High aluminum content in bone of marine mammals and its relation with source levels and origin.

Although aluminum is widely distributed in the earth's crust, its environmental availability and wildlife assimilation rates are only partially known. Here we analyze aluminum concentrations in bone from 10 species of marine mammals inhabiting 3 geographic areas subject to different aluminum inputs: the Río de la Plata estuary (Uruguay), the coastal waters of Mauritania and the Galapagos archipelago (Ecuador). Overall, concentrations were unusually high as compared to those of terrestrial animals, with lowest concentrations in the Galapagos archipelago, then the Río de la Plata estuary and finally Mauritania. The aluminum source varied between regions, prevailing anthropogenic sources in the Río de la Plata Estuary and natural sources (wind-blown dust) in Mauritanian waters. The type of source determined contamination levels: anthropogenic sources were most significant for coastal species and showed a decline with distance of habitat from shoreline, while natural sources had a higher influence on open waters because of the dearth of biogenic silica that eliminates aluminum from the water column. Since aluminum remains in bone for several decades, marine mammal bone reflects historical levels of aluminum and therefore is a good bioindicator of the aluminum concentration of the marine environment.

Evaluating pesticide effects on freshwater invertebrate communities in alpine environment: a model ecosystem experiment.

Pesticide loads in streams are potentially one of the most relevant stressors for macroinvertebrate communities. Nevertheless, real effects provoked at the community level are still largely unknown. Model ecosystems are frequently used as tools for the risk assessment of pesticides, especially for their regulation, however, they can be also applied to site-specific risk assessment in order to gain better understanding of the responses of aquatic ecosystems to chemical stress. In the present work, an experimental system was composed of 5 artificial streams that reproduced a mountain lotic environment under controlled conditions. This study was aimed to better understand, whether (and how) the biological community was influenced by pesticides pulse exposures. 5 mixture load events were simulated over the productive season (March-July 2010): biological community was regularly sampled and nominal concentrations of water were tested. The results were interpreted comparing the output of different metrics and statistical methodologies. The sensitivity of different metrics was analyzed considering single exposure events (maximum Toxic Units) as well as overall temporal trends. Results showed how some common taxonomic metrics (e.g. taxa richness, Shannon's index, total abundance of organisms, and the Extended Biotic Index) were not suitable to identify the effects of pesticides at community level. On the contrary EPT%, SPEAR(pesticide) and the Principal Response Curve methodology proved to be sensitive to this kind of stress, providing comparable results. Temporal trends of these metrics proved to be related to the concentration of chemicals. Remarkably, the first Principal Response Curve illustrates the trend followed by the most vulnerable species, while the second is more related to the trend of opportunistic species. A high potential risk for the invertebrate community was highlighted by a statistically significant decline of 40 points (comparison with the control) in both SPEAR(pesticide) and EPT%.

Sensitivity assessment of freshwater macroinvertebrates to pesticides using biological traits.

Assessing the sensitivity of different species to chemicals is one of the key points in predicting the effects of toxic compounds in the environment. Trait-based predicting methods have proved to be extremely efficient for assessing the sensitivity of macroinvertebrates toward compounds with non specific toxicity (narcotics). Nevertheless, predicting the sensitivity of organisms toward compounds with specific toxicity is much more complex, since it depends on the mode of action of the chemical. The aim of this work was to predict the sensitivity of several freshwater macroinvertebrates toward three classes of plant protection products: organophosphates, carbamates and pyrethroids. Two databases were built: one with sensitivity data (retrieved, evaluated and selected from the U.S. Environmental Protection Agency ECOTOX database) and the other with biological traits. Aside from the "traditional" traits usually considered in ecological analysis (i.e. body size, respiration technique, feeding habits, etc.), multivariate analysis was used to relate the sensitivity of organisms to some other characteristics which may be involved in the process of intoxication. Results confirmed that, besides traditional biological traits, related to uptake capability (e.g. body size and body shape) some traits more related to particular metabolic characteristics or patterns have a good predictive capacity on the sensitivity to these kinds of toxic substances. For example, behavioral complexity, assumed as an indicator of nervous system complexity, proved to be an important predictor of sensitivity towards these compounds. These results confirm the need for more complex traits to predict effects of highly specific substances. One key point for achieving a complete mechanistic understanding of the process is the choice of traits, whose role in the discrimination of sensitivity should be clearly interpretable, and not only statistically significant.

Ecological vulnerability analysis: a river basin case study.

