Biomarkers in toxicology versus ecological risk assessment

Impacts of warming and acidification on pesticide toxicity in continental aquatic environments: A scientometric and systematic map

Carbon dioxide emissions are altering aquatic ecosystems by causing water acidification and temperature increases, and these environments are also facing pesticide contamination. We present a scientometric and systematic map of these impacts in continental aquatic environments, aiming to provide an overview of research investigating the effects of temperature and acidification on pesticide toxicity. Our findings reveal a significant increase in research output on this topic, especially over the past seven years, with the United States leading due to high pesticide use and rigorous environmental monitoring. International collaborations remain low. High-impact journal publications underscore the importance of this topic. The primary focus is on temperature-pesticide interactions, highlighting the need for studies on pesticide-acidification interactions driven by climate change. The most studied class of pesticides is insecticides, particularly chlorpyrifos. Animals such as fish and crustaceans are the most frequently used organisms in ecotoxicological tests, indicating the need for broader assessments of impacts on other aquatic groups. Synergistic effects in interactions were prevalent, stressing the importance of an integrated approach in considering the interplay between temperature, pH, and pesticides. The information presented in this study directs and encourages studies in areas that have not yet addressed this topic.

Active monitoring of long-eared owl (Asio otus) nestlings reveals widespread exposure to anticoagulant rodenticides across different agricultural landscapes

The widespread use of anticoagulant rodenticides (ARs) poses a worldwide threat to farmland wildlife. These compounds accumulate in tissues of both target and non-target species, potentially endangering both direct consumers and their predators. However, investigations on ARs in blood of free-ranging predatory birds are rare. Here, the long-eared owl (Asio otus) has been used as a model predator to assess AR exposure in different agricultural landscapes from a Mediterranean semiarid region. A total of 69 owlets from 38 nests were blood-sampled over 2021 and 2022, aiming to detect AR residues and explore factors that determine their exposure, such as land uses. In addition, prothrombin time (PT) test was conducted to assess potential effects of AR contamination. Overall, nearly all the samples (98.6 %) tested positive for at least one compound and multiple ARs were found in most of the individuals (82.6 %). Among the ARs detected, flocoumafen was the most common compound (88.4 % of the samples). AR total concentration (ΣARs) in blood ranged from 0.06 to 34.18 ng mL-1, detecting the highest levels in the most intensively cultivated area. The analysis of owl pellets from 19 breeding territories showed relevant among-site differences in the contribution of rodents and birds into the diet of long-eared owls, supporting its high dietary plasticity and indicating AR presence at multiple trophic levels. Moreover, a positive and significant correlation was found between ΣARs and PT (Rho = 0.547, p < 0.001), which demonstrates the direct effect of ARs on free-living nestlings. Our results provide a preliminary overview of AR exposure in a little-studied owl species inhabiting agricultural and rural landscapes. Despite the low detected levels, these findings indicate widespread exposure -often to multiple compounds- from early life stages, which raises concern and draws attention to an ongoing and unresolved contamination issue.

2,4-D-based herbicide underdoses cause mortality, malformations, and nuclear abnormalities in Physalaemus cuvieri tadpoles

Amphibians are considered bioindicators of the environment due to their high sensitivity and involvement in terrestrial and aquatic ecosystems. In the last two decades, 2,4-D has been one of the most widely used herbicides in Brazil and around the world, as its use has been authorized for genetically modified crops and therefore has been detected in surface and groundwater. Against this background, the aim of this work was to investigate the effects of environmentally relevant concentrations of 2,4-D-based herbicides on survival, malformations, swimming activity, presence of micronuclei and erythrocyte nuclear abnormalities in Physalaemus cuvieri tadpoles. The amphibians were exposed to six concentrations of 2,4-D-based herbicides: 0.0, 4.0, 30.0, 52.5, 75.0, and 100 μg L-1, for 168 h. At concentrations higher than 52.5 μg L-1, significantly increased mortality was observed from 24 h after exposure. At the highest concentration (100 μg L-1), the occurrence of mouth and intestinal malformations was also observed. The occurrence of erythrocyte nuclear abnormalities at concentrations of 30.0, 52.5, 75.0 and 100 μg L-1 and the presence of micronuclei at concentrations of 52.5, 75.0, and 100 μg L-1 were also recorded. These effects of 2,4-D in P. cuvieri indicate that the ecological risk observed at concentrations above 10.35 μg L-1 2,4-D may represent a threat to the health and survival of this species, i.e., exposure to 2,4-D at concentrations already detected in surface waters in the species' range is toxic to P. cuvieri.

