Validation trial of Japan's zinc water quality standard for aquatic life using field data

This study sought to validate Japan's zinc water quality standard for aquatic life (algae and benthic invertebrates) based on field survey data. The effects of zinc on aquatic life, especially algae and benthic invertebrates, were investigated mainly in water areas with upstream basins that contain mines. Seven biological indicators (number of cells or individuals, number of taxa, number of EPT taxa, number of collector–gatherer taxa of benthic invertebrates, and Simpson index, Shannon–Weiner index, and Margalef index for algae and benthic invertebrates) were analyzed with respect to zinc concentrations and the zinc toxic equivalent quantity (Zn-TEQ), and additive contribution from other metals was assumed. The results showed that the number of taxa of algae and benthic invertebrates significantly decreased with increases in zinc concentration and Zn-TEQ. For benthic invertebrates, six of the metrics (all except the number of individuals) tended to decrease with increases in zinc concentration and Zn-TEQ. The effect level of biocenosis (ELB) was defined as the concentration at which the metrics decrease significantly with Wilcoxon's rank sum test. The ELB calculated for zinc was in the range of 16–54 μg/L for zinc concentration and 38–50 μg/L for Zn-TEQ; thus, Japan's environmental zinc standard for the protection of aquatic life, at 30 μg/L, was found to be a level consistent with these results.     

Combined use of biomarkers and in situ bioassays in Daphnia magna to monitor environmental hazards of pesticides in the field

The aim of this investigation was to evaluate toxicity effects of pesticides in aquatic invertebrates using in situ bioassays with the local species, Daphnia magna. Investigations were carried out in the Delta del Ebro (northeast Spain) during the main growing season of rice (May-August). Measures of energy consumption (i.e., algal grazing) and of specific biochemical responses (biomarkers) were conducted in individuals transplanted at four stations, including a clean site upstream of the affected area and the three main channels that collect and drain the water from the rice fields into the sea. Seventeen pesticides were analyzed in water by on-line solid-phase extraction-liquid chromatography-tandem mass spectrometry. The results obtained indicated high levels of pesticides in water, with peak values of 487 microg/L for bentazone, 8 microg/L for methyl-4-chlorophenoxyacetic acid, 5 microg/L for propanil, 0.8 microg/L for molinate, and 0.7 microg/L for fenitrothion. Measured biological responses denoted severe effects on grazing rates; a strong inhibition of cholinesterases and carboxylesterases, which are specific biomarkers of organophosphorous and carbamate pesticides; and altered patterns of the antioxidant enzyme catalase and the phase II metabolizing enzyme glutathione S-transferase. Correlation analysis with pesticide residue levels converted to toxic units relative to its acute 48-h median lethal concentration of D. magna indicated significant and negative coefficients between the dominant pesticide residues and the observed biological response, thus denoting a clear cause-and-effect relationship. The results emphasize the importance of considering specific (biomarkers) as well as more generalized and ecologically related (grazing) in situ responses to identify and evaluate biological effects of environmental contaminants in the field.     

Review of recent proteomic applications in aquatic toxicology

Over the last decade, the environmental sciences have witnessed an incredible movement towards the utilization of high-throughput molecular tools that are capable of detecting simultaneous changes of hundreds, and even thousands, of molecules and molecular components after exposure of organisms to different environmental stressors. These techniques have received a great deal of attention because they not only offer the potential to unravel novel mechanisms of physiological and toxic action but are also amenable to the discovery of biomarkers of exposure and effects. In this article, we review the state of knowledge of one of these tools in ecotoxicological research: proteomics. We summarize the state of proteomics research in fish, and follow with studies conducted with aquatic invertebrates. A brief discussion on proteomic methods is also presented. We conclude with some ideas for future proteomic studies with fish and aquatic invertebrates.     