Assessing and quantifying ecosystem vulnerability is a key issue in site-specific ecotoxicological risk assessment. In this paper, the concept of vulnerability, particularly referred to aquatic ecosystems is defined. Sensitivity to stressors, susceptibility for exposure and recovery capability are described as component of vulnerability of biological communities. The potential for habitat changes must also be considered in ecosystem vulnerability assessment. A procedure based on the application of an ecosystem vulnerability index is proposed. The method allows the assessment of vulnerability of riverine ecosystems to multiple stressors. The procedure is applied to two river systems in northern Italy: River Serio, subject to strong human pressure, and River Trebbia, in semi-natural conditions, as reference system. Macrozoobenthos is chosen as the indicator community. The actual quality of River Serio was evaluated as the result of the multiple stressor pressure on the reference system. Values and limitations of the approach are discussed.

Ecological vulnerability in risk assessment--a review and perspectives.

This paper reviews the application of ecological vulnerability analysis in risk assessment and describes new developments in methodology. For generic non-site-specific assessments (e.g. for the requirements of most European directives on dangerous chemicals) risk is characterised just on the basis of the ratio between an effect indicator and an exposure indicator. However, when the actual risk for a specific ecosystem is desired, the concept of ecological vulnerability may be more appropriate. This calls for a change in thinking, from sensitivity at the organism level to vulnerability at higher organization levels, and thus forms the link from laboratory toxicology to field effects at population, community or ecosystem level. To do so, biological and ecological characteristics of the ecosystems under concern are needed to estimate the ecological vulnerability. In this review we describe different vulnerability analysis methods developed for populations (of a single species), communities (consisting of different populations of species) and ecosystems (community and habitat combined). We also give some examples of methods developed for socio-ecological systems. Aspects that all methods share are the use of expert judgment, the input of stakeholders, ranking and mapping of the results, and the qualitative nature of the results. A new general framework is presented to guide future ecological vulnerability analysis. This framework can be used as part of ecological risk assessment, but also in risk management. We conclude that the further quantification of ecological vulnerability is a valuable contribution to vulnerability assessment.

Establishment of a cross-European field site network in the ALARM project for assessing large-scale changes in biodiversity.

The field site network (FSN) plays a central role in conducting joint research within all Assessing Large-scale Risks for biodiversity with tested Methods (ALARM) modules and provides a mechanism for integrating research on different topics in ALARM on the same site for measuring multiple impacts on biodiversity. The network covers most European climates and biogeographic regions, from Mediterranean through central European and boreal to subarctic. The project links databases with the European-wide field site network FSN, including geographic information system (GIS)-based information to characterise the test location for ALARM researchers for joint on-site research. Maps are provided in a standardised way and merged with other site-specific information. The application of GIS for these field sites and the information management promotes the use of the FSN for research and to disseminate the results. We conclude that ALARM FSN sites together with other research sites in Europe jointly could be used as a future backbone for research proposals.

POP bioaccumulation in macroinvertebrates of alpine freshwater systems.

This study serves to investigate the uptake of POPs in the different trophic levels (scrapers, collectors, predators, shredders) of macroinvertebrate communities sampled from a glacial and a non-glacial stream in the Italian Alps. The presented results show that the contaminant concentrations in glacial communities are generally higher compared to those from non-glacial catchments, highlighting the importance of glaciers as temporary sinks of atmospherically transported pollutants. Moreover, the data also suggests that in mountain systems snow plays an important role in influencing macroinvertebrate contamination. The main chemical uptake process to the macroinvertebrates is considered to be bioconcentration from water, as similar contaminant profiles were observed between the different trophic levels. The role of biomagnification/bioaccumulation is thought to be absent or negligible. The enrichment of chemicals observed in the predators is likely to be related to their greater lipid content compared to that of other feeding groups.

Comparison of glacial and non-glacial-fed streams to evaluate the loading of persistent organic pollutants through seasonal snow/ice melt.

The release of persistent organic pollutants (PCBs, HCB, HCHs and DDTs) accumulated in Alpine glaciers, was studied during spring-summer 2006 on the Frodolfo glacial-fed stream (Italian Alps). Samples were also taken on a non-glacial stream in the same valley, to compare POP contribution from different water sources (glacier ice, recent snow and spring). In late spring and early summer (May, June) recent snow melting is the most important process. POP contamination is more affected by local emissions and transport, and comparable levels have been measured in both streams for all studied compounds. In late summer and autumn (July-October), the contribution of ice melting strongly increases. In the glacial-fed stream the concentration of chlorinated pesticides (HCHs and DDTs) is about one order of magnitude higher than in the non-glacial-fed. A different behaviour was observed for PCBs, characterised by a peak in June showing, in both streams, concentrations three orders of magnitude higher than the background levels measured in May and in October. This result should be attributed to local emissions rather than long range atmospheric transport (LRAT). This hypothesis is supported by the PCB congener profile in June strictly comparable to the most commonly used Aroclor technical mixtures. The different seasonal behaviour observed for the different groups of chemicals indicates the POP loading in glacial streams is a combined role of long range atmospheric transport and local emission.

