Effects Of Contaminant Exposure Research Articles

Advancing environmental monitoring across the water continuum combining biomarker analysis in multiple sentinel species: A case study in the Seine-Normandie Basin (France)

Nowadays, biomarkers are recognized as valuable tools to complement chemical and ecological assessments in biomonitoring programs. They provide insights into the effects of contaminant exposures on individuals and establish connections between environmental pressure and biological response at higher levels. In the last decade, strong improvements in the design of experimental protocols and the result interpretation facilitated the use of biomarker across wide geographical areas, including aquatic continua. Notably, the statistical establishment of reference values and thresholds enabled the discrimination of contamination effects in environmental conditions, allowed interspecies comparisons, and eliminated the need of a reference site.The aim of this work was to study freshwater-estuarine-coastal water continua by applying biomarker measurements in multi-species caged organisms. During two campaigns, eight sentinel species, encompassing fish, mollusks, and crustaceans, were deployed to cover 25 sites from rivers to the sea. As much as possible, a common methodology was employed for biomarker measurements (DNA damage and phagocytosis efficiency) and data interpretation based on guidelines established using reference values and induction/inhibition thresholds (establishment of three effect levels).The methodology was successfully implemented and allowed us to assess the environmental quality. Employing multiple species per site enhances confidence in observed trends. The results highlight the feasibility of integrating biomarker-based environmental monitoring programs across a continuum scale. Biomarker results align with Water Framework Directive indicators in cases of poor site quality. Additionally, when discrepancies arise between chemical and ecological statuses, biomarker findings offer a comprehensive perspective to elucidate the disparities. Presented as a pilot project, this work contributes to gain insights into current biomonitoring needs, providing new questions and perspectives.

Eggshell composition of Amazon turtle (Podocnemis expansa) is altered after incubation in substrates containing glyphosate and fipronil formulations

Besides its crucial role during embryo development, eggshells are an essential bioindicator of environmental contaminants. However, the effects of contaminant exposure during incubation on the eggshell composition remain poorly known for freshwater turtles. Accordingly, we tested the effects of incubating the eggs of Podocnemis expansa in substrates containing glyphosate and fipronil formulations on the eggshell's level of mineral and dry matter, crude protein, nitrogen, and ethereal extract. Eggs were incubated in sand moistened with water contaminated with glyphosate Atar 48 at concentrations of 65 or 6500 μg/L, fipronil Regent 800 WG at concentrations of 4 or 400 μg/L, or the combination of 65 μg/L glyphosate and 4 μg/L fipronil and 6500 μg/L glyphosate with 400 μg/L fipronil. Exposure to the tested pesticides, alone or in association, altered the chemical composition of the eggshell of P. expansa, reducing the eggshell's moisture and crude protein content and increasing levels of ethereal extract. These changes may cause significant deficiencies in the mobilization of water and nutrients to the embryo, affecting the development and reproductive success of P. expansa.

Laboratory investigation on the retention performance of a soil-bentonite mixture used as an engineered barrier: insight into the effects of ionic strength and associated heavy metal ions.

Soil-bentonite (S-B) materials are promising backfill materials for use as engineered barriers in heavy metal-contaminated sites. The effects of contaminant exposure on the retention performance of the S-B barrier remain unrevealed. In this study, based on the pollution status of an abandoned ferroalloy factory located in southern China, the retention performance of the S-B mixture toward Cr(VI) and Zn(II) was studied through adsorption and diffusion experiments sequentially; the separate effect of ionic strength (binary solution) and the combined effect of ionic strength and associated heavy metal ion (ternary solution) were discussed. In NaCl-Cr(VI)/Zn(II) binary solutions, the adsorption of Zn(II) onto the S-B mixture is larger than that of Cr(VI). Kd, Qmax, and ɛacc (accessible porosity) of Cr(VI) increase through increasing ionic strength, while Zn(II) shows the opposite trend; De (effective diffusion coefficient) values for both Cr(VI) and Zn(II) increased with increasing ionic strength and follow a sequence of Cr(VI) > Zn(II), indicating a better retention performance of the S-B mixture to Zn(II). For a given ionic strength, the adsorption of Zn(II) was larger than that of Cr(VI), which can be attributed to the retention specificity of the S-B mixture to anion and cation. In Cr(VI)-Zn(II)-NaCl ternary solutions, the adsorptions of Cr(VI) and Zn(II) are enhanced in varying degrees when compared with their binary solution, which probably could be attributed to the ion bridge role of Cr(VI)/Zn(II) to connect each other that relatively increased the adsorption capacity of S-B material. This work will contribute to an in-depth understanding of the retention performance of the S-B mixture in complicated chemical environments and facilitate the selection of future remediation strategies.

