Geert R. de Snoo

Response predictions for organisms water-exposed to metal mixtures: a meta-analysis.

To develop a multimetal toxicity model requires insight into the relationships between the composition of metal mixtures and their toxicological effects on organisms. As a first step in developing such a model, quantitative data from binary and higher mixture studies of Cu, Cd, and Zn were compiled and used to assess trends in toxicological effects on various organisms. The findings of this meta-analysis show relatively little occurrence of additive effects compared with antagonistic and synergistic effects. This observation held true irrespective of test species, environmental compartment, or metal concentrations in the mixture. However, the type of effect was significantly correlated with the metal combination tested and the selected toxicological endpoint. It was also found that different methods were used for assessing deviation from additivity in the various individual studies. For robust comparison, standardization on this point is required. Toxicological responses of organisms to metal mixtures were shown to be hard to predict and were often slightly less than or slightly more than additive. The interactions observed could not be explained by metal-metal interactions alone. We therefore conclude that with current scientific knowledge it is not yet possible to predict responses to metal mixtures in individual cases; at best this is possible only in terms of general patterns. Nevertheless, in the context of environmental risk policy, the assumption of additivity produces a conservative prediction of toxicity, because toxicity of a metal mixture will be either predicted correctly or overpredicted by default in approximately 75% of all cases. The use of models based on noninteraction is satisfactory from this regulatory perspective.

Life cycle assessment of aquaculture systems—a review of methodologies

PurposeAs capture fishery production has reached its limits and global demand for aquatic products is still increasing, aquaculture has become the world’s fastest growing animal production sector. In attempts to evaluate the environmental consequences of this rapid expansion, life cycle assessment (LCA) has become a frequently used method. The present review of current peer-reviewed literature focusing on LCA of aquaculture systems is intended to clarify the methodological choices made, identify possible data gaps, and provide recommendations for future development within this field of research. The results of this review will also serve as a start-up activity of the EU FP7 SEAT (Sustaining Ethical Aquaculture Trade) project, which aims to perform several LCA studies on aquaculture systems in Asia over the next few years.MethodsFrom a full analysis of methodology in LCA, six phases were identified to differ the most amongst ten peer-reviewed articles and two PhD theses (functional unit, system boundaries, data and data quality, allocation, impact assessment methods, interpretation methods). Each phase is discussed with regards to differences amongst the studies, current LCA literature followed by recommendations where appropriate. The conclusions and recommendations section reflects on aquaculture-specific scenarios as well as on some more general issues in LCA.ResultsAquaculture LCAs often require large system boundaries, including fisheries, agriculture, and livestock production systems from around the globe. The reviewed studies offered limited coverage of production in developing countries, low-intensity farming practices, and non-finfish species, although most farmed aquatic products originate from a wide range of farming practices in Asia. Apart from different choices of functional unit, system boundaries and impact assessment methods, the studies also differed in their choice of allocation factors and data sourcing. Interpretation of results also differed amongst the studies, and a number of methodological choices were identified influencing the outcomes.Conclusions and recommendationsEfforts should be made to increase transparency to allow the results to be reproduced, and to construct aquaculture related database(s). More extensive data reporting, including environmental flows, within the greater field of LCA could be achieved, without compromising the focus of studies, by providing supporting information to articles and/or reporting only ID numbers from background databases. More research is needed into aquaculture in Asia based on the latest progress made by the LCA community.

Species-specific toxicity of copper nanoparticles among mammalian and piscine cell lines.

Abstract The four copper nanoparticles (CuNPs) with the size of 25, 50, 78 and 100 nm and one type of micron-sized particles (MPs) (∼500 nm) were exposed to two mammalian (H4IIE and HepG2) and two piscine (PLHC-1 and RTH-149) cell lines to test the species-specific toxicities of CuNPs. The results showed that the morphologies, ion release and size of the particles all played an important role when investigating the toxicity. Furthermore, the authors found that the particle forms of CuNPs in suspensions highly contribute to the toxicity in all exposed cell lines whereas copper ions (Cu2+) only caused significant responses in mammalian cell lines, indicating the species-specific toxicity of CuNPs. This study revealed that the morphologies, ion release rate of NPs as well as the species-specific vulnerabilities of cells should all be considered when explaining and extrapolating toxicity test results among particles and among species.