The use and misuse of biomarkers in ecotoxicology

Substantial efforts have been devoted to developing and applying biomarkers for use in ecotoxicology. These efforts have resulted partly from a desire for early warning indicators that respond before measurable effects on individuals and populations occur and partly as an aid to identifying the causes of observed population- and community-level effects. Whereas older biomarkers focused on measures of organism physiology or biochemistry, advances in molecular biology are extending the biomarker philosophy to the level of the genes (i.e., ecotoxicogenomics). However, the extent to which biomarkers are able to provide unambiguous and ecologically relevant indicators of exposure to or effects of toxicants remains highly controversial. In the present paper, we briefly discuss the application of biomarkers in ecotoxicology and ecological risk assessment, and we provide examples of how they have been applied. We conclude that although biomarkers can be helpful for gaining insight regarding the mechanisms causing observed effects of chemicals on whole-organism performance and may, in some cases, provide useful indicators of exposure, individual biomarker responses should not be expected to provide useful predictions of relevant ecological effects--and probably not even predictions of whole-organism effects. Suites of biomarkers are only likely to provide increased predictability if they can be used in a comprehensive mechanistic model that integrates them into a measure of fitness. Until this can be achieved, biomarkers may be useful for hypothesis generation in carefully controlled experiments. However, because the aims of environmental monitoring and ecological risk assessment are to detect and/or predict adverse chemical impacts on populations, communities, and ecosystems, we should be focusing our efforts on improving methods to do this directly. This will involve developing and testing models of appropriate complexity that can describe real-world systems at multiple scales.     

Laboratory and field evaluations of novaluron, a new insect growth regulator (IGR), against Culex mosquitoes

Limited laboratory and field studies have indicated that the insect growth regulator (IGR) novaluron exhibits good activity against larvae of pest species in the orders Coleoptera, Hemiptera (suborder Heteroptera), and Lepidoptera by both ingestion and contact. We completed laboratory and field studies to evaluate activity and efficacy of novaluron against Culex mosquitoes. In laboratory studies, novaluron was highly active against Cx. quinquefasciatus, as indicated by low levels of inhibition of emergency (IE), at the 50% level, IE50 (0.159 ppb for 2nd-stage larvae and 0.118 ppb for 4th-stage larvae) and IE90, at the 90% level, (0.604 ppb for 2nd-stage larvae and 0.595 ppb for 4th-stage larvae). In outdoor microcosm and mesocosm studies against natural populations, novaluron yielded excellent control of immature Culex mosquitoes for up to 14 days at 1.25, 2.5, and 5 ppb in microcosms, and for up to 7 days at the dosages of 1, 5, and 10 mg/m2 in mesocosms. Based on qualitative observations, novaluron seemed to have a favorable margin of safety for nontarget aquatic invertebrates cohabiting with mosquito larvae. Further large-scale field studies are warranted to evaluate initial efficacy and longevity of novaluron against various mosquito species, as well as its safety for nontarget biota.     

The validity of bioelectrical impedance models in clinical populations.

Bioelectrical impedance analysis (BIA) is the most commonly used body composition technique in published studies. Herein we review the theory and assumptions underlying the various BIA and bioelectrical impedance spectroscopy (BIS) models, because these assumptions may be invalidated in clinical populations. Single-frequency serial BIA and discrete multifrequency BIA may be of limited validity in populations other than healthy, young, euvolemic adults. Both models inaccurately predict total body water (TBW) and extracellular water (ECW) in populations with changes in trunk geometry or fluid compartmentalization, especially at the level of the individual. Single-frequency parallel BIA may predict body composition with greater accuracy than the serial model. Hand-to-hand and leg-to-leg BIA models do not accurately predict percent fat mass. BIS may predict ECW, but not TBW, more accurately than single-frequency BIA. Segmental BIS appears to be sensitive to fluid accumulation in the trunk. In general, bioelectrical impedance technology may be acceptable for determining body composition of groups and for monitoring changes in body composition within individuals over time. Use of the technology to make single measurements in individual patients, however, is not recommended. This has implications in clinical settings, in which measurement of individual patients is important.     