Hydrogen Peroxide Stress Induced in the Marine Cyanobacterium Synechococcus aeruginosus and Phormidium valdarianum

Biochemical markers against hydrogen peroxide-induced oxidative stress were developed in marine cyanobacteria under standard laboratory conditions. To find out the ability to cope with different concentrations of hydrogen peroxide, two species of marine cyanobacteria including unicellular and filamentous forms were exposed for shorter duration. Synechococcus aeruginosus and Phormidium valderianum tolerated hydrogen peroxide by showing the highest growth of Superoxide dismutase in Synechococcus aeruginosus and Phormidium valderianum, catalase in Synechococcus aeruginosus, peroxidase in Synechococcus aeruginosus and Phormidium valderianum, Glutathione S-transferase in Synechococcus aeruginosus and Phormidium valderianum which were identified as biochemical markers of oxidative stress against H2O2 in marine cyanobacteria. Synechococcus aeruginosus showed new isoforms for Superoxide dismutase, catalase, peroxidase, Glutathione peroxidase, and Glutathione S-transferase and Phormidium valderianum for Superoxide dismutase, peroxidase, and Glutathione S-transferase. Synechococcus aeruginosus is suggested as the indicator species for biochemical markers against hydrogen peroxide in marine cyanobacteria. Peroxidase is suggested as biochemical enzyme marker. The present investigated on these new isoenzymes were identified as biochemical markers for oxidative stress.

Can carbon nanofibers affect anurofauna? Study involving neotropical Physalaemus cuvieri (Fitzinger, 1826) tadpoles

Although carbon nanotubes' (CNTs) toxicity in different experimental systems (in vivo and in vitro) is known, little is known about the toxic effects of carbon nanofibers (CNFs) on aquatic vertebrates. We herein investigated the potential impact of CNFs (1 and 10 mg/L) by using Physalaemus cuvieri tadpoles as experimental model. CNFs were able to induce nutritional deficit in animals after 48-h exposure to them, and this finding was inferred by reductions observed in body concentrations of total soluble carbohydrates, total proteins, and triglycerides. The increased production of hydrogen peroxide, reactive oxygen species and thiobarbituric acid reactive substances in tadpoles exposed to CNFs has suggested REDOX homeostasis change into oxidative stress. This process was correlated to the largest number of apoptotic and necrotic cells in the blood of these animals. On the other hand, the increased superoxide dismutase and catalase activity has suggested that the antioxidant system of animals exposed to CNFs was not enough to maintain REDOX balance. In addition, CNFs induced increase in acetylcholinesterase and butyrylcholinesterase activity, as well as changes in the number of neuromasts evaluated on body surface (which is indicative of the neurotoxic effect of nanomaterials on the assessed model system). To the best of our knowledge, this is the first report on the impact of CNFs on amphibians; therefore, it broadened our understanding about ecotoxicological risks associated with their dispersion in freshwater ecosystems and possible contribution to the decline in the populations of anurofauna species.

Toxicokinetic analysis of commonly used pesticides using data on acute poisoning cases from Hyderabad, South India

Organophosphorus pesticides (OPs) interfere with the activity of acetylcholinesterase (AChE), a vital enzyme that regulates the functioning of the nervous system, resulting in acetylcholine (Ach) accumulation at the synapses and myoneural junctions. It remains unknown whether the commonly used OPs in South India also interfere with the AChE activity and their toxicokinetics in humans remains poorly understood. We collected peripheral blood samples from OP-associated suicide cases (hospitalised) and analysed the pesticide concentration and AChE activity, and the toxicokinetics of six commonly used pesticides. LC-MS/MS was used for the estimation of pesticide concentration. Based on a comparison of six pesticide kinetic profiles and toxicokinetic parameters, we concluded that chlorpyrifos ingestion resulted in the highest concentration of chlopyrifos among the identified pesticides, followed by acephate, triazophos, propanil, while dimethoate exhibited the lowest concentration. Based on a time-course analysis, we observed a faster elimination phase for monocrotophos and dimethoate. We observed that there was a significant decrease in the mean concentration of monocrotophos (64 ng/mL) (P = 0.015), while the mean value of AChE (1.08 unit/mL) increased over time. While monocrotophos and dimethoate elimination phases were remarkable in human subjects, the other pesticides did notdemonstrate similar elimination phases owing to their low rate of metabolism and high stability.

