Complex roles for sulfation in the toxicities of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are persistent organic toxicants derived from legacy pollution sources and their formation as inadvertent byproducts of some current manufacturing processes. Metabolism of PCBs is often a critical component in their toxicity, and relevant metabolic pathways usually include their initial oxidation to form hydroxylated polychlorinated biphenyls (OH-PCBs). Subsequent sulfation of OH-PCBs was originally thought to be primarily a means of detoxication; however, there is strong evidence that it may also contribute to toxicities associated with PCBs and OH-PCBs. These contributions include either the direct interaction of PCB sulfates with receptors or their serving as a localized precursor for OH-PCBs. The formation of PCB sulfates is catalyzed by cytosolic sulfotransferases, and, when transported into the serum, these metabolites may be retained, taken up by other tissues, and subjected to hydrolysis catalyzed by intracellular sulfatase(s) to regenerate OH-PCBs. Dynamic cycling between PCB sulfates and OH-PCBs may lead to further metabolic activation of the resulting OH-PCBs. Ultimate toxic endpoints of such processes may include endocrine disruption, neurotoxicities, and many others that are associated with exposures to PCBs and OH-PCBs. This review highlights the current understanding of the complex roles that PCB sulfates can have in the toxicities of PCBs and OH-PCBs and research on the varied mechanisms that control these roles.

Toxic potential assessment of hair dye developer 2,4,5,6-tetraaminopyrimidine sulfate exposed under ambient UVB radiation

Synthetic cosmetics, particularly hair dyes, are becoming increasingly popular among people of all ages and genders. 2,4,5,6-tetraaminopyrimidine sulfate (TAPS) is a key component of oxidative hair dyes and is used as a developer in several hair dyes. TAPS has previously been shown to absorb UVB strongly and degrade in a time-dependent manner, causing phototoxicity in human skin cells. However, the toxic effects of UVB-degraded TAPS are not explored in comparison to parent TAPS. Therefore, this research work aims to assess the toxicity of UVB-degraded TAPS than TAPS on two different test systems, that is, HaCaT (mammalian cell) and Staphylococcus aureus (a bacterial cell). Our result on HaCaT has illustrated that UVB-degraded TAPS is less toxic than parent TAPS. Additionally, UVB-exposed TAPS and parent TAPS were given to S. aureus, and the bacterial growth and their metabolic activity were assessed via CFU and phenotype microarray. The findings demonstrated that parent TAPS reduced bacterial growth via decreased metabolic activity; however, bacteria easily utilized the degraded TAPS. Thus, this study suggests that the products generated after UVB irradiation of TAPS is considered to be safer than their parent TAPS.

Investigating and modeling the toxicity of arsenate on wheat root elongation: Assessing the effects of pH, sulfate and phosphate

Excessive arsenic in soil and groundwater will not only seriously affect the growth of plants, but also endanger human health through the food chain. However, there are few studies on the effects of metalloid speciation and anion competition on the toxicity of arsenate [As(Ⅴ)]. To investigate the effects of accompanying anions and pH on the toxicity of As(Ⅴ) on wheat root elongation, wheat roots were exposed to the concentrations of As(Ⅴ) in the solution ranged from 0 to 500 mM and different levels of pH (4.5-8.0) and different accompanying anions (H₂PO₄^-, SO₄^2-, NO₃^- and Cl^-) for five days. The root length of wheat was measured and the biotic ligand model (BLM) was developed to predict the potential toxicity of As(V) speciation to wheat roots. The results illustrated that EC50 of total As(V) (EC50{As(Ⅴ)_T}) values increased from 6.88 to 33.9 μM with increasing pH values from 4.5 to 8.0, suggesting that increasing pH alleviated As(Ⅴ) toxicity. The EC50{AsO₄^3-} and EC50{HAsO₄^2-} values increased from 0.001 to 4342 μM and from 0.0214 to 27.4 μM, respectively, while the EC50{H₂AsO₄^-} and EC50{H₃AsO₄} values sharply decreased from 6.62 to 2.68 μM and from 41.8 μM to 5.34 nm, respectively, when pH increased from 4.5 to 8.0. The toxicity of As(Ⅴ) decreased as the H₂PO₄^- and SO₄^2- activities increased but not when the activities of NO₃^- and Cl^- increased, indicating that SO₄^2- and H₂PO₄^- showed competitive effects with As(Ⅴ) on the binding sites. Based on BLM theory, the stability constants were obtained: [Formula: see text] = 3.70; [Formula: see text] = 4.08; [Formula: see text] = 4.77; [Formula: see text] = 6.50; [Formula: see text] = 2.09 and [Formula: see text] = 1.86, with f_AsBL^50%= 0.30 and β = 1.73. Results implied that BLM performed well in As(Ⅴ) toxicity prediction when coupling toxic species AsO₄^3-, HAsO₄^2-, H₂AsO₄^-, and H₃AsO₄, and the competition of SO₄^2- and H₂PO₄^- for binding sites. The current study provides a useful tool to accurately predict As(V) toxicity to wheat roots.

Different activation methods in sulfate radical-based oxidation for organic pollutants degradation: Catalytic mechanism and toxicity assessment of degradation intermediates

With the continuous development of industrialization, a growing number of refractory organic pollutants are released into the environment. These contaminants could cause serious risks to the human health and wildlife, therefore their degradation and mineralization is very critical and urgent. Recently sulfate radical-based advanced oxidation technology has been widely applied to organic pollutants treatment due to its high efficiency and eco-friendly nature. This review comprehensively summarizes different methods for persulfate (PS) and peroxymonosulfate (PMS) activation including ultraviolet light, ultrasonic, electrochemical, heat, radiation and alkali. The reactive oxygen species identification and mechanisms of PS/PMS activation by different approaches are discussed. In addition, this paper summarized the toxicity of degradation intermediates through bioassays and Ecological Structure Activity Relationships (ECOSAR) program prediction and the formation of toxic bromated disinfection byproducts (Br-DBPs) and carcinogenic bromate (BrO₃^-) in the presence of Br^-. The detoxification and mineralization of target pollutants induced by different reactive oxygen species are also analyzed. Finally, perspectives of potential future research and applications on sulfate radical-based advanced oxidation technology in the treatment of organic pollutants are proposed.

Effect of carbon source and metal toxicity for potential acid mine drainage (AMD) treatment with an anaerobic sludge using sulfate-reduction

This study compares sulfate-reduction performance in an anaerobic sludge with different carbon sources (ethanol, acetate, and glucose). Also, the toxic effect of copper was evaluated to assess its feasibility for possible acid mine drainage (AMD) treatment. Serological bottles with 1.5 g VSS/L and 150 mL of basal medium (0.67 g COD/g SO₄^2- at a 7-8 pH) were used to determine the percentage of electron equivalents, maximum specific methanogenic (SMA), and sulfide generation activities (SGA). The copper effect was evaluated in a previously activated sludge in batch bioassays containing different concentrations of copper (0-50 mg/L), 3 gVSS/L, and 150 mL of basal medium (0.67 g COD/g SO₄^2-). Carbon source bioassays with glucose obtained the best results in terms of the SGA (1.73 ± 0.34 mg S^2-/g VSS•d) and SMA (10.41 mg COD-CH₄/g VSS•d). The electron flow in the presence of glucose also indicated that 21.29 ± 5.2% of the metabolic activity of the sludge was directed towards sulfidogenesis. Copper toxicity bioassays indicated that a considerable decline in metabolic activity occurs above 10 mg/L. The 20%IC, 50%IC, and 80%IC were 4.5, 14.94, and 35.31 mg Cu/L. Compared to the other carbon sources tested, glucose proved to be a suitable electron donor since it favors sulfidogenesis. Finally, copper concentrations above 15 mg/L inhibited metabolic activity in the toxicity bioassays.

Mechanisms, kinetics and eco-toxicity assessment of singlet oxygen, sulfate and hydroxyl radicals-initiated degradation of fenpiclonil in aquatic environments

Fenpiclonil is an agricultural phenylpyrrole fungicide, which raise the concern about its ecotoxicological effects. In this paper, we investigate the indirect photochemical transformation mechanisms, environmental persistence and eco-toxicity of fenpiclonil initiated by various active oxidants (¹O₂, •OH and SO₄•‾) in aquatic environments. The results shown that ¹O₂ can react with pyrrole ring by cycloaddition pathways to form the endo-peroxides. In addition, •OH and SO₄•‾ initial mechanisms are calculated, suggesting that •OH-initiated mechanisms play a dominant role in the degradation process of fenpiclonil at high rate constants (2.26 ×10⁹ M^-1 s^-1, at 298 K). The kinetic calculation results indicate that high temperature is more favorable for the degradation of fenpiclonil. To better understand the adverse effects of the transformation products formed during the subsequent reaction of •OH-adduct IM10, the computational toxicology has been used for the toxicity estimation. The results show that aquatic toxicity of these products decrease with degradation process, especially the decomposition products (TP3 and TP4). However, TP1 and TP2 are still toxic and developmental toxicant. The study provides guidance for further experimental research and industrial application of fungicide degradation from the perspective of theoretical calculation.