Probabilistic risk assessment of cotton pyrethroids: V. Combining landscape-level exposures and ecotoxicological effects data to characterize risks

Since their introduction, synthetic pyrethroid insecticides have generated regulatory concerns regarding their toxicity to fish and aquatic invertebrates. In this paper we assess the potential for risks to aquatic ecosystems in cotton-growing areas, focusing on cypermethrin as a suitable representative of the pyrethroid class and static water bodies (ponds and lakes) as worst-case water bodies because of low levels of dilution. Reviews of cypermethrin effects under laboratory and field conditions have characterized the potential aquatic effects of the chemical. Also, a landscape-level exposure characterization has been conducted in a worst-case cotton-growing county, Yazoo County, Mississippi, USA, to provide a more realistic exposure characterization than is possible using standard model scenarios. Risks were characterized using the standard tier I and II approaches of the U.S. Environmental Protection Agency. In addition, a probabilistic risk assessment was conducted by comparing landscape-level exposure calculations for ponds and lakes in Yazoo County (modified tier II analysis) with distributions of laboratory effect concentrations and with data from field studies. Risk characterization using tier I and tier II models demonstrated a level of concern for certain aquatic organisms. However, modified tier II analysis showed that exposure concentrations are unlikely to exceed concentrations that might cause ecologically significant effects. Indeed, in the vast majority of cases, concentrations in the modified tier II analysis were several orders of magnitude lower than those at which effects would be predicted on the basis of laboratory and field data. The conclusion of minimal potential for adverse ecological effects was also supported by field studies, which showed that impacts on aquatic systems were negligible, even at concentrations many times higher than the modified tier II exposure concentrations.     

Investigation of animal and algal bioassays for reliable saxitoxin ecotoxicity and cytotoxicity risk evaluation

Contamination of water bodies by saxitoxin can result in various toxic effects in aquatic organisms. Saxitoxin contamination has also been shown to be a threat to human health in several reported cases, even resulting in death. In this study, we evaluated the sensitivity of animal (Neuro-2A) and algal (Chlamydomonas reinhardtii) bioassays to saxitoxin effect. Neuro-2A cells were found to be sensitive to saxitoxin, as shown by a 24 h EC50 value of 1.5 nM, which was obtained using a cell viability assay. Conversely, no saxitoxin effect was found in any of the algal biomarkers evaluated, for the concentration range tested (2-128 nM). These results indicate that saxitoxin may induce toxic effects in animal and human populations at concentrations where phytoplankton communities are not affected. Therefore, when evaluating STX risk of toxicity, algal bioassays do not appear to be reliable indicators and should always be conducted in combination with animal bioassays.     

Chronic toxicities of surfactants and detergent builders to algae: a review and risk assessment

Surfactants are high volume chemicals used primarily in detergent products and are found in natural waters. The toxic effects of representative surfactants on aquatic life have been determined and summarized in greater detail for animal test species than for aquatic vegetation. This paper summarizes the chronic toxicity levels for algae, an important trophic level in aquatic ecosystems. Toxic effects have been determined for a few commercially important surfactants and primarily for cultured freshwater algae under the controlled conditions of the laboratory where inhibition, and in some cases, stimulation have been observed. The reported toxicities of surfactants have varied widely over several orders of magnitude and the effect levels are compound and species-specific. Species sensitivity can vary as much as three orders of magnitude to the same surfactant and the effects of different surfactants on the same algal species can vary as much as four orders of magnitude. Therefore, data generalizations and extrapolations are difficult but anionic and nonionic surfactants and detergent builders are relatively non-toxic when compared to various cationic monoalkyl and dialkyl quaternary ammonium salts. Recent toxicity studies conducted in the field monitoring the effects of several surfactants used in commercial products on various structural and functional parameters of natural algal communities have shown toxicity to be less in many cases than that predicted from laboratory tests. Furthermore, the field-derived effect levels typically exceed the reported measured environmental levels of the corresponding surfactants indicating the likelihood of no impact. Additional field studies are needed to substantiate this trend for these and other commercially important surfactants particularly for natural saltwater algal assemblages for which the toxicity data base is unavailable.     