Effects of glyphosate, cypermethrin, and chlorpyrifos on hematological parameters of the tegu lizard (Salvator merianae) in different embryo stages

Different studies have demonstrated effects of pesticides during embryo development in vertebrates and stage-dependent effects, but there is no information concerning this for Salvator merianae. We evaluated the effects of the herbicides Glyphosate Roundup (GLY-RU) and Glyphosate Panzer Gold (GLY-PZ); and the insecticides Chlorpyrifos (CPF) and Cypermethrin (CYP), and their complex mixtures, at different concentrations in hematological parameters of S. merianae embryos at two different development stages. The analyzed parameters were Total and Differential White Blood Cells Count, Heterophils/Lymphocytes index (H/L), Lobularity index, and Natural Antibodies (Nabs titres), as well as growth, embryo mortality and birth delay. Heterophils decreased in the intermediate concentrations tested of CYP and GLY-RU, in animals exposed at 33-days development. Lymphocytes increased in the intermediate concentration tested of GLY-RU, and the H/L index decreased in the maximum concentration tested of GLY-RU. NAbs titres increased in those animals exposed to the maximum CYP concentration tested. However, animals exposed at 3/5-days development showed no differences among treatments in most of the analyzed parameters, suggesting a stage-dependent response. Nevertheless, those animals exposed to GLY-PZ showed lower Nabs titres in relation to negative control. These results suggest effects on different hematological parameters related to the immune system of S. merianae, according to the used pesticide (herbicide or insecticide), its concentration and commercial formulation (GLY-RU or GLY-PZ), and the stages of development of the exposed animals. Our results reveal the importance of carrying out studies that evaluate the effects of permanent exposure of living beings and their environments to these toxics.

Biomarker responses and biotransformation capacity in Arctic and temperate benthic species exposed to polycyclic aromatic hydrocarbons

Monitoring parameters for the assessment of oil and gas related contaminants and their biological effects need validation before application in the Arctic. For such monitoring purposes, we evaluated the potential use of three biomarkers (acetylcholinesterase, acyl-CoA oxidase and glutathione S-transferase) for application to an Arctic bivalve (Astarte borealis) and determined the body residue of pyrene and two pyrene metabolites (1-hydroxypyrene and pyrene-1-glucuronide) in Arctic benthic species (bivalve: Macoma calcarea; polychaete: Nephtys ciliata) and temperate benthic species (bivalve: Limecola balthica; polychaete: Alitta virens) in order to establish the potential of polycyclic aromatic hydrocarbons (PAHs) metabolite profiles as biomarkers of exposure in such species. Experimental PAH exposure levels were probably too low (0.2-1.7 mg/kg dry weight in sediment) to induce or inhibit biomarker responses in A. borealis. Concentrations of pyrene and pyrene metabolites varied between species, although no consistent patterns could be established among taxonomic groups and locations. Metabolites made up to 79% of the total pyrene concentrations, indicating that basal metabolic activity is affecting pyrene kinetics even at low concentrations in all species. This indicates that Arctic and temperate species could show similar metabolism patterns of PAHs, although more insight into the effects of confounding factors is needed.

Effects of cypermethrin (pyrethroid), glyphosate and chlorpyrifos (organophosphorus) on the endocrine and immune system of Salvator merianae (Argentine tegu)

Several geographical areas where Salvator merianae is distributed in Argentina are included in regions with agricultural activity and exposed to pesticide formulations. Some pesticides could affect defense mechanisms being able alter structures of some components of immune and endocrine systems. To assess the potential effects of pesticides in this reptile under seminatural conditions, on the immune system and endocrine responses in S. merianae we analyzed several blood parameters. Total (TWBCC), differential (DWBCC) white blood cells count, heterophils/lymphocytes index (H/L), lobularity index (LI), natural antibodies (NAbs) titres, complement system (CS), and corticosterone concentration were analyzed in animals exposed to a mixture of cypermethrin (25%), glyphosate (66.2%) and chlorpyrifos (48%) formulations. In addition, body size was considered in these analyzes. TWBCC and NAbs revealed lower values in organisms exposed to pesticides respect to a control indicating a possible immunosuppression effect. Besides, the LI showed a greater number of lobes in organism exposed demonstrating symptoms of chronic infection. In addition, we observed a reduced growth in these animals possibly related to a less energy investment in body mass to maintain an active defense against pesticides. Finally, we found high levels of plasma corticosterone in animals exposed to mix formulation that could demonstrate neuroendocrine axis activation. Other parameters like DWBCC, H/L index and activity of CS showed no differences in treated animals respect to control group, which could indicate low sensibility of these parameters to the concentration of pesticides used. Our results provide evidence of the toxic effects of pesticides on different immune system parameters, but also a trade-off among these parameters, corticosterone levels and growth. In this way, we can conclude that the formulated pesticides applied widely and constantly in the areas occupied by S. merianae, would be affecting its immune and endocrine systems and therefore its ability to defend against external agents. This kind of studies is of great interest to know the possible responses of wild species to anthropogenic disturbances such as pesticide contamination.