Changes and relationship of N6-methyladenosine modification and long non-coding RNAs in oxidative damage induced by cadmium in pancreatic β-cells

N⁶-methyladenosine (m⁶A) modification and m⁶A-modified Long non-coding RNAs (LncRNAs) play crucial roles in various pathological processes, yet their changes and relationship in cadmium-induced oxidative damage are largely unknown. Here, five m⁶A-modified LncRNAs (LncRNA-TUG1, LncRNA-PVT1, LncRNA-MALAT1, LncRNA-XIST, LncRNA-NEAT1), which have been evidenced to involve in oxidative damage, were selected and their binding proteins were submitted to bioinformatics analysis. Our analysis results showed that these five m⁶A-modified LncRNAs bound to different regulatory proteins of m⁶A modification, implicating that m⁶A modification on LncRNAs may synergistically control by multiple regulatory proteins. Furthermore, the detection data revealed that levels of m⁶A modification, methyltransferase-like 3 (METTL3) and fat mass and obesity-associated protein (FTO) were all significantly decreased in CdSO₄-induced oxidative damage, which was demonstrated by increasing ROS accumulation and MDA contents as well as decreasing SOD activities. More importantly, LncRNA-MALAT1 and LncRNA-PVT1 indicated downward trend and showed positive relationship with m⁶A modification. Collectively, our results showed that m⁶A modification and m⁶A-modified LncRNAs may involve in oxidative damage induced by cadmium.

Brevisulcenals-A1 and A2, Sulfate Esters of Brevisulcenals, Isolated from the Red Tide Dinoflagellate Karenia brevisulcata

Two different types of polycyclic ether toxins, namely brevisulcenals (KBTs) and brevisulcatic acids (BSXs), produced by the red tide dinoflagellate Karenia brevisulcata, were the cause of a toxic incident that occurred in New Zealand in 1998. Four major components, KBT-F, -G, -H, and -I, shown to be cytotoxic and lethal in mice, were isolated from cultured K. brevisulcata cells, and their structures were elucidated by spectroscopic analyses. New analogues, brevisulcenal-A1 (KBT-A1) and brevisulcenal-A2 (KBT-A2), toxins of higher polarity than that of known KBTs, were isolated from neutral lipophilic extracts of bulk dinoflagellate culture extracts. The structures of KBT-A1 and KBT-A2 were elucidated as sulfated analogues of KBT-F and KBT-G, respectively, by NMR and matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI TOF/TOF), and by comparison with the spectra of KBT-F and KBT-G. The cytotoxicities of the sulfate analogues were lower than those of KBT-F and KBT-G.

Sulfate toxicity to early life stages of European whitefish (Coregonus lavaretus) in soft freshwater

Sulfate occurs naturally in the aquatic environment but its elevated levels can be toxic to aquatic life in freshwater environments. We investigated the toxicity of sulfate in humic, soft freshwater to whitefish (Coregonus lavaretus) from fertilization of eggs to hatching i.e. during the critical phases of whitefish early development. Anadromous Kokemäenjoki whitefish eggs and sperm during fertilization, embryos and larvae were exposed in the long-term 175-day incubation to seven different sodium sulfate (Na₂SO₄) concentrations from 44 to 2 000 mg SO₄ L^-1. Endpoint variables were the fertilization success, offspring survival and larval growth. Egg fertilization and early embryonic development were the most sensitive developmental stages of whitefish to sulfate, although the fertilization success and survival of embryos decreased only in the highest concentration of 2 000 mg SO₄ L^-1. The survival during late embryonic period, hatching and the 5-day larval period was high and no difference between the control and sulfate treatments were observed. LC₅₀-values of sulfate for early embryonic period and for the entire embryonic and larval period was 1 413 and 1 161 mg L^-1, respectively. The NOEC (No-observed Effect Concentration) of sulfate for the both periods was 1 207 mg L^-1. The tolerance of whitefish early stages to sulfate toxicity seems to be on the same level as the tolerance of other salmonids' early stages.

Theoretical investigation on the contribution of HO, SO4- and CO3- radicals to the degradation of phenacetin in water: Mechanisms, kinetics, and toxicity evaluation

Indirect oxidation induced by reactive free radicals, such as hydroxyl radical (HO), sulfate radical (SO₄^-) and carbonate radical (CO₃^-), plays an important or even crucial role in the degradation of micropollutants. Thus, the coadjutant degradation of phenacetin (PNT) by HO, SO₄^- and CO₃^-, as well as the synergistic effect of O₂ on HO and HO₂ were studied through mechanism, kinetics and toxicity evaluation. The results showed that the degradation of PNT was mainly caused by radical adduct formation (RAF) reaction (69% for Г, the same as below) and H atom transfer (HAT) reaction (31%) of HO. For the two inorganic anionic radicals, SO₄^- initiated PNT degradation by sequential radical addition-elimination (SRAE; 55%), HAT (28%) and single electron transfer (SET; 17%) reactions, while only by HAT reaction for CO₃^-. The total initial reaction rate constants of PNT by three radicals were in the order: SO₄^- > HO > CO₃^-. The kinetics of PNT degradation simulated by Kintecus program showed that UV/persulfate could degrade target compound more effectively than UV/H₂O₂ in ultrapure water. In the subsequent reaction of PNT with O₂, HO and HO₂, the formation of mono/di/tri-hydroxyl substitutions and unsaturated aldehydes/ketones/alcohols were confirmed. The results of toxicity assessment showed that the acute and chronic toxicity of most products to fish increased and to daphnia decreased, and acute toxicity to green algae decreased while chronic toxicity increased.

Raman spectroscopic technique towards understanding the degradation of phenol by sodium persulfate in hot compressed water

Degradation of phenol by sodium persulfate (SPS) in hot compressed water (HCW) was investigated in a lab-built fused quartz tube reactor (FQTR) coupled with Raman spectroscopy system. The species of S₂O₈^2-, SO₄^2-, HSO₄^-, SO₃^2- and HSO₃^- in the reaction system were qualitatively and quantitatively analyzed by Raman spectroscopy. The hydrothermal stability of phenol and SPS at different temperature and the degradation of phenol by SPS were also studied. The results indicated that phenol was not stable in aqueous solution above 200 °C, and that only SO₄^2- was generated in the hydrolysis of SPS at temperatures below 50 °C, and SO₄^2- and HSO₄^- were generated at higher temperatures. The maximum conversion rate (90.93%) and mineralization efficiency (38.88%) of phenol by SPS was obtained at reaction temperature of 300 °C with 180 min reaction time. During the degradation of phenol by SPS, HSO₄^- was the main product and S∗ (not detected by Raman spectroscopy) exhibits a positive correlation with temperature. In addition, a degradation pathway of phenol by SPS was proposed. The degradation data for the kinetic analysis indicated that the reaction followed pseudo first-order kinetics, and the reaction rate constants (k_s) were given as k_{50 °C} = 0.0083 min^-1, k_100°C = 0.0197 min^-1, k_{200 °C} = 0.0498 min^-1, k_{300 °C} = 0.0619 min^-1 and k_400°C = 0.0505 min^-1 at 30 min reaction. Moreover, the activation energy (12.580 kJ mol^-1), the enthalpy change (9.064 kJ mol^-1) and the entropy change (-222.104 J mol^-1) of the reaction were also calculated.

Toxicokinetic Studies in Piglets Reveal Age-Related Differences in Systemic Exposure to Zearalenone, Zearalenone-14-Glucoside, and Zearalenone-14-Sulfate

Juveniles are considered as one of the most vulnerable population groups concerning mycotoxins and their modified forms. The weaning stage is a particularly vulnerable period in the life of mammals, reflected in intestinal and immune dysfunction. The current study investigated the toxicokinetic (TK) characteristics of zearalenone (ZEN), zearalenone-14-glucoside (ZEN14G), and zearalenone-14-sulfate (ZEN14S) in weaned (4-week-old) piglets, by means of oral and intravenous administration of equimolar doses, i.e., 331, 500, and 415 μg/kg bodyweight, respectively. Plasma and urine were sampled pre- and post-administration and were quantitatively analyzed for ZEN, ZEN14G, ZEN14S, and in vivo metabolites by liquid chromatography-high-resolution mass spectrometry. Tailor-made TK models were elaborated to process data. A statistical comparison of the results was performed with TK data obtained in a previously reported study in pigs of 8 weeks of age. Additionally, porcine plasma protein binding was determined to support TK findings. The TK results for ZEN, ZEN14G, and ZEN14S, obtained in 4- and 8-week-old pigs, revealed significant age-related differences, based on differences in intestinal permeability, body fat content, gastrointestinal transit time, and biotransformation, with a special emphasis on an increased absorbed fraction of ZEN14G, i.e., 94 vs 61% in 4- compared to 8-week-old pigs. Since the growing pig has been reported to be a suitable pediatric animal model for humans concerning TK processes, these results may contribute to refine the risk assessment concerning modified ZEN forms in juvenile animals and humans.