Variation of POP concentrations in fresh-fallen snow and air on an Alpine glacier (Monte Rosa).

To understand better the mechanisms ruling the fate of POPs (persistent organic pollutants) in cold environments, a field campaign sampling fresh-fallen snow and air on an Alpine glacier was carried out during Summer 2003. The concentrations of all analyzed chemicals in fresh-fallen snow show a sharp decrease over time, particularly for the more volatile POPs, confirming the rather limited literature evidence of a rapid decline of such substances from the snowpack and/or ice. Even if the results presented here are preliminary and should be confirmed by further studies, some evidence of the influence of a night/day cycle of temperature on POP deposition and revolatilization mechanisms has been highlighted. Finally, the role of cold condensation and long-range atmospheric transport in the contamination of higher altitudes in this Alpine system has been substantiated, particularly for OC pesticides.

Joint algal toxicity of 16 dissimilarly acting chemicals is predictable by the concept of independent action.

For a predictive assessment of the aquatic toxicity of chemical mixtures, two competing concepts are available: concentration addition and independent action. Concentration addition is generally regarded as a reasonable expectation for the joint toxicity of similarly acting substances. In the opposite case of dissimilarly acting toxicants the choice of the most appropriate concept is a controversial issue. In tests with freshwater algae we therefore studied the extreme situation of multiple exposure to chemicals with strictly different specific mechanisms of action. Concentration response analyses were performed for 16 different biocides, and for mixtures containing all 16 substances in two different concentration ratios. Observed mixture toxicity was compared with predictions, calculated from the concentration response functions of individual toxicants by alternatively applying both concepts. The assumption of independent action yielded accurate predictions, irrespective of the mixture ratio or the effect level under consideration. Moreover, results even demonstrate that dissimilarly acting chemicals can show significant joint effects, predictable by independent action, when combined in concentrations below individual NOEC values, statistically estimated to elicit insignificant individual effects of only 1%. The alternative hypothesis of concentration addition resulted in overestimation of mixture toxicity, but differences between observed and predicted effect concentrations did not exceed a factor of 3.2. This finding complies with previous studies, which indicated near concentration-additive action of mixtures of dissimilarly acting substances. Nevertheless, with the scientific objective to predict multi-component mixture toxicity with the highest possible accuracy, concentration addition obviously is no universal solution. Independent action proves to be superior where components are well known to interact specifically with different molecular target sites, and provided that reliable statistical estimates of low toxic effects of individual mixture constituents can be given. With a regulatory perspective, however, fulfilment of both conditions may be regarded as an extraordinary situation, and hence concentration addition may be defendable as a pragmatic and precautionary default assumption.

Water quality objectives for mixtures of toxic chemicals: problems and perspectives.

The need to develop water quality objectives not only for single substances but also for mixtures of chemicals seems evident. For that purpose, the conceptual basis could be the use of the two existing biometric models: concentration addition (CA) and independent action (IA), which is also called response addition. Both may allow calculation of the toxicity of mixtures of chemicals with similar modes of action (CA) or dissimilar modes of action (IA), respectively. The joint research project Prediction and Assessment of the Aquatic Toxicity of Mixtures of Chemicals (PREDICT) within the framework of the IVth Environment and Climate Programme of the European Commission, provided the opportunity to address (a) chemometric and QSAR criteria to classify substances as supposedly similarly or dissimilarly acting; (b) the predictive values of both models for the toxicity of mixtures at low, statistically nonsignificant effect concentrations of the individual components; and (c) the predictability of mixture toxicity at higher levels of biological complexity. In this article, the general outline, methodological approach, and some preliminary findings of PREDICT are presented. A procedure for classifying chemicals in relation to their structural and toxicological similarities has been developed. The predictive capabilities of CA and IA models have been demonstrated for single species and, to some extent, for multispecies testing. The role of very low effect concentrations in multiple mixtures has been evaluated. Problems and perspectives concerning the development of water quality objectives for mixtures are discussed.

Predicting the joint algal toxicity of multi-component s-triazine mixtures at low-effect concentrations of individual toxicants.

