Bioaccumulation Assessment Research Articles

Assessment of plant growth attributes, bioaccumulation, enrichment, and translocation of heavy metals in water lettuce (Pistia stratiotes L.) grown in sugar mill effluent

ABSTRACTThis study was conducted to assess the pollutant uptake capability of water lettuce (Pistia stratiotes L.) in terms of bioaccumulation, enrichment, and translocation of heavy metals grown in sugar mill effluent. Results showed that the maximum fresh weight (328.48 ± 2.04 gm kg−1), total chlorophyll content (2.13 ± 2.03 mg g−1 fwt), and relative growth rate, RGR (11.89 gg−1 d−1) of P. stratiotes were observed at 75% concentration of the sugar mill effluent after 60 days of phytoremediation experiment. The bioaccumulation factor (BF) of different heavy metals was greater than 1 with 50% and 75% concentrations of sugar mill effluent and this indicated that P. stratiotes was hyperaccumulator or phytoremediator of these metals. The enrichment factor (EF < 2 for Cu, Fe, Cr, Pb, Zn, and Mn) and (EF > 2 for Cd) indicated that P. stratiotes mineral enrichment deficient and it moderately enriched the different heavy metals. Moreover, translocation factor (TF) was less than 1 which indicated the low mobility of metals in different parts (root and leaves) of P. stratiotes after phytoremediation. Therefore, P. stratiotes can be used for phytotreatment of sugar mill effluent up to 50% to 75% concentrations and considered as hyperaccumulator aquatic plant for different heavy metals and other pollutants from the contaminated effluents.

Assessment of metals bioaccumulation and bioavailability in mussels Mytilus galloprovincialis exposed to outfalls pollution in coastal areas of Casablanca

The present work aims to study the metallic contamination of four sampling sites located nearby major sewage outfalls of the Casablanca coast (Morocco), using indigenous mussels Mytilus galloprovincialis as bioindicators of pollution. This research offered the opportunity to study trace metals bioaccumulation mechanisms, which represent a major factor in assessment processes of the pollution effects in coastal ecosystem health. The bioavailability and the bioaccumulation of trace metals (Cu, Zn, Ni, Pb) were evaluated in order to compare the metallic contamination in mussels’ tissues and find a possible correlation with physiological parameters of this filter feeding species. Our results showed a significant spatiotemporal variation of bioaccumulation, compared to control. A significant correlation coefficient between metals (Zn and Pb) bioavailability and physiological index (CI) was revealed in mussels from the most polluted location. The seasonal variation of trace metal accumulation was also raised; the highest values recorded during the dry period.

Assessment of heavy metal bioaccumulation in sorghum from neutral saline soils in the Po River Delta Plain (Northern Italy)

Po River Delta is situated in the Padania Plain at the confluence with the Adriatic Sea. Since the second half of the nineteenth century, human activities have been focused on the reclamation of wetlands, in order to use them for agricultural purposes. Nowadays these reclaimed soils are mainly used to cultivate cereals and horticultural crops. The mail problem related to this kind of soils is their capability to retain heavy metals. These can be transferred to the cultivations and to the humans, being in some cases very dangerous. It is therefore fundamental to investigate the amount of heavy metals present in reclaimed soils and that which could be transferred to the plants. With this aim, a reclaimed soil that has been used for sorghum cultivation was chosen as test field. Heavy metal concentrations of the soil, the rhizosphere and the seeds, as well as the roots and some aerial parts of the sampled sorghum were measured, respectively. High Cr and Ni concentrations were detected in the soil and rhizosphere samples, related to their natural availability due to the presence of chlorite and serpentine in these soils. On the contrary in the seeds, micronutrients such as Zn and Cu have higher concentrations with respect to Cr and Ni, but all the metals (except Cd) are below the national admitted limits. Metals classified as non-essential for humans (As, Cd, Cr, Ni) are scarcely absorbed by the plant, and their average concentrations decreased according to this pathway: soil > rhizosphere > root > aerial parts > seed. Cd, Zn and As are richer in the rhizosphere with respect to the bulk soil.