Simulated sulfuric and nitric acid rain inhibits leaf breakdown in streams: A microcosm study with artificial reconstituted fresh water

Acid rain containing SO₄^2- and NO₃^- in China has been a public concern for decades. However, a decrease of SO₂ has been recorded since the government enacted a series of policies to control its emission. To comprehensively evaluate the consequence of realistic and future acid deposition scenarios, this study explored the effects of mixed acid rain with different molar ratios of SO₄^2- and NO₃^- (0:1, 1:0, 2:1, 1:1, and 1:2) on stream leaf breakdown through a microcosm experiment. A significant inhibition of leaf breakdown rate was observed when the ratio was 1:2 with reduced microcosm pH, fungal biomass, enzyme activities as well as the frequencies of hub general in the fungal community. In conclusion, the ratio of SO₄^2- and NO₃^- in acid rain was an important factor that could have a profound impact on leaf breakdown, even on ecosystem structure and functioning of streams.

Physicochemical and Toxicological Assay of Leachate from Malt Spent Rootlets Biochar

The aim of this study was to characterize the leachate derived from biochar produced from malt spent rootlets (MSR) and to evaluate the required washing level in order to provide water free from inorganic substances. MSR biochar was placed in a column and subjected to six serial washes with distilled water, and the leachate was analysed for main anions and heavy metals. The 1st wash aliquot contained increased levels of mainly phosphates (980 mg/L) and chlorides (760 mg/L), and lower levels of nitrates, sulfates, fluoride and bromide, which were decreased over washes. Zero concentrations were observed after three washes for most anions. The increased levels of Zn, Be, Cs, Mn, V and Se determined in the 1st wash aliquot were eliminated in the successive washes. The toxic potency of each wash aliquot, determined by the use of the fairy shrimp Thamnocephalus platyurus showed that the 1st and 2nd MSR biochar leachates were toxic with 4.52 and 1.46 toxic units (TU), respectively, followed by a significant elimination of toxicity after further washes.

Acute and Chronic Toxicity of Sodium Nitrate and Sodium Sulfate to Several Freshwater Organisms in Water-Only Exposures

Elevated nitrate (NO₃ ) and sulfate (SO₄ ) in surface water are of global concern, and studies are needed to generate toxicity data to develop environmental guideline values for NO₃ and SO₄ . The present study was designed to fill existing gaps in toxicity databases by determining the acute and/or chronic toxicity of NO₃ (tested as NaNO₃ ) to a unionid mussel (Lampsilis siliquoidea), a midge (Chironomus dilutus), a fish (rainbow trout, Oncorhynchus mykiss), and 2 amphibians (Hyla versicolor and Lithobates sylvaticus), and to determine the acute and/or chronic toxicity of SO₄ (tested as Na₂ SO₄ ) to 2 unionid mussels (L. siliquoidea and Villosa iris), an amphipod (Hyalella azteca), and 2 fish species (fathead minnow, Pimephales promelas and O. mykiss). Among the different test species, acute NO₃ median effect concentrations (EC50s) ranged from 189 to >883 mg NO₃ -N/L, and chronic NO₃ 20% effect concentrations (EC20s) based on the most sensitive endpoint ranged from 9.6 to 47 mg NO₃ -N/L. The midge was the most sensitive species, and the trout was the least sensitive species in both acute and chronic NO₃ exposures. Acute SO₄ EC50s for the 2 mussel species (2071 and 2064 mg SO₄ /L) were similar to the EC50 for the amphipod (2689 mg SO₄ /L), whereas chronic EC20s for the 2 mussels (438 and 384 mg SO₄ /L) were >2-fold lower than the EC20 of the amphipod (1111 mg SO₄ /L), indicating the high sensitivity of mussels in chronic SO₄ exposures. However, the fathead minnow, with an EC20 of 374 mg SO₄ /L, was the most sensitive species in chronic SO₄ exposures whereas the rainbow trout was the least sensitive species (EC20 > 3240 mg SO₄ /L). The high sensitivity of fathead minnow was consistent with the finding in a previous chronic Na₂ SO₄ study. However, the EC20 values from the present study conducted in test water containing a higher potassium concentration (3 mg K/L) were >2-fold greater than those in the previous study at a lower potassium concentration (1 mg K/L), which confirmed the influence of potassium on chronic Na₂ SO₄ toxicity to the minnow. Environ Toxicol Chem 2020;39:1071-1085. © 2020 SETAC.

A synthetic heparin mimetic that allosterically inhibits factor XIa and reduces thrombosis in vivo without enhanced risk of bleeding

BACKGROUND

Human factor XIa (FXIa) is an actively pursued target for development of safer anticoagulants. Our long-standing hypothesis has been that allosterism originating from heparin-binding site(s) on coagulation enzymes is a promising approach to yield safer agents.

OBJECTIVES

To develop a synthetic heparin mimetic as an inhibitor of FXIa so as to reduce clot formation in vivo but not carry high bleeding risk.

METHODS

We employed a gamut of methods involving synthetic chemistry, biophysical biochemistry, enzyme assays, blood and plasma coagulation assays, and in vivo thrombosis models in this work.

RESULTS

Sulfated chiro-inositol (SCI), a non-saccharide mimetic of heparin, was synthesized in three steps in overall yields of >50%. SCI inhibited FXIa with potency of 280 nmol/L and preferentially engaged FXIa's heparin-binding site to conformationally alter its active site. SCI inhibition of FXIa could be rapidly reversed by common antidotes, such as protamine. SCI preferentially prolonged plasma clotting initiated with recalcification, rather than thromboplastin, alluding to its intrinsic pathway-based mechanism. Human blood thromboelastography indicated good ex vivo anticoagulation properties of SCI. Rat tail bleeding and maximum-dose-tolerated studies indicated that no major bleeding or toxicity concerns for SCI suggesting a potentially safer anticoagulation outcome. FeCl3 -induced arterial and thromboplastin-induced venous thrombosis model studies in the rat showed reduced thrombus formation by SCI at 250 μg/animal, which matched enoxaparin at 2500 μg/animal.

CONCLUSIONS

Overall, SCI is a highly promising, allosteric inhibitor of FXIa that induces potent anticoagulation in vivo. Further studies are necessary to assess SCI in animal models mimicking human clinical indications.

Assessment of Fish Embryo Survival and Growth by In Situ Incubation in Acidic Boreal Streams Undergoing Biomining Effluents

The applicability of an in situ incubation method in monitoring the effects of metal mining on early life stages of fish was evaluated by investigating the impacts of a biomining technology utilizing mine on the mortality, growth, and yolk consumption of brown trout (Salmo trutta) and whitefish (Coregonus lavaretus) embryos. Newly fertilized eggs were incubated from autumn 2014 to spring 2015 in six streams under the influence of the mine located in North-Eastern Finland and in six reference streams. Although the impacted streams clearly had elevated concentrations of several metals and sulfate, the embryonic mortality of the two species did not differ between the impacted and the reference streams. Instead, particle accumulation to some cylinders had a significant impact on the embryonic mortality of both species. In clean cylinders, mortality was higher in streams with lower minimum pH. However, low pH levels were evident in both the reference and the mine-impacted groups. The embryonic growth of neither species was impacted by the mining activities, and the growth and yolk consumption of the embryos was mainly regulated by water temperature. Surprisingly, whitefish embryos incubated in streams with lower minimum pH had larger body size. In general, the applied in situ method is applicable in boreal streams for environmental assessment and monitoring, although in our study, we did not observe a specific mining impact differing from the effects of other environmental factors related to catchment characteristics.

Calcium ameliorates the toxicity of sulfate salinity in Brassica rapa

Salinity stress in Brassica, often only associated with osmotic effects and the toxicity of Na⁺, was more severe when applied as Na₂SO₄ than as NaCl, indicating that SO₄^2- ions had toxic effects as well. Application of 10 mM calcium in the form of CaCl₂ in the growth medium of plants only slightly ameliorated growth impairment by NaCl and KCl, but almost completely prevented negative effects of Na₂SO₄ and K₂SO₄ on plant biomass production. This effect was calcium specific, as MgCl₂ ameliorated sulfate toxicity to a much lower extent. This sulfate toxicity coincided with a strong decrease in the plant content of calcium and manganese upon sulfate salinity. Application of CaCl₂ largely alleviated this decrease, however, it did not prevent the higher tissue concentration of sulfate. CaCl₂ prevented the increase in organic sulfur compounds presumably by reducing of relative gene expression of ATP-sulfurylase (ATPS) and adenosine 5'-phosphosulfate reductase (APR) indicating a possible regulation of sulfate assimilation by calcium. The upregulation of the genes encoding for Group 4 sulfate transporters (Sultr4;1 and 4;2) upon sulfate salinity, was absent in the presence of CaCl₂. Therefore, additional calcium may facilitate an increased vacuolar capacity for sulfate accumulation.