Chronic toxicity of commercial chlorpyrifos to earthworm Pheretima peguana

A chronic toxicity study was conducted in earthworms (Pheretima peguana) exposed to soil spiked with chlorpyrifos at concentrations of 0, 0.1, 1, 10, and 100 mg/kg soil dry matter for 7, 14, and 28 days. The integrity of the coelomocyte lysosomal membrane, nervous system, and male reproductive tissue was monitored using, respectively, the neutral-red retention assay, acetylcholinesterase (AChE) enzyme assay, and histomorphology of spermatogenic cells in the seminal vesicles and cocoon production (at 28 days after 28 days' exposure). Chlorpyrifos decreased the coelomocyte neutral-red retention time (NRRT) significantly (p < 0.05) at concentrations > 0.1 mg/kg soil as early as day 7 of exposure and was dose- and time-dependent. Chlorpyrifos inhibition of AChE activity was greater at day 7 than at day14 (p < 0.05) indicating possibly nerve recovery. Chlorpyrifos induced concentration-dependent damage to spermatogenic cells and cytophores in premature stages. The number and size of premature, maturing, and fully mature spermatogenic stages were increased at low concentrations (<1 mg/kg) but a number of these maturation stages declined at higher concentrations (10 and100 mg/kg) on day 28. The most severe effects were observed in the maturing and fully mature stages at the highest chlorpyrifos concentration, and this had an adverse impact on cocoon production and cocoon viability. Collectively, the results suggest induction of widespread effects on multiple organ systems in P. peguana exposed to chlorpyrifos. Although NRRT and AChE activity were the most sensitive of the biomarkers, cocoon production and cocoon viability could still be considered as diagnostic tools for monitoring effects from low-dose long-term chlorpyrifos toxicity and for evaluating population effects. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1450-1459, 2016.

Earthworm biomarker responses on exposure to commercial cypermethrin

Cypermethrin is a synthetic pyrethroid insecticide used worldwide in agriculture, home pest control, disease vector control, and food safety. It accumulates in soil. Therefore, traces of cypermethrin may frequently appear in vegetables grown in contaminated soil. There is a push now to develop biomarkers as early warning indicators of environmental pollution. In this study, DNA damage (tail DNA%, tail length, and olive tail moment), the micronucleus, neutral red retention (NRR) time, and pinocytic adherence ability of coelomocytes were investigated in Pheretima peguana earthworms exposed to cypermethrin in filter paper tests. The NRR time of earthworm coelomocytes decreased significantly at a concentration of 3.5 × 10(-3) µg · cm(-2) (1/100 LC50 ) after 48 h exposure, with a highly negative correlation with cypermethrin concentration. Pinocytic adherence ability of coelomocytes also declined significantly at a cypermethrin concentration of 3.5 × 10(-2) µg · cm(-2) (1/10 LC50 ). The DNA damage to earthworm coelomocytes (tail DNA%, tail length, and olive tail moment) increased considerably at the highest concentration (3.5 × 10(-1) µg · cm(-2) ) although the correlation between tail DNA% and cypermethrin concentration was low. Thus, physiological biomarkers were more sensitive than the genotoxic effects in earthworms exposed to commercial cypermethrin. Although a suite of earthworm biomarkers could be used to evaluate cypermethrin terrestrial pollution, the NRR test is easier to conduct and a more sensitive indicator.