Product Carbon Footprints and Their Uncertainties in Comparative Decision Contexts

In response to growing awareness of climate change, requests to establish product carbon footprints have been increasing. Product carbon footprints are life cycle assessments restricted to just one impact category, global warming. Product carbon footprint studies generate life cycle inventory results, listing the environmental emissions of greenhouse gases from a product’s lifecycle, and characterize these by their global warming potentials, producing product carbon footprints that are commonly communicated as point values. In the present research we show that the uncertainties surrounding these point values necessitate more sophisticated ways of communicating product carbon footprints, using different sizes of catfish (Pangasius spp.) farms in Vietnam as a case study. As most product carbon footprint studies only have a comparative meaning, we used dependent sampling to produce relative results in order to increase the power for identifying environmentally superior products. We therefore argue that product carbon footprints, supported by quantitative uncertainty estimates, should be used to test hypotheses, rather than to provide point value estimates or plain confidence intervals of products’ environmental performance.

Toxicological Mixture Models are Based on Inadequate Assumptions

The interactions of thousands of chemicals in the environment with millions of biological species ultimately determine whether a given mixture of chemicals has marginal or catastrophic consequences. The foundations for toxicological effect models of mixtures were laid by pharmacologists in the 1920s (1, 2). At the time, the problem of joint action was solved mathematically by simply adding doses and responses, on the assumption that compounds do not influence each other’s physiological action. In environmental risk assessment and human toxicology, our understanding of the toxicity of mixtures is still based on these concepts, with addition forming the basis for all models, regardless of the sophistication of the mixture models employed or the number of additional interactions (e.g., with respect to exposure) defined (3). We believe the time is ripe for a new approach, for there is evidence that additivity is not in all cases as universal as has been postulated for more than 80 years. To determine whether classical mixture models are valid, we performed a metastudy on metal mixture responses compiled from the literature. Our metastudy was performed by assembling data of peer-reviewed articles published from 1981 to 2007 available via the ISI Web of Science database. The aim was not full coverage of all papers concerning mixtures, but to obtain a representative overview of papers on metal mixtures. The articles were a selection of binary or tertiary mixture toxicity studies on the effects of Cd, Cu, and/ or Zn. In total, 19 studies were included, giving 91 records on metal combinations: 67 binary mixture combinations and 24 tertiary mixture combinations. To properly deal with multiple modes of exposure, possibly leading to different interactions, we made a distinction between metal toxicity via oral uptake and via passive uptake from the environment. For this study, only organisms for which the latter constituted the primary route were considered. Studies on freshwater (41 records) and marine organisms (31 records) as well as on soil-dwelling organisms (19 records) were included, with the proviso for terrestrial studies that only soil-dwelling organisms exposed to pore water were considered. Fate of metals in the solutions was not explicitly accounted for because of lack of information on the physicochemical water properties determining metal speciation. More details on the records used in our study are available upon request. With regard to the toxic effects of mixtures, two reference models are available for the analysis of noninteractive joint action (1, 2). Joint action is classified as similar when the primary site of action is the same for both or all the compounds (eq 1), and dissimilar when the site of action differs (eq 2).

Spatial and Temporal Variation of Watertype-Specific No-Effect Concentrations and Risks of Cu, Ni, and Zn

Geographical and temporal variations in metal speciation were calculated and water-type specific sensitivities were derived for a range of aquatic species, using surveillance water chemistry data that cover almost all surface water types in The Netherlands. Biotic ligand models for Cu, Zn, and Ni were used to normalize chronic no-effect concentrations (NOEC) determined in test media toward site-specific NOEC for 372 sites sampled repeatedly over 2007-2010. Site-specific species sensitivity distributions were constructed accounting for chemical speciation. Sensitivity of species as well as predicted risks shifted among species over space and time, due to changes in metal concentrations, speciation, and biotic ligand binding. Sensitivity of individual species (NOEC) and of the ecosystem (HC5) for Cu, Ni, and Zn showed a spatial variation up to 2 orders of magnitude. Seasonality of risks was shown, with an average ratio between lowest and highest risk of 1.3, 2.0, and 3.6 for Cu, Ni, and Zn, respectively. Maximum risks of Cu, Ni, and Zn to ecosystems were predicted in February and minimum risks in September. A risk assessment using space-time specific HC5 of Cu and Zn resulted in a reduction of sites at risk, whereas for Ni the number of sites at risks increased.