Measurement of kinetic parameters for biotransformation of polycyclic aromatic hydrocarbons by trout liver S9 fractions: Implications for bioaccumulation assessment.

In vitro substrate depletion methods developed by the pharmaceutical industry are being used with increasing frequency to support chemical bioaccumulation assessments for fish. However, the application of these methods to high log K ow chemicals poses special challenges. Biotransformation of three polycyclic aromatic hydrocarbons (PAHs) was measured using trout liver S9 fractions. Measured activity declined with incubation time and was reduced by acetone (used as a spiking solvent) at concentrations greater than 0.5%. Addition of alamethicin, a pore-forming peptide used to support UDP-glucuronosyltransferase activity, also reduced activity in a concentration-dependent manner. The substrate concentration dependence of activity was evaluated to estimate K M and V max values for each compound. Derived kinetic constants suggested that all three PAHs are transformed by the same reaction pathway and indicated an inverse correlation between K M and chemical log K ow. Binding effects on activity were evaluated by measuring unbound chemical concentrations across a range of S9 protein levels. Reaction rates were proportional to the unbound concentration except when these concentrations approached saturating levels, providing a direct demonstration of the free chemical hypothesis. These findings suggest that previous in vitro work with high log K ow compounds was conducted at inappropriately high substrate concentrations resulting in underestimation of true in vivo activity. Preliminary calculations also indicate that PAH metabolism in fish may approach saturation during standardized in vivo testing efforts, potentially resulting in concentration-dependent accumulation and/or steady-state levels of accumulation greater than those which occur in a natural setting.

Stable nitrogen and carbon isotopes in sediments and biota from three tropical marine food webs: Application to chemical bioaccumulation assessment.

Studies of trophodynamics and contaminant bioaccumulation in tropical marine ecosystems are limited. The present study employed stable isotope and trace contaminant analysis to assess sources of primary productivity, trophic interactions, and chemical bioaccumulation behavior in 2 mangrove food webs and 1 offshore coastal marine food web in Singapore. Samples of sediment, phytoplankton, mangrove leaves, clams, snails, crabs, worms, prawns, and fishes were analyzed for stable carbon and nitrogen isotope values, as well as concentrations of persistent organic pollutants. In the mangrove food webs, consumers exhibited similar δ13 C values, probably because of the well-mixed nature of these systems. However, the 2 primary consumers (common nerite and rodong snail) exhibited distinct δ13 C values (-21.6‰ vs -17.7‰), indicating different carbon sources. Fish from Singapore Strait exhibited similar δ13 C values, indicating common carbon sources in this offshore marine food web. The highest trophic level was found in glass perchlet (trophic level = 3.3) and tilapia (trophic level = 3.4) in the 2 mangrove food webs and grunter (trophic level = 3.7) in the Singapore Strait food web. Concentrations of polychlorinated biphenyl (PCB 153) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) concentrations ranged from 0.9 to 84.6 ng/g lipid weight and from <0.2 to 267.4 ng/g lipid weight, respectively. The trophic magnification factors of PCB 153 and p,p'-DDE ranged between 1.63 and 4.62, indicating biomagnification in these tropical marine food webs. The findings provide important information that will aid future chemical bioaccumulation assessment initiatives. Environ Toxicol Chem 2017;36:2521-2532. © 2017 SETAC.

Development of human biotransformation QSARs and application for PBT assessment refinement

Toxicokinetics heavily influence chemical toxicity as the result of Absorption, Distribution, Metabolism (Biotransformation) and Elimination (ADME) processes. Biotransformation (metabolism) reactions can lead to detoxification or, in some cases, bioactivation of parent compounds to more toxic chemicals. Moreover, biotransformation has been recognized as a key process determining chemical half-life in an organism and is thus a key determinant for bioaccumulation assessment for many chemicals. This study addresses the development of QSAR models for the prediction of in vivo whole body human biotransformation (metabolism) half-lives measured or empirically-derived for over 1000 chemicals, mainly represented by pharmaceuticals. Models presented in this study meet regulatory standards for fitting, validation and applicability domain. These QSARs were used, in combination with literature models for the prediction of biotransformation half-lives in fish, to refine the screening of the potential PBT behaviour of over 1300 Pharmaceuticals and Personal Care Products (PPCPs). The refinement of the PBT screening allowed, among others, for the identification of PPCPs, which were predicted as PBTs on the basis of their chemical structure, but may be easily biotransformed. These compounds are of lower concern in comparison to potential PBTs characterized by large predicted biotransformation half-lives.

