Sub-lethal Effects of Manufactured Nanoparticles on Fish: Bioenergetics, Brain, and Behaviour

Lead Research Organisation: University of Plymouth
Department Name: Unlisted

Abstract

Manufactured nanomaterials are new materials that have many potential beneficial applications (e.g., new textiles, electronics, building materials, medical devices etc.). However, like any substance, they must be assessed for their safety and effects on the environment. Our recent laboratory work has shown that some nanomaterials are toxic to fish, and one particular area of concern is neurotoxicity, effects on the brain, and on behaviour. This project aims to investigate these effects in detail by exposing rainbow trout to two different materials; carbon nanotubes and titanium dioxide nanoparticles. We will measure subtle changes in animal behaviour and correlate this with changes in the brain tissue (measured using physiological, histological and molecular techniques). The project also includes a risk assessment workshop, where we will discuss the results, and enable some decisions on how much of these new materials can be released into the environment and what the hazards are to wildlife, and human health.

Publications

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Description The overall aim of the research was to investigate the sub-lethal effects of waterborne exposure to two very different engineered nanomaterials, titanium dioxide nanoparticles and carbon nanotubes, on the brain and behaviour of fishes. This work was conducted using rainbow trout. The main finding was that sub-lethal exposures to these materials did subtly change the swimming speed distributions of trout. Mechanistic investigations suggest that the cause of the change in behaviour was mostly due to systemic hypoxia leading to changes in swimming ability. Brain histopathology did show some oxidative stress and some subtle changes in the nerve cells, but not enough to cause acute neurological dysfunction of the brain. A review paper from our laboratory (Handy et al. 2011 published in the Journal of Fish Biology) summarises the current state of knowledge on the effects of engineered nanomaterials on fishes, including effects on the nervous system, brain and behaviour. This review highlights a number of areas where knowledge of the effects of engineered nanomaterials on fishes is limit, including effects on the immune and nervous systems. We also did some additional experiments on nano copper, since copper metal is a known neurotoxic chemical. This work showed that nano forms of copper are toxic to fishes, and do cause pathologies in several internal organs including the brain. Copper nanoparticles appear to be more toxic than the other materials studied in our research. The research programme also included some in vitro work to investigate the direct effect of engineered nanomaterials on nerves. These in vitro studies were conducted using a classic nerve preparation from shore crabs. The main finding was that a range of different metallic nanoparticles, carbon nanotubes, and C60 fullerenes had no effect on the generation of action potentials, their refractory period or the ability to repeat stimulations. This work, published in the Nanotoxicology, appears to be the first firm direct evidence that engineered nanomaterials do not interfere with the action potential of nerves. There was as a tied PhD research project investigating the reproductive and bioenergetic effects of these materials, using zebrafish and sticklebacks as model organisms. The main issue here was whether or not nanomaterial exposure resulted in changes in bioenergetics such that the big aspects of energy expenditure in fish (locomotion, growth, reproduction, or body maintenance) also changed. The main finding was that the energetic composition of the fish did not change (proximate composition of carcass: protein, lipid, carbohydrate), and that energy expenditure was redirected a little from locomotion to tissue repair (as with other contaminants). The studentship followed the reproductive issues. This work showed that zebrafish exposed to nanomaterials can reproduce, but the quality of the embryos is reduced. Critically, the unexposed off-spring show deleterious effects. This appears to be the first report showing latent toxicity of engineered nanomaterials on a new generation of unexposed animals (Ramsden et al 2013, published in Aquatic Toxicology).
Exploitation Route One of the underlying drivers for this research was to provide data that could be used internationally in understanding the hazards and risks of nanomaterials, as well as providing methodology to conduct hazard assessments. This research will be of use to the Organisation for Economic Co-operation and Development (OECD) at the working party on manufactured nanomaterials (WPMN), contributing to knowledge on hazards. Similarly, there will be national level agencies with interests in this data from the view point on environmental risk assessment (e.g., Defra in the UK, and the US EPA). Our mechanistic studies on fishes have provided evidence that engineered nanomaterials can affect the brain and behaviour of animals. This information is of value to the clinical community in assessing the potential neurological risks of nanomaterials, and also in relation to the wider issue of long term public health risks. This aspect was discussed at a technical workshop held at the 4th NanoImpactNet Integrating Conference and 1st QNano Integrating Conference in Dublin 27th February to 2 March 2012, Symposium C: Sub-lethal Effects of manufactured Nanoparticles on the Brain and Behaviour. This engaged industry, government and the academic community from across Europe. The presentations and some of the discussions are available on U-Tube, http://www.youtube.com/watch?v=a-acxBteAIw . It was necessary also to validate methods for determining nanomaterial in fish tissues during the research, and subsequently a patent is in progress for the detection of titanium dioxide nanoparticles in fish/shellfish (UK Patent application No: 1207745.9). This will provide a valid method that can be used by regulatory agencies (e.g., for food safety), as well as a tool for use by researchers.
Sectors Agriculture/ Food and Drink,Chemicals,Environment,Healthcare,Pharmaceuticals and Medical Biotechnology

URL http://www.plymouth.ac.uk/pages/view.asp?page=32421
 
Description This research is likely to have an impact on hazard and risk assessments for nanomaterials, particularly at the Organisation for Economic Co-operation and Development (OECD) at the working party on manufactured nanomaterials (WPMN). Presently (April 2013), it is too early to measure the impact on this community because our research is recently published. It was necessary also to validate methods for determining nanomaterial in fish tissues during the research, and subsequently a patent is in progress for the detection of titanium dioxide nanoparticles in fish/shellfish (UK Patent application No: 1207745.9). This will provide a valid method that can be used by regulatory agencies (e.g., for food safety), as well as a tool for use by researchers.
First Year Of Impact 2013
Sector Agriculture, Food and Drink,Chemicals,Environment,Government, Democracy and Justice,Manufacturing, including Industrial Biotechology
Impact Types Economic,Policy & public services