Using tailored information and public commitment to improve the environmental quality of farm lands: An example from the Netherlands

By adopting nature conservation practices, farmers can enhance the environmental quality and biodiversity of their land. In this exploratory study, a behavioral intervention that focused on improving Dutch farmers’ nature conservation practices was developed and tested. This intervention was based on insights derived from social psychology and combined tailored information and public commitment. Participating farmers were divided in three groups: one group received tailored information only, one group received both tailored information and a public commitment manipulation, and one group served as a control. A questionnaire measuring relevant aspects of conservation was completed before and after the intervention. Results show that tailored information combined with public commitment making resulted in a stronger desire to engage in conservation, an increase in surface area of non-subsidized natural habitat, and an increase in time farmers spent on conservation. The intervention affected both subsidized and non-subsidized conservation, but the effects were stronger for non-subsidized conservation.

Invertebrates in field margins:taxonomic group diversity and functional group abundance in relation to age

Sown, temporary field margins are a common agri-environment scheme (AES) in the Netherlands. Despite their wide application, though, there has been scarcely any long-term monitoring of the succession of invertebrates. In the field margins of 40 farms, invertebrate diversity and the abundance of three functional groups were assessed in relation to age. The diversity in terms of number of species groups was found to increase with the age of the margins. The abundance of herbivores and detritivores also showed a positive correlation with the age of the margins. However, the abundance of predators decreased with increasing age. Older margins showed a higher total vegetation cover and fewer plant species, also resulting in lower plant species evenness. We suggest several changes to the current AES regulations. For the conservation of invertebrate diversity, longer-lasting field margins are desirable. In addition, old margins are favoured by detritivores, a group that has particular difficulty finding suitable habitats in agricultural landscapes. However, such margins are less favourable from an agricultural perspective, as they appear unsuitable for high abundances of potentially useful predators and the high vegetation cover attracts many potentially harmful herbivores. To circumvent this, the AES might be extended by incorporating hay-making, which would reduce standing biomass and might lead to more predators and fewer herbivores.

Factors contributing to overuse of pesticides in western China

As one of the worlds largest producers and consumers of pesticides, China faces a range of environmental and public health threats through long-term overuse of these chemicals. This study suggests a number of key factors contributing to pesticide overuse in rural China, which are examined by means of a literature review and a field survey among farming households, local officials and consumers in western Chinas Yunnan and Guizhou provinces. The authors conclude that, in addition to the traditionally targeted gaps in technical knowledge, there are a number of sociological and political factors contributing to pesticide overuse, which require closer attention. A number of potential solutions are proposed as a reference point for policy-makers and researchers in this field.

Asian corn borer (ACB) and non-ACB pests in GM corn (Zea mays L.) in the Philippines

BACKGROUND The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), has become the most damaging pest in corn in south-east Asia. Corn farmers in the Philippines have incurred great yield losses in the past decades because of ACB infestation. Bacillus thuringiensis (Bt) and Bt herbicide-tolerant (BtHT) corns have been developed to reduce borer attacks worldwide. This study assessed the extent of ACB and non-ACB pest infestations in both GM and non-GM corn in Isabela Province, the Philippines. Specific aims were to reinvestigate the efficacy of Bt corn in controlling ACB, to evaluate what parts of Bt corn plants are susceptible to ACB, to monitor the potential development of ACB resistance and to evaluate whether secondary pests dominate in an ACB-free Bt corn environment. The study involved preparatory interviews with farmers, site selection, field scouting and visual inspection of 200 plants along 200 m transect lines through 198 cornfields. RESULTS Bt corn can efficiently reduce the ACB pest problem and reduce borer damage by 44%, to damage levels in Bt and BtHT corn of 6.8 and 7% respectively. The leaves of Bt corn were more susceptible, while cobs of Bt corn were less affected by ACB. Non-ACB pests were common in Bt toxin-free cornfields and reduced in non-GM cornfields where ACB was abundant. No secondary pest outbreaks were found in ACB-free Bt cornfields. CONCLUSION Bt and BtHT corn hybrids containing the Cry1Ab protein performed well in Isabela Province. Reduced cob damage by ACB on Bt fields could mean smaller economic losses even with ACB infestation. The occurrence of ACB in Bt and BtHT cornfields, although at a moderate and insignificant level, could imply the potential development of resistance to Bt toxin.