Seasonal assessment of biological indices, bioaccumulation, and bioavailability of heavy metals in sea urchins Paracentrotus lividus from Algerian west coast, applied to environmental monitoring.

The aim of the present work was to extend our knowledge on the variability of trace metals in sea urchin tissues, focusing on seasonal fluctuations (2010 February for "winter," May for "spring," August for "summer," November for "autumn") in the three different sampling sites of Algerian west coast (Oran Harbor (S1), Ain Defla (S2), and Hadjaj (belonging to Mostaganem City S3)). For this purpose, the bioavailability (metal indices) and bioaccumulation (metal concentrations in soft tissues) of heavy metals (Zn, Cu, Pb, and Cd), the physiological characteristics (e.g., biological indices such as condition index (CI), repletion index (RI), gonad index (GI)), and the biometric parameters (diameter (D) and the height (H)) of sea urchins Paracentrotus lividus were assessed and related to seasons and sites. To investigate the metal bioavailability to sea urchins more precisely, the metal indices were used as a reliable tool in the present work, instead of the metal concentrations only. The interest to standardize metal concentrations with the weight of the urchin test is to overcome the metal burden variations in the soft tissues of urchin related to the seasonal weight changes of the soft body of animal. We evidence that the most contaminated sites were S1 and S2. Furthermore, it should be noted that the bioavailability of metals, corresponding to the values of metal indices, is also more pronounced in S1 and S2 compared to that measured in S3. Thus, a correlation is observed between seasonal metal content in urchin tissues from the three sites and the corresponding metal indices. The high metal concentrations were obtained during the period when RI and CI were highest. So, it appears that the bioaccumulation of metals in sea urchins of the three sites studied is significantly influenced by the reproductive cycle and diet, feeding activity, and physiological state of these organisms. We noticed that the sea urchins from the sites S1 and S2 were small in size. It is probable that these animals, whose internal tissues contained high concentrations of metals, have been exposed to metal pollution, which might have affected both their growth and altered their physiological capacity. This approach is very original and might be used in the monitoring of the quality of coastal waters, and the present work provided a useful data set for Mediterranean monitoring network.

In vitro to in vivo extrapolation of biotransformation rates for assessing bioaccumulation of hydrophobic organic chemicals in mammals.

Incorporating biotransformation in bioaccumulation assessments of hydrophobic chemicals in both aquatic and terrestrial organisms in a simple, rapid, and cost-effective manner is urgently needed to improve bioaccumulation assessments of potentially bioaccumulative substances. One approach to estimate whole-animal biotransformation rate constants is to combine in vitro measurements of hepatic biotransformation kinetics with in vitro to in vivo extrapolation (IVIVE) and bioaccumulation modeling. An established IVIVE modeling approach exists for pharmaceuticals (referred to in the present study as IVIVE-Ph) and has recently been adapted for chemical bioaccumulation assessments in fish. The present study proposes and tests an alternative IVIVE-B technique to support bioaccumulation assessment of hydrophobic chemicals with a log octanol-water partition coefficient (KOW ) ≥ 4 in mammals. The IVIVE-B approach requires fewer physiological and physiochemical parameters than the IVIVE-Ph approach and does not involve interconversions between clearance and rate constants in the extrapolation. Using in vitro depletion rates, the results show that the IVIVE-B and IVIVE-Ph models yield similar estimates of rat whole-organism biotransformation rate constants for hypothetical chemicals with log KOW ≥ 4. The IVIVE-B approach generated in vivo biotransformation rate constants and biomagnification factors (BMFs) for benzo[a]pyrene that are within the range of empirical observations. The proposed IVIVE-B technique may be a useful tool for assessing BMFs of hydrophobic organic chemicals in mammals. Environ Toxicol Chem 2017;36:1934-1946. © 2016 SETAC.

