Environmental Contaminants In Fish Research Articles

Neurotoxins in a water supply reservoir: An alert to environmental and human health

Reservoirs are important source of power generation, recreation, and water supply. Nevertheless, human activities have favored the bloom of toxic cyanobacteria in many reservoirs, which has resulted in environmental, social, and economic problems. This study aims to evaluate the water quality of a reservoir in South Brazil through the analysis of cyanobacteria and cyanotoxins PSTs (Paralytic Shellfish Toxins) and biomarkers of environmental contamination in fish. For this purpose, water samples and fish (Geophagus brasiliensis) (Perciformes: Cichlidae) were collected from September 2013 to May 2014. The fish G. brasiliensis were separated in two groups. The first one “site group” was euthanized after the sampling and their weight and length were measured. The blood, brain, muscle and liver were collected for chemical, biochemical and genetics biomarkers analysis. The second group “depuration group” was submitted to depuration experiment for 40 days in clean water. After that, the same procedures as for the first group were carried out. Cylindrospermopsis raciborskii was the dominant cyanobacteria found in the reservoir, and it showed a density above the recommended limit by Brazilian legislation of 20,000 cells/mL. Results showed that the fish accumulate PSTs in the Reservoir and these were not eliminated after 40 days. The biochemical and genotoxic biomarkers showed a significant difference between “site groups” and “depuration groups”, which suggests a recovery of the antioxidant system and a reduction of cellular damage after 40 days in clean water. In conjunction with results reported earlier by others, Alagados Reservoir, in South Brazil, appears to have a persistent contamination of cyanotoxins. Moreover, the mixture of contaminants which may be present in the water body can explain the seasonal differences in fish at the sampled points.

Effects of Mercury Chloride on Oxidative Stress Biomarkers of Some Tissues of the African Catfish Clarias gariepinus (Burchell, 1822)

The present study evaluates in Clarias gariepinus the oxidative damage associated with two sub-chronic exposures to mercury chloride. The destructive effects of mercury chloride on the African Catfish, Clarias gariepinus was revealed in terms of protein carbonyl (PC), lipid peroxidation (LPO), DNA damage and nitric oxide (NO) as oxidative stress biomarkers. Super oxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx), glutathione reductase (GR), glutathione-s-Transferase (GST), glutathione (GSH) and total antioxidant (TAO) in the gills, kidney and liver can be used as biomarkers to identify possible environmental contamination in fish. This study aimed to investigate the impact of HgCl2 (0.04 and 0.12 ppm) for 14 and 28 days of the activity of the selected parameters in different tissues of Clarias gariepinus. The activity of SOD, CAT, Gpx and TAO dropped when compared to the control groups without mercury chloride exposure in all tissues under investigation. The pattern of variations in GST, GR and GSH activity in mercuryinduced groups were significantly increased than that of the control group. Also, NO, CP, LPO and DNA damage, were recorded with a pattern of a significant increase toward exposure period in all tissues under investigation.

Nutrients and Chemical Pollutants in Fish and Shellfish. Balancing Health Benefits and Risks of Regular Fish Consumption

Dietary patterns and lifestyle factors are clearly associated with at least five of the ten leading causes of death, including coronary heart disease, certain types of cancer, stroke, non-insulin insulin-dependent diabetes mellitus, and atherosclerosis. Concerning specifically fish and seafood consumption, its beneficial health effects in humans are clearly supported by an important number of studies performed in the last 30 years. These studies have repeatedly linked fish consumption, especially those species whose contents in omega-3 fatty acids are high, with healthier hearts in the aging population. The nutritional benefits of fish and seafood are also due to the content of high-quality protein, vitamins, as well as other essential nutrients. However, a number of studies, particularly investigations performed in recent years, have shown that the unavoidable presence of environmental contaminants in fish and shellfish can also mean a certain risk for the health of some consumers. While prestigious international associations as the American Heart Association have recommended eating fish at least two times (two servings a week), based on our own experimental results, as well as in results from other laboratories, we cannot be in total agreement with that recommendation. Although a regular consumption of most fish and shellfish species should not mean adverse health effects for the consumers, the specific fish and shellfish species consumed, the frequency of consumption, as well as the meal size, are essential issues for adequately balancing the health benefits and risks of regular fish consumption.

