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8.4 Nanomaterials As engineered nanomaterials are expected to be used in a wide range of product types, it is likely that a range of environmental regulatory frameworks will apply to them. For example, industrial uses are likely to be covered by the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulations, whereas applications in the pharmaceutical, biocides, veterinary medicines and plant protection products will be covered by other specific frameworks (e.g. Aitken et al., 2006).
8.5 Other regulatory frameworks
Many ECs, that are not covered by the mechanisms described above, are likely to be covered by the recent EU Regulation (EC) No. 1907/2006, the REACH Regulations, which entered into force on June 1, 2007. REACH will require an environmental safety assessment of all chemicals used or imported into the EU in quantities exceeding one tonne. The Water Framework Directive and the new European soils policy may also influence the management of ECs in the natural environment.
9. Risk mitigation
In the event that an EC is identified as posing an unacceptable risk to the environment, there are a number of options that exist for managing or mitigating the risks. For example, over recent years there has been a steadily increasing drive within the pharmaceutical industry towards the synthesis of „greener‟ pharmaceuticals and the adoption of green chemistry methods and technologies (Clark et al., 2008). The majority of improvements have been made to the manufacturing process, although increasing emphasis is being placed on the development of approaches for minimising impacts during use including the development of more efficient wastewater treatment technologies, and development of pharmaceuticals that are benign by design or designed for biodegradability (Clark et al., 2008). The implementation of tax and other incentives could make these eco-pharmacostewardship approaches more attractive to pharmaceutical companies and hence increase their uptake.
Classification and labelling approaches may also help to minimise risks. A good example of such a scheme is a system running in Sweden which is a voluntary scheme that targets active pharmaceutical substances where information on their environmental impacts is made publicly available on websites and in information booklet (Stockholms Läns landsting, 2006). The extension of a model similar to the Swedish scheme could potentially be desirable on a European level. Key issues for developing and implementing classification & labelling schemes include the standardisation of the information used, the criteria applied, who provides the information and mode of communication (Clark et al., 2008).
In Europe, drug take back schemes of unused/expired medication are an obligatory postpharmacy stewardship approach that reduces the discharge of pharmaceuticals into environmental waters and minimises the amounts of pharmaceuticals entering landfill sites. Although the contribution of improper disposal of pharmaceuticals to the overall environmental burden is generally believed to be minor (Daughton and Ruhoy, 2009), drug take back schemes are still considered to be important.
High levels of public awareness and education on the environmental consequences of the disposal of unused/expired drugs are key for the success of such schemes.
Changes in agricultural practices may also minimise the risks of ECs to the environment. A range of approaches can be used including changes in treatment timings and intensities, changes in manure/sludge application rates and timings, development of recommendations on when not to apply manure and biosolids (e.g. where slopes are unsuitable), and specification of buffer zones can protect water bodies (Pope et al., 2009). For example, injection application has been shown to reduce overland runoff of pharmaceuticals and personal care products when compared to a broadcast application (Topp et al., 2008). The timing of application might also minimize the risk of contamination. For example, the application of sewage sludge during dry periods would minimise the potential for some substances to be transported to surface waters.
10. Environmental risks of ECs in the future
It is also important to recognize new contaminants will emerge in the future due to a range of drivers including: demographic change; changes in land use; changes in waste disposal practices (e.g. moving to composting and anaerobic digestion approaches with subsequent application of the compost, digestate etc. to land); and global climate change. A recent study (Boxall et al., 2009) explored the potential impacts of climate change on the risks of contaminants in agricultural systems, focusing on the UK environment. The study concluded that climate change is likely to impact the dispersion of chemicals in the environment (Figure 4). In addition changes in climate are likely to affect the amounts and types of chemical used for in agriculture. Future risks of chemicals could therefore be very different than today so it is important that we begin to assess the implications of climate change for changes in environmental and human exposures to chemicals and the subsequent impacts in the near term and in the future. Based on the work, overall it is anticipated that climate change will result in an increase in risks of chemicals from agriculture to environmental and human health. The magnitude of the increases will be highly dependent on the contaminant type. Climate change will fuel increased use of pesticides and biocides as farming practices intensify. Extreme weather events will mobilise contaminants from soils and faecal matter, potentially increasing their bioavailability. Climate change will also affect the fate and transport of chemical contaminants in agricultural systems. Increases in temperature and changes in moisture content are likely to reduce the persistence of chemicals while changes in hydrological characteristics are likely to increase the potential for contaminants to be transported to water supplies. Risks of many particulate and particleassociate contaminants could therefore increase significantly. The study concluded that it should be possible to manage many of these risk increases through better regulation, monitoring and the development of long-term research programmes.
11. How can policy makers identify emerging contaminants of most concern?
It is clear from the above that a wide range of ECs will be released to the environment and that the nature of the ECs released to the environment will vary both temporally and spatially. We probably do not have the resources to experimentally assess the risks of every potential EC and there is therefore an urgent need for approaches that can be applied by environmental agencies and/or policy makers within a particular region to identify ECs of most concern. These ECs would then be the focus of monitoring investigations and fate and effects studies. Over the past few years there has been increasing interest in the development of prioritization approaches for identifying ECs of most concern. In this Section a number of these approaches that have been used for agricultural ECs are described.
