% (w/w) Tween 80. However, in co-culture with Phanerochaete chrysosporium, JY3A reduced the concentration of pyrene by nearly 55.4% after 7days of incubation.

Sublethal genotoxicity and cell alterations by organophosphorus pesticides in MCF-7 cells: implications for environmentally relevant concentrations

Organophosphorus pesticide (OPP) toxicity is believed to be mediated through inhibition of acetylcholinesterase (AChE). Given their widespread distribution in aquatic systems and their ability to undergo chemical transformation, their environmental impacts at sublethal concentrations in nontarget organisms have become an important question. We conducted a number of mammalian-cell genotoxic and gene expression assays and examined cellular biochemical changes that followed low-dose exposure of MCF-7 cells to fenitrothion, diazinon, and the aqueous degradate of diazinon, 2-isopropyl-6-methyl-4-pyrimidinol (IMP). After exposure to the OPPs at low concentrations (10(-12) M to 10(-8) M), greater than twofold elevations in micronucleus formation were noted in MCF-7 cell cultures that went on to exhibit greater than 75% clonogenic survival; these levels of chromosomal damage were comparable to those induced by 10(-6) M benzo[a]pyrene, a known genotoxic agent. At this low concentration range, a fenitrothion-induced twofold elevation in B-cell leukemia/lymphoma-2 (BCL-2) and cytochrome P450 isoenzyme (CYP1A1) gene expressions was observed. Principal component analysis-linear discriminant analysis (PCA-LDA) of derived infrared (IR) spectra of vehicle control (nonexposed) and OPP-exposed cells highlighted that both fenitrothion and diazinon induced marked biochemical alterations in the lipid, protein, and DNA/RNA absorbance regions. Our findings demonstrate that the two OPP parent chemicals and IMP degradate can mediate a number of toxic effects or cellular alterations at very low concentrations. These are independent of just selective inhibition of AChE, with potential consequences for nontarget organisms exposed at environmentally relevant concentrations. Further assays on relevant aquatic organism cell lines are now recommended to understand the mechanistic low-dose toxicity of these chemicals present in aquatic systems.

Nontarget analysis of polar contaminants in freshwater sediments influenced by pharmaceutical industry using ultra-high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometry

A comprehensive analytical procedure for a reliable identification of nontarget polar contaminants in aquatic sediments was developed, based on the application of ultra-high-pressure liquid chromatography (UHPLC) coupled to hybrid quadrupole time-of-flight mass spectrometry (QTOFMS). The procedure was applied for the analysis of freshwater sediment that was highly impacted by wastewater discharges from the pharmaceutical industry. A number of different contaminants were successfully identified owing to the high mass accuracy of the QTOFMS system, used in combination with high chromatographic resolution of UHPLC. The major compounds, identified in investigated sediment, included a series of polypropylene glycols (n=3-16), alkylbenzene sulfonate and benzalkonium surfactants as well as a number of various pharmaceuticals (chlorthalidone, warfarin, terbinafine, torsemide, zolpidem and macrolide antibiotics). The particular advantage of the applied technique is its capability to detect less known pharmaceutical intermediates and/or transformation products, which have not been previously reported in freshwater sediments.