Gas chromatography–triple quadrupole tandem mass spectrometry: a powerful tool for the (ultra)trace analysis of multiclass environmental contaminants in fish and fish feed

A new method for rapid determination of 73 target organic environmental contaminants including 18 polychlorinated biphenyls, 16 organochlorinated pesticides, 14 brominated flame retardants and 25 polycyclic aromatic hydrocarbons in fish and fish feed using gas chromatography coupled with triple quadrupole tandem mass spectrometry (GC-MS/MS) was developed and validated. GC-MS/MS in electron ionization mode was shown to be a powerful tool for the (ultra)trace analysis of multiclass environmental contaminants in complex matrices, providing measurements with high selectivity and sensitivity. Another positive aspect characterizing the newly developed method is a substantial simplification of the sample preparation, which was achieved by an ethyl acetate QuEChERS (quick, easy, cheap, effective, rugged and safe) based extraction followed by silica minicolumn clean-up. With use of this sample preparation approach the sample laboratory throughput was increased not only because six samples may be prepared in approximately 1 h, but also because all the above-mentioned groups of contaminants can be determined in a single GC-MS/MS run. Under the optimized conditions, the recoveries of all target analytes in both matrices were within the range from 70 to 120% and the repeatabilities were 20% or less. The method quantification limits were in the range from 0.005 to 1 μg kg(-1) and from 0.05 to 10 μg kg(-1) for fish muscle tissue and fish feed, respectively. The developed method was successfully applied to the determination of halogenated persistent organic pollutants and polycyclic aromatic hydrocarbons in fish and fish feed samples.

Fish intake and type 2 diabetes in Japanese men and women: the Japan Public Health Center–based Prospective Study

Although fish intake can improve glucose metabolism, results of some prospective studies in Western populations suggest potential adverse effects of environmental contaminants in fish on type 2 diabetes risk. However, data from populations with high fish consumption are scarce. We prospectively investigated the association between fish intake and type 2 diabetes risk in Japanese adults. The participants were 22,921 men and 29,759 women aged 45-75 y who completed a questionnaire of the second survey for the Japan Public Health Center-based Prospective Study and who had no history of diabetes. Diet was ascertained by using a 147-item food-frequency questionnaire. ORs of self-reported, physician-diagnosed type 2 diabetes over 5 y were estimated by using logistic regression. During the 5-y period, 971 new cases (572 men and 399 women) of type 2 diabetes were self-reported. In men, fish intake was significantly associated with a decreased risk of type 2 diabetes; multivariable-adjusted ORs of type 2 diabetes for the highest compared with the lowest quartile of intake were 0.73 (95% CI: 0.54, 1.00; P-trend = 0.04) for total fish and seafood and 0.68 (95% CI: 0.50, 0.92; P-trend = 0.016) for small and medium fish (horse mackerel and sardine, saury and mackerel, and eel). Additional analysis by fat content of fish did not detect any significant association for each category. In women, fish intake was not appreciably associated with type 2 diabetes risk. In a population with high fish and seafood intake, fish consumption was associated with a lower risk of type 2 diabetes in men but not in women.

Influence of gender, feeding regimen, and exposure duration on gene expression associated with xenobiotic metabolism in fathead minnows (Pimephales promelas)

Little is known about how gender and diet affect the metabolism of environmental contaminants in fish. This study was undertaken to compare these differences in hepatic mRNA expression of two genes associated with xenobiotic metabolism: the pregnane x-receptor (PXR) and cytochrome P450 3A4 (CYP3A4). PXR is an ideal receptor to study xenobiotic metabolism as it binds to a vast array of anthropogenic compounds and induces transcription of genes involved in metabolizing xenobiotic compounds, such as CYP3A4. In this study FHM were separated by gender and feeding regimen (fed versus unfed), and injected with control (corn oil), clotrimazole, or pregnene-16α-olone, and expression monitored after 2- and 5-days of treatment. Our research indicates that there are gender- and diet-specific differences in the expression of PXR and CYP3A4, the most striking of which was a significant increase in the expression of PXR and CYP3A4 in unfed females as compared to all other groups. Understanding the relationship among xenobiotic metabolism, gender and diet would be of particular interest in the study of contaminated habitats, where fish may have to adapt to reductions in food quantity or quality while being exposed to toxic compounds.