Research on the socio-ethical impact of biomarker use and the communication processes in ECNIS NoE and NewGeneris IP

Current research projects using human biomarkers in their search for better knowledge on the interaction between environment and human health are facing sensitive ethical issues. Researchers may be put in situations in which it is unclear how to act in accordance with all necessary legal requirements on ethical aspects of research. As a consequence, scientific opportunities and important developments of which many individuals will benefit, may be missed. Sound scientific research in the field of environment and health may benefit from a "rethinking" of current theoretical frameworks and procedures issuing from clinical medicine, putting emphasis on decisional autonomy and the protection of the individual and to a much lesser degree taking into account the concept of "public interest". The protection of individuals participating in studies in the field of environmental health calls, e.g., new communication strategies from recruitment to debriefing, at individual as well as at societal levels. Research on the socio ethical aspects on HBM within ECNIS and Newgeneris is situated at the interface of science, ethics and law and should be considered in the context of one final goal: contributing to guidelines for a harmonized socio-ethical and legal approach of human biomonitoring activities in the EU, including procedures for effective and appropriate communication both a the individual and at the collective level, resulting in a European research atmosphere in which scientific research related to development and use of human biomarkers is promoted, and in which a simultaneous protection of the rights and dignity of the study subjects is guaranteed. A harmonized socio-ethical and legal approach not only increases the possibilities for comparison between data generated but may also allow for more equality in the protection of the rights of each citizen of the European Union.     

Subchronic effects of dipyrone on the fish species Rhamdia quelen

The use of the non-steroidal anti-inflammatory drugs such as dipyrone is so widespread that this drug and its metabolites have been detected in effluents and surface water. This study aimed to evaluate the potential toxic effects of dipyrone on the aquatic environment, using a native fish species, Rhamdia quelen. Fish were exposed to three concentrations of dipyrone, 0.5, 5 and 50 μg/L, in the water for 15 days, and hematological, biochemical, genetic and morphological biomarkers were evaluated. The glutathione S-transferase activity decreased in the highest concentration in relation to the control group. In addition, hematocrit, red blood cells and thrombocyte counts were decreased in all three exposed groups in relation to the control group. The comet assay showed DNA damage at the lowest concentration of dipyrone and significant kidney damage. Those results suggest that a constant exposure of aquatic organisms to dipyrone presents potential toxic effects.     

Daphnia magna responses to a vertebrate estrogen receptor agonist and an antagonist: a multigenerational study

Whereas ecological risk assessments rely on standardized aquatic toxicity tests to assess ecological hazards, these techniques have limited utility for endocrine-active compounds, including select pharmaceuticals. Due to structural similarity between of vertebrate estrogens and ecdysone, previous studies suggest that endocrine-active pharmaceuticals may interfere with invertebrate endocrine systems, while other investigations do not support these suggestions. We assessed effects of the pharmaceuticals 17alpha-ethinylestradiol and faslodex, model therapeutics designed to interact with vertebrate estrogen receptors, on endocrine biomarkers and transgenerational life-history parameters of a model invertebrate, Daphnia magna. Identical studies were performed with 20-hydroxyecdysone and testosterone, which served as positive controls for ecdysteroid receptor agonism and antagonism, respectively. Results from this study at biochemical, individual and population levels suggest that a mammalian estrogen receptor agonist and antagonist did not act through the ecdysone receptor in D. magna. Acute-to-chronic ratios based on various chronic responses ranged from 2.59 to 5.18 for 17alpha-ethinylestradiol and 1.29-12.9 for faslodex. Toxicity exerted by these therapeutics on D. magna likely resulted from non-endocrine-mediated responses. Mechanism-specific biomarkers, multigenerational designs and population growth models may be useful to assess organismal and population level responses to low-level exposures, which may serve to reduce uncertainty in future hazard assessments of invertebrate responses to endocrine-active pharmaceuticals in the environment.     

