[Show abstract][Hide abstract] ABSTRACT: An in vitro bioassay procedure was used to investigate the toxic action of chlorophenols on mitochondrial respiratory parameters The toxicity of these compounds was evaluated by determining their effects on the energy coupled reverse electron transfer (RET) in submitochondrial particles (SMPs) from beef heart mitochondria The bioassay procedure is based on the spectrophotometric recording of the effects of toxicants on the rate of NAD+ reduction, induced by ATP and succinate at the first site level of the respiratory chain The toxicity end point was expressed as the toxicant concentration that causes 50% inhibition of NAD+ reduction rate (EC50). The EC50 values determined for the 14 tested chlorophenols ranged from 17 mg/L for 2 chlorophenol to 0 081 mg/L for pentachlorophenol, indicating a general trend of increasing toxicity with increasing chlorine substitution Among chlorophenol isomers, which have the same number of chlorine atoms, a lesser toxicity was associated with ortho-substituted chlorophenols, whereas meta substituted chlorophenols were much more toxic The EC50 values were compared with the toxicity data for a variety of bioassays, by means of linear regression analysis High degrees of correlation obtained with toxicity tests involving different freshwater species demonstrate the ability of SMPs to reproduce the toxic effects of the tested compounds upon aquatic organisms This supports the assessment that the respiratory chain is the main target of this class of toxicants Results obtained with chlorophenols and, in previous studies, with other environmental contaminants confirm the suitability of the SMP bioassay as a prescreening or complementary short term test for monitoring aquatic toxicity
[Show abstract][Hide abstract] ABSTRACT: The effects on mitochondrial respiratory parameters of linear alkylbenzene sulfonates (LAS), nonylphenol polyeth-oxylates (NPEO), and some of their biotransformation products, namely sulfophenyl carboxylates (SPCs), nonylphenol (NP), and nonylphenoxy acetic acid (NP1EC), were recorded by using the in vitro response of submitochondrial particles (SMP) from beef heart. The toxicity of these compounds was estimated by determining their effects on the energy-coupled reverse electron transfer (RET), which is induced by ATP and succinate at the first site level of the respiratory chain and reduces exogenous NAD+ to NADH. The toxicity of the substances, expressed as the toxicant concentration decreasing the reduction rate of NAD+ to an extent of 50% (EC50), ranged from 0.61 mg/L for a commercial LAS mixture to 18,000 mg/L for individual SPCs; from 1.3 mg/L for NPEO, with an average of 10 ethoxy units, to 8.2 and 1.8 mg/L for NP1EC and NP, respectively. These results were related to the molecular structure of each compound class and compared with the toxicity values obtained by a variety of biological systems currently used for toxicity testing. The acute toxicity data have demonstrated that (a) the SMP bioassay is suitable for reproducing the toxicological response of whole organisms, such as fishes and invertebrates, to the tested chemicals; and (b) the hydrophobic moiety of these compounds plays a significant role in eliciting their toxic effects. From a toxicological standpoint, attention must be paid to the occurrence in natural waters of residual LAS, whereas in the case of NPEO both unaltered surfactant and all biotransformation products need to be identified and quantified.
[Show abstract][Hide abstract] ABSTRACT: The concentration changes of 12 metals (As, Hg, Cd, Cr, Co, Cu, Pb, Mn, Ni, V, Zn, Fe, and Hg) in the soft tissues of Tapes philippinarum during growth were investigated. Clams were seeded in two contaminated areas of the Venice lagoon (San Giuliano and Fusina) and in an area of the Marano lagoon (Lignano Sabbiadoro) close to the clam-farm where the seed was produced. Metal trends were very different according to the considered element, the study site and the growth period.
Arsenic was always higher in clam tissues than in surface sediments and suspended particles in all the three stations. Mercury, Cd and Cu were higher in the clams from Marano and Fusina but not in those from San Giuliano. Zinc and Co in clams exceeded the concentrations in the sediment and suspended particles only at Marano. The other elements (Cr, Pb, Mn, Ni, and Fe) were always higher in SPM and sediments. In general metal concentrations in clams were more highly correlated to concentrations in the suspended particles rather than in the surface sediments and in suspended clams rather than in bottom clams, nevertheless significant differences between stations and contaminants were found. Metal concentrations in clams were always lower than the European regulatory limits.