Effects of ultraviolet A on the activity of two metabolic enzymes, DNA damage and lipid peroxidation during early developmental stages of the African catfish, Clarias gariepinus (Burchell, 1822).

Many ultraviolet-A (UVA)-induced biochemical and physiological changes are valid as biomarkers using aquatic species for detection of the degree of stress. Changes in the concentration and activities of enzymes, such as glucose-6-phosphate dehyderogenase (G6PDH), lactate dehyderogenase (LDH), DNA damage and lipid peroxidation (LPO), can be used as biomarkers to identify possible environmental contamination in fish. This study aimed to investigate the impact of UVA on the activity of the selected enzymes, DNA damage and LPO during early developmental stages of the African catfish Clarias gariepinus. Embryo hemogenates were used for measurements of G6PDH, LDH, DNA damage and LPO concentrations and activities spectrophotometrically at 37°C. The normal ontogenetic variations in enzyme activities, DNA damage and LPO of the early developmental stages (24–168 h-PFS; hours-post fertilization stage) were studied. There was a significant decrease in the activity of G6PDH till 120 h-PFS. Then after 120 h-PFS, the activity of such enzymes insignificantly increased toward higher stages. The LDH activity was recorded with a pattern of decrease till 96 h-PFS, followed by a significant increase toward 168 h-PFS. The polynomial pattern of variations in DNA damage and LPO was also evident. The patterns of the enzyme activities, corresponding DNA damage and LPO of the early ontogenetic stages under the influence of three different UVA doses (15, 30 and 60 min), were recorded. The pattern of variations in G6PDH activity in UVA-induced groups was similar to that of the control group with variation in the magnitude of such activity. In all treated groups, LDH activity decreased till 96 h-PFS, then increased till 168 h-PFS. Within each of the embryonic stages, the increase in UVA led to a significant increase in DNA damage. A significant increase in lipid peroxidation under UVA doses was recorded. The variability in number and molecular weight of proteins under exposure to UVA was evident, reflecting some of the genetic and transcriptional changes during exposure and development.

Mortality in a cohort with high fish consumption

Our aim was to assess the mortality of fishermen and fishermen's wives in Finland, presuming that the mortality reflects their high consumption of contaminated fish. All Finnish fishermen, registered since 1980, were identified from the Professional Fishermen Register (N = 6410), and the fishermen's wives from the national population register (N = 4260). The cohorts were individually linked with cause-of-death data until 2005 at Statistics Finland. The follow-up started in the year after the first registration as a fisherman and at marriage (if later) for the wives. The standardized mortality ratios (SMRs) were calculated based on the national mortality rates. In addition, blood samples and food frequency questionnaire data were collected from a volunteer sample. The average fish consumption and serum concentrations of fish-derived fatty acids and environmental contaminants were higher among the fishermen and their wives than among the general population from the same region. The fishermen and their wives had lower mortality from all causes (SMR 0.78, 95% confidence interval (CI) 0.73-0.82, and 0.84, 0.76-0.93, respectively), and ischaemic heart diseases (0.73, 0.65-0.81, and 0.65, 0.50-0.83) than the general population. Mortality from cerebrovascular diseases and malignant neoplasms was decreased among the fishermen (0.67, 0.52-0.85, and 0.90, 0.80-1.01), but not among the wives. In addition, the fishermen's mortality from water transport accidents was extremely high (8.31, 5.65-11.79). The fishermen and their wives had lower mortality from many natural causes. The high intakes of environmental contaminants in fish were not seen as excess mortality.