Contaminant exposure effects in a changing climate: how multiple stressors can multiply exposure effects in the amphipod Hyalella azteca.

Global climate change (GCC) is likely to intensify the synergistic effects between altered physicochemical parameters [of changing habitats] and other anthropogenic threats, such as water pollution, posing increased risks to aquatic biodiversity. As such, it is critical to understand how organisms will respond to changes in water temperature and salinity in the presence of contaminants. We exposed the epibenthic amphipod Hyalella azteca to a 3 × 3 factorial treatment design of three temperatures and three salinities ranging from 12 to 18 °C and 0 to 8 parts per thousand (ppt), respectively, in combination with a low-level environmentally relevant concentration of the pyrethroid insecticide bifenthrin (1 ng/L). Effects on survival and swimming behavior were evaluated after 96 h exposure. Transcription of a select suite of genes was monitored at 24, 48, and 96 h using quantitative polymerase chain reaction (qPCR). Our results not only demonstrate that the changes in salinity and temperature result in negative effects to invertebrate survival, behavior, and gene response, but that the effects were significantly more pronounced in the presence of bifenthrin. This is particularly important since greater thermal fluctuations, changes in timing and extent of glacial melt, and changes in precipitation, could result in H. azteca experiencing lower temperatures at times that coincide with increased spraying of pyrethroids. These environmentally relevant exposures using the standard test species H. azteca provide essential information for understanding effects caused by GCC in conjunction with increasing pesticide use, further highlighting the need to incorporate GCC impacts into risk assessments of contaminants of concern.

Impacts of presence of lead contamination in clayey soil–calcium bentonite cutoff wall backfills

Previous studies have shown that clayey soil admixed with Ca-bentonite can be considered as an alternative backfill for slurry-trench cutoff walls. However, the effects of contaminant exposure on the engineering properties of the clayey soil/Ca-bentonite backfills, such as compressibility and hydraulic conductivity, have not been investigated. This study presents several series of oedometer tests conducted to evaluate the compressibility and hydraulic conductivity of clayey soil/Ca-bentonite backfills exposed to different levels of lead (Pb) contamination. Kaolin is used as the base clayey soil, and it is amended with Ca-bentonite at three content levels (5, 10 and 15% by dry weight) to prepare the backfill samples. Pb is a representative metal contaminant commonly found at contaminated sites. The backfills are prepared by thoroughly mixing the kaolin–bentonite mixture with Pb concentrations of 60, 120 and 600mmol/L. The results reveal that the level of Pb concentration and bentonite content are the critical factors that affect the compressibility of the backfill. The ratio of the compression index of the Pb-contaminated backfill to that of the clean backfill decreases with an increase in the Pb concentration and bentonite content. The void ratio at an effective vertical compression stress of 1kPa is a useful characteristic parameter to correlate with the compression index for all the backfills tested here. The Pb-contaminated backfills exhibit a maximum fifty-fold increase in hydraulic conductivity when compared to clean backfills. The hydraulic conductivity of the clean backfills and those contaminated at low concentration of Pb (60mmol/L) is generally less than the typical regulatory limit of 10−9m/s; whereas the hydraulic conductivity exceeds the regulatory limit when the Pb concentration is higher than 120mmol/L. The ratio of hydraulic conductivity for Pb-contaminated backfills to that for clean backfill decreases with an increase in the effective vertical compression stress. This indicates that under relatively higher effective vertical compression stress conditions the detrimental effect of Pb on hydraulic conductivity can be insignificant. The hydraulic conductivity of the Pb-contaminated backfills decreases slightly when there is an increase in the bentonite content for a given Pb concentration, while the hydraulic conductivity ratio increases significantly with a rise in the bentonite content. A proposed empirical method is assessed to predict the hydraulic conductivity of Pb-contaminated clayey soil/Ca-bentonite backfills as well as clean ones subjected to vertical compressive stress lower than 1600kPa. Using this method, the predicted hydraulic conductivity values fall in the range of 1/3 to 3 times those obtained from the oedometer tests.