Applications of new technology in molecular epidemiology and their relevance to occupational medicine

Technological advances in molecular biology over the past 2 decades have offered more complex techniques that can be used to study the role of specific exogenous agents and host variables that cause ill health. Increasingly, studies in human populations use this new technology, combined with epidemiological methods, to shed light on the understanding of the biological processes associated with development of disease. This approach has many potential applications in occupational and environmental medicine (OEM), and some aspects of the work in this growing field are reviewed. An understanding of biochemistry and genetics at the molecular level, specific knowledge on metabolism and mechanisms of action, and epidemiology have become increasingly important for the OEM practitioner. This is necessary to consider the major question of validation and relevance of these molecular biomarkers. As end users, OEM practitioners should also consider the impact of these advances on their practices. For example, the availability of genetic tests to identify susceptible workers raises issues of ethics, individual privacy, right to work, and the relevance of such tests. Several studies have presented data on the association of environmental measurements and various biomarkers for internal and biologically effective dose, genetic polymorphisms, and early response markers. Given the limitations of individual molecular biomarkers in assessing risk to health, and the multifactorial nature of environmental disease, it is likely that such an approach will increase our understanding of the complex issue of mechanisms of disease and further refine the process of risk assessment.

 

     

The use of enzymatic biomarkers in two marine invertebrates Nereis diversicolor and Patella vulgata for the biomonitoring of Tangier's bay (Morocco)

The fast increase of anthropogenic activities has led to a continual influx of xenobiotics into the marine ecosystems. Quantifying biochemical parameters in marine invertebrates makes possible the evaluation of pollutants' damaging effect. In fact, to examine the health state of Tangier's bay, we focused on the study of catalase, esterase, acetylcholinesterase and alpha-amylase activities as biomarkers in two species of marine invertebrates Nereis diversicolor (Polychaeta, Nereidae) and Patella vulgata (Mollusca, Prosobranchia), collected from different sites along the Mediterranean coastline of Tangier. Our results showed that these biochemical parameters are disturbed following the level of decreasing environmental quality, and for this reason they are promising in the biomonitoring studies of the Moroccan marine environment.     

Regulatory frameworks for copper considering chronic exposures of the population

Copper is an essential nutrient that is toxic in excess. Copper intakes from a balanced diet appear to meet the needs of most healthy individuals, because overt deficiency and toxicity are rare. Some uncertainty, however, persists because of limitations in currently available biomarkers used to assess copper status and the paucity of data available to establish tolerable upper levels of intake. Current policies and regulations pertaining to food fortification, nutritional supplements, and drinking water appear to be effective in providing for adequate copper intakes in many populations, although high levels of exposure, through overzealous fortification, supplementation, or drinking water exposure, may be possible under some circumstances. Surveillance and monitoring programs to evaluate copper exposures of human populations should continue and should be refined as new biomarkers become available.     

Total Suspended Solids Effects on Freshwater Lake Biota Other than Fish

Protective benchmarks for the effects of total suspended solids (TSS) on freshwater aquatic biota primarily focus on fish; whether these benchmarks will also protect their prey or co-existing lower trophic level aquatic biota was uncertain. We conducted an extensive literature review of TSS effects on those organisms comprising the food webs upon which fish living in lakes depend: phytoplankton, zooplankton, periphyton, and benthic invertebrates. The available literature indicates that TSS benchmarks that protect sensitive life stages of lake fish will also protect their supporting food webs; in other words, the function of lake aquatic communities will be protected and maintained.     