Environmental Contaminants in Fish and Their Associated Risk to Piscivorous Wildlife in the Yukon River Basin, Alaska

Organochlorine chemical residues and elemental contaminants were measured in northern pike (Esox lucius), longnose sucker (Catostomus catostomus), and burbot (Lota lota) from 10 sites in the Yukon River Basin (YRB) during 2002. Contaminant concentrations were compared to historical YRB data and to toxicity thresholds for fish and piscivorous wildlife from the scientific literature. A risk analysis was conducted to screen for potential hazards to piscivorous wildlife for contaminants that exceeded literature-based toxicity thresholds. Concentrations of total DDT (sum of p,p'-homologs; 1.09-13.6 ng/g), total chlordane (0.67-7.5 ng/g), dieldrin (<0.16-0.6 ng/g), toxaphene (<11-34 ng/g), total PCBs (<20-87 ng/g), TCDD-EQ (<or=1.7 pg/g), arsenic (0.03-1.95 microg/g), cadmium (<0.02-0.12 microg/g), copper (0.41-1.49 microg/g), and lead (<0.21-0.27 microg/g) did not exceed toxicity thresholds for growth and reproduction in YRB fish. Concentrations of mercury (0.08-0.65 microg/g), selenium (0.23-0.85 microg/g), and zinc (11-56 microg/g) exceeded toxicity thresholds in one or more samples and were included in the risk analysis for piscivorous wildlife. No effect hazard concentrations (NEHCs) and low effect hazard concentrations (LEHCs), derived from literature-based toxicity reference values and avian and mammalian life history parameters, were calculated for mercury, selenium, and zinc. Mercury concentrations in YRB fish exceeded the NEHCs for all bird and small mammal models, which indicated that mercury concentrations in fish may represent a risk to piscivorous wildlife throughout the YRB. Low risk to piscivorous wildlife was associated with selenium and zinc concentrations in YRB fish. Selenium and zinc concentrations exceeded the NEHCs and LEHCs for only the small bird model. These results indicate that mercury should continue to be monitored and assessed in Alaskan fish and wildlife.

An examination of the trade-offs in public health resulting from the use of default exposure assumptions in fish consumption advisories

Efforts to provide for public health protection from environmental contaminants in fish have resulted in various advisories or recommendations with regard to fish consumption from local, state, and federal agencies. These advisories are based on measured levels of contaminants in fish that are combined with values for body weight and portion size to produce an estimate of an “acceptable” consumption frequency (e.g., eat no more than once per month). Because values for body weight and portion size are generally generic default values, they do not necessarily relate to a specific population or to any individual in that population. Thus, the use of default values may result in underprotection or overprotection in any given case. Given the benefits of fish consumption and the risks from overexposure to various toxicants, vigilance is required by custodians of public health to ensure that populations are protected while being cautious not to over- or underprotect them. In this analysis, we examine the “acceptable” consumption limits derived for fish species/groups consumed by three specific populations and determine the extent of public health protection afforded by these limits. To accomplish this, the “acceptable” consumption frequencies are derived based, in part, on default assumptions and are compared to intakes calculated from empirically derived species-specific individual consumption and demographic data. Sensitivity analyses and population-specific probabilistic assessments of exposure are conducted to identify those values and/or assumptions which might significantly influence the resulting fish consumption advisories. Three populations were chosen for study based on their ability to represent populations of greatest concern: those most sensitive and/or those most exposed. We conclude from this investigation that consumption pattern data, contaminant data and body weight data together can be used to make fish consumption advisories more focused and, therefore, less likely to be under- or overprotective.

Health benefits and potential risks related to consumption of fish or fish oil

The nutritional benefits of fish consumption relate to the utilization of proteins of high biological value, as well as certain minerals and vitamins that fish provide. Fish or fish oil contains omega-3 polyunsaturated fatty acids (PUFAs) that appear to play several useful roles for human health. Conversely, some carcinogenic contaminants are also stored in the adipose tissue of fish. The objective of this paper is to evaluate the potential health benefits and risks related to the consumption of fish or fish oil. Health benefits related to the consumption of fish or omega-3 PUFAs were obtained by an extensive literature search. Potential health risks related to carcinogenic contaminants (e.g., dioxin, PCB, etc.) in fish were estimated using the U.S. EPA-approved cancer risk assessment guidelines. Potential health risk estimates were evaluated by comparing them with the acceptable excess risk level of 10 −6–10 −4. Scientific data indicate that the consumption of fish or fish oil containing omega-3 PUFAs reduces the risk of coronary heart disease, decreases mild hypertension, and prevents certain cardiac arrhythmias and sudden death. Risk estimates in humans for carcinogenic environmental contaminants in fish ranged from an excess risk level of 3 × 10 −6–9 × 10 −4. These risk estimates appeared to meet the acceptable excess risk level criteria. Therefore, consumption of fish in accordance with the State of Michigan Fish Advisory Guidelines is safe and should be encouraged. The top 11 fish species [e.g., sardines, mackerel, herring (Atlantic and Pacific), lake trout, salmon (Chinook, Atlantic, and Sockeye), anchovy (European), sablefish, and bluefish] provide an adequate amount of omega-3 PUFAs (2.7–7.5 g/meal) and appear to meet the nutritional recommendation of the American Heart Association.