A number of previous studies have been performed to identify priority emerging environmental pollutants (e.g. Boxall et al., 2003; Thomas et al., 2004; Capelton et al., 2006; Sinclair et al., 2006;
Sanderson et al., 2003; Table 3). These have considered a range of classes (veterinary and human medicines and degradates), different exposure pathways and have been aimed at different protection goals (selected priority lists of relevance to agricultural systems are given in Appendix A).
P = particulate; PA = particle-associated; S = soluble; V = volatile The size of the arrow indicates the magnitude of change in the transport pathway. The letters indicate the types of contaminant that will be transported by the pathway (P = particles, PA = particle associated; S = soluble; V = volatile). The size of the letter indicates that importance of the pathway for that contaminant type.
Source: Taken from Boxall et al. (2009).
Table 4. Previous horizon scanning studies for emerging environmental contaminants
Most of these approaches integrate data on the potential hazard of an EC to either organisms in the environment or to human health and combine this with estimates of exposure. As no experimental data are available on the ecotoxicity and environmental properties of most ECs, the prioritization approaches that have been used are very reliant on modelling predictions of fate and effects data. As stated in Section 4, many of the modelling approaches that are available for estimating fate properties and exposure are not necessarily appropriate for many classes of ECs so the priority lists should be viewed with some caution. By developing new or improved models for assessing the fate and effects of ECs and integrating these into prioritisation schemes, it should be possible in the future to identify ECs of most concern and to focus testing requirements. The prioritisation approaches have also focused on single compounds and interactions of ECs have not been considered.
12. Knowledge gaps and research needs
From the previous sections, it is clear that over the last few years that there has been increasing interest in the risks of emerging contaminants in the environment and there are also examples where ECs have caused catastrophic impacts on ecosystems (e.g. the effects of diclofenac and vultures). It is therefore critical that we continue to work to identify ECs of most concern in a logical and pragmatic
manner. In order to do this, there are many questions that need to be addressed:
What are the risks of substances that have yet to be studied? – Due to resource limitations only a small proportion of substances in use today have been investigated. There is therefore a need to develop an understanding of how other substances will affect the environment and for the further development of approaches for identifying substances of most concern.
How can we analyse certain emerging contaminants in environmental media? – While there have been significant advances in analytical technology over the last decade which now allows us to detect many classes of emerging contaminants at low levels in complex media, for selected contaminants (e.g. engineered nanomaterials), method development is still in its infancy (e.g. Tiede et al., 2008).
Are we considering all the main exposure pathways? – Current regulatory environmental risk assessment approaches for assessing exposure to ECs focus on leaching to groundwater and runoff to surface waters from soils. It is possible that important exposure pathways are being missed and it is also likely that different exposure pathways will vary in importance from one geographical location to another. There is a real need to identify all the potential pathways of exposure of environmental organisms to ECs that occur across the globe and, where appropriate, to develop models to cope with additional pathways.
How can we better assess ecotoxicity? It is possible that current standard ecotoxicity tests may not always catch the impacts of selected emerging contaminants (e.g. pharmaceutical effects on birds). The use of more subtle endpoints such as impacts on behaviour, physiology and biochemistry might help as could „read across‟ approaches from mammalian toxicology and pharmacology studies to environmental organisms.
How will ECs interact with a) each other; and b) other contaminants? – The environment will be exposed to a mixture of ECs and other contaminants. The combined effects of these mixtures are likely to be greater than the single compounds alone. It is important that we begin to understand how ECs interact with each other and with other contaminant classes and that methods are developed for identifying the implications of these interactions in terms of risk to the environment. These studies should not only focus on toxicant-toxicant interactions but also interactions which have an indirect impact on risk.
What do the ecotoxicity data mean? – A number of subtle effects have been demonstrated following exposure to selected emerging contaminants at environmentally realistic concentrations. We need to establish what these data mean, if anything, in terms of effects on ecosystem functioning.
What are the mechanisms determining and fate and behaviour of emerging contaminants? – For many traditional contaminants, our understanding of those factors and processes affecting fate and behaviour in the environment is well developed and models are available for predicting a range of important fate parameters (e.g. sorption, bioaccumulation).
However, for many emerging chemical contaminant classes, other fate mechanisms appear to be important. In the future we need to try and further understand these mechanisms in order to develop improved models for use in environmental risk assessment. Additionally we need to better understand the effects of manure, sludge and waste matrices on contaminant behaviour in agricultural systems.
How can we mitigate against any identified risks? – In the event that a risk of an emerging contaminant to the environment is identified, it may be necessary to introduce treatment and mitigation options. By better understanding those factors controlling the fate and behaviour or different classes of emerging contaminant, we should be better placed to optimise existing remediation technologies or develop new approaches to reduce risks.
What will agricultural systems look like in the future and how will this effect contaminant risk? – Agricultural systems are likely to look very different in the future due to land use, demographic and climate change. These changes are likely to affect the risks of contaminants in agricultural systems. It is therefore important that we begin to assess how agricultural systems might change in the future and to assess how these changes will affect contaminant inputs, exposure, effects and risks.
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