[Show abstract][Hide abstract] ABSTRACT: Acid extractions represent a simple and effective tool for the assessment of metal contamination, origin and bioavailability in the aquatic environment. Optimized microwave-assisted procedures utilizing two extractions (8 M HNO3 and 1 M HCl) were developed. Particular attention was given to the evaluation of efficiency and selectivity of the developed procedures. This involved an examination of the sediment and the extraction residues by Mössbauer spectroscopy and X-ray diffractometry. These instrumental approaches were used to identify the geochemical phases associated with acid decomposition. Microwave digestion with 8 M HNO3 produced an efficient solubilization of the most important metal-bearing phases and left unaffected only the minerals (quartz, feldspars, muscovite) with a negligible metal content, thus providing a good estimate of the total metal concentrations. The 1 M HCl extraction, despite the limitation due to the incomplete solubilization of pyrite and to the partial dissolution of sheet silicates, represents a simple and effective technique for providing an estimate of the bioavailable metal fraction in sediments. The combined use of the two microwave-assisted acid extractions can provide a rapid and simple approach for the risk assessment of metal-polluted sediments.
[Show abstract][Hide abstract] ABSTRACT: A simple and rapid in vitro toxicological assay, utilizing submitochondrial particles (SMP), has been used to evaluate the toxic effects of fifteen herbicides belonging to the phenol and phenoxyalkanoic acid chemical classes. The SMP assay allows the quantitative evaluation of the toxicity of compounds with different mechanisms of action: uncouplers, inhibitors of the enzyme complexes involved in reverse electron transfer and in oxidative phosphorylation and chemicals that alter the membrane structure. The two groups of herbicides showed different levels of toxicity. For phenol derivatives, EC50 values ranged from 0.16 microM (ioxynil) to 6.7 microM (2,4-dinitrophenol), whereas for phenoxy herbicides EC50 values ranged from 21 microM (2,4,5-trichlorophenoxyacetic acid, 2,4,5-T) to 110 microM (4-chloro-2-methylphenoxyacetic acid, MCPA). On the average, the toxicity of phenolic compounds is greater than that of phenoxyalkanoic acids by two orders of magnitude. Quantitative structure-activity relationships (QSAR) were developed between EC50 values and various molecular descriptors. The results suggest the existence of different mechanisms of action for the two classes of compounds. The findings obtained for phenolic herbicides are consistent with a protonophoric uncoupling mechanism, whereas for phenoxy herbicides a non-specific mode of action at membrane level can be hypothesized.
Toxicology in Vitro 01/2006; 19(8):1035-43. · 2.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Atmospheric deposition in the lagoon of Venice and river inputs from the watershed were collected and analysed from 1998 to 1999 using the same analytical methods. The input from riverine sources largely prevails (>70%) over that from the atmosphere for As, Cr, Fe, Mn, Ni, nitrogen and phosphorus. Equivalent amounts of Hg, Pb, PCBs, HCB are discharged into the lagoon from the two sources, whilst atmospheric inputs prevail for Cd, ammonia and dioxins. A comparison with figures of maximum allowable discharges (MAD) for various compounds, recently set by the Italian Ministry for the Environment, showed that total inputs (riverine+atmospheric) of trace metals were below the MAD thresholds only for Cr, Cu, Ni and Zn. The total inputs of Cu and Ni, and Cr and Zn were approximately 20 and 40% of the MAD limit, respectively. The total phosphorus input of 284t was close to the imposed limit, whilst the inorganic nitrogen load alone (>4000t) was much higher than the MAD for total nitrogen. For those metals (As, Cd, Hg and Pb) and persistent organic pollutants, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) where the MAD states that the load should tend to ‘0’ (no discharge), the measured inputs of 4.8 (As) and 5.1t (Pb), 151 (Cd) and 39kg (Hg), 18g (PCDD/Fs) and 440mg (Toxicity Equivalents, TEQs, of PCDD/Fs) are by definition ‘above’ the MAD. The principal component analysis (PCA) of loading data and input profiles (markers) of production typologies showed that river and atmosphere contributions can be easily separated and recognised due to their different fingerprints. Riverine inputs were similar to chemical and glass work production markers, whereas atmospheric loadings were mainly influenced by chemical industry (PVC and VCM production), metallurgy and paper-mill.