Toxicology and ecotoxicology of persistent organic microcontaminants in aquatic systems

Persistent organic pollutants (POP) are a heterogeneous group of chemicals widely distributed in the aquatic environment. Some classes cause adverse effects in the biota at minute concentrations, persist in the environment for a long time, and bioaccumulate in animal tissues. Several strategies exist today to monitor their levels and evaluate their effects in the environment. Particularly, some interesting approaches have recently been developed in the field of biomarkers, although much work seems to be required to study the relationships between toxic responses at different levels of the biological organization of interest and concentration levels in tissues.     

Linking molecular biomarkers with higher level condition indicators to identify effects of copper exposures on the endangered delta smelt (Hypomesus transpacificus)

The delta smelt (Hypomesus transpacificus) is an endangered pelagic fish species endemic to the Sacramento-San Joaquin estuary (CA, USA), and considered an indicator of ecosystem health. Copper is a contaminant of concern in Californian waterways that may affect the development and survival of this endangered species. The experimental combination of molecular biomarkers with higher level effects may allow for interpretation of responses in a functional context that can be used to predict detrimental outcomes caused by exposure. A delta smelt microarray was developed and applied to screen for candidate molecular biomarkers that may be used in monitoring programs. Functional classifications of microarray responses were used along with quantitative polymerase chain reaction determining effects upon neuromuscular, digestive, and immune responses in Cu-exposed delta smelt. Differences in sensitivity were measured between juveniles and larvae (median lethal concentration = 25.2 and 80.4 μg/L Cu(2+), respectively). Swimming velocity declined with higher exposure concentrations in a dose-dependent manner (r = -0.911, p < 0.05), though was not statistically significant to controls. Genes encoding for aspartoacylase, hemopexin, α-actin, and calcium regulation proteins were significantly affected by exposure and were functionally interpreted with measured swimming responses. Effects on digestion were measured by upregulation of chitinase and downregulation of amylase, whereas downregulation of tumor necrosis factor indicated a probable compromised immune system. Results from this study, and many others, support the use of functionally characterized molecular biomarkers to assess effects of contaminants in field scenarios. We thus propose that to attribute environmental relevance to molecular biomarkers, research should concentrate on their application in field studies with the aim of assisting monitoring programs.     

Development of biotic ligand models for chronic manganese toxicity to fish, invertebrates, and algae

Ecotoxicity tests were performed with fish, invertebrates, and algae to investigate the effect of water quality parameters on Mn toxicity. Models were developed to describe the effects of Mn as a function of water quality. Calcium (Ca) has a protective effect on Mn toxicity for both fish and invertebrates, and magnesium (Mg) also provides a protective effect for invertebrates. Protons have a protective effect on Mn toxicity to algae. The models derived are consistent with models of the toxicity of other metals to aquatic organisms in that divalent cations can act as competitors to Mn toxicity in fish and invertebrates, and protons act as competitors to Mn toxicity in algae. The selected models are able to predict Mn toxicity to the test organisms to within a factor of 2 in most cases. Under low-pH conditions invertebrates are the most sensitive taxa, and under high-pH conditions algae are most sensitive. The point at which algae become more sensitive than invertebrates depends on the Ca concentration and occurs at higher pH when Ca concentrations are low, because of the sensitivity of invertebrates under these conditions. Dissolved organic carbon concentrations have very little effect on the toxicity of Mn to aquatic organisms.     

Ecological mechanisms important for the biotic changes in acidified Lakes in Scandinavia

We describe some mechanisms behind the biotic changes in acidified lakes in Scandinavia. Besides direct effects, such as reduced reproduction or survival of fish and invertebrates due to low pH or exposure to toxic metals, we emphasize the importance of indirect effects. Mechanisms involved are of an ecological character; such as a shift of top predatores from fish to invertebrates and a reduced decomposition rate due to decreased abundance of detrivores, as well as feed-back effects on the abiotic environment; such as reduced productivity and turnover rate of nutrients and an increase in water transparency. We include the aspects of how bird species in aquatic habitats may be indirectly affected.