Herbicidal s-triazines are widespread contaminants of surface waters. They are highly toxic to algae and other primary producers in aquatic systems. This results from their specific interference with photosynthetic electron transport. Risk assessment for aquatic biota has to consider situations of simultaneous exposure to various of these toxicants. In tests with freshwater algae we predicted and determined the toxicity of multiple mixtures of 18 different s-triazines. The toxicity parameter was the inhibition of reproduction of Scenedesmus vacuolatus. Concentration-response analyses were performed for single toxicants and for mixtures containing all 18 s-triazines in two different concentration ratios. Experiments were designed to allow a valid statistical description of the entire concentration-response relationships, including the low concentration range down to EC1. Observed effects and effect concentrations of mixtures were compared to predictions of mixture toxicity. Predictions were calculated from the concentration-response functions of individual s-triazines by applying the concepts of concentration addition and independent action (response addition) alternatively. Predictions based on independent action tend to underestimate the overall toxicity of s-triazine mixtures. In contrast, the concept of concentration addition provides highly accurate predictions of s-triazine mixture toxicity, irrespective of the effect level under consideration and the concentration ratio of the mixture components. This also holds true when the mixture components are present in concentrations below their individual NOEC values. Concentrations statistically estimated to elicit non-significant effects of only 1% still contribute to the overall toxicity. When present in a multi-component mixture they can co-operate to give a severe joint effect. Applicability of the findings obtained with s-triazines to mixtures of other contaminants in aquatic systems and consequences for risk assessment procedures are discussed.

QSAR and chemometric approaches for setting water quality objectives for dangerous chemicals.

In order to evaluate environmentally safe levels of dangerous chemicals, there is the need for a set of toxicological data on organisms representative of the ecosystems, which is often unavailable or inadequate. In this article, a predictive approach was applied to a set of 125 chemicals (derived from the European priority list in compliance with Directive 76/464/EEC), for which water quality objectives were available. Toxicological data on organisms representative of the aquatic environment (algae, Daphnia, and fish) were taken from the literature or predicted by means of quantitative structure--activity relationships. This provided toxicological data on all three organisms for 97 of 125 chemicals and on at least two organisms (Daphnia and fish) for the whole data set. Principal Component Analysis was applied in order to perform an a priori classification of chemicals based on toxicity data. Then several classification models, based on traditional and nontraditional molecular descriptors, were applied. Classification models gave results in agreement with the a priori classification as well as with the original water quality objectives classification. The behavior of some outliers was explained. The approach described appears to be a useful tool for the preliminary classification of chemicals that are dangerous to the aquatic environment for which toxicological data are inadequate.

Rating systems for pesticide risk classification on different ecosystems.

A novel approach is proposed to quantitatively assess the environmental risks associated with the use of plant protection products. Different ranking indexes for the classification of pesticide risk in various environmental systems at different time and space scales have been developed: PRIHS-1 and PRIHS-2 (Pesticide Risk Index for Hypogean Soil Systems), PRIES-1 and PRIES-2 (Pesticide Risk Index for Epygean Soil Systems), and PRISW-1 and PRISW-2 (Pesticide Risk Index for Surface Water Systems). Such indexes identify the risk for each environmental system immediately after a pesticide spraying (PRIHS-1, PRIES-1, and PRISW-1) or in a wider time--space scale scenario (PRIHS-2, PRIES-2, and PRISW-2). Moreover, a general index (ERIP: Environmental Risk Index of Pesticides) was developed for quantifying the comprehensive risk for the environment. The indexes were calibrated by applying to a large number of pesticides for which data were available. The results of the different indexes are compared and the value and limitations of the approach are discussed.

QSAR approach for the selection of congeneric compounds with a similar toxicological mode of action.

The selection of compounds with a similar toxicological mode of action is a key problem in the study of chemical mixtures. In this paper, an approach for the selection of chemicals with similar mode of action, based on the analysis of structural similarities by means of QSAR and chemometric methods, is described. As a first step, a complete representation of chemical structures for examined chemicals (phenylureas and triazines) by different sets of molecular descriptors allows a preliminary exploration of similarity using multi-dimensional scaling (MDS). The use of genetic algorithm (GA) to select the most relevant molecular descriptors in modeling toxicity data makes it possible to develop predictive toxicity models. The final step is a similarity analysis, based again on MDS, using selected molecular descriptors, really relevant in describing the toxicological effect.

3D-modelling and prediction by WHIM descriptors. Part 8. Toxicity and physico-chemical properties of environmental priority chemicals by 2D-TI and 3D-WHIM descriptors.

In environmental and ecotoxicological problems, the need for more general predictive models is one of the aims of the science. To reach this objective, the models, even if capable of producing more approximate values, must be applicable to the huge number of chemicals put on the market that are discharged in the environment, at least for setting priority lists among potentially hazardous substances. Theoretically, the problem is not insurmountable if one assumes that all properties of a chemical (physico-chemical, biological, toxicological) are related to its structural features. The challenge is to describe and represent, on a quantitative basis, all molecular structural features in order to use them as independent variables in a quantitative structure-activity model. In this paper, structural, topological, and 3D-WHIM descriptors are used for modelling toxicological and physico-chemical properties of compounds that are included in the European Union's so-called "List 1" of priority chemicals dangerous for the aquatic environment.