Chemodiversity in freshwater health.

Dissolved organic matter may offer a way to track and restore the health of fresh waters.

Assessment of the water quality and toxicity effects on zebrafish (Danio rerio) of a stream near a phosphorus chemical plant in Guizhou Province, southwestern China.

To reveal the influence of the phosphorus chemical industry (PCI) on regional water environmental quality and safety, the water quality and ecotoxicological effects of a stream near a phosphorus chemical plant (PCP) in Guizhou Province, southwestern China, were investigated based on water samples collected from the stream. The results showed that the average concentrations of NH3-N, TN, P, F-, Hg, Mn, and Ni were 3.14 mg/L, 30.09 mg/L, 3.34 mg/L, 1.18 mg/L, 1.06 µg/L, 45.82 µg/L, and 11.30 µg/L, respectively. The overall water quality of the stream was in the heavily polluted category, and NH3-N, TN, P, F-, and Hg were the main pollution factors. The degree of pollution was in the order of rainy period > transitional period > dry period, and the most polluted sample site was 1100 m from the PCP. After 28 days of exposure to stream water, there was no significant change in the growth parameters of zebrafish. The gills of zebrafish showed a small amount of epithelial cell detachment and a small amount of inflammatory cell infiltration, and the liver tissue displayed a large amount of hepatocyte degeneration with loose and lightly stained cytoplasm. Compared with the control group, the %DNA in tail, tail length, tail moment, and olive tail moment were significantly increased (p < 0.05), indicating that the water sample caused DNA damage in the peripheral blood erythrocytes of zebrafish. The stream water in the PCI area was found to be polluted and exhibited significant toxicity to zebrafish, which could pose a threat to regional ecological security.

Assessment of toxicity potential of neglected Mithi River water from Mumbai megacity, India, in zebrafish using embryotoxicity, teratogenicity, and genotoxicity biomarkers.

The Mithi River begins at Vihar Lake and flows through the industrial hub of the city of Mumbai, India, and merges with the Arabian Sea at Mahim Creek. The current study was carried out to assess the ecotoxicological effects of the Mithi River surface water in zebrafish (Danio rerio) embryos. Water samples were collected from ten sampling sites (S1 to S10) located along the course of the Mithi River. The toxicity of water samples was assessed using a zebrafish embryo toxicity test (ZFET). Water samples were diluted from all sites at 1:0, 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, and 1:128 times. The lowest and highest LDil 20 values for 96 h were estimated as 9.16 and 74.18 respectively for the S2 and S5 sites. The results of embryotoxicity and teratogenicity assays indicated a significant difference (p < 0.0001) between embryos exposed to control and sampling sites (except S1) for various endpoints such as mortality, egg coagulation, pericardial edema, yolk sac edema, tail bend, and skeletal deformities. The histopathological analysis revealed various lesions, ascertaining the toxic effects of water samples. The comet assay revealed significantly higher DNA damage (except S1) in embryos exposed to sites S5 and S6 with OTM values of 4.46 and 2.48 respectively. The results indicated that the Mithi River is polluted with maximum pollution load at the middle stretches. The study further indicated that the pollutants in the Mithi River (except S1) could potentially be hazardous to the aquatic organisms; therefore, continuous biomonitoring of the river is needed for its revival.

Transmission of Microcystins in Natural Systems and Resource Processes: A Review of Potential Risks to Humans Health.

The rapid rise of microcystins (MCs) poses a serious threat to global freshwater ecosystems and has become an important issue of global public health. MCs have considerable stability and are the most widely distributed hepatotoxins. It cannot only accumulate in aquatic organisms and transfer to higher nutrients and levels, but also be degraded or transferred during the resource utilization of cyanobacteria. No matter which enrichment method, it will lead to the risk of human exposure. This review summarizes the research status of MCs, and introduces the distribution of MCs in different components of aquatic ecosystems. The distribution of MCs in different aquatic organisms was summarized, and the potential risks of MCs in the environment to human safety were summarized. MCs have polluted all areas of aquatic ecosystems. In order to protect human life from the health threats caused by MCs, this paper also proposes some future research directions to promote MCs control and reduce human exposure to MCs.

Toxicological effects of tire rubber-derived 6PPD-quinone, a species-specific toxicant, and dithiobisbenzanilide (DTBBA) in the marine rotifer Brachionus koreanus.