[Show abstract][Hide abstract] ABSTRACT: Samples of Mytilus galloprovincialis collected in different sites of the Venice lagoon (Italy) were investigated for total arsenic concentrations by ICP-AES and for single arsenic species by HPLC-ICP-MS. For this purpose, an analytical procedure for the sensitive and efficient speciation of the arsenic species As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AB), arsenocholine (AC), and four arsenosugars was optimised. The total arsenic and the single arsenic species were determined in both the hepatopancreas (digestive gland) and the remaining soft tissues in order to verify the different arsenic accumulation in the body parts of mussels. Arsenic compounds were extracted from the mussels with a methanol/water mixture; the extracts were evaporated to dryness, redissolved in water, and chromatographed in an anion-exchange column, a Hamilton PRP-X100. Only small quantities or traces of inorganic arsenic were detected in the mussels. The majority of arsenic compounds detected in the extracts were organic species, with a predominance of arsenobetaine and of an arsenosugar. In addition, a greater arsenic accumulation in the digestive glands of mussels was observed.
Science of The Total Environment 10/2005; 348(1-3):267-77. · 3.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In order to assess the actual pollutant loads from the drainage basin, the twelve major tributaries of the Venice Lagoon were monitored and studied in the period 1998-2000 in the framework of the DRAIN project. A specific sampling scheme was designed to investigate the effects of the different regimes, including floods, in the transport of total and dissolved metals, nitrogen and phosphorous species as well as organic micropollutants. The loads were calculated from data collected during the year of 1999, since this year displayed a value close to the mean in terms of the distribution of total rainfall on the drainage basin. The annual values for the different pollutants are reported and discussed. A comparison with the estimates of previous investigations highlights the significant advancement provided by the DRAIN project results in the understanding of the drainage basin contribution to the pollution of the lagoon. Finally, the importance of flood events on the overall balance of materials and pollutants delivered to the lagoon is emphasized.
Environment International 10/2005; 31(7):939-47. · 6.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study a procedure of sequential extraction of metals from sediments was applied to samples from the lagoon of Venice. Compared to the measurement of total concentrations, the knowledge of metal partitioning among sediment phases can help in estimating the risk posed by metal polluted sediments and give information on contamination sources and on the factors that influence metal enrichment in sediments. The results permitted to estimate for each metal the percentage of the total content that could be potentially remobilized from sediments, owing to changes in environmental conditions. The immediately available fraction represented in general a low proportion of the total content. An important proportion of most metals (except for Zn, Cd and Cu) was associated to residual phases and therefore was not expected to be released under the normal environmental conditions. The large amounts of metals bound to Fe-Mn oxides/hydroxides confirmed the strong scavenging efficiency of this phase. The carbonate phase was the preferential associative form for Pb, Cd and Zn, whereas Cu was bound in prevalence to the organic matter/sulphide phase.
Annali di Chimica 05/2003; 93(4):329-36. · 0.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A rapid and relatively low cost bioassay, usable in routine screening water test, was developed by Perin et al (Int. Conf. “Environment, Food and Public Health”, Rovereto, Italy, 1991), based on the original work of George A. Blondin (Institute for Enzyme Research Madison, WI USA). The bioassay is based on the oxygen consumption by frozen Beef Heart Mitochondria at -22 °C (FM22), monitored by a Clark electrode, and interfaced to a PC to collect test analysis data. A piecewise regression through an Excel® Macro identified the break point in the oxygen consumption due to the toxicant action and calculated the toxicity. In order to verify sensitivity of the bioassay blank tests were carried out to verify the oxygen consumption linear fitting, and toxicity tests were performed using pure organic and inorganic compounds. The suitability of the bioassay for environmental research was verified by testing different water effluents (surface water, sewage treatment, industrial plant effluents etc). According to the FM22 bioassay gave, accordingly, different quantitative response. The FM22 bioassay resulted, therefore, highly reproducible in the toxicity test with pure compounds and was a good predictor of toxicity for environmental samples, usable for easy and rapid routine application.