Halogenated environmental contaminants in fish from Estonian coastal areas

Polychlorinated biphenyls (PCBs), DDT-related substances and hexachlorocyclohexane (HCH) isomers were analysed in fish from Estonian coastal waters.The content of persistent organic pollutants (POPs) in fish (perch ( Perca fluviatilis) and flounder ( Platichtys flesus)) from the coastal waters of Estonia is not a danger to human health. Even the maximum concentrations that we have determined are lower than the standards set by the World Health Organization (WHO). The results do not exclude the need to monitor toxicants in fish also in the future, because the use of hazardous chemicals in the Baltic Sea region will probably continue.

Differential Inhibition of Xenobiotic-Metabolizing Carboxylesterases by Organotins in Marine Fish

The hydrolytic metabolism of xenobiotics in the liver of two tropical marine fish, Siganus canaliculatus and Acanthopagrus latus, was found to be catalyzed by both microsomal and cytosolic carboxylesterases; the latter forms were more active than the former. Remarkably greater efficiency of S. canaliculatus for p-nitrophenylacetate hydrolysis was attributed to manyfold higher Vmax and lower Km values of hepatic microsomal and cytosolic carboxylesterases of S. canaliculatus as compared with those of A. latus. Comparative characterization of the in vitro responses of hepatic microsomal and cytosolic carboxylesterases to the organotin group of marine pollutants—tributyltin (TBT), triphenyltin (TPT), and dibutyltin (DBT), a relatively persistent metabolite of TBT—revealed species-, isozymic form-, and organotin structure-related differences in the hydrolytic detoxication. In general, carboxylesterases of S. canaliculatus exhibited severalfold greater susceptibility to organotin inhibition and DBT was the most potent inhibitor (IC50 in micromolar range). Notably, the IC50 of SnCl2, a metal present in all the compounds studied, was higher than 2 mM. Cytosolic forms in both species were more sensitive to organotin inhibition than microsomal counterparts. In line with these differences the nature of inhibition of cytosolic and microsomal carboxylesterases by organotins was competitive and noncompetitive, respectively. These results suggest that organotins may aggravate the toxicity of other environmental contaminants in fish and other aquatic organisms. Moreover, highly sensitive cytosolic carboxylesterases of S. canaliculatus liver may serve as molecular biomarkers of organotin pollution.

The usefulness of histopathology in aquatic toxicity studies

1. 1. A survey was carried out to examine the usefulness of histopathology for the identification of toxic effects of environmental contaminants in fish. 2. 2. Two small fish species, Poecilia reticulata (guppy) and Oryzias latipes (medaka) were used, and two exposure periods (1 and 3 months) were chosen. 3. 3. The following compounds were studied: β-hexachlorocyclohexane, bis(tri- n-tributyltin)oxide, di- n-butyltindichloride, sodium bromide, methyl bromide, and methylmercury chloride. 4. 4. The following is concluded: histopathology provides useful data in characterizing toxic effects in fish; there is a slight advantage for Poecilia reticulata over Oryzias latipes; there is no advantage for 3 months exposure vs 1 month.