The ingredients of tire-rubber products include a complex range of chemicals additives, most of which are leached into surrounding water as unmeasured toxicants with unexplored ecotoxicological impacts. The present study summarizes the reported species-specific acute toxicity of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), the ozonation product of anti-oxidant 6PPD used in tire rubber. Also, chronic toxicity and oxidative response of 6PPD-Q and another tire-rubber derivative, 2',2'''-dithiobisbenzanilide (DTBBA), in rotifer Brachionus koreanus were investigated. Although 6PPD-Q has been reported to be highly toxic to several species of salmonids, only moderate chronic toxicity was observed in B. koreanus. In contrast, DTBBA significantly retarded the population growth and fecundity. The varying toxicity of 6PPD-Q and DTBBA was linked to the level of reactive oxygen species in which DTBBA exposure caused a significant concentration-dependent increase. Our results imply unanticipated risks to aquatic species posed by chemical additives in tire-rubber which may be considered emerging contaminants of toxicological concern.

Solvent exposure strongly linked to Parkinson's.

Military recruits exposed to TCE decades ago have increased risk of the brain disease.

Oxidative stress responses as a marker of toxicity in mice exposed to polluted groundwater from an automobile junk market in South-Western Nigeria.

The global trade in used vehicles and their components generates huge financial benefits but leads to detrimental environmental consequences including groundwater pollution and potential adverse health effects mediated by free-radical processes such as lipid peroxidation. We investigated oxidative stress responses in thirty-six, female mice orally exposed (via drinking) to graded concentrations (0%, 50%, and 100%) of groundwater from a well located within a major automobile junk market in SW-Nigeria containing extremely high levels of arsenic (0.332 ± 0.089 mg/l) and seventeen PAHs, which serves as domestic water supply. Blood samples from the mice were assayed for selected biochemical parameters at intervals of 7, 14, and 28 days. A significant dose- and duration-dependent increase in malondialdehyde (MDA) and Myeloperoxidase (MPO) confirmed oxidative stress onset due to exposure to the polluted well-water, while a significant decline in nitric oxide (NO-) levels may suggest impaired endothelial smooth-muscle relaxation which may lead to the development of metabolic diseases over time. Superoxide dismutase (SOD) and reduced glutathione (GSH) showed a contrasting trend with Glutathione peroxidase (GPx), while Glutathione-S-Transferase (GST) declined significantly by the 28th day. Two clusters were identified by principal component analysis-one involving MDA, SOD, and GSH suggesting that antioxidant responses driven mainly by SOD and GSH proved insufficient in scavenging the free radicals generated by lipid peroxidation. NO- and total protein clustered together possibly due to the significant declines in both over the study period. Histological examination of liver tissue of exposed mice corroborated the above findings and highlights the need for urgent remedial action.

Impact of sublethal phenol in freshwater fish Labeo rohita on biochemical and haematological parameters.

Phenol, an aromatic chemical commonly found in domestic and industrial effluents, upon its introduction into aquatic ecosystems adversely affects the indigenous biota, the invertebrates and the vertebrates. With the increased demand for agrochemicals, a large amount of phenol is released directly into the environment as a byproduct. Phenol and its derivatives tend to persist in the environment for longer periods which in turn poses a threat to both humans and the aquatic ecosystem. In our current study, the response of Labeo rohita to sublethal concentrations of phenol was observed and the results did show a regular decrease in biochemical constituents of the targeted organs. Exposure of Labeo rohita to sublethal concentration of phenol (22.32 mg/L) for an epoch of 7, 21 and 28 days shows a decline in lipid, protein, carbohydrate content and phosphatase activity in target organs such as the gills, muscle, intestine, liver and kidney of the fish. The present study also aims to investigate the toxic effects of phenol with special reference to the haematological parameters of Labeo rohita. At the end of the exposure period, the blood of the fish was collected by cutting the caudal peduncle with a surgical scalpel. And it was observed that the red blood corpuscle count (RBC), white blood corpuscle (WBC), haemoglobin count (Hb), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) values showed a decline after exposure to phenol for 7 days, while white blood corpuscle (WBC) shows an increased count. At 21 days and 28 days, all the haematological parameters showed a significant decrease.

How Health Care Organizations Can Be Stewardship Leaders.

Mismanagement of hospital waste can release harmful, deleterious contaminants into soil, water, and air. Irresponsible or noncompliant handling of health care waste can have far-reaching environmental and public relations consequences. This article describes legal, safe, sustainable health care waste stream management as a challenge to health care leaders that can be met by implementing good stewardship practices.