Evaluation of EROD and CYP3A4 activities in earthworm Eisenia fetida as biomarkers for soil heavy metal contamination

In this study, the effects of heavy metals (Cd, Cu, Pb, Zn) on EROD and CYP3A4 activities in the earthworm Eisenia fetida were evaluated to find out their possible induction and potential as biomarkers for soil heavy metal contamination. The earthworms were exposed to increasing concentrations of Cd (0.1-8 mg L(-1)), Cu (10-200 mg L(-1)), Pb (20-400 mg L(-1)) or Zn (50-400 mg L(-1)) in filter papers for 48 h. EROD activity was significantly changed in dose-dependent manners after exposure to each of the four metals. CYP3A4 activity was significantly induced by Cd and Pb, rather by Cu and Zn. This is the first report on heavy metal-induced changes of CYP3A4 activity in earthworms. Among the four heavy metals, Cd was the most potent inducing EROD and CYP3A4. While EROD and CYP3A4 activities showed a similar trend, EROD is more sensitive than CYP3A4 activity in E. fetida as a biomarker for heavy metals pollution.

Successful treatment of extreme acute lead intoxication

Severe acute lead intoxications are rare and are associated with accidental or purposeful ingestion. There were only few cases of severe to fatal poisonings reported in literature in children. We report a case of acute lead intoxication in a child with extremely high lead blood level of 20.4 μmol/L (422.7 μg/dL), who was treated with chelation and in whom significant organ dysfunction did not develop. Documented significant high level above 3.37 μmol/L (corresponding to 70 μg/dL) in this patient persisted for approximately 24 h. Adequate, single or combined chelatation therapy in early phase of acute lead poisoning is essential for the further patient’s outcome.

Spillway-induced salmon head injury triggers the generation of brain alphaII-spectrin breakdown product biomarkers similar to mammalian traumatic brain injury

Recent advances in biomedical research have resulted in the development of specific biomarkers for diagnostic testing of disease condition or physiological risk. Of specific interest are alphaII-spectrin breakdown products (SBDPs), which are produced by proteolytic events in traumatic brain injury and have been used as biomarkers to predict the severity of injury in humans and other mammalian brain injury models. This study describes and demonstrates the successful use of antibody-based mammalian SBDP biomarkers to detect head injury in migrating juvenile Chinook salmon (Oncorhynchus tshawytscha) that have been injured during passage through high-energy hydraulic environments present in spillways under different operational configurations. Mortality and injury assessment techniques currently measure only near-term direct mortality and easily observable acute injury. Injury-based biomarkers may serve as a quantitative indicator of subacute physical injury and recovery, and aid hydropower operators in evaluation of safest passage configuration and operation actions for migrating juvenile salmonids. We describe a novel application of SBDP biomarkers for head injury for migrating salmon. To our knowledge, this is the first documented cross-over use of a human molecular biomarker in a wildlife and operational risk management scenario.

Cellular stress reactions assessed by gender and species in spiders from areas variously polluted with heavy metals

In the funnel web spider Agelena labyrinthica (Agelenidae; A. l.), sheet web spider Linyphia triangularis (Linyphiidae; L. t.) and wolf spider Xerolycosa nemoralis (Lycosidae; X. n.) from two differently polluted meadow sites in southern Poland, we studied the relations between antioxidant parameters (glutathione, GSH; glutathione peroxidases, GPOX, GSTPx; catalase, CAT; stress proteins-Hsp70, metallothioneins Mts), the intensity of apoptosis and necrosis, and heavy metal burdens of the midgut gland. Cellular reactions against stress caused by pollutants seemed to be sex-dependent. The concentrations of Zn and Cu in the midgut glands of male A. l. and X. n. were more than double that of the females, from both study sites. In male spiders from the heavily polluted site, both negative correlations (activity of caspase-3-like proteins vs Cu, Zn concentration; number of depolarized mitochondria vs Cu concentration) and positive correlations (number of necrotic cells vs Cu concentrations; activity of CAT vs Zn ) were noted. The defense of males against high metal content and its prooxidative effects is based mainly on GSH and CAT. In females the antioxidative reactions are species-specific and depend mainly on high peroxidase activity and on stress protein level. The increase in the number of apoptotic cells in the midgut gland of female spiders from the heavily polluted site suggests the defensive role of this process in maintaining the proper functioning of this organ.