Assessment of biotransfer and bioaccumulation of cadmium, lead and zinc from fly ash amended soil in mustard-aphid-beetle food chain.

The present study investigates the extent of biotransfer and bioaccumulation of cadmium (Cd), lead (Pb) and zinc (Zn) from fly ash amended soil in mustard (Brassica juncea)-aphid (Lipaphis erysimi)-beetle (Coccinella septempunctata) food chain and its subsequent implications for the beetle. The soil was amended with fly ash at the rates of 0, 5, 10, 20 and 40% (w/w). Our results showed that the uptake of Cd, Pb and Zn from soil to mustard root increased with the increase in fly ash application rates, but their root to shoot translocation was relatively restricted. Increase in chlorophyll content and dry mass of mustard plant on treatments ≥20% even at elevated accumulation of Cd (1.67mgkg-1), Pb (18.25mgkg-1) and Zn (74.45mgkg-1 dry weight) in its shoot showed relatively higher tolerance of selected mustard cultivar to heavy metal stress. The transfer coefficient (TC1) of Cd from mustard shoot to aphid was always >1, indicating that Cd biomagnified in aphids at second trophic level. But, there was no biomagnification of Cd in adult beetles at third trophic level. Zinc accumulation was 2.06 to 2.40 times more in aphids than their corresponding host shoots and 1.26-1.35 times more in adult beetles than their prey (aphids) on which they fed. Lead was only metal whose TC was <1 at both second and third trophic levels. The elimination of Cd via honeydew of aphids was most efficient as the ratio of metal in honeydew to aphid (ranging from 0.21 to 0.26) was higher than the Pb (0.16 to 0.20) and Zn (0.07 to 0.09). The statistically consistent (p>0.05) biomass and predation rate of predatory beetles indicated that all levels of soil amendments with fly ash did not have any lethal or sub-lethal effects on beetles.

Assessment of Heavy Metals and Bioaccumulation in Periwinkle (Tympanotonus fuscatus var. radula (L.))Obtained from the Upper Reaches of the Bonny Estuary, Nigeria

The aim of this study was to assess accumulation of heavy metals in tissues of Periwinkle (Tympanotonus fuscatus var radula (L.)) obtained from Azuabie creek using Okujagu creek as control location. Fifty samples were collected from each site for three months (October-December 2015). Atomic Absorption Spectrophotometric technique was used in heavy metal analysis. Mean metal concentrations in sediments were as follows Zn: 178.08 mgkg-1; Cd: 0.3 mgkg-1; Cr: 14.27 mgkg-1 and Pb: 18.75 mgkg-1. While those in Periwinkle tissue with biosediment accumulation factor (BAF) in parenthesis were thus Zn: 24.42 mgkg-1 (0.137); Cd: 0.02 mgkg-1 (0.067); Cr: 1.57 mgkg-1 (0.11) and Pb 0.01 mgkg-1 0.001). The result of BAF of metals indicated low values which could be related to assimilation and excretion rate of heavy metals in the organisms examined. Variations in the concentration of Zn in the gastropod tissues showed significant difference (p<0.01) between sites, likewise, Cr (p<0.001) and Cd (p<0.05). In conclusion, comparison between the two creeks showed that tissue samples from St1, St2 and St3 (Azuabie creek) had higher concentration of metals in relation to the control station (Okujagu creek) indicating potentials for accumulation, mainly due to differences in anthropogenic activities. Cr, Cd and Pb concentrations in tissue had mean values less than the recommended limits in seafood by FAO/WHO however, regular monitoring is required to observe perturbations.