Hydroxylated and sulfated metabolites of commonly observed airborne polychlorinated biphenyls display selective uptake and toxicity in N27, SH-SY5Y, and HepG2 cells

Although neurotoxicity and hepatotoxicity have long been associated with exposure to polychlorinated biphenyls (PCBs), less is known about the selective toxicity of those hydroxylated PCBs (OH-PCBs) and PCB sulfates that are metabolites derived from exposure to PCBs found in indoor air. We have examined the toxicity of OH-PCBs and PCB sulfates derived from PCBs 3, 8, 11, and 52 in two neural cell lines (N27 and SH-SY5Y) and an hepatic cell line (HepG2). With the exception of a similar toxicity seen for N27 cells exposed to either OH-PCB 52 or PCB 52 sulfate, these OH-PCBs were more toxic to all three cell-types than their corresponding PCB or PCB sulfate congeners. Differences in the distribution of individual OH-PCB and PCB sulfate congeners between the cells and media, and the ability of cells to interconvert PCB sulfates and OH-PCBs, were important components of cellular sensitivity to these toxicants.

In situ assessment of Karaj River genotoxic impact with the alkaline comet assay and micronucleus test, on feral brown trout (Salmo trutta fario)

The in situ evaluation of the genotoxic impact of the Karaj River was performed using the comet and micronucleus (MN) assays in erythrocytes, liver, gill and kidney of indigenous brown trout, Salmo trutta fario from three different stations, including Varangerud, Asara and Purkan. The results showed that DNA damage significantly increased in sampled fish erythrocytes, liver and gill from low levels in the upstream river (Varangerud) via intermediate levels in downstream (Purkan) to high levels in the middle of the river (Asara), correlating with the river increasing pollution gradient. Gill was the most sensitive tissue followed by blood and liver. Kidney did not respond to the genotoxic gradient of the river. MN test (as a complementary assay) of liver cells of fish was a sensitive biomarker of genotoxic exposure. MN test in blood, gill and kidney did not reflect the genotoxic condition of the river.

Sulfate Aerosols Promote Lung Cancer Metastasis by Epigenetically Regulating the Epithelial-to-Mesenchymal Transition (EMT)

Secondary inorganic aerosols (SIA), particularly sulfate aerosols, are central particulate matter (PM) constituents of severe haze formation in China and exert profound impacts on human health; however, our understanding of the mechanisms by which sulfate aerosols cause malignancy in lung carcinogenesis remains incomplete. Here, we show that exposure to secondary inorganic aerosols induced the invasion and migration of lung epithelial cells, and that (NH₄)₂SO₄ exerted the most serious effects in vitro and promoted lung tumor metastasis in vivo. This action was associated with alterations of phenotype markers in the epithelial-to-mesenchymal transition (EMT), such as the up-regulation of fibronectin (Fn1) and the down-regulation of E-cadherin (E-cad). Hypoxia-inducible factor 1α (HIF-1α)-Snail signaling, regulated by the generation of reactive oxygen species (ROS), was involved in the (NH₄)₂SO₄-induced EMT, and the potent antioxidant N-acetylcysteine (NAC) inhibited the activation of HIF-1α-Snail and blocked the EMT, cell invasion, and migration in response to (NH₄)₂SO₄. Additionally, CpG hypermethylation in the E-cad promoter regions partly contributed to the (NH₄)₂SO₄-regulated E-cad repression, and the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-Aza) restored the (NH₄)₂SO₄-induced down-regulation of E-cad. Our findings reveal a potential mechanistic basis for exploring the association between sulfate aerosol exposure and increased malignancy during lung carcinogenesis, and suggest new approaches for the treatment, improvement, and prevention of lung cancer resulting from sulfate aerosol exposure in severe haze-fog.

Sulfate transport kinetics and toxicity are modulated by sodium in aquatic insects

The salinization of freshwater ecosystems is emerging as a major ecological issue. Several anthropogenic causes of salinization (e.g. surface coal mining, hydro-fracking, road de-icing, irrigation of arid lands, etc.) are associated with biodiversity losses in freshwater ecosystems. Because insects tend to dominate freshwater ecology, it is important that we develop a better understanding of how and why different species respond to salinity matrices dominated by different major ions. This study builds upon previous work demonstrating that major ion toxicity to the mayfly Neocloeon triangulifer was apparently due to the ionic composition of water rather than specific conductance. Synthetic waters with low Ca:Mg ratios and high SO₄:Na ratios produced toxicity, whereas waters with higher Ca:Mg ratios and lower SO₄:Na ratios were not toxic to mayflies at comparable conductivities. Here we used a radiotracer approach to show that Mg did not competitively exclude Ca uptake at environmentally realistic ratios in 4 aquatic insect species. We characterized SO₄ uptake kinetics in 5 mayflies and assessed the influence of different ions on SO₄ uptake. Dual label experiments show an inverse relationship between SO₄ and Na transport rates as SO₄ was held constant and Na was increased, suggesting that Na (and not Cl or HCO₃) is antagonistic to SO₄ transport. Based on this observation, we tested the hypothesis that increasing Na would protect against SO₄ induced toxicity in a Na-dependent manner. Increasing Na from 0.7 to 10.9mM improved 96-h survivorship associated with 20.8mM SO₄ from 44% to 73% in a concentration dependent manner. However, when Na reached 21.8mM, survivorship decreased to 16%, suggesting that other interactive effects of major ions caused toxicity under those conditions. Thus, the combination of elevated sulfate and low sodium commonly observed in streams affected by mountaintop coal mining has the potential to cause toxicity in sensitive aquatic insects. Overall, it is important that we develop a better understanding of major ion toxicity to effectively mitigate and protect freshwater biodiversity from salinization.

Tolerance of whitefish (Coregonus lavaretus) early life stages to manganese sulfate is affected by the parents

European whitefish (Coregonus lavaretus) embryos and larvae were exposed to 6 different manganese sulfate (MnSO₄ ) concentrations from fertilization to the 3-d-old larvae. The fertilization success, offspring survival, larval growth, yolk consumption, embryonic and larval Mn tissue concentrations, and transcript levels of detoxification-related genes were measured in the long-term incubation. A full factorial breeding design (4 females × 2 males) allowed examination of the significance of both female and male effects, as well as female-male interactions in conjunction with the MnSO₄ exposure in terms of the observed endpoints. The MnSO₄ exposure reduced the survival of the whitefish early life stages. The offspring MnSO₄ tolerance also was affected by the female parent, and the female-specific mean lethal concentrations (LC50s) varied from 42.0 mg MnSO₄ /L to 84.6 mg MnSO₄ /L. The larval yolk consumption seemed slightly inhibited at the exposure concentration of 41.8 mg MnSO₄ /L. The MnSO₄ exposure caused a significant induction of metallothionein-A (mt-a) and metallothionein-B (mt-b) in the 3-d-old larvae, and at the exposure concentration of 41.8 mg MnSO₄ /L the mean larval mt-a and mt-b expressions were 47.5% and 56.6% higher, respectively, than at the control treatment. These results illustrate that whitefish reproduction can be impaired in waterbodies that receive Mn and SO₄ in concentrations substantially above the typical levels in boreal freshwaters, but the offspring tolerance can be significantly affected by the parents and in particular the female parent. Environ Toxicol Chem 2017;36:1343-1353. © 2016 SETAC.

Transcriptomics analysis of early embryonic stem cell differentiation under osteoblast culture conditions: Applications for detection of developmental toxicity

The mouse embryonic stem cell test (mEST) is a promising in vitro assay for predicting developmental toxicity. In the current study, early differentiation of D3 mouse embryonic stem cells (mESCs) under osteoblast culture conditions and embryotoxicity of cadmium sulfate were examined. D3 mESCs were exposed to cadmium sulfate for 24, 48 or 72h, and whole genome transcriptional profiles were determined. The results indicate a track of differentiation was identified as mESCs differentiate. Biological processes that were associated with differentiation related genes included embryonic development and, specifically, skeletal system development. Cadmium sulfate inhibited mESC differentiation at all three time points. Functional pathway analysis indicated biological pathways affected included those related to skeletal development, renal and reproductive function. In summary, our results suggest that transcriptional profiles are a sensitive indicator of early mESC differentiation. Transcriptomics may improve the predictivity of the mEST by suggesting possible modes of action for tested chemicals.

Comparative Developmental Toxicity of Desalination Brine and Sulfate-Dominated Saltwater in a Euryhaline Fish

Desalination is a promising sustainable solution to meet growing water needs of cities across the United States. However, the environmental impacts of the resulting filtrate (brine) discharged to surface water need to be evaluated before large-scale desalination can be successful in the United States. Developing fish are especially sensitive to changes in salinity and varying ionic composition. Limited research is available on the impacts of hypersalinity on chronic vertebrate embryonic development, particularly on sublethal effects. To investigate this, Japanese medaka (Oryzias latipes) embryos were treated with: (1) graphite filtered freshwater; (2) artificial seawater [17, 35, 42, 56, and 70 parts per thousand (ppt)]; (3) effluent from a desalination facility at Monterey Bay Aquarium, CA, diluted to 75, 50, and 25% with 35 ppt artificial seawater to simulate mixing (39, 42, 46, and 50 ppt); (4) artificial San Joaquin River water (CA, USA) (9, 13, and 17 ppt); and (5) artificial San Joaquin River water diluted to 75, 50, and 25% with artificial seawater to simulate estuarine mixing in the San Francisco Bay (13, 19, 24, and 30 ppt). Percent hatch, survival post hatch, deformities, swim bladder inflation, and median day to hatch were recorded to calculate EC₅₀ (50% effect concentration) and NOEC (no observable effect concentration) values. No significant difference was observed between artificial seawater and Monterey Bay aquarium effluent (EC₅₀ = 45-55 ppt). However, San Joaquin River water decreased survival post hatch and increased deformities in comparison to artificial seawater and San Joaquin River water mixed with seawater, suggesting that unique ion compositions may play a role in embryo and larval toxicity.