Exploring the influence mechanism of dissolved organic matter on the bioavailability and thyroid hormone disrupting effect of zinc: A case study of effluents from galvanizing plants.

The effect of dissolved organic matter (DOM) on metal bioavailability and toxicity is a complex process. Effluents from galvanizing plants containing large amounts of DOM and Zn were selected to investigate the potential influence and mechanism of DOM on Zn bioavailability and its role in inducing thyroid hormone disrupting effects. Thyroid hormone disrupting effects were evaluated using a recombinant thyroid hormone receptor ß gene yeast assay. The results suggest that Zn could be the main metal contributor to the toxic effects. Then, Zn-binding characteristics with different fluorescent components of DOM were analyzed using three-dimensional excitation emission matrix fluorescence spectroscopy (3DEEM) and revealed that Zn was more susceptible to interactions with fulvic-like materials. Furthermore, DOM altered the cellular biouptake and compartmentalization processes of Zn by downregulating Zn transmembrane transport-related genes (ZRT1, ZRT2 and ZAP1) and upregulating detoxification-related genes (COT1 and ZRC1), thus altering thyroid toxicity. These results provide comprehensive insights into the influence and mechanism of DOM on bioavailability and thyroid toxicity of Zn and suggest that the influence is associated with complex physical, chemical and biological processes, indicating that more refined medium constraints along with subtle biological reactions should be considered when predicting the bioavailability and toxicity of Zn in environmental water samples.

Current Trends and New Challenges in Marine Phycotoxins.

Marine phycotoxins are a multiplicity of bioactive compounds which are produced by microalgae and bioaccumulate in the marine food web. Phycotoxins affect the ecosystem, pose a threat to human health, and have important economic effects on aquaculture and tourism worldwide. However, human health and food safety have been the primary concerns when considering the impacts of phycotoxins. Phycotoxins toxicity information, often used to set regulatory limits for these toxins in shellfish, lacks traceability of toxicity values highlighting the need for predefined toxicological criteria. Toxicity data together with adequate detection methods for monitoring procedures are crucial to protect human health. However, despite technological advances, there are still methodological uncertainties and high demand for universal phycotoxin detectors. This review focuses on these topics, including uncertainties of climate change, providing an overview of the current information as well as future perspectives.

Emerging Marine Biotoxins in European Waters: Potential Risks and Analytical Challenges.

Harmful algal blooms pose a challenge regarding food safety due to their erratic nature and forming circumstances which are yet to be disclosed. The best strategy to protect human consumers is through legislation and monitoring strategies. Global warming and anthropological intervention aided the migration and establishment of emerging toxin producers into Europe's temperate waters, creating a new threat to human public health. The lack of information, standards, and reference materials delay effective solutions, being a matter of urgent resolution. In this work, the recent findings of the presence of emerging azaspiracids, spirolildes, pinnatoxins, gymnodimines, palitoxins, ciguatoxins, brevetoxins, and tetrodotoxins on European Coasts are addressed. The information concerning emerging toxins such as new matrices, locations, and toxicity assays is paramount to set the risk assessment guidelines, regulatory levels, and analytical methodology that would protect the consumers.

Occurrence and stability of ptesculentoside, caudatoside and ptaquiloside in surface waters.

The illudane glycosides ptesculentoside (PTE), caudatoside (CAU) and ptaquiloside (PTA) are found in bracken ferns (Pteridium sp.). PTA is known to contaminate water bodies adjacent to bracken ferns and hence contribute to water toxicity. This study for the first time reports the presence of PTE and CAU in surface waters with concentrations up to 5.3 µg L-1 and outlines their stability under semi-natural conditions using water of two diverse lakes at their natural pH or pH adjusted to 6.5, with temperature controlled at 5 or 15 °C, and in the presence or absence of microbial activity. Under the same set of tested conditions the three illudane glycosides degraded at similar rates: with half-lives of approximately two days at pH 7.4 and 15 °C, and approximately 12 days at pH 5.2-6.5 and 5 °C. The water origin had significant influence on the degradation rates, but only due to its difference in pH. In most cases, the degradation rates of all the three illudane glycosides could be predicted using the existing first-order model for PTA hydrolysis. As PTE and CAU exhibit the same leaching pattern and stability as PTA, previous predictions of bracken environmental impact are likely underestimated, as PTE and CAU have not been monitored and included in the risk assessment.

Incubation media modify silver nanoparticle toxicity for whitefish (Coregonus lavaretus) and roach (Rutilus rutilus) embryos.