Are “silent effects” really silent? Shifting methodological practices and conceptual assumptions to improve detection of early subtle neurobehavioral effects of contaminant exposure

Are “silent effects” really silent? Shifting methodological practices and conceptual assumptions to improve detection of early subtle neurobehavioral effects of contaminant exposure

Analysis of gene expression in Homarus americanus larvae exposed to sublethal concentrations of endosulfan during metamorphosis

Agricultural pesticide runoff has been suspected as the cause of numerous fish kills in rivers throughout Prince Edward Island but the impact on the surrounding marine environment is unknown. Endosulfan, an organochlorine pesticide, is a potent neurotoxin and molt inhibitor used to combat the Colorado potato beetle however it has the potential to affect non-target organisms including the American lobster (Homarus americanus). Metamorphosis is a critical stage of development and the effects of contaminant exposure during this time are largely unknown in lobster. A 14day endosulfan exposure was performed to identify the effects on survival, development and gene expression in lobster larvae during metamorphosis; all of which were predicted to be negatively impacted. The higher endosulfan concentrations resulted in greater mortality and a significant increase in the number of days required to reach metamorphosis in surviving animals. A custom made H. americanus microarray was used for monitoring the changes in expression of 14,592 genes at the termination of the exposure. Genes with >1.5 fold change and identified as being significant at p<0.05 using one-way ANOVA were selected for further analysis. A total of 707 genes were identified as being significantly differentiated, however with only ~40% annotation of the array, the majority of these genes were unknown. Annotated genes of interest were involved in many processes: development, metabolism, immunity and oxidative stress response and gene regulation. Nine genes of interest (histone H1, farnesoic acid O-methyltransferase, cuticle protein, glutathione S-transferase, thioredoxin, NADH dehydrogenase, ecdysone nuclear receptor Fushi tarazu F1 (FTZ-F1), ferritin and ecdysone inducible protein E75 (EIP-E75)) were selected for RT-qPCR validation of the microarray results. The RT-qPCR method was more sensitive than the microarray yet detected similar expression patterns. The two highest endosulfan concentrations resulted in increased mortalities, developmental delays in reaching metamorphosis and significant changes in gene expression. This research provides a foundation for using microarray gene expression profiles as screening tools for exploring the impact of environmental contaminants on lobster.

Endocrine disruptors and children's sex‐dimorphic behaviour

Environmental toxicants can modulate endocrine function. Interest has been directed at those chemicals which interact with sex hormone because of their potentially irreversible effects on brain development. Studies on the effects of in utero and lactational exposure to hormone‐modulating pollutants have focused on cognitive function. Study objectives included: a) identification of a combination of behaviours that differentiate between boys and girls; and b) determination if early chemical exposure affects variability in sex‐dimorphic behaviours. We utilized an established epidemiologic cohort (New York State Angler Cohort Study) assembled to assess the influence of contaminated sport fish consumption on health in adults and their offspring. Children 5 to 11 years of age were targeted. Using a postal questionnaire survey methodology in which a parent served as the informant, 1,112 of 1,692 households contacted (66%) returned completed questionnaires on 1,415 children (52% male, 48% female). Maternal report confirms both pre‐ and postnatal contaminant exposures: 40% of the mothers consumed sport fish for 1 yr and 28% of their offspring ate contaminated fish. Consumption durations do not differentiate respondents from nonrespondents. A discriminant function based upon gender behaviour scale scores was robust in differentiating boys and girls. Stepwise multiple regression analyses revealed that masculine behaviour increased among boys with age and the number of years of maternal sport fish consumption whereas feminine behaviour increased among girls with the duration of breast‐feeding. Increased age and previous live‐births were associated with more masculine behaviour in the girls. For both sexes, exposure was unrelated to the prevalence of learning problems, non‐right handedness, or behavioural problems. Although this study does not rule out differential gender socialization influences, the findings are consistent with an effect of contaminant exposure on sex‐dimorphic behaviours in humans. This study was in part funded with grants from the National Institute of Environmental Health Sciences, NIH (R03ES08500‐01), the Great Lakes Protection Fund (RM791‐3021), and the Agency for Toxic Substances and Disease Registry (H75/ATH298338).

Contaminant exposure and biomarker responses in spectacled eiders (Somateria fischeri) from St. Lawrence Island, Alaska.

Effects of chemical contaminant exposure may be contributing to the decline of spectacled eiders (Somateria fischeri) nesting in coastal areas of western Alaska. We evaluated chemical exposure and potential effects in 20 male eiders collected near St. Lawrence Island, Alaska. Analytes included metals, trace elements, chlorinated organics, and (137)Cesium ((137)Cs). Effects of contaminant exposure were evaluated using histopathology and biochemical measures of porphyrin profiles, cytochrome P450 activities, and metallothionein (MT) concentrations. Copper, cadmium, and selenium concentrations were elevated in spectacled eiders when compared to literature values for other marine birds. Only a few samples had trace concentrations of chlorinated organic compounds. Muscle (137)Cs levels were all below the average minimum quantifiable concentration of 0.079 Bq/g. No histopathological lesions were associated with elevated contaminant concentrations in liver, kidney, or testes. Protoporphyrin was found in highest concentration in both the liver and kidneys, followed by coproporphyrin and uroporphyrin, respectively. Hepatic uroporphyrin concentrations correlated significantly to hepatic arsenic concentrations. Mean activities of hepatic EROD, MROD, BROD, and PROD were consistent with other avian species. Comparisons of cadmium/MT ratios from this study to published literature ratios in seven marine avian species suggest that, although adult male spectacled eiders have elevated liver concentrations of certain MT-inducing metals, their MT concentrations are not as strongly induced as would be predicted based on literature values. Despite elevated metal concentrations, the apparent good health of the St. Lawrence Island birds suggests that should these contaminants be a factor in population declines, they likely act by decreasing fecundity or survival of young rather than via direct health impacts on adult male spectacled eiders.