Hypoxia acclimation and subsequent reoxygenation partially prevent Mn-induced damage in silver catfish

This study investigated if hypoxia acclimation modifies the hematological and oxidative profiles in tissues of Mn-exposed silver catfish (Rhamdia quelen), and if such modifications persist upon subsequent reoxygenation. Silver catfish acclimated to hypoxia (~3mgL^-1) for 10days and subsequently exposed to Mn (~8.1mgL^-1) for additional 10days exhibited lower Mn accumulation in plasma, liver and kidney, even after reoxygenation, as compared to normoxia-acclimated fish. Hypoxia acclimation increased per se red blood cells count and hematocrit, suggesting adaptations under hypoxia, while the reoxygenation process was also related to increased hematocrit and hemoglobin per se. Fish exposed to Mn under normoxia for 20days showed decreased red blood cells count and hematocrit, while reoxygenation subsequent to hypoxia increased red blood cells count. Hypoxia acclimation also prevented Mn-induced oxidative damage, observed by increased reactive species generation and higher protein carbonyl levels in both liver and kidney under normoxia. Mn-exposed fish under hypoxia and after reoxygenation showed decreased plasma transaminases in relation to the normoxia group. Moreover, acclimation to hypoxia increased reduced glutathione levels, catalase activity and Na⁺/K⁺-ATPase activity in liver and kidney during Mn exposure, remaining increased even after reoxygenation. These findings show that previous acclimation to hypoxia generates physiological adjustments, which drive coordinated responses that ameliorate the antioxidant status even after reoxygenation. Such responses represent a physiological regulation of this teleost fish against oxygen restriction and/or Mn toxicity in order to preserve the stability of a particular tissue or system.

Chronic exposure to manganese sulfate leads to adverse dose-dependent effects on the neurobehavioral ability of rats

Manganese sulfate is the main combustion product of methylcyclopentadienyl manganese tricarbonyl (MMT). Currently, little is known about the neurobehavioral consequences of chronic manganese sulfate exposure. In this study, rats were treated with 0, 5.0, 10.0, and 20.0 mg/kg MnSO₄ ·H₂ O for 24 consecutive weeks via intraperitoneal injection. During the treatment period, spatial learning-memory ability was measured using the Morris water maze (MWM). At the end of the exposure period, spontaneous motor behavior and emotional status, hippocampal histologic changes, and Hsp70 mRNA levels were measured using the open-field test (OFT), hematoxylin-eosin staining and real-time quantitative PCR (RT-PCR), respectively. A dose-dependent decrease was noted in the spatial learning-memory ability and the spontaneous activities of rats (P < 0.05), and negative emotions differed significantly between the exposed groups and the control group (P < 0.05). Moreover, overt morphological changes in the hippocampuses of the exposed rats were detected. Cellular degeneration and death were also found. The Hsp70 mRNA levels of the hippocampal areas in the 20.0 mg/kg group (1.567 ± 0.236) were significantly increased compared with the control group (P < 0.05). These results suggest that chronic exposure to manganese sulfate can have adverse dose-dependent effects on rats' neurobehavioral ability, and the mechanism of abnormal hippocampal Hsp70 expression needs to be further explored. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1571-1579, 2016.

Chloride and sulphate toxicity to Hydropsyche exocellata (Trichoptera, Hydropsychidae): Exploring intraspecific variation and sub-lethal endpoints

The rivers and streams of the world are becoming saltier due to human activities. In spite of the potential damage that salt pollution can cause on freshwater ecosystems, this is an issue that is currently poorly managed. Here we explored intraspecific differences in the sensitivity of freshwater fauna to two major ions (Cl(-) and SO4(2-)) using the net-spinning caddisfly Hydropsyche exocellata Dufour 1841 (Trichoptera, Hydropsychidae) as a model organism. We exposed H. exocellata to saline solutions (reaching a conductivity of 2.5mScm(-1)) with Cl(-):SO4(2-) ratios similar to those occurring in effluents coming from the meat, mining and paper industries, which release dissolved salts to rivers and streams in Spain. We used two different populations, coming from low and high conductivity streams. To assess toxicity, we measured sub-lethal endpoints: locomotion, symmetry of the food-capturing nets and oxidative stress biomarkers. According to biomarkers and net building, the population historically exposed to lower conductivities (B10) showed higher levels of stress than the population historically exposed to higher conductivities (L102). However, the differences between populations were not strong. For example, net symmetry was lower in the B10 than in the L102 only 48h after treatment was applied, and biomarkers showed a variety of responses, with no discernable pattern. Also, treatment effects were rather weak, i.e. only some endpoints, and in most cases only in the B10 population, showed a significant response to treatment. The lack of consistent differences between populations and treatments could be related to the high salt tolerance of H. exocellata, since both populations were collected from streams with relatively high conductivities. The sub-lethal effects tested in this study can offer an interesting and promising tool to monitor freshwater salinization by combining physiological and behavioural bioindicators.

Particulate matter properties and health effects: consistency of epidemiological and toxicological studies

Identifying the ambient particulate matter (PM) fractions or constituents, critically involved in eliciting adverse health effects, is crucial to the implementation of more cost-efficient abatement strategies to improve air quality. This review focuses on the importance of different particle properties for PM-induced effects, and whether there is consistency in the results from epidemiological and experimental studies. An evident problem for such comparisons is that epidemiological and experimental data on the effects of specific components of ambient PM are limited. Despite this, some conclusions can be drawn. With respect to the importance of the PM size-fractions, experimental and epidemiological studies are somewhat conflicting, but there seems to be a certain consistency in that the coarse fraction (PM10-2.5) has an effect that should not be neglected. Better exposure characterization may improve the consistency between the results from experimental and epidemiological studies, in particular for ultrafine particles. Experimental data indicate that surface area is an important metric, but composition may play an even greater role in eliciting effects. The consistency between epidemiological and experimental findings for specific PM-components appears most convincing for metals, which seem to be important for the development of both pulmonary and cardiovascular disease. Metals may also be involved in PM-induced allergic sensitization, but the epidemiological evidence for this is scarce. Soluble organic compounds appear to be implicated in PM-induced allergy and cancer, but the data from epidemiological studies are insufficient for any conclusions. The present review suggests that there may be a need for improvements in research designs. In particular, there is a need for better exposure assessments in epidemiological investigations, whereas experimental data would benefit from an improved comparability of studies. Combined experimental and epidemiological investigations may also help answer some of the unresolved issues.

Assessment of dynamic surface leaching of monolithic surface road materials

Construction materials have to satisfy, among others, health and environment requirements. To check the environmental compatibility of road construction materials, release of hazardous substances into water must be assessed. Literature mostly describes the leaching behaviour of recycled aggregates for potential use in base or sub-base layers of roads. But little is known about the release of soluble substances by materials mixed with binders and compacted for intended use on road surface. In the present study, we thus performed a diffusion test with sequential renewal of water during a 64 day period according to CEN/TS 16637-2 specifications, on asphalt concretes and hydraulically bound monoliths, two common surface road materials. It is shown that release of dangerous substances is limited in these hydrodynamic conditions. It was particularly true for asphalt concrete leachates where no metallic trace element, sulphate, chloride or fluoride ion could be quantified. This is because of the low hydraulic conductivity and the low polarity of the petroleum hydrocarbon binder of these specimens. For hydraulically bound materials around 20,000 mg/m(2) of sulphate diffused from the monoliths. It is one order of magnitude higher than chloride diffusion and two orders of magnitude higher than fluoride release. No metallic trace element, except small quantities of copper in the last eluate could be quantified. No adverse effect is to be expected for human and environmental health from the leachates of these compacted surface road construction materials, because all the measured parameters were below EU (Council Directive 98/83/EC) or WHO guidelines for drinking water standards.