Toxicological studies were performed to examine silver nanoparticle (AgNP, size: 14.4 ± 2.5 nm) transformation within three different test media and consequent effects on embryos of whitefish (Coregonus lavaretus) and roach (Rutilus rutilus). The test media, namely ASTM very hard water, ISO standard dilution medium, and natural lake water differed predominantly in ionic strength. Total silver was determined using inductively coupled plasma mass spectrometry (ICP-MS), while AgNPs were characterized by transmission electron microscopy and single particle ICP-MS. Silver species distributions were estimated via thermodynamic speciation calculations. Data demonstrated that increased AgNP dissolution accompanied by decreasing ionic strength of the test medium did not occur as noted in other studies. Further, other physicochemical parameters including AgNP size and metallic species distribution did not markedly affect AgNP-induced toxicity. Irrespective of the test medium, C. lavaretus were more sensitive to AgNP exposure (median lethal concentration after 8 weeks: 0.51-0.73 mg/L) compared to R. rutilus, where adverse effects were only observed at 5 mg/L in natural lake water. In addition, AgNP-induced toxicity was lower in the two standard test media compared to natural lake water. Currently, there are no apparent studies assessing simultaneously the sensitivity of C. lavaretus and R. rutilus to AgNP exposure. Therefore, the aim of this study was to (1) investigate AgNP-induced toxicity in C. lavaretus and R. rutilus cohabiting in the same aquatic environment and (2) the role played by test media in the observed effects of AgNPs on these aquatic species.

Fipronil use and associated effects on hematological and biochemical parameters of blue land crab (Cardisoma guanhumi Latreille): Ecological implication.

Fipronil is used to control pests to improve farm yield, however, indiscriminate use of fipronil has been reported to endanger crabs leading to their extinction. Therefore, this study investigated the impact of fipronil on several hematological and biochemical parameters of blue land crabs. We exposed blue land crabs to either fipronil or to a control treatment; fipronil reduced the protein content of the crab and also led to hematological and oxidative damages to the crabs' oxy-hemocyanin. Based on our results, there is need for guided use of agrochemicals such as fipronil to avoid/reduce their adverse effects on economically important species such as crabs.

Influence of nutrient status on the response of the diatom Phaeodactylum tricornutum to oil and dispersant.

Phytoplankton play a central role in our ecosystems, they are responsible for nearly 50 percent of the global primary productivity and major drivers of macro-elemental cycles in the ocean. Phytoplankton are constantly subjected to stressors, some natural such as nutrient limitation and some manmade such as oil spills. With increasing oil exploration activities in coastal zones in the Gulf of Mexico and elsewhere, an oil spill during nutrient-limited conditions for phytoplankton growth is highly likely. We performed a multifactorial study exposing the diatom Phaeodactylum tricornutum (UTEX 646) to oil and/or dispersants under nitrogen and silica limitation as well as co-limitation of both nutrients. Our study found that treatments with nitrogen limitation (-N and-N-Si) showed overall lower growth and chlorophyll a, lower photosynthetic antennae size, lower maximum photosynthetic efficiency, lower protein in exopolymeric substance (EPS), but higher connectivity between photosystems compared to non-nitrogen limited treatments (-Si and +N+Si) in almost all the conditions with oil and/or dispersants. However, certain combinations of nutrient limitation and oil and/or dispersant differed from this trend indicating strong interactive effects. When analyzed for significant interactive effects, the-N treatment impact on cellular growth in oil and oil plus dispersant conditions; and oil and oil plus dispersant conditions on cellular growth in-N-Si and-N treatments were found to be significant. Overall, we demonstrate that nitrogen limitation can affect the oil resistant trait of P. tricornutum, and oil with and without dispersants can have interactive effects with nutrient limitation on this diatom.

NPA-Cu2+ Complex as a Fluorescent Sensing Platform for the Selective and Sensitive Detection of Glyphosate.