Application of Multiple Bioindicators to Differentiate Spatial and Temporal Variability from the Effects of Contaminant Exposure on Fish

Bioindicators of fish health were measured from 1989 through 1994 in populations of redbreast sunfish ( Lepomis auritus) at three sites within a stream receiving inputs of mixed contaminants from an industrial facility, and at two reference sites. Bioindicator responses differed for fish from contaminated and reference sites throughout the study period, but temporal trends at contaminated sites reflected improved water quality associated with pollution-control efforts. Temporal variability unrelated to contaminant exposure strongly influenced the response of bioindicators at both reference and contaminated sites, but spatial variability rarely influenced these responses. Temporal variability was less influential on slower responding indicators at higher levels of biological organization. The diverse response characteristics of indicators increased the ability to differentiate natural from anthropogenic sources of variability. Integrated bioindicator responses were compared among site–year groups by multivariate canonical analysis. The primary canonical variable, associated with differences in growth, exhibited trends consistent with the timing of pollution-control efforts. Two indicators of contaminant exposure (7-ethoxyresorufin O-deethylase activity and polychlorinated biphenyls in fish muscle) also exhibited trends consistent with the timing of pollution-control efforts, but the likelihood of possible mechanistic linkages cannot be assessed with available data.

Influence of ecological factors on the relationship between mfo induction and fish growth: Bridging the gap using neural networks

Relationships between molecular and biochemical effects of contaminant exposure and organism-level effects are difficult to establish primarily because: (1) the large differences in time-scales of the responses; (2) the complexity of mechanisms involved in such relationships; and (3) the influence of ecological factors on the expression of higher-level responses to stress. In this study we investigated the relationship between mixed function oxidase (MFO) induction and growth in fish as influenced by principal ecological factors in the environment, such as habitat quality, competition and food availability. Because of the complexity and non-linearity of interactions among these factors, we applied a back-propagation neural network approach to investigate this relationship. Inputs into the network included an indicator of contaminant exposure 7-ethoxyresorufin O-deethylase, EROD) and several ecological variables, while growth rate served as the single output variable. Under the field conditions and contaminant exposure regimes observed in this study, EROD in the model simulation contributed minimal marginal ability to predict growth. Indirect effects of contaminants on growth could occur, however, through influences on food chain processes or behavioral dynamics of fish populations.

Multidisciplinary Assessment of Pollution at Three Sites in Long Island Sound

Winter flounder (Pseudopleuronectes americanus) were sampled from three sites located near Norwalk, New Haven, and Niantic, Connecticut, in Long Island Sound during February 1987, to evaluate the degree of chemical contamination and to determine possible effects of contaminant exposure. At each site, sediment and infaunal invertebrates were also collected and analyzed for trace metals and organic chemicals. Specimens of liver and kidney from winter flounder were examined for histopathological conditions, including the presence of macrophage aggregates in liver tissue. Liver samples were also analyzed for DNA damage (i.e., the formation of adducts between DNA and chemical contaminants). Blood samples were collected and analyzed for erythrocyte micronuclei. The sampling site near New Haven was determined to be the most affected site, from the standpoints of greater chemical contamination and possible effects on winter flounder. Concentrations of aromatic hydrocarbons (AHs) and polychlorinated biphenyls (PCBs) were highest in sediment from this site, and the highest prevalences of the histopathological changes and DNA alterations were also found in the livers of winter flounder from this site. No differences in the concentrations of contaminants in fish or in frequencies of erythrocyte micronuclei in fish blood were found between sites. None of the sites sampled had contaminant levels or prevalences of lesions as high as previously found at other East Coast locations (e.g., Boston Harbor, Massachusetts, Raritan Bay, New York). Overall, our results indicate moderate levels of pollution at two of the urban sites in Long Island Sound and provide a framework for expanded studies to better define the extent and impact of chemical pollution in Long Island Sound.