Cytotoxic activity of selenosulfate versus selenite in tumor cells depends on cell line and presence of amino acids

Based on acute cytotoxicity studies, selenosulfate (SeSO3 (-)) has been suggested to possess a generally higher toxic activity in tumor cells than selenite. The reason for this difference in cytotoxic activity remained unclear. In the present study, cytotoxicity tests with human hepatoma (HepG2), malignant melanoma (A375), and urinary bladder carcinoma cells (T24) showed that the selenosulfate toxicity was very similar between all three tested cell lines (IC50 6.6-7.1 μM after 24 h). It was largely independent of exposure time and presence or absence of amino acids. What changed, however, was the toxicity of selenite, which was lower than that of selenosulfate only for HepG2 cells (IC50 > 15 μM), but similar to and higher than that of selenosulfate for A375 (IC50 4.7 μM) and T24 cells (IC50 3.5 μM), respectively. Addition of amino acids to T24 cell growth medium downregulated short-term selenite uptake (1.5 versus 12.9 ng Se/10(6) cells) and decreased its cytotoxicity (IC50 8.4 μM), rendering it less toxic than selenosulfate. The suggested mechanism is a stronger expression of the xc (-) transport system in the more sensitive T24 compared to HepG2 cells which creates a reductive extracellular microenvironment and facilitates selenite uptake by reduction. Selenosulfate is already reduced and so less affected. The cytotoxic activity of selenosulfate and selenite to tumor cells therefore depends on the sensitivity of each cell line, supplements like amino acids as well as the reductive state of the extracellular environment.

Effects of sulfate on microcystin production, photosynthesis, and oxidative stress in Microcystis aeruginosa

Increasing sulfate in freshwater systems, caused by human activities and climate change, may have negative effects on aquatic organisms. Microcystis aeruginosa (M. aeruginosa) is both a major primary producer and a common toxic cyanobacterium, playing an important role in the aquatic environment. This study first investigated the effects of sulfate on M. aeruginosa. The experiment presented here aims at analyzing the effects of sulfate on physiological indices, molecular levels, and its influencing mechanism. The results of our experiment showed that sulfate (at 40, 80, and 300 mg L(-1)) inhibited M. aeruginosa growth, increased both intracellular and extracellular toxin contents, and enhanced the mcyD transcript level. Sulfate inhibited the photosynthesis of M. aeruginosa, based on the decrease in pigment content and the down-regulation of photosynthesis-related genes after sulfate exposure. Furthermore, sulfate decreased the maximum electron transport rate, causing the cell to accumulate surplus electrons and form reactive oxygen species (ROS). Sulfate also increased the malondialdehyde (MDA) content, which showed that sulfate damaged the cytomembrane. This damage contributed to the release of intracellular toxin to the culture medium. Although sulfate increased superoxide dismutase (SOD) activities, expression of sod, and total antioxidant capacity in M. aeruginosa, it still overwhelmed the antioxidant system since the ROS level simultaneously increased, and finally caused oxidative stress. Our results indicate that sulfate has direct effects on M. aeruginosa, inhibits photosynthesis, causes oxidative stress, increases toxin production, and affects the related genes expression in M. aeruginosa.

[THE EFFECT OF ACID RAIN ON ULTRASTRUCTURE AND FUNCTIONAL PARAMETERS OF PHOTOSYNTHETIC APPARATUS OF PEA LEAVES]

The effects of simulated acid rain (SAR) on the ultrastructure and functional parameters of the photosynthetic apparatus were studied using 14-day-old pea leaves as test system. Pea plants were sprayed with an aqueous solution containing NaNO₃(0.2 mM) and Na₂SO₄(0.2 mM) (pH 5.6, a control variant), or with the same solution, which was acidified to pH 2.5 (acid variant). Functional characteristics were determined by chlorophyll fluorescence analysis. Acid rain application caused reduction in the efficiency of the photosynthetic electron transport by 25%, which was accompanied by an increase by 85% in the quantum yield of thermal dissipation of excess light quanta. Ultrastructural changes in chloroplast were registered by transmission electron microscopy (TEM) after two days of the SAR-treatment of pea leaves. In this case, the changes in the structure of grana, heterogeneity of thylakoids packaging in granum, namely, the increase of intra-thylakoid gaps and thickness of granal thylakoids compared to the control were found. The migration of protein complexes in thylakoid membranes of chloroplasts isolated from leaves treated with SAR was suppressed. It was shown also that carbonic anhydrase activity was inhibited in chloroplast preparations isolated from SAR-treated pea leaves. We proposed a hypothesis on the possible inactivation of thylakoid carbonic anhydrase under SAR and its involvement in the inhibition of photochemical activity of chloroplasts. The data obtained allows to suggest that acid rains negatively affect the photosynthetic apparatus disrupting the membrane system of chloroplast.

Acute and chronic toxicity of sodium sulfate to four freshwater organisms in water-only exposures

The acute and chronic toxicity of sulfate (tested as sodium sulfate) was determined in diluted well water (hardness of 100 mg/L and pH 8.2) with a cladoceran (Ceriodaphnia dubia; 2-d and 7-d exposures), a midge (Chironomus dilutus; 4-d and 41-d exposures), a unionid mussel (pink mucket, Lampsilis abrupta; 4-d and 28-d exposures), and a fish (fathead minnow, Pimephales promelas; 4-d and 34-d exposures). Among the 4 species, the cladoceran and mussel were acutely more sensitive to sulfate than the midge and fathead minnow, whereas the fathead minnow was chronically more sensitive than the other 3 species. Acute-to-chronic ratios ranged from 2.34 to 5.68 for the 3 invertebrates but were as high as 12.69 for the fish. The fathead minnow was highly sensitive to sulfate during the transitional period from embryo development to hatching in the diluted well water, and thus, additional short-term (7- to 14-d) sulfate toxicity tests were conducted starting with embryonic fathead minnow in test waters with different ionic compositions at a water hardness of 100 mg/L. Increasing chloride in test water from 10 mg Cl/L to 25 mg Cl/L did not influence sulfate toxicity to the fish, whereas increasing potassium in test water from 1 mg K/L to 3 mg K/L substantially reduced the toxicity of sulfate. The results indicate that both acute and chronic sulfate toxicity data, and the influence of potassium on sulfate toxicity to fish embryos, need to be considered when environmental guidance values for sulfate are developed or refined.

The effect of sulfate on selenate bioaccumulation in two freshwater primary producers: A duckweed (Lemna minor) and a green alga (Pseudokirchneriella subcapitata)

Predicting selenium bioaccumulation is complicated because site-specific conditions, including the ionic composition of water, affect the bioconcentration of inorganic selenium into the food web. Selenium tissue concentrations were measured in Lemna minor and Pseudokirchneriella subcapitata following exposure to selenate and sulfate. Selenium accumulation differed between species, and sulfate reduced selenium uptake in both species, indicating that ionic constituents, in particular sulfate, are important in modifying selenium uptake by primary producers.

Effects of environmentally relevant mixtures of major ions on a freshwater mussel

The Clinch and Powell Rivers (Virginia, USA) support diverse mussel assemblages. Extensive coal mining occurs in both watersheds. In large reaches of both rivers, major ion concentrations are elevated and mussels have been extirpated or are declining. We conducted a laboratory study to assess major ion effects on growth and survival of juvenile Villosa iris. Mussels were exposed to pond water and diluted pond water with environmentally relevant major ion mixtures for 55 days. Two treatments were tested to mimic low-flow concentrations of Ca(2+), Mg(2+), [Formula: see text] , [Formula: see text] , K(+) and Cl(-) in the Clinch and Powell Rivers, total ion concentrations of 419 mg/L and 942 mg/L, respectively. Mussel survival (>90%) and growth in the two treatments showed little variation, and were not significantly different than in diluted pond water (control). Results suggest that major ion chronic toxicity is not the primary cause for mussel declines in the Clinch and Powell Rivers.

Exposure to Elemental Carbon, Organic Carbon, Nitrate, and Sulfate Fractions of Fine Particulate Matter and Risk of Preterm Birth in New Jersey, Ohio, and Pennsylvania (2000-2005)

BACKGROUND

Particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) has been consistently associated with preterm birth (PTB) to varying degrees, but roles of PM2.5 species have been less studied.

OBJECTIVE

We estimated risk differences (RD) of PTB (reported per 106 pregnancies) associated with change in ambient concentrations of elemental carbon (EC), organic carbon (OC), nitrates (NO3), and sulfates (SO4).

METHODS

From live birth certificates from three states, we constructed a cohort of singleton pregnancies at or beyond 20 weeks of gestation from 2000 through 2005 (n = 1,771,225; 8% PTB). We estimated mean species exposures for each week of gestation from monitor-corrected Community Multi-Scale Air Quality modeling data. RDs and 95% confidence intervals (CIs) for four PTB categories were estimated for each exposure using linear regression, adjusted for maternal race/ethnicity, marital status, education, age, smoking, maximum temperature, ozone, and season of conception. We also adjusted for other species in multi-species models.

RESULTS

RDs varied by exposure window and outcome period. EC was positively associated with PTB after 27 and before 35 weeks of gestation. For example, for a 0.25-μg/m(3) increase in EC exposure during gestational week 9, RD = 96 (95% CI: -20, 213) and RD = 145 (95% CI: -50, 341) for PTB during weeks 28-31 and 32-34, respectively. Associations with OCs were null or negative. RDs for NO3 were elevated with exposure in early weeks of gestation, and null in later weeks. RDs for SO4 exposure were positively associated with PTB, though magnitude varied across gestational weeks. We observed effect measure modification for associations between EC and PTB by race/ethnicity and smoking status.