Cellular effects of environmental contamination in fish from the River Elbe and the North Sea

Results of the tissue and cellular responses (light and electron microscopy, cytochemistry) of the liver of flounder ( Platichthys flesus L.) from a current interdisciplinary study are presented. Fish were sampled along a pollution gradient from the Elbe estuary towards the northern part of the Wadden Sea coast and the Eider estuary (reference areas). Livers of different age groups of flounder (0, I, II, III) were investigated in order to relate the degree of tissue lesions to the ‘exposure time’ or lifespan the fish inhabits the differently contaminated areas. The severity of pathological liver changes corresponds to the accumulation of contaminants (HCB, PCBs, OCS, d,y-HCH, Hg) and differs significantly with prolonged residence at the sites investigated. Liver ultrastructure revealed evidence of severe perturbations of the intracellular organization (disorganization of rough endoplasmic reticulum, lysosomes-lipofuscin, lipid accumulation, defects of cytoskeleton) to cellular responses indicating the initiation of detoxification processes (smooth endoplasmic reticulum, lysosomes) and ‘normal’ compartmentation of hepatocytes along the pollution gradient investigated. Based on the studies of normal liver structure and its pathological phenomena indicating a key role of the lysosomal system, the lysosomal stability test ( N-acetyl-hexosaminidase) was applied in order to relate tissue and cellular pathology to cytochemical indices reflecting the biochemistry of the injured tissue. First results revealed a highly significant negative correlation between the stability of the lysosomal membrane to the degree of liver lesions. Furthermore, the initial results obtained from the mouth of the Elbe estuary and a northern reference area in the Wadden Sea inferred significant differences with respect to lysosomal stability.

Use of Laboratory Studies in Assessing the Behaviour of Contaminants in Fish Inhibiting Natural Ecosystems

Abstract The behavior of environmental contaminants in fish was examined using information from chemical, toxicological, and physiological laboratory studies, and field residue measurements to establish the relative importance of the bioconcentration and biomagnification pathways, and environmental concentrations on residue accumulation in natural ecosystems. It is suggested that indices such as the bioconcentration factor (BCF) and octanol-water partition coefficient (Kow) can be effectively used to analyze the fate of contaminants in natural ecosystems provided their limitations are recognized. It is proposed that other indices like the bioaccumulation factor (BAF) and biological half-life could also be used for evaluation. A simulation of the contaminant dynamics of a salmonid is presented, and the kinetics are used to illustrate the differences in behavior of the more environmentally relevant organic contaminants present in the Lake Ontario environment.

Biological and Toxicologtcal Effects of Environmental Contaminants in Fish and Their Eggs

Rainbow trout (Salmo gairdneri), white sucker (Catostomus commersoni), white bass (Morone chrysops), smallmouth bass (Micropterus dolomieui), and yellow perch (Perca flavescens) were collected from Lakes Ontario and Erie to examine the relationship between contaminant levels in females and their eggs. Factors such as the percent lipid in the fish and percent of total lipid deposited in the eggs significantly influenced (P &lt; 0.01) contaminant transfer. The percentages of the 9–11 organic contaminants transferred generally showed less variation within a species than the percentages for a substance transferred among the five species examined. This relationship was consistent even though there was over a 10-fold range in contaminant concentrations within a given species. Mercury did not demonstrate this response because the percentage in eggs was low for all species. The levels of PCB monitored in eggs of rainbow trout collected from Lake Ontario suggest that egg and fry survival rates could be affected based on the toxicological evidence from other studies. An examination of the possible effects of spawning on the kinetics of contaminants among these species suggests that relative body concentrations of organic contaminants may be decreased by 5% or be increased by 10%, and mercury levels may be increased by 6–22% following the deposition of eggs. The amount of change varies with species and is influenced by the percent egg weight of body weight, and the rate of contaminant transfer from females to eggs.Key words: toxicology, contaminants, reproduction, Lake Ontario, Lake Erie

A novel biopsy technique for monitoring environmental contaminants in fish.

Biopsy techniques have long been used in animal studies (FISLER and DRENICK 1972, TREVIN0 et al 1973) and in various medical applications in humans (EDWARDS 1973). The methods do not appear fo have heen successfully applied in environmental samples involving small animals, birds and fish. This seems tobe attributable in part to the size of cote sample extractab!e with the biopsy instruments normally available. However, with the rapid advaneement of analytical techniques which perm 8 of the reliable ana!ysis of smaller and smaller samples, it seems timely to report on the successful use of a biopsy sampl 8 program dur 8 a large scale tagging of sea mullet (Mug 8 cephalus Linnaeus) from a poliuted estuarine region.