Ecotoxicity Sample Clauses
Ecotoxicity. The deleterious effects of excess copper on soil microbial communities are well established. It is, after all, because of its antimicrobial effects that copper is used in agriculture. Given that fungi and bacteria play a critical role in trophic webs and in the completion of biogeochemical cycles, it is hardly surprising that disruption of soil microbial communities can lead to an impoverishment of locally available resources for other ecosystem consumers. The toxicity of copper for specific components of the soil fauna, such as the springtail Folsomia candida, has also been shown. Impacts on other indicator species, such as earthworms, are less clear. Estimates of lethal copper concentrations for adult worms vary: some studies have found significantly increased mortality rates at concentrations of 150 mg/kg of soil, whereas others have found no effect at these levels. Copper seems to have a low acute toxicity for the earthworm test-species Eisenia foetida, with median lethal concentrations (LC50) above 5,500 mg/kg of dry soil in laboratory conditions. At lower levels, chronic toxicity for earthworms is often observed: delayed sexual maturity, reduction in the number of cocoons, reduced hatching rates. Quantities of copper that show no measurable impact on these lifecycle parameters can still have observable effects on worm physiology. It is thus reasonable to assume that copper contamination of soils has long-term chronic effects on earthworm population dynamics and other soil fauna components that are important to the maintenance of soil structure and biogeochemical cycling. Copper applications are also toxic for fungal species used as biocontrol agents (for example, Beauveria bassiana, used against pest insects). Nanoparticles containing copper have also been shown to be toxic for the plant-soil system, although it is not clear whether this toxicity is caused by the nanoparticles themselves or by an associated release of copper ions. Effects on plants are similar to those caused by an excess accumulation of copper ions in soil: a dramatic reduction in growth of the exposed plants and a modification of the ionic balance in plant tissues. Effects on soil microbial communities (attributed generally to the release of copper ions) have not been described in detail, but have been shown: reductions in microbial diversity, reductions in soil bacterial communities favourable to plant growth, reductions in iron uptake by both plants and microbes. It would appear ...
Ecotoxicity. The key question addressing the sixth risk potential (parallel to accumulation, inflammation/immunotoxicity and genotoxicity) of the flow chart is: Is ecotoxicity expected? If this question is answered with no: no nanospecific potential for health risk is expected and risk assessment can be performed in the conventional way. If this question is answered with yes: nanospecific data/testing is required (see testing strategy).
Ecotoxicity. ▇▇▇▇▇▇▇▇▇▇▇ and Olszyna (2015) published a review about ecotoxicological effects of graphene family nanomaterials. The finding shows that: • Bacterial metabolic activity, bacterial viability, and biological removal of nutrients, such as organics, nitrogen, and phosphorus, were significantly impacted by the presence of Graphene Oxide (GO) in the activated sludge at a concentration of 50 mg/L. Also, GO interaction with wastewater produced significant amount of reactive oxygen species (ROS), which could be one of the responsible mechanisms for the toxic effect of GO. • Graphene was found toxic to the algae Dunaliella tertiolecta. • Authors also showed the presence of graphene aggregates into the gut of crustacean ▇.▇▇▇▇▇▇. A 48-h exposure experiment revealed an altered pattern of oxidative stress biomarkers, resulting in a significant increase of catalase activities in graphene 1 mg/L treated A.salina and a significant increase of glutathione peroxidase activities. Increased levels of lipid peroxidation of membranes were also observed by authors. However, despite the toxic-suggestive results, no acute toxicity was demonstrated by the authors with respect to A. salina. Tests on Amphibalanus amphitrite (cirripedia, crustacea) larvae in two phases of development: cyprids and naupilius, showed that the increasing concentrations of GO (0.01, 0.1, and 0.5 mg/mL) and increasing exposure times (24, 48, and 72 h) lead to decreases in the swimming speed of nauplii and to increases in their mortality. • GO studies on zebrafish embryos showed that GO can cause actual toxicity to organisms inducing slight hatching delay of zebrafish embryos at a high dosage of 50 mg/L. Authors demonstrated that embryos exposed to GO exhibited more moderate toxic effects. The overt morphological malformation was bent spine, minor tail malformations and body degradation and opaqueness in yolk which may be an indicative of apoptotic tissue in zebrafish embryos. • Combined morphological and physiological analyses on plants indicated that after 20 days of exposure to 500 to 2000 mg/L of graphene caused a significant inhibition of plant growth and biomass level. Significant effects were also detected showing a concentration-dependent increase in ROS and cell death as well as visible symptoms of necrotic lesions, indicating graphene-induced adverse effects on cabbage, tomato, and red spinach mediated by oxidative stress necrosis. Significant negative impacts of GO concentrations starting at 100 ...
Ecotoxicity. The observed testicular and sperm effects of melamine identified in experimental animals (rats) are considered relevant for identification of probable serious effects on the environment. They can impact reproduction and can have an effect on the population level. Rats are rodents and rodents represent approximately 42% of all mammalian species. Rodents play an important role in the environment, for example in the dispersal of seed and spores, pollination, energy and nutrient cycling, modification of plant succession and species composition. Rodents are a food source for many predators. There is also scientific evidence of probable serious effects on fish (mortality and growth) and on aquatic invertebrates (mobility, poor condition). As supporting information, effects were observed on terrestrial birds (decreased egg shell strength). These effects are serious because they also can have an effect on population level. These effects are also significant when combined with environmental fate properties leading to irreversible and increasing presence in the environment for the reasons described below. The concern raised by melamine is triggered by individual properties as well as by combination of its properties. The combination of the substance intrinsic properties persistency, mobility and potential for being transported in the water phase over long distances lead to a potential to cause an irreversible presence in the aquatic environment, together with a widespread contamination of the aquatic environment. Due to its low tendency for adsorption, melamine will not attach to suspended or organic matter in the environment to any significant degree. Due to the lack of abiotic and biotic degradation of melamine, it is expected that there is no significant removal of melamine by biological processes in conventional municipal sewage treatment plants dealing with mixed sewage that predominantly originates from households. Thus, the overall amount of melamine emitted from production and use is, if at all, only marginally reduced by the treatment processes in such municipal sewage treatment plants. It is acknowledged that sewage treatment plants that are specifically designed to treat sewage predominantly originating from industrial sites may achieve a higher removal efficiency. Such industrial sewage treatment plants are specifically designed to reflect the local situation and site specific legal requirements. Although such industrial sewage treatment plants may be re...