CONCLUSION

EC and SO4 may contribute to associations between PM2.5 and PTB. Associations varied according to the timing of exposure and the timing of PTB.

Contrasting effects of chloride on growth, reproduction, and toxicant sensitivity in two genetically distinct strains of Hyalella azteca

The strain of Hyalella azteca (Saussure: Amphipoda) commonly used for aquatic toxicity testing in the United States has been shown to perform poorly in some standardized reconstituted waters frequently used for other test species. In 10-d and 42-d experiments, the growth and reproduction of the US laboratory strain of H. azteca was shown to vary strongly with chloride concentration in the test water, with declining performance observed below 15 mg/L to 20 mg/L. In contrast to the chloride-dependent performance of the US laboratory strain of H. azteca, growth of a genetically distinct strain of H. azteca obtained from an Environment Canada laboratory in Burlington, Ontario, Canada, was not influenced by chloride concentration. In acute toxicity tests with the US laboratory strain of H. azteca, the acute toxicity of sodium nitrate increased with decreasing chloride in a pattern similar not only to that observed for control growth, but also to previous acute toxicity testing with sodium sulfate. Subsequent testing with the Burlington strain showed no significant relationship between chloride concentration and the acute toxicity of sodium nitrate or sodium sulfate. These findings suggest that the chloride-dependent toxicity shown for the US laboratory strain may be an unusual feature of that strain and perhaps not broadly representative of aquatic organisms as a whole.

Full-life chronic toxicity of sodium salts to the mayfly Neocloeon triangulifer in tests with laboratory cultured food

Although insects occur in nearly all freshwater ecosystems, few sensitive insect models exist for use in determining the toxicity of contaminants. The objectives of the present study were to adapt previously developed culturing and toxicity testing methods for the mayfly Neocloeon triangulifer (Ephemeroptera: Baetidae), and to further develop a method for chronic toxicity tests spanning organism ages of less than 24 h post hatch to adult emergence, using a laboratory cultured diatom diet. The authors conducted 96-h fed acute tests and full-life chronic toxicity tests with sodium chloride, sodium nitrate, and sodium sulfate. The authors generated 96-h median lethal concentrations (LC50s) of 1062 mg Cl/L (mean of 3 tests), 179 mg N-NO3 /L, and 1227 mg SO4 /L. Acute to chronic ratios ranged from 2.1 to 6.4 for chloride, 2.5 to 5.1 for nitrate, and 2.3 to 8.5 for sulfate. The endpoints related to survival and development time were consistently the most sensitive in the tests. The chronic values generated for chloride were in the same range as those generated by others using natural foods. Furthermore, our weight-versus-fecundity plots were similar to those previously published using the food culturing method on which the present authors' method was based, indicating good potential for standardization. The authors believe that the continued use of this sensitive mayfly species in laboratory studies will help to close the gap in understanding between standard laboratory toxicity test results and field-based observations of community impairment.

[MORPHOFUNCTIONAL ADJUSTMENT VASCULAR AND CELLULAR COMPONENTS OF THE CEREBELLAR CORTEX IN EXPOSURE TO BODY SULFATES OF COPPER, ZINC AND IRON]

In order to analyze the morphological and morphometric reconstructions of the vascular bed, and Purkinje cells of the cerebellar cortex of rats in long-term action (for 90 days) on the body of sulphates of copper, zinc and iron, an experiment was conducted on 48 adult white male rats weighing 200-250 g in age 5-7 months. We used anatomical, morphometric, statistical and common methods of microanatomical research. It was found that the combined effect on the body of sulphates of copper and zinc, and iron in the cerebellum has enough expressive toxicity, which affects the condition of the vascular bed, and Purkinje cells. The degree of morphological transformations is in direct proportion to the duration of the experiment. In the pathogenesis of violations leading role played by hypoxia, develop signs of swelling of the cerebellar cortex with signs hemorrhagic infiltration, the severity of which is maximum on the 60th day of the experiment.

The short-term association of selected components of fine particulate matter and mortality in the Denver Aerosol Sources and Health (DASH) study

BACKGROUND

Associations of short-term exposure to fine particulate matter (PM2.5) with daily mortality may be due to specific PM2.5 chemical components. Daily concentrations of PM2.5 components were measured over five years in Denver to investigate whether specific PM2.5 components are associated with daily mortality.

METHODS

Daily counts of total and cause-specific deaths were obtained for the 5-county Denver metropolitan region from 2003 through 2007. Daily 24-hour concentrations of PM2.5, elemental carbon (EC), organic carbon (OC), sulfate and nitrate were measured at a central residential monitoring site. Using generalized additive models, we estimated relative risks (RRs) of daily death counts for daily PM2.5 and four PM2.5 component concentrations at single and distributed lags between the current and three previous days, while controlling for longer-term time trend and meteorology.

RESULTS

RR of total non-accidental mortality for an inter-quartile increase of 4.55 μg/m(3) in PM2.5 distributed over 4 days was 1.012 (95 % confidence interval: 0.999, 1.025); RRs for EC and OC were larger (1.024 [1.005, 1.043] and 1.020 [1.000, 1.040] for 0.33 and 1.67 μg/m(3) increases, respectively) than those for sulfate and nitrate. We generally did not observe associations with cardiovascular and respiratory mortality except for associations with ischemic heart disease mortality at lags 3 and 0-3 depending on the component. In addition, there were associations with cancer mortality, particularly for EC and OC, possibly reflecting advanced deaths of a frail population.

CONCLUSIONS

PM2.5 components possibly from combustion-related sources are more strongly associated with daily mortality than are secondary inorganic aerosols.

[Effects of chronic manganese sulfate toxicity test on myocardial ultrastructure and heart organ index of rats]

OBJECTIVE

To observe the effects of manganese sulfate on blood pressure, myocardial ultrastructure and heart organ index of rats.

METHODS

Forty male SPF SD rats were randomly divided into 4 groups: control group (0 mg/kg), 5 mg/kg dose group, 15 mg/kg dose group and 25 mg/kg dose group, 10 rats each group. Intraperitoneal injection was performed for six months, by five times each week, the rat blood pressure was measured by tail cuff method, and the heart organ index of the rats was computed. Three rats were selected from each group randomly, and the myocardial ultrastructure of the rats was observed by using transmission electron microscopy (TEM). The BMD and BMDL between manganese sulfate injected dose and the rats heart organ index were evaluated by BMD (Benchmark Dose).

RESULTS

There was no significant of blood pressure between the experimental group and the control group (P > 0.05).The heart organ indexes of the four groups were 0.24% ± 0.10%, 0.25% ± 0.02%, 0.26% ± 0.02%, and 0.24% ± 0.02%. Statistical significance of heart organ indexes was found between the 15 mg/kg dose group and the control group (P < 0.05). Observed by TEM, we found that-different degrees of mitochondrial crest fracture or disappear, mitochondria swelling, hydropic change and myocardial fibers degeneration happened in the rats of the three exposed groups, but not the control group. The BMD and BMDL were calculated as 9.33 mg/kg and 4.28 mg/kg in the study of manganese sulfate injected dose and the rats heart organ index.

CONCLUSION

Chronic manganese poisoning can lead to myocardial mitochondria superfine lesions, myocardial fiber damage and heart organ index change in rats.

Weight-of-evidence approach in assessment of ecotoxicological risks of acid sulphate soils in the Baltic Sea river estuaries

Acidity and leaching of metals from acid sulphate soils (ASSs) impair the water quality of receiving surface waters. The largest ASS areas in Europe are found in the coasts of the northern Baltic Sea. We used weight-of-evidence (WoE) approach to assess potential risks in 14 estuary sites affected by ASS in the Gulf of Finland, northern Baltic Sea. The assessment was based on exposure and effect profiles utilizing sediment and water metal concentrations and concurrent pH variation, sediment toxicity tests using the luminescent bacterium Vibrio fischeri and the midge Chironomus riparius, and the ecological status of benthic macroinvertebrate communities. Sediment metal concentrations were compared to national sediment quality criteria/guidelines, and water metal concentrations to environmental quality standards (EQSs). Hazard quotients (HQs) were established for maximum aluminium, cadmium and zinc concentrations at low pH based on applicable US EPA toxicity database. Sediment metal concentrations were clearly elevated in most of the studied estuaries. The EQS of cadmium (0.1 μg/l) was exceeded in 3 estuaries out of 14. The pH-minima were below the national threshold value (5.5) between good and satisfactory water quality in 10 estuaries. V. fischeri bioluminescence indicated toxicity of the sediments but toxic response was not observed in the C. riparius emergence test. Benthic invertebrate communities were deteriorated in 6 out of 14 sites based on the benthic invertebrate quality index. The overall ecotoxicological risk was assessed as low in five, moderate in three and high in five of the estuary sites. The risk assessment utilizing the WoE approach indicated that harmful effects of ASSs are likely to occur in the Baltic Sea river estuaries located at the ASS hotspot area.