Comparative Assessment of Total Hydrocarbon Content and Bioaccumulation of Heavy Metals in Sarotherodon Melanotheron at Atlas Cove Area and Okobaba of Lagos Lagoon

Industrial waste discharge has increased the hazard of water pollution. The total hydrocarbon content and bioaccumulation of heavy metals in Sarotherodon melanotheron at Atlas cove area and at Okobaba end of Lagoon Lagos were assessed between November, 2014 and January, 2015. The physicochemical parameters were determined according to APHA-AWWA-WEF and heavy metals in the fish species were determined using Atomic Absorption Spectrometer. The total hydrocarbon content (THC) in the fish samples were analysed by using Soxhlet extraction gravimetric methods. The heavy metal values evaluated are Fe, Cr, Pb, Ni and Cu. The concentration of Iron (Fe) in Sarotherodon melanotheron was 72.72 ± 125.95mg/kg, Chromium (Cr)- 10.29 ± 4.61mg/kg; Lead (Pb)- 1.08 ± 0.23mg/kg; Nickel (Ni)- 0.39 ± 0.26mg/kg; and Copper (Cu)- 0.20 ± 0.26mg/kg at Atlas cove area while at Okobaba the concentration were;Fe-115.98±87,Cr-5.25±1.02,Pb-2.04±1.50,Ni-0.78±0.08,and Cu is 0.36±0.15mg/kg. The levels of accumulation of all the heavy metals in Sarotherodon melanotheron were above the WHO permissible limits. The concentration of n- alkanes in Sarotherodon melanotheron at Atlas cove was 164.69 ± 97.04µg/g, polycyclic aromatic hydrocarbon (PAH) was 73.58 ± 72.48µg/g, and total petroleum hydrocarbon was 526.67 ± 214.34µg/g. The average intake of polycyclic aromatic hydrocarbon through fish consumption at Atlas cove area was estimated to be 5039.94 ± 49.2mg/kg; body weight/day. The mean concentration of n-alkanes hydrocarbon in Sarotherodon melanotheron at Okobaba was 152.62±54.11µg/g, the PolycyclicAromatic Hydrocarbon (PAH) was 74.4±50.30 µg/g.The carcinogenic high molecular weight polycyclic aromatic hydrocarbons (HMW-PAH) were of higher concentrations than the lower molecular weight polycyclic aromatic hydrocarbon (LMW-PAH). Therefore, Atlas cove area is more exposed to carcinogenic health risks associated with the consumption of the studied fish than Okobaba end of Lagos Lagoon. This indicates significant carcinogenic health risks associated with the consumption of black jaw Tilapia fish caught from the study areas.

In Vivo Biotransformation Rates of Organic Chemicals in Fish: Relationship with Bioconcentration and Biomagnification Factors.

In vivo dietary bioaccumulation experiments for 85 hydrophobic organic substances were conducted to derive the in vivo gastrointestinal biotransformation rates, somatic biotransformation rates, bioconcentration factors (BCF), and biomagnification factors (BMF) for improving methods for bioaccumulation assessment and to develop an in vivo biotransformation rate database for QSAR development and in vitro to in vivo biotransformation rate extrapolation. The capacity of chemicals to be biotransformed in fish was found to be highly dependent on the route of exposure. Somatic biotransformation was the dominant pathway for most chemicals absorbed via the respiratory route. Intestinal biotransformation was the dominant metabolic pathway for most chemicals absorbed via the diet. For substances not biotransformed or transformed exclusively in the body of the fish, the BCF and BMF appeared to be closely correlated. For substances subject to intestinal biotransformation, the same correlation did not apply. We conclude that intestinal biotransformation and bioavailability in water can modulate the relationship between the BCF and BMF. This study also supports a fairly simple rule of thumb that may be useful in the interpretation of dietary bioaccumulation tests; i.e., chemicals with a BMFL of <1 tend to exhibit BCFs based on either the freely dissolved (BCFWW,fd) or the total concentration (BCFWW,t) of the chemical in the water that is less than 5000.

Separation of Bacteria, Protozoa and Carbon Nanotubes by Density Gradient Centrifugation.

