Limitations of the Holistic Metrics

On the other hand, when the holistic metrics are used in parallel with the mass metrics referred to above, the results and conclusions about greenness may show differences. This is a consequence of the nature of the evaluation—systemic vs. reductionist—which implies that different components of the greenness may be captured in the assessment of the system by different metrics, as exemplified in Table 8.6. This table shows that some material components, like masses, yields, etc., are caught only by mass metrics, as these provide quantitative values. This lack of completeness is a limitation of the holistic metrics (as well as of the mass metrics), but is inherent to their systemic nature. This situation suggests that in practice the use of mass metrics in parallel with the holistic metrics, as often made in the cases studied, provides a fuller account of greenness. 

The term greenness is unavoidably ambiguous and amenable to a variety of interpretations, because the concept it tries to convey in GC is extremely complex the greenness synergistically compounds the complexities of the chemistry, the environment and their systemic connections, especially the impacts of chemicals and their manufacture on the environment. However, the evaluation of greenness, although only relative, is important for the prosecution of GC as noted in several recent articles on its development and future.  

In eonelusion, these holistic tools enhance the understanding of GC and of greenness evaluation problems, as well as of the practice of the Twelve Prineiples, being also useful to facilitate their incorporation in teaching activities. Therefore they seem to be a contribution suitable for the development of practices in chemistry that must be proactively changed to reach sustainable chemistry, which is the ultimate purpose of green chemistry. 

Kent (ed.), Kent Riegel s Handbook of Industrial Chemistry, 11th edn, vol. 1, Springer, 2007. 

Lapkin and D. J. C. Constable, Green Chemistry Metrics Measuring and Monitoring Sustainable Processes, Wiley, 2009. 

---

The main limitation of these holistic metrics based on the GC principles is that some of the risks are captured simultaneously by several principles, as exemplified in Figure 8.10, and consequently the evaluations made by the... 

To overcome this limitation, a different approach can be used to start the metrification with the assumption of a systems thinking mindset and pursuing the conception of holistic metrics that can provide a global view of the chemical greenness for each case to be studied. This view should inelude all, or at least a large number, of the relevant greenness dimensions, along whieh the evaluation is made in parallel. 

---