Industrial dust sulphate and its effects on biochemical and morphological characteristics of Morus (Morus alba) plant in NCR Delhi

Abundance of CaCO3 rich soil dust is a typical feature of atmospheric environment in the Indian region. During prevailing dry weather conditions, dustfall is deposited onto the foliar surfaces of plant affecting their morphology, stomata and the levels of biochemical constituents. This study reports the chemical characteristics of dustfall, its effect on foliar morphology and biochemical constituents of a medicinal plant (Morus alba) at two sites which are differentiated on the basis of landuse pattern, viz., (i) residential, Jawaharlal Nehru University (JNU), and (ii) industrial, Sahibabad (SB), located in the National Capital Region (NCR) of Delhi. Dustfall was characterized for major anions (F(-), Cl(-), NO3 (-) and SO4 (--)) and cations (Na(+), NH4 (+), K(+), Mg(++) and Ca(++)). Biochemical parameters such as chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, proline and ascorbic acid were determined in foliar samples. The results showed that the dustfall fluxes of all the major ions were found to be higher at the industrial site (SB) as compared to the residential site (JNU). Foliar analysis revealed that the levels of biochemical parameters were more affected at SB site due to higher levels of dust SO4 (--) contributed by various anthropogenic sources resulting in more stressful conditions affecting the biochemistry of the plant. The possible entry pathways for dust SO4 (--) into foliar cells are also discussed in the paper. It was noticed that the deposition of urban dust was responsible for the damage of trichome, epidermis, cuticle and stomatal guard cells significantly affecting foliar morphology. SB exhibited more damage to these morphological parts suggesting that industrial dust is harmful to the plants.

TOXICITY OF CHLORPYRIPHOS CONTAINING FORMULATION AND HEAVY ELEMENTS (Cd, Pb) TO CHICKEN EMBRYOS

The phytotoxic effect of cadmium sulphate, lead acetate and chlorpyriphos containing insecticide Pyrinex 48 EC were investigated on chicken embryos on late developmental stage (day 19 of incubation). The eggs were injected by 0.1 ml amount of lead acetate (0.1%), of cadmium sulphate (0.01%), of Pyrinex 48 EC (chlorpyriphos, 480 g/l; 1%) and as a control 0.1 ml of bird-physiologic saline solution (0.75%). The treatments were performed on day 0 of incubation, and the embryos were examined on day 19. Number of embryonic death, developmental abnormalities and body weight of embryos were recorded on day 19. The body weight of embryos reduced significantly, the rate of embryo mortality increased, but teratogenic effect was not realised by the single treatment of lead acetate and cadmium sulphate. By the single administration of PYRINEX 48 EC the average body weight of embryos resulted in a significant decrease and the rate of embryo mortality and developmental anomalies were increased and it was found to be embryo toxic and teratogenic in the embryos. The increased embryo toxic effect can occur by the additive effect of the heavy elements (cadmium sulphate and lead acetate) and the PYRINEX 48 EC.

Toxicity of sulfate and chloride to early life stages of wild rice (Zizania palustris)

Despite the importance of wild rice (Zizania palustris) in the Great Lakes region of North America, its sensitivity to sulfate is not well understood. A 21-d hydroponic experiment was performed to determine the toxicity of sulfate to wild rice seeds and seedlings. Effects of 6 sulfate concentrations ranging from 10 mg/L to 5000 mg/L and of chloride salts at equivalent conductivity were evaluated to determine whether adverse effects were attributable to sulfate or to conductivity-related stress. Sulfate treatment decreased root length, shoot length, and leaf number, and increased phytotoxic effects at concentrations of 5000 mg/L relative to a 50 mg/L control. The time to 30% mesocotyl emergence decreased at 2500 mg/L sulfate, indicating a potential stimulatory effect. Sulfate exposures of ≤ 5000 mg/L had no effect on 5 additional end points. Multiple regression analysis indicated that most observed changes could be attributed to conductivity-related stress rather than sulfate per se, with the exception of shoot length and leaf number. Chloride was more toxic than sulfate, as determined by root length and phytotoxicity. In summary, sulfate concentrations below 5000 mg/L did not adversely affect early-life stage wild rice during a 21-d period, and effects at 5000 mg/L sulfate were attributable to conductivity-related stress rather than sulfate toxicity in 2 of 4 end points.

Short-term airborne particulate matter exposure alters the epigenetic landscape of human genes associated with the mitogen-activated protein kinase network: a cross-sectional study

BACKGROUND

Exposure to air particulate matter is known to elevate blood biomarkers of inflammation and to increase cardiopulmonary morbidity and mortality. Major components of airborne particulate matter typically include black carbon from traffic and sulfates from coal-burning power plants. DNA methylation is thought to be sensitive to these environmental toxins and possibly mediate environmental effects on clinical outcomes via regulation of gene networks. The underlying mechanisms may include epigenetic modulation of major inflammatory pathways, yet the details remain unclear.

METHODS

We sought to elucidate how short-term exposure to air pollution components, singly and/or in combination, alter blood DNA methylation in certain inflammation-associated gene networks, MAPK and NF-κB, which may transmit the environmental signal(s) and influence the inflammatory pathway in vivo. To this end, we utilized a custom-integrated workflow-molecular processing, pollution surveillance, biostatical analysis, and bioinformatic visualization-to map novel human (epi)gene pathway-environment interactions.

RESULTS

Specifically, out of 84 MAPK pathway genes considered, we identified 11 whose DNA methylation status was highly associated with black carbon exposure, after adjusting for potential confounders-age, sulfate exposure, smoking, blood cell composition, and blood pressure. Moreover, after adjusting for these confounders, multi-pollutant analysis of synergistic DNA methylations significantly associated with sulfate and BC exposures yielded 14 MAPK genes. No associations were found with the NF-κB pathway.

CONCLUSION

Exposure to short-term air pollution components thus resulted in quantifiable epigenetic changes in the promoter areas of MAPK pathway genes. Bioinformatic mapping of single- vs. multi-exposure-associated epigenetic changes suggests that these alterations might affect biological pathways in nuanced ways that are not simply additive or fully predictable via individual-level exposure assessments.

Investigation of the toxicity of common oxidants used in advanced oxidation processes and their quenching agents

The inhibitory effect of commonly known oxidants and their quenching agents was investigated by employing a battery of toxicity tests. Hydrogen peroxide toxicity could be effectively eliminated by the enzyme catalase, whereas sodium thiosulfate and ascorbic acid were recommended as suitable quenching agents for the removal of the oxidants persulfate and peroxymonosulfate in the Vibrio fischeri bioassays. None of the studied quenching agents was found to be suitable for persulfate and peroxymonosulfate in the Daphnia magna bioassays since high inhibitory effects were obtained for both oxidants. In the case of Pseudokirchneriella subcapitata, manganese dioxide powder should be used as an alternative quenching agent to catalase, since this enzyme exhibited a highly toxic effect towards these microalgae. Sodium sulfite, which is extensively used as a quenching agent, was not appropriate for quenching peroxymonosulfate in all studied bioassays.

Reduction of acute toxicity and genotoxicity of dye effluent using Fenton-coagulation process

Dye wastewater exhibits significant ecotoxicity even though its physico-chemical parameters meet the discharge standards. In this work, the acute toxicity and genotoxicity of dye effluent were tested, and the Fenton-coagulation process was carried out to detoxify this dye effluent. The acute toxicity was evaluated according to the mortality rate of zebrafish, and genotoxicity was evaluated by micronucleus (MN) and comet assays. Removal of color and chemical oxygen demand (COD) was also investigated. The results indicated that the dye effluent showed strong acute toxicity and genotoxicity to zebrafish. After 4h of treatment by Fenton-coagulation process, the dye effluent exhibited no significant acute toxicity and genotoxicity to zebrafish. In addition, its COD was less than 50mg/L, which met the discharge standard. It demonstrates that Fenton-coagulation process can comprehensively reduce the acute toxicity and genotoxicity as well as the COD of the dye effluent.

Genome-wide approach in Arabidopsis thaliana to assess the toxicity of cadmium sulfide quantum dots

Cadmium sulfide quantum dots (CdS QDs) are used in the manufacture of a number of electronics products. Their small size allows their ready entry into living cells, but as yet no attempt has been made to assess their toxicity. Our aim was to exploit two Ds transposition-induced mutant lines of Arabidopsis thaliana which tolerated exposure to CdS QDs to identify the genetic basis of their tolerance. Both a genome-wide top-down (from mutant to genes) and a bottom-up (from gene expression to phenotype) approach were applied. The differential responses of the mutants compared to the wild type showed that sensitivity to CdS QDs was unrelated to sensitivity to Cd(2+) ions. A transcriptomic analysis identified a number of genes whose transcript abundance was correlated with the tolerance. The phenotype of one of the mutants was correlated with the overexpression of ELM2, an MYB containing gene visited by a Ds transposon. Segregation analysis showed that the genetic basis of CdS QDs tolerance in both mutants was monogenic. The phenotype of the other mutant could be explained by the mutation of HCF101, a gene involved in photosynthesis.