The plasma proteome, adductome and idiosyncratic toxicity in toxicoproteomics research

Toxicoproteomics uses the discovery potential of proteomics in toxicology research by applying global protein measurement technologies to biofluids and tissues after host exposure to injurious agents. Toxicoproteomic studies thus far have focused on protein profiling of major organs and biofluids such as liver and blood in preclinical species exposed to model toxicants. The slow pace of discovery for new biomarkers, toxicity signatures and mechanistic insights is partially due to the limited proteome coverage derived from analysis of native organs, tissues and body fluids by traditional proteomic platforms. Improved toxicoproteomic analysis would result by combining higher data density LC-MS/MS platforms with stable isotope labelled peptides and parallel use of complementary platforms. Study designs that remove abundant proteins from biofluids, enrich subcellular structures and include cell specific isolation from heterogeneous tissues would greatly increase differential expression capabilities. By leveraging resources from immunology, cell biology and nutrition research communities, toxicoproteomics could make particular contributions in three inter-related areas to advance mechanistic insights and biomarker development: the plasma proteome and circulating microparticles, the adductome and idiosyncratic toxicity.

The determination of earthworm species sensitivity differences to cadmium genotoxicity using the comet assay

The concept of species sensitivity differences is important in ecotoxicology and environmental risk assessment, but testing usually focuses on lethality of toxicants. The effects on the suborganismal level are mostly ignored; therefore, the present study assessed a biomarker of genotoxicity (the alkaline comet assay) to compare species sensitivities. Five earthworm species (Amynthas diffringens, Aporrectodea caliginosa, Dendrodrilus rubidus, Eisenia fetida and Microchaetus benhami) were exposed for 48 h to sublethal concentrations of cadmium sulphate in reconstituted soil water and DNA integrity was evaluated with the parameter Tail DNA %. Significant amounts of DNA damage were detected in three (A. caliginosa, D. rubidus and E. fetida) species. E. fetida exhibited the highest level of DNA damage, although D. rubidus showed the highest increase (3-fold) in DNA damage from the control. All exposed earthworms accumulated Cd, although body loads did not correspond with DNA damage levels; most of the Cd was probably sequestrated and rendered harmless.

Hepatic and immune biological effect assays in C57BL/6 mice to measure polycyclic aromatic hydrocarbon bioavailability under laboratory exposures with increasing environmental relevance

BACKGROUND

Monitoring biological responses that are mediated via the aryl-hydrocarbon receptor (AhR) in animals exposed to environmental contaminants can indicate both the presence of chemicals that act through this biochemical pathway and whether these chemicals are bioavailable.

OBJECTIVES

The use of an ex-situ method that incorporated biological responsiveness monitoring in mice for determining the presence of 'biologically active' hydrocarbons in contaminated soils was investigated.

METHODS

The use of C57BL/6 as a test organism was validated by determining hepatic and immune responsiveness to two polyaromatic hydrocarbons (PAHs): 3,4 benz[a]pyrene (B[a]P) and 1,2 benz (a)anthracene (BA) administered via intraperitoneal (i.p.) injection. The responsiveness of mice exposed to soils spiked with hydrocarbons or ex situ exposures to soil removed from two contaminated sites was also investigated.

RESULTS AND DISCUSSION

Mice that were exposed to B[a]P via i.p. injections showed a 14-fold increase in liver microsomal ethoxyresorufin O-deethylase (EROD) activity compared to the control group. In contrast EROD activity following BA exposure at the same level was not significantly enhanced. Mouse immune response was significantly inhibited in a dose-dependent manner by i.p. injections of B[a]P. No significant inhibition occurred with the same doses of BA. Following i.p. exposure, the retention of B[a]P in mouse carcasses was greater than BA. Mice exposed to clean soils spiked with environmentally relevant concentrations of B[a]P and BA failed to show any significantly different hepatic or immune responses. Carcass residue data indicated a limited uptake of PAH from the soil. In contrast, EROD activity in mice exposed (ex situ) to hydrocarbon-contaminated soils removed from a fuel-loading depot and decommissioned gas works was significantly enhanced (4- and 2-fold respectively). However, this increase in EROD activity did not appear to correlate with either soil or carcass PAH concentrations.

CONCLUSIONS AND OUTLOOK

These results support the assumption that B[a]P has a higher affinity for the aryl hydrocarbon receptor (AhR) compared to BA. Soil parameters such as organic carbon content, structure and particle size distribution can modulate the bioavailability of contaminants to biological receptors. These factors are implicated in the lack of responsiveness demonstrated in the spiked soil experiments. However the responsiveness of EROD activity in mice exposed (ex situ) to soil contaminated with complex mixtures of hydrocarbon compounds confirms the potential usefulness of this model to determine the presence of 'biologically active' compounds in aged soils removed from contaminated sites.