1st SETAC World Congress “Ecotoxicology and Environmental Chemistry - A Global Perspective”; 03/2003
[Show abstract][Hide abstract] ABSTRACT: Sperm cell and embryo toxicity tests using the Mediterranean sea urchin Paracentrotus lividus were performed to assess the toxicity of tributyltin chloride, bis(tributyltin)oxide, triphenyltin acetate, and triphenyltin hydroxide. Toxicity values (mean effective concentration [EC50]) ranged from 2.97 to 18.5 microg/L for sperm cells and from 1.11 to 2.62 microg/L for embryos. For sperm cells, the toxicity of the two tributyl compounds was significantly greater than that of two triphenyl compounds; for embryos, the triphenyl compounds appeared to be more toxic. Study of embryotoxic effects highlighted closely concentration-dependent damages, the most sensitive stages corresponding to the crucial phases of differentiation (gastrula and prisma). Both EC50 and no-observed-effect concentration values for the four organotin compounds are similar to those reported in the literature for early life stages of other marine organisms.
Environmental Toxicology and Chemistry 05/2002; 21(4):859-64. · 2.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The toxic effects of eighteen substituted anilines were determined by means of a short-term in vitro assay, using submitochondrial particles (SMP) as biosensors. The assay allows for the quantification of the effects of toxicants that act specifically on mitochondrial respiratory functions, like uncouplers and inhibitors, or non-specifically, by disturbing the structure and functioning of the inner mitochondrial membrane. The obtained EC(50) values range from 72.5 to 1910 micromol/l. The type and position of the substituents are of fundamental importance in determining the toxic potency. In general, the presence of electron-withdrawing substituents produces higher toxic effects, whereas electron-donating groups seem to reduce the toxicity. Quantitative structure-activity relationships (QSAR) showed that toxicity values were correlated with the Hammett sigma constant and with hydrogen bonding capacity descriptors, such as E(LUMO), E(HOMO) and Q(+). The results indicate that toxicity increases with increasing the hydrogen bonding donor capacity of the NH(2) group and support the hypothesis of a mechanism of action based on hydrogen bonding formation between the amino group of anilines and polar groups at the membrane/water interface. Such an interaction would cause a derangement of the membrane structure and, as a consequence, a disturbance of its functioning.
Biochimica et Biophysica Acta 03/2002; 1558(2):151-60. · 4.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effects on mitochondrial respiration of 15 chloroanilines were recorded by using the in vitro response of submitochondrial particles (SMP) from beef heart mitochondria. The bioassay procedure for SMP is based on the process of reverse electron transfer, which can be negatively affected by inhibitors of electron transport, by uncouplers, and by chemicals that impair membrane integrity. The EC50 values, determined for the tested chloroanilines, indicate a general tendency of increasing toxicity with increasing chlorine substitution. In order to validate the results obtained and to evaluate the capability of the SMP assay to reproduce the toxic effects of the examined compounds on different freshwater species, the EC50 values were compared with literature data from other biological assays regarding both in vitro systems and whole organisms. A good correlation was found in particular with two widely used testing systems, the Microtox and the Tetrahymena assays. In addition, quantitative structure-activity relationships (QSARs) were established between the EC50 values and various molecular descriptors for hydrophobic, steric, and electronic interactions. The results obtained were utilized to elucidate the mechanism of toxic action of chloroanilines, which are commonly reported to act by the polar narcosis mode of action. Moreover, they confirmed that the SMP assay can be a useful tool for studying the toxicity of chemicals that act nonspecifically by impairing membrane structure and functions.
Environmental Toxicology and Chemistry 05/2001; 20(4):826-32. · 2.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study heavy metal pollution in surface sediments of the Lagoon of Venice (Italy) was investigated. Attention was focused on the evaluation of the amounts of heavy metals that can potentially be released into the overlying water column, under particular environmental conditions, thus becoming bioavailable. To this end, the partitioning of heavy metals among different geochemical phases was determined by a procedure of sequential selective extractions. This approach can provide useful information for assessing the risk posed to the Lagoon ecosystem by metal contaminated sediments and for estimating the anthropogenic heavy metal content. In general, higher levels of contamination were found in sediments sampled in areas situated in the proximity of sources of pollutants and in degraded sites, which presented limited water circulation and prevailing anoxic conditions. The results of the sequential extraction procedure showed that partitioning is dependent on the metal considered: in particular, Pb, Cu, Zn and Cd were bound mainly to the most labile phases of sediments, whereas Cr and Ni were found prevalently in the residual fraction.