Sustainable production and use of carbon nanotube (CNT)-enabled materials require efficient assessment of CNT environmental hazards, including the potential for CNT bioaccumulation and biomagnification in environmental receptors. Microbes, as abundant organisms responsible for nutrient cycling in soil and water, are important ecological receptors for studying the effects of CNTs. Quantification of CNT association with microbial cells requires efficient separation of CNT-associated cells from individually dispersed CNTs and CNT agglomerates. Here, we designed, optimized, and demonstrated procedures for separating bacteria (Pseudomonas aeruginosa) from unbound multiwall carbon nanotubes (MWCNTs) and MWCNT agglomerates using sucrose density gradient centrifugation. We demonstrate separation of protozoa (Tetrahymena thermophila) from MWCNTs, bacterial agglomerates, and protozoan fecal pellets by centrifugation in an iodixanol solution. The presence of MWCNTs in the density gradients after centrifugation was determined by quantification of 14C-labeled MWCNTs; the recovery of microbes from the density gradient media was confirmed by optical microscopy. Protozoan intracellular contents of MWCNTs and of bacteria were also unaffected by the designed separation process. The optimized methods contribute to improved efficiency and accuracy in quantifying MWCNT association with bacteria and MWCNT accumulation in protozoan cells, thus supporting improved assessment of CNT bioaccumulation.

Use of toxicokinetic data in bioaccumulation assessment

Use of toxicokinetic data in bioaccumulation assessment

Interlaboratory evaluation of the assessment of arsenic bioaccumulation from field collected sediments using Hexagenia spp.

Standardized bioaccumulation testing of aquatic organisms is essential to understanding the impact of historical contamination on the quality of water and sediment. A standardized 28-d laboratory bioaccumulation method with a freshwater burrowing mayfly, Hexagenia spp., has been developed and internally validated by the Ontario Ministry of the Environment and Climate Change (MOECC). An interlaboratory comparison was conducted to assess the precision of this method. Field-collected sediment contaminated with arsenic was chosen for the present study. Control and test sediments were subsampled and sent to 6 laboratories to perform the bioaccumulation test. One laboratory failed to meet the control survival criterion of ≥80%. When results of this laboratory are removed from the arsenic accumulation assessment, the mean interlaboratory variability (expressed as coefficient of variation) of the arsenic whole-body concentration is reduced from 44% to 24% in the test sediment-exposed Hexagenia spp. There was no significant interlaboratory difference between the Hexagenia spp. arsenic accumulations. While improved culturing and organism holding guidance may increase laboratory success, the MOECC Hexagenia spp. bioaccumulation test method has tight biological method precision when the control survival criterion is met. Environ Toxicol Chem 2016;35:2448-2455. © 2016 SETAC.

Deriving bioconcentration factors and somatic biotransformation rates from dietary bioaccumulation and depuration tests.

The present study develops, applies, and tests a method for deriving empirical bioconcentration factors and somatic biotransformation rate constants from dietary bioaccumulation tests and simplified bioaccumulation experiments that measure depuration rates. In this approach, measurement of the chemical concentration in the water is not required. The method aims to improve bioaccumulation assessment, reduce cost and animal use, and shorten experiments. Environ Toxicol Chem 2016;35:2968-2976. © 2016 SETAC.

Comparative assessment of TPHs and bioaccumulation in some fresh fish species in the Qua lbeo River of Eket of Akwa lbom State in Nigeria

This investigation was carried out in four different locations mapped out along the river bank. Twelve water samples were collected and six different fresh fish species that are frequently consumed were caught. They include: African red snapper (Lutjanus agennes), Yellow tail (Seriola lalandi), Barracuda (Sphyraena barracuda), Atlantic Croker (Micropogonias undulates), Catfish (Clarias gariepinus) and Tilapia (Oreochromis niloticus). Samples were subjected to screening using gas chromatography and flame ionization detector instrument. Results revealed presence of total petroleum hydrocarbon (TPH) contaminant in all the fish samples and varies with species significantly at p &gt;0.05. The profound TPH compound is Nonane with molecular formula C9H20. 9 x 10-9 mg/l was adapted as Nonane concentration in water samples. Nonane concentration in fish samples showed African red snapper 3.9565±4.64648 mg/l, Yellow tail 8.7243±2.15546 mg/l, Barracuda 6.2555±0.48889 mg/l, Atlantic Croker 9.3866±0.42208 mg/l, Catfish 4.1973±1.52959 mg/l and Tilapia 6.0039±0.96487 mg/l respectively. The bioaccumulation factor varies in fish species, where the Yellow tail have higher bioaccumulation factor 969,369061, followed by Barracuda 695,067209, Tilapia 667,101072, Catfish 466,368366, African red Sniper 439,616275 and Crocker fish 104,2956024 respectively. This investigation reveal considerably the extent of bioaccumulation of TPH contaminants in aquatic animal models and making unsafe for consumption as some fishes bio-accumulate nonane beyond permissible limitBangladesh J. Sci. Ind. Res. 51(2), 147-154, 2016