Biochemical markers of oxidative stress in Perna viridis exposed to mercury and temperature

Oxidative damage and antioxidant properties have been studied in Perna viridis subjected to short-term exposure to Hg along with temperature (72h) and long-term temperature exposures (14 days) as pollution biomarkers. The elevated thiobarbituric acid reactive substances (TBA-RS) levels observed in gills and digestive gland under exposure to Hg, individually and combined with temperature, as also long-term temperature stress have been assigned to the oxidative damage resulting in lipid peroxidation (LPX). Increased activities of antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-S-transferase (GST) both in gills and digestive glands under long-term exposures to temperatures are more prominent to heat rather than cold stress suggesting activation of physiological mechanism to scavenge the ROS produced during heat stress. Also decreased values of reduced glutathione (GSH) on long exposures to temperature stress indicate utilisation of this antioxidant, either to scavenge oxiradicals or act in combination with other enzymes, was more than its production capacity under heat stress. The results suggest that temperature variation does alter the active oxygen metabolism by modulating antioxidant enzyme activities, which can be used as biomarker to detect sublethal effects of pollution.

Apoptosis and biochemical biomarkers of stress in spiders from industrially polluted areas exposed to high temperature and dimethoate

The aim of this study was to evaluate the relations between apoptosis and the activity of antioxidant enzymes (superoxide dismutase; catalase) and quantitative changes in stress protein positive cells (Hsp70; metallothionein) in midgut glands of funnel web spiders Agelena labyrinthica (Agelenidae) and wolf spiders Pardosa lugubris (Lycosidae) exposed to high temperature and pesticide under laboratory conditions. The spiders were collected from two meadow ecosystems differently polluted with metals (Olkusz and Pilica, southern Poland). Under stress conditions, P. lugubris had fewer apoptotic cells in the midgut glands than A. labyrinthica. In P. lugubris from both sites, the observed increase in the percentage of metallothionein and Hsp70-positive cells, simultaneous with intensification of superoxide dismutase and catalase activity, suggests an anti-apoptotic function of those proteins in representatives of wandering spiders. In the midgut glands of A. labyrinthica, heat shock and dimethoate increased the number of Annexin V-positive cells as well as the amounts of mitochondria with low transmembrane potential (DeltaPsi(m)) versus the control. The changes in the percentage of MT- and Hsp70-positive cells in funnel web spiders were less than in wolf spiders. The absence of change in SOD and CAT activity in A. labyrinthica shows that the participation of those enzymes in antioxidant reactions is minimal in this species.

Environmental contaminant-mixture effects on CNS development, plasticity, and behavior

Environmental contaminants within the polycyclic aromatic hydrocarbon (PAH) and halogenated aromatic hydrocarbon class have been shown to cross the placenta exposing the fetus to the contaminant body burden of the mother. Consequently, a gestational exposure to environmental contaminants may result in increased adverse health outcomes, possibly affecting cognitive performance. Benzo(a)pyrene [B(a)P] and 2,3,7,8, tetrachlorodibenzo-p-dioxin (TCDD) are two prototypical environmental contaminants. A systematic review of the literature suggests that there may be a relationship between vulnerability in susceptible populations and health disparities. The purpose of this mini-review is to provide a point of reference for neurotoxicological studies of environmental contaminant mixture effects on indices of development in general, and on neurodevelopment in particular. Environmental contaminant-mixture-induced decrements in (1) birth index, (2) N-methyl-D-aspartate receptor (NMDA) mRNA expression, (3) long-term potentiation (LTP), (4) fixed-ratio performance learning behavior, and (5) experience-dependent activity related cytoskeletal-associated protein (Arc) mRNA and protein expression collectively support associations between neurobehavioral deficits and gestational exposure to environmental levels of these contaminants. Collectively, data are presented in this mini-review evaluating the effect of gestational exposure to environmental contaminant-mixtures on specific indices of learning and memory, including hippocampal-based synaptic plasticity mechanisms. These indices serve as templates for learning and memory, and as such, from a vulnerability perspective, may serve as targets for dysregulation during development in susceptible populations that have been disproportionately exposed to these contaminants. Included in this review is also a discussion of the relevance of developing biomarkers for use within the framework of cumulative risk-assessment.