Modelling the release, transport and fate of engineered nanoparticles in the aquatic environment:a review

Engineered nanoparticles, that is, particles of up to 100 nm in at least one dimension, are used in many consumer products. Their release into the environment as a consequence of their production and use has raised concern about the possible consequences. While they are made of ordinary substances, their size gives them properties that are not manifest in larger particles. It is precisely these properties that make them useful. For instance titanium dioxide nanoparticles are used in transparent sunscreens, because they are large enough to scatter ultraviolet light but too small to scatter visible light. To investigate the occurrence of nanoparticles in the environment we require practical methods to detect their presence and to measure the concentrations as well as adequate modelling techniques. Modelling provides both a complement to the available detection and measurement methods and the means to understand and predict the release, transport and fate of nanoparticles. Many different modelling approaches have been developed, but it is not always clear for what questions regarding nanoparticles in the environment these approaches can be applied. No modelling technique can be used for every possible aspect of the release of nanoparticles into the environment. Hence it is important to understand which technique to apply in what situation. This article provides an overview of the techniques involved with their strengths and weaknesses. Two points need to be stressed here: the modelling of processes like dissolution and the surface activity of nanoparticles, possibly under influence of ultraviolet light, or chemical transformation has so far received relatively little attention. But also the uncertainties surrounding nanoparticles in general—the amount of nanoparticles used in consumer products, what constitutes the appropriate measure of concentration (mass or numbers) and what processes are relevant—should be explicitly considered as part of the modelling

Reproductive impairment in the zebrafish, Danio rerio, upon chronic exposure to 1,2,3-trichlorobenzene.

Most organic pollutants are supposed to act via the mechanism of nonpolar narcosis upon acute exposure. Because the chronic effects of these compounds are still relatively unknown, in this study a chronic toxicity experiment was performed with zebrafish, Danio rerio, exposed to 1, 2, 3-trichlorobenzene (123TCB), a nonpolar narcotic. Fish were exposed in a flow-through system for 68 and 147 days. Parameters measured are survival, growth, reproduction, and glycogen and protein content. The only parameter which was influenced was the number of eggs produced per female, resulting in an E

Acetylcholinesterase inhibition and increased food consumption rate in the zebrafish, Danio rerio, after chronic exposure to parathion.

Acetylcholinesterase (AChE) inhibition is widely regarded as a good biomarker of exposure to organophosphorus pesticides (OP). However, less is known about the relationship between AChE inhibition and consequences for growth, reproduction and survival on organisms. Acute toxicity tests with fish have shown that high percentages of AChE inhibition are needed to cause detrimental effects, but not much is known about the consequences of chronic exposure to this group of chemicals for both AChE activity and higher levels of biological organisation. In this study, zebrafish (Danio rerio) were exposed to sublethal concentrations of the OP parathion for 250 days in a flow-through system. Besides AChE activity, a variety of other parameters were measured: whole-body protein and lactate content, consumption rate, survival, growth and reproduction. AChE inhibition was correlated with exposure concentration, but not with exposure time, and was significant above 0.9 μg/l after 144 days and above 4.3 μg/l after 250 days of exposure. Both parathion and the cosolvent dimethylsulfoxide (DMSO) significantly increased food consumption rate of the fish. Survival, growth, reproduction and lactate content were not affected, while protein concentrations showed only minor effects. These findings support the hypothesis that AChE is a very sensitive biomarker for exposure, but not accurately predict higher level adverse effects following long-term exposure to OPs. © 2003 Elsevier B.V. All rights reserved

Sensitivity of the zebrafish (Danio rerio) early life stage test for compounds with different modes of action.

The sensitivity of the early life stage (ELS) toxicity test for two compounds with different modes of action was determined, and related to other toxicity tests with the same compounds. The zebrafish, Danio rerio, was used as a test organism, and the two model compounds were 1,2,3-trichlorobenzene (123TCB), a non-polar narcotic, and parathion, an acetylcholinesterase (AChE) inhibitor. Hatching and survival after 28 days were significantly reduced in the highest 123TCB treatment (263 μg/l), but not in any of the parathion treatments. Growth of the larvae was negatively affected at parathion concentrations above 20 μg/l, while AChE was only significantly inhibited at the highest concentration, 93 μg/l. No effects on growth were found in the 123TCB treatments. In comparison with acute and chronic studies with both compounds, the ELS test turned out to be less sensitive than chronic studies and more sensitive than acute studies. The difference in sensitivity between the tests systems seems however, to depend on the mode of action of the compound. © 2002 Elsevier Science Ltd. All rights reserved