Assessment of bio-accumulation of bacteria in oysters from shellfish growing waters in Ashtamudi Lake (Kerala, India): A RAMSAR wetland

Oysters are commercially cultured from the Ashtamudi Lake in India, and support 12,000 tonnes of bivalve fisheries/year. Oysters and oyster growing waters were sampled from July 2012 to June 2013 for analysis of total coliforms (TC), faecal coliforms (FC), Escherichia coli, faecal Streptococci (FS) and total plate counts (TPC). E. coli MPN values in oyster growing waters were below the threshold limits set by the USFDA and EU during the months of December to April. Seasonally, the highest MPN values for E. coli were obtained during the monsoon season (June–September), and this trend gradually decreased during the post-monsoon (October–January) and pre-monsoon (February–May) periods. E. coli displayed a significant (p<0.01) variation in accumulation during different seasons. A strong negative correlation (R2=−0.70, p<0.05) between temperature and E. coli numbers in oysters was observed, while rainfall and E. coli were positively correlated (R2=0.695, p<0.05). Hence, we strongly recommend depuration and proper cooking of oysters before consumption during the monsoon season.

Cytotoxicity and cellular uptake of perfluorocarboxylic acids

Abstract To address the health and environmental concerns associated with perfluorocarboxylic acids, the assessment of cytotoxicity and bioaccumulation of perfluorocarboxylic acids is essential. This study investigated the effect of perfluorocarboxylic acids having various chain lengths on mouse melanoma B16 cells. The extent of cytotoxicity of perfluorohexanoic acid (C6), perfluoroheptanoic acid (C7), perfluorooctanoic acid (C8), perfluorononanoic acid (C9) and perfluorodecanoic acid (C10) within a concentration range of 0.25–1600 μg/ml was determined. Based on results, the viability of cells was 90% or higher in the presence of C6, C7, C8 at a concentration of up to 200 μg/ml, indicating that B16 cells are safe in the presence of C6, C7 and C8. On the other hand, moderate cytotoxicity was observed with C9 or C10, even at a relatively low concentration of 25 μg/ml. When cells were incubated in the presence of the same concentration (100 or 200 μg/ml) of perfluorocarboxylic acids, the number of live cells decreased as the perfluoroalkyl chain length increased suggesting that long-chained perfluorocarboxylic acids are more cytotoxic than short-chained perfluorocarboxylic acids. The correlation between cellular uptake and perfluoroalkyl chain length was also investigated. The presence of C6 in the cells was not detected probably because of poor uptake. On the other hand, the presence of C7–C10 in the cells was confirmed and quantified by LC ESI MS. Results showed that cellular uptake of long-chained perfluorocarboxylic acids were significantly higher than short-chained perfluorocarboxylic acids.

Comparison between active and passive biomonitoring strategies for the assessment of genotoxicity and metal bioaccumulation in Echinogammarus veneris (Crustacea: Amphipoda)

The aim of this study was to investigate the relevance and the robustness of active and passive approaches used in freshwater biomonitoring with the ecologically relevant gammarid amphipod Echinogammarus veneris. To assess the contaminant bioavailability in two rivers of Latium (Central Italy), we measured the genotoxic potential in haemocytes by comet assay and metal bioaccumulation in tissues by analytical methods. We adopted an active strategy of exposure in situ and a passive method of sampling in situ. In the first case, the gammarids were exposed in cages in several sampling sites selected along two rivers, while in the sampling in situ, individuals were collected directly in the same sampling sites and then analyzed. The results indicate that the comet assay carried out on haemocytes from caged individuals proved to be a sensitive tool for freshwater genotoxicity monitoring. However, the sampling in situ is more appropriate for a realistic understanding of the presence of trace metal in E. veneris.