[Show abstract][Hide abstract] ABSTRACT: The toxicity of a series of chlorophenols, determined by a short-term in vitro assay utilizing mammalian submitochondrial particles, was related to the physicochemical and structural properties of these compounds.Quantitative Structure-Activity Relationships were defined by correlating EC50 values with six molecular descriptors, chosen to represent lipophilic, electronic and steric effects: the n-octanol/water partition coefficient (log KOW), the constant of Hammett (Σσ), the acid dissocidtion constant (pKa), the first order valence molecular connectivity index (1ζv), the perimeter of the efficacious section (ΣD) and the melting point (m.p.). The results of regression analysis showed that log Kow is the most successful descriptor, indicating that the ability of chlorophenols to partition into the lipid bilayer of the mitochondrial membrane has an important role in determining their toxic effects. These results are consistent with a molecular mechanism of uncoupling action based on the chemiosmotic theory and on the protonophoric properties of chlorophenols. The quality of the QSAR models confirms the suitability of the SNIP assay as a short-term prediction tool for aquatic toxicity of environmental pollutants acting on respiratory functions.
[Show abstract][Hide abstract] ABSTRACT: A field investigation was performed to evaluate the suitability of three nereid polychaetes species as biomonitors for sediment contamination by Cd and Zn in the Venetian lagoon (Italy). With regard to the treatment and subsequent chemical analysis of the animals, a specific methodology was set up. Metal concentrations in sediments and tissues were compared for 20 stations. Cd bioaccumulation was detected in all species, although bioaccumulation factors and the concentration trends were different. This finding could be explained by a difference in the metal bioavailability or in the accumulation strategy of species. Zn results have confirmed the presence of a regulation strategy in the nereid polychaetes, as previously reported.
[Show abstract][Hide abstract] ABSTRACT: The toxicity of 14 organotin compounds was investigated by means of two short-term in vitro bioassays, the submitochondrial particle (SMP) test and the Microtox® test. The first bioassay makes use of SMPs and is based on the effects of toxicants on reverse electron transport, which is induced by adenosine triphosphate and succinate at the first site level of the respiratory chain. Microtox is a well known test system that uses marine luminescent bacteria and quantifies toxicity by measuring the reduction of luminescence caused by toxic chemicals. Very good agreement was observed between the median effective concentration (EC50) values determined for organotin compounds by means of the two bioassays. Toxicity depended on both the number and kind of organic substituents bound to the tin atom. It followed the order triorganotins > diorganotins ≈ tetraorganotins > monoorganotins. Within each series, butyltin and phenyltin compounds exhibited the highest toxicity. Microtox and SMP EC50 values were successfully correlated with toxicity data for aquatic organisms, demonstrating the usefulness of these bioassays as prescreening or complementary tools for monitoring aquatic toxicity. Moreover, to investigate the suitability of the two assays in providing information on the mechanism of toxic action of organotins, EC50 values were correlated with various physicochemical and structural parameters of the tested compounds. The results obtained showed that these parameters are poor descriptors of organotin toxicity; in particular, the poor correlations found between EC50 values and log Kow could be ascribed to the fact that different modes of action govern the biological activity of mono-, di-, tri-, and tetraorganotin compounds, respectively.
[Show abstract][Hide abstract] ABSTRACT: The space-time distribution of some pollutants (Cu, Pb, Zn, Cd, Fe, Mn, V, Ni, Cr) in the sludge of the canals of Venice was studied. The contamination levels were comparable to, or higher, than those measured in the most polluted sediments of the Lagoon of Venice. Sediments were collected by two different sampling techniques: 1) collection of sediment cores (upper 5 cm) by a syringe-type corer; 2) collection by traps, placed on the bottom of the canal. Traps permitted the sampling of sediments essentially resuspended by overlying water turbulence. This sediment fraction is subjected to variations of its physicochemical parameters (principally change of redox conditions) and therefore to pollutant exchange at the water/sediment interface.The metals principally exchanged during sediment resuspension were Cd, Pb, Zn and Cu. These metals have principally an anthropogenic origin and are bound to the most labile geochemical phases of the sediment (such as sulphides), which can be oxidised during sediment resuspension, releasing metals into the water. Fe, Cr and Ni were only partially exchanged, while Mn and V were generally not exchanged; a significant fraction of these metals is of natural origin and is bound to the most refractory phases of the sediment.
Water Air and Soil Pollution 09/1997; 99(1):255-263. · 1.75 Impact Factor