The emerging literature on the ecotoxicity of nanoparticles and nanomaterials is summarised, then the fundamental physico-chemistry that governs particle behaviour is explained in an ecotoxicological context. Techniques for measuring nanoparticles in various biological and chemical matrices are also outlined. The emerging ecotoxicological literature shows toxic effects on fish and invertebrates, often at low mg l(-1) concentrations of nanoparticles. However, data on bacteria, plants, and terrestrial species are particularly lacking at present. Initial data suggest that at least some manufactured nanoparticles may interact with other contaminants, influencing their ecotoxicity. Particle behaviour is influenced by particle size, shape, surface charge, and the presence of other materials in the environment. Nanoparticles tend to aggregate in hard water and seawater, and are greatly influenced by the specific type of organic matter or other natural particles (colloids) present in freshwater. The state of dispersion will alter ecotoxicity, but many abiotic factors that influence this, such as pH, salinity, and the presence of organic matter remain to be systematically investigated as part of ecotoxicological studies. Concentrations of manufactured nanoparticles have rarely been measured in the environment to date. Various techniques are available to characterise nanoparticles for exposure and dosimetry, although each of these methods has advantages and disadvantages for the ecotoxicologist. We conclude with a consideration of implications for environmental risk assessment of manufactured nanoparticles.

No abstract

No abstract

Toxicity data for tropical species are often lacking for ecological risk assessment. Consequently, tropical and subtropical countries use water quality criteria (WQC) derived from temperate species (e.g., United States, Canada, or Europe) to assess ecological risks in their aquatic systems, leaving an unknown margin of uncertainty. To address this issue, we use species sensitivity distributions of freshwater animal species to determine whether temperate datasets are adequately protective of tropical species assemblages for 18 chemical substances. The results indicate that the relative sensitivities of tropical and temperate species are noticeably different for some of these chemicals. For most metals, temperate species tend to be more sensitive than their tropical counterparts. However, for un-ionized ammonia, phenol, and some pesticides (e.g., chlorpyrifos), tropical species are probably more sensitive. On the basis of the results from objective comparisons of the ratio between temperate and tropical hazardous concentration values for 10% of species, or the 90% protection level, we recommend that an extrapolation factor of 10 should be applied when such surrogate temperate WQCs are used for tropical or subtropical regions and a priori knowledge on the sensitivity of tropical species is very limited or not available.

This paper considers whether current standard ecotoxicity methods are fit for purpose for assessing the hazards of engineered nanoparticles. We conclude that the types of test species and biological endpoints used within standard environmental hazard assessment frameworks are generally appropriate. However, there are areas of considerable uncertainty associated with characterisation of nanoparticle exposure in test systems that apply to all ecotoxicity testing guidelines, except those in which dosing of nanoparticles is oral. These include the way in which the substance is dosed into, and maintained within, the test medium; measurement and characterisation of nanoparticles in the test system; better understanding and reporting of abiotic factors that influence behaviour of nanoparticles in the test medium; and agreement on how dosimetric data should be reported.

Abstract-The no observed effect concentration (NOEC) is currently a major summary statistic in ecotoxicity testing. Its use is heavily criticized, partly because it is a poor estimator of ''safe'' chemical concentrations. In this short communication, we review the limited information available on the percentage effect that corresponds with the NOEC, a value designated the EC NOEC , and calculate EC NOEC values for fish growth data. The average EC NOEC for different test protocols was found to vary widely, with values for chronic studies ranging from 10 to 34%. Individual results varied even more widely. This analysis suggests that the NOEC is neither a consistent summary statistic nor an indicator of safe concentrations of toxic chemicals.

Abstract-The relative sensitivity of amphibians to chemicals in the environment, including plant protection product active substances, is the subject of ongoing scientific debate. The objective of this study was to compare systematically the relative sensitivity of amphibians and fish to chemicals. Acute and chronic toxicity data were obtained from the U.S. Environmental Protection Agency (U.S. EPA) ECOTOX database and were supplemented with data from the scientific and regulatory literature. The overall outcome is that fish and amphibian toxicity data are highly correlated and that fish are more sensitive (both acute and chronic) than amphibians. In terms of acute sensitivity, amphibians were between 10-and 100-fold more sensitive than fish for only four of 55 chemicals and more than 100-fold more sensitive for only two chemicals. However, a detailed inspection of these cases showed a similar acute sensitivity of fish and amphibians. Chronic toxicity data for fish were available for 52 chemicals. Amphibians were between 10-and 100-fold more sensitive than fish for only two substances (carbaryl and dexamethasone) and greater than 100-fold more sensitive for only a single chemical (sodium perchlorate). The comparison for carbaryl was subsequently determined to be unreliable and that for sodium perchlorate is a potential artifact of the exposure medium. Only a substance such as dexamethasone, which interferes with a specific aspect of amphibian metamorphosis, might not be detected using fish tests. However, several other compounds known to influence amphibian metamorphosis were included in the analysis, and these did not affect amphibians disproportionately. These analyses suggest that additional amphibian testing is not necessary during chemical risk assessment. Environ. Toxicol. Chem. 2013;32:984-994.

Field-based (in situ) approaches are used increasingly for measuring biological effects and for stressor diagnoses in aquatic systems because these assessment tools provide realistic exposure environments that are rarely replicated in laboratory toxicity tests. Providing realistic exposure scenarios is important because environmental conditions can alter toxicity through complex exposure dynamics (e.g., multiple stressor interactions). In this critical review, we explore the information provided by aquatic in situ exposure and monitoring methods when compared with more traditional approaches and discuss the associated strengths and limitations of these techniques. In situ approaches can, under some circumstances, provide more valuable information to a decision maker than information from surveys of resident biota, laboratory toxicity tests, or chemical analyses alone. A decision tree is provided to assist decision makers in determining when in situ approaches can add value.