Glyphosate is a highly effective, low-toxicity, broad-spectrum herbicide, which is extensively used in global agriculture to control weeds and vegetation. However, glyphosate has become a potential threat to human and ecosystem because of its excessive usage and its bio-concentration in soil and water. Herein, a novel turn-on fluorescent probe, N-n-butyl-4-(3-pyridin)ylmethylidenehydrazine-1,8-naphthalimide (NPA), is proposed. It efficiently detected Cu2+ within the limit of detection (LOD) of 0.21 µM and displayed a dramatic turn-off fluorescence response in CH3CN. NPA-Cu2+ complex was employed to selectively and sensitively monitor glyphosate concentrations in real samples accompanied by a fluorescence turn-on mode. A good linear relationship between NPA and Cu2+ of glyphosate was found in the range of 10-100 µM with an LOD of 1.87 µM. Glyphosate exhibited a stronger chelation with Cu2+ than NPA and the system released free NPA through competitive coordination. The proposed method demonstrates great potential in quantitatively detecting glyphosate in tap water, local water from Songhua River, soil, rice, millet, maize, soybean, mung bean, and milk with mild conditions, and is a simple procedure with obvious consequences and no need for large instruments or pretreatment.

New Insights into Alterations in PL Proteins Affecting Their Binding to DNA after Exposure of Mytilus galloprovincialis to Mercury-A Possible Risk to Sperm Chromatin Structure?

Mercury (Hg) is a highly toxic and widespread pollutant. We previously reported that the exposure of Mytilus galloprovincialis for 24 h to doses of HgCl2 similar to those found in seawater (range 1-100 pM) produced alterations in the properties of protamine-like (PL) proteins that rendered them unable to bind and protect DNA from oxidative damage. In the present work, to deepen our studies, we analyzed PL proteins by turbidimetry and fluorescence spectroscopy and performed salt-induced release analyses of these proteins from sperm nuclei after the exposure of mussels to HgCl2 at the same doses. Turbidity assays indicated that mercury, at these doses, induced PL protein aggregates, whereas fluorescence spectroscopy measurements showed mercury-induced conformational changes. Indeed, the mobility of the PLII band changed in sodium dodecyl sulphate-polyacrylamide gel electrophoresis, particularly after exposure to 10-pM HgCl2, confirming the mercury-induced structural rearrangement. Finally, exposure to HgCl2 at all doses produced alterations in PL-DNA binding, detectable by DNA absorption spectra after the PL protein addition and by a decreased release of PLII and PLIII from the sperm nuclei. In conclusion, in this paper, we reported Hg-induced PL protein alterations that could adversely affect mussel reproductive activity, providing an insight into the molecular mechanism of Hg-related infertility.

Reproductive toxicity due to herbicide exposure in freshwater organisms.

Excessively used pesticides in agricultural areas are spilled into aquatic environments, wherein they are suspended or sedimented. Owing to climate change, herbicides are the fastest growing sector of the pesticide industry and are detected in surface water, groundwater, and sediments near agricultural areas. In freshwater, organisms, including mussels, snails, frogs, and fish, are exposed to various types and concentrations of herbicides. Invertebrates are sensitive to herbicide exposure because their defense systems are incomplete. At the top of the food chain in freshwater ecosystems, fish show high bioaccumulation of herbicides. Herbicide exposure causes reproductive toxicity and population declines in freshwater organisms and further contamination of fish used for consumption poses a risk to human health. In addition, it is important to understand how environmental factors are physiologically processed and assess their impacts on reproductive parameters, such as gonadosomatic index and steroid hormone levels. Zebrafish is a good model for examining the effects of herbicides such as atrazine and glyphosate on embryonic development in freshwater fish. This review describes the occurrence and role of herbicides in freshwater environments and their potential implications for the reproduction and embryonic development of freshwater organisms.

A dosage-effect assessment of acute toxicology tests of microplastic exposure in filter-feeding fish.

Abundant microplastics was found in aquatic ecosystem and aquatic organisms, which raised many concerns in public. Silver carp (Hypophthalmichthys molitrix), a species filter-feeding planktivorous fish, feed on particle between 4 and 85 µm in size, and the respiratory process works together with feeding mechanism when filtering plankton from water. The aim of this study was to assess the physiological response of silver carp exposed to 5 µm polystyrene microspheres during 48 h of exposure followed by 48 h of depuration through the gill histology, and oxidative stress biomarkers in intestine. The results revealed that microplastics can pass through the whole digestive tract of silver carp and be excreted by feces. Low microplastic concentration (80 µg/L) induced oxidative stress and up-regulation of TUB84 and HSP70 gene in intestine, and silver carp have ability to recover after the exposure to microplastic was removed. High microplastic concentration (800 µg/L) definitely cause significant damage to gills and intestines, in this situation, far beyond the possibility of fish own repair, and even when the threaten removed, silver carp can't recovery soon. Our studies assessed the dosage-effect relationship with physiological stress on silver carp when exposure to microplastics.