Thematic Page 9: Summary of the Renegade Nanoparticle Risk Assessment Protocol for NanoRem Field Deployments
Paul Nathanail, Andy Gillett, Caroline McCaffrey & Judith Nathanail
Land Quality Management Ltd (www.lqm.co.uk), @lqmtweets, firstname.lastname@example.org)
3. Risk Assessment Protocol Development for NP Deployment in Groundwater
4. Conceptual Site Model Development
5. Additional Resources on the NanoRem Web Site
6. Feedback and Opinion
The aim of this page is to summarise the way NanoRem is tackling the assessment of risks posed by any nanoparticles (NPs) injected into polluted groundwater that migrate beyond the intended treatment zone. A detailed technical review of the issues was carried out to inform a NanoRem specific protocol for use in field trials. This will form the basis of a widely available risk assessment protocol once the field trials and laboratory experimentation phases of NanoRem have been completed.
The aim of NanoRem is to support and develop the appropriate use of nanotechnology for contaminated soil and groundwater remediation. NanoRem focuses on facilitating practical, economic and exploitable nanotechnology for in situ remediation. This can only be achieved in parallel with a comprehensive understanding of the environmental risk-benefit balance for the use of NPs.
3 Risk Assessment Protocol Development for NP Deployment in Groundwater
One of NanoRem’s objectives is to provide field evidence of the safe and effective deployment of NPs to remediate polluted groundwater. The health and safety aspects of injecting NPs do not pose a particularly novel challenge. However it is necessary to consider the extent of potential risks posed by injecting NPs into groundwater. Risk assessment specialists from Nottingham-based SME Land Quality Management Ltd (LQM) developed a protocol to allow the NanoRem field trials to evaluate the risks posed by NPs that do not get consumed in the remediation process. The fate, transport and toxicity of these so called renegade NPs was considered during an expert elicitation workshop organised by LQM at its University of Nottingham Innovation Park offices. The workshop outcomes, supported with evidence from the literature, formed the basis for a simple protocol for field trial sites to use to evaluate the risk posed by their NP deployment and demonstrate to regulators the trials would be safe.
Photo 1 Summer 2013 Expert Elicitation Workshop facilitated by NanoRem partner Land Quality Management Ltd (© Land Quality Management 2013)
LQM’s work focused on the risks posed by the NPs being researched by NanoRem (See NanoRem 2014 News Letter). While these NPs could have a significant toxicity, the workshop participants agreed that it would be substantially less potent than highly ecotoxic nano-silver. Furthermore the NPs are likely to interact with the aquifer matrix, each other and groundwater to rapidly cease to be mobile NPs. They are therefore likely to be difficult to penetrate into the aquifer more than a few metres from the point of injection.
4 Conceptual Site Model Development
For an environmental risk to exist all of the following must be present: a source of contamination (S), a receptor (R) and a pathway(s) (P) linking the two - i.e. a contaminant linkage (S-P-R) and such linkages are shown on the conceptual site model (CSM) see Figure 1 (See NanoRem 2014 News Letter).
A CSM addressing the possible risk from renegade NPs needs to be created separately from, and is in addition to, the CSM which should already have been developed for the contamination problem at the site that is driving the need to remediate. For the pre-deployment risk assessment for NP injection, the NP themselves are considered as the source, with the CSM used as a tool to consider whether there are potential pathways for NPs to any relevant receptors.
Figure 1 Cross section from CSM (This site is an illustrative example only and does not represent any of the pilot sites) (© Land Quality Management 2014) (See NanoRem 2014 News Letter).
Receptors that could be affected by NPs include: human health, surface water, ecosystems and, though to a lesser extent, groundwater, although for some of these the potential exposure scenarios are unlikely. Despite the uncertainties identified in our current knowledge base and that NanoRem laboratory and field studies are addressing, LQM identified a range of circumstances that indicate NPs can be safely deployed. These include an absence of receptors (other than the already contaminated groundwater), where a site has pathway interruption (e.g. a down gradient permeable reactive barrier) or limited NP transport means the receptor would not be reached by renegade NPs.
Since developing the protocol, LQM staff provided detailed online training and face to face mentoring to case study partners on the development of their conceptual site models to help them then apply the protocol to their sites. The site specific evaluation of the risks posed by injected NPs forms part of the evidence submitted to relevant regulators and other stakeholders in order to gain the necessary site specific permissions to carry out the field trials.
Overall while there are considerable uncertainties particularly with regard to NP transport, the ability of NP to penetrate far into the formation is likely to be limited. At this stage such a protective situation is welcome. Once the results of the field trials are available, LQM will update the risk assessment protocol for eventual publication and consideration for wider take up. Further details are available on application to the authors of this thematic page using the contact details in the title block.
5 Additional resources on the NanoRem web site
Additional summary information is also available on the following online pages:
Currently we have the following FAQ pages: