Fixing the fuzz around nanomaterials
Little is known about the potential risks posed by nanomaterials present in waste streams. Dr Steve Hankin looks at the challenges this poses in terms of disposal
Nanotechnology is a fast-growing industry-enabler that brings new benefits, but also challenges, to industrial-scale production. Its proliferation across a range of industries, for example the advanced materials, cosmetics and personal care sectors, has led to new forms of waste streams that contain residue nanomaterials. The challenge for the waste management industry will be how best to dispose of these waste streams.
While scientists continue to study the environmental fate and impact of nanomaterials - largely through using pristine materials in laboratory tests rather than aged or waste-stream-conditioned materials - there are, as yet, few clear conclusions regarding the long-term behaviour of nanomaterials and their distribution in the environment.
Equally important, there is little information about the potential risks that they may pose. Ndeke Musee's Nanowastes and the environment: potential new waste management paradigm raises serious concerns about the uncontrolled release of nanomaterials into the environment through nanowastes, and the potential consequences should industry and government fail to resolve any potential impacts.
He offers a number of practical suggestions, the most prominent being the need for a systematic risk assessment framework of nanomaterials in actual waste streams. Musee also calls for a well-defined nanowastes classification protocol; industrial-driven and legislative initiatives; and appropriate technologies for handling and treating nanowaste streams.
In Europe, there has been some movement. The European Parliament's resolution of 24 April 2009 explicitly called on the European Commission to evaluate the need to review waste legislation, emission limit values and environmental quality standards in air and water legislation to adequately manage nanomaterials.
The EC responded and the Review of Environmental Legislation for the Regulatory Control of Nanomaterials carried out jointly by the Brussels-based environmental law and policy consultancy Milieu and London-based AMEC Environment & Infrastructure, was published in September 2011.
It concluded that the main challenge in covering nanomaterials under the Waste Framework Directive is the uncertainty surrounding the classification of specific nanomaterials as hazardous under the Classification, Labelling and Packaging (CLP) Regulation.
The Milieu/AMEC report also drew attention to the disposal of consumer products that contain nanomaterials in municipal waste streams, even if those nanomaterials had been identified as hazardous under CLP. In this instance, upstream product control could offer a route for controlling the releases of specific nanomaterials found to exhibit hazardous properties.
Another report finding was that scientists have focused less on the environmental exposure pathways for nanomaterials in waste than those in water. This has made it difficult for observers to assess coverage and identify specific knowledge gaps. What the findings appear to suggest is that both EU regulators and practitioners on the ground are struggling to manage a risk that remains essentially unquantifiable.
At the EU level, regulators do not have the ecotoxicology data required to assess whether nanomaterials could qualify as priority substances under the Water Framework Directive. At the same time, waste managers have very little knowledge about the behaviour of nanomaterials in recycling processes. Meanwhile, producers that notify nanomaterials under CLP do not have data on the intrinsic properties of specific nanomaterials.
At the other end of the waste stream, operators of waste water treatment plants are unable to determine how efficient the treatment techniques are in removing nanomaterials. Arguably, the question of whether nanomaterial-containing waste(s) present a significant environmental risk still needs to be resolved by the nanotechnology research community as it develops new materials and looks at safety issues.
The importance of waste issues has been recognised, however. The British Standards Institution, for instance, published the Disposal of manufacturing process waste containing manufactured nano-objects - guide (PAS 138:2012), which provides guidance on the safe disposal of manufacturing process waste that contains unbound nanomaterials.
This document includes appropriate disposal routes; the preparation of waste materials for transfer to a waste disposal company; and information that should be provided to those involved in waste disposal. It also includes a decision tree to assist users in applying its recommendations.
With increasing attention being given to life cycle considerations in research projects that support the development of nanotechnology-based products, greater knowledge about nanomaterial waste issues, such as recycling, biodegradation, the potential for environmental accumulation and any subsequent effects and their mitigation, should emerge.
While our understanding of the environmental impact of nanomaterials in waste is still developing, it would be prudent to adopt disposal routes that either eliminate or reduce their potential release to the environment.
Dr Steve Hankin is senior consultant in risk assessment and section head at SAFENANO