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Waste Plastic and Pharmaceuticals, Could an Integrated Solution Help? Karel D. Klika* Molecular Structure Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69009 , Germany removal by WWTPs, some are present only in exceedingly low concentrations. But the concern is that physiological effects are occurring even at these low concentrations, and likewise behavioral changes are similarly being observed in wildlife also at these low concentrations.1 Though some PPCPs are not persistent in the environment as they are photolabile or metabolizable, steady-state concentrations arise due to continual discharge. There is also the question of synergetic interactions between drugs which are difficult to evaluate given the resulting complex mixtures. For water-borne pollutants, one remediation approach is the use of adsorbents to retain contaminants and efforts directed toward new wonder materials such as “white graphene”5 (porous boron nitride nanosheets) have shown to be highly effective in the laboratory for removing pollutants with high adsorption capacities and reusability rates. Ultimately though, it is cost effectiveness and accessibility that will determine adoption of a method.
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The problems of plastic waste have been well highlighted.2,3 The enormous volume of material produced renders plastic ubiquitous as unmanaged garbage and persistent due to its degradation resilience which leads to the aesthetic depreciation of both nature and the habitat of man. Macroplastic is a threat to fauna by way of ingestion, entanglement, or smothering3− ingestion can lead to blockage of the digestive or pleural tracts; to the entry of microplastics/nanoparticles into organs, tissues, or cells; while entanglement can lead to death, injury, or suffering for an animal.2 Macroplastic represents a risk to ecosystems by facilitating alien species transportation.2 Other problems include the release of toxins either present in plastics from their manufacture3 or of toxins adsorbed from the environment such as PPCPs, persistent organic pollutants (POPs), and other priority pollutants.2−4 Thus, the burden placed on the environment by plastic waste is unsustainable,2 notwithstanding the ca. 4% and 3−4% of fossil fuels that are used for materials and energy, respectively, in plastics manufacture. A depiction of current plastics usage is portrayed in Figure 1 indicating that most plastic ends up in either landfill or the environment and very little is recycled or used for energy recovery. A way forward would clearly be to increase substantially both the amount that is recycled to approach a closed-loop system and that which is used for energy recovery.
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lastic waste and pharmaceutical and personal care products (PPCPs) are two environmental contaminates that engender considerable concern and represent as great a risk as any other priority pollutant.1−4 To reduce the impact of plastics on the environment, we need to design and facilitate the means of recycling more, produce more benign plastics that do not leach toxins, produce plastics that incinerate benignly or are biodegradable, and design plastics that can have greater functionality at the end-of-life-cycle stage. Similarly for PPCPs, we need to be selective about the ones in use with a preference for ones that are more easily degraded in the environment or are more easily retained prior to entry into the environment. In my view, new approaches to these problems need to be sought and an integrated approach represents an alternative contribution to limiting the environmental impact of waste plastic and PPCPs.
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PHARMACEUTICAL HAZARDS PPCPs are ubiquitous in aqueous systems and are inevitably associated with discharge from wastewater treatment plants (WWTPs) handling municipal wastewater or water from agricultural and animal handling facilities as much as from industrial or medical facilities.1 This is due both to the excretion of drugs, diagnostic agents, or nutraceuticals and wash water containing topically applied products as well as the inappropriate domestic disposal of unwanted drugs. The problems with PPCPs are their physiological effects, present obviously by desire,1 and despite many PPCPs resisting © 2013 American Chemical Society
PLASTIC HAZARDS
Received: August 2, 2013 Accepted: August 16, 2013 Published: August 29, 2013 10111
dx.doi.org/10.1021/es403576t | Environ. Sci. Technol. 2013, 47, 10111−10112
Environmental Science & Technology
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The author declares no competing financial interests.
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REFERENCES
(1) Brodin, T.; Fick, J.; Jonsson, M.; Klaminder, J. Dilute concentrations of a psychiatric drug alter behavior of fish from natural populations. Science 2013, 339, 814−815. (2) Rochman, C. M.; Browne, M. A.; Halpern, B. S.; Hentschel, B. T.; Hoh, E.; Karapanagioti, H. K.; Rios-Mendoza, L. M.; Takada, H.; Teh, S.; Thompson, R. C. Classify plastic waste as hazardous. Nature 2013, 494, 169−171. (3) Rochman, C. M. Plastics and priority pollutants: A multiple stressor in aquatic habitats. Environ. Sci. Technol. 2013, 47, 2439−2440. (4) Teuten, E. L.; Saquing, J. M.; Knappe, D. R. U.; Barlaz, M. A.; Jonsson, S.; Björn, A.; Rowland, S. J.; Thompson, R. C.; Galloway, T. S.; Yamashita, R.; Ochi, D.; Watanuki, Y.; Moore, C.; Hung Viet, P.; Seang Tana, T.; Prudente, M.; Boonyatumanond, R.; Zakaria, M. P.; Akkhavong, K.; Ogata, Y.; Hirai, H.; Iwasa, S.; Mizukawa, K.; Hagino, Y.; Imamura, A.; Saha, M.; Takada, H. Transport and release of chemicals from plastics to the environment and to wildlife. Philos. Trans. R. Soc. B 2009, 364, 2027−2045. (5) Lei, W.; Portehault, D.; Liu, D.; Qin, S.; Chen, Y. Porous boron nitride nanosheets for effective water cleaning. Nat. Commun. 2013, 4, 1777.
Figure 1. Conceptual depiction of the current disposal destinations of plastics together with an ideal scenario dominated by a closed-loop system as well as a more practical strategy.
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SEARCH FOR AN INTEGRATED SOLUTION Thus one consideration is to render disposed-of plastic as a more functional waste, and since plastics have the ability to adsorb PPCPs and other toxins, why not use waste plastic for such a purpose? After using waste plastic to adsorb and thereby remove PPCPs and other priority pollutants from wastewater prior to discharge into the environment, the plastic could then be disposed of in an environmentally benign way, for example, incineration with the recovery of energy/heat to further minimize environmental impact. However, what is needed is for a match to be made or a synergy created between the drugs in use and the plastics in use to gain maximum effect. This can come about through pressure arising from legislation or financial incentives for preferential use of those materials that adsorb better the drugs in use and for those drugs that are better adsorbed by the materials in use. Further optimization can arise through the redesign and development of both new plastics and PPCPs for such a system to achieve the desired target of high adsorption. The adsorption capacity and rate of toxin uptake can also be enhanced not only by chemical design of the drugs and the plastics, but by mechanical processing the waste plastic to increase the surface area and alter the topology to maximize toxin uptake. There is the question of components present in the plastic leaching into the wastewater, but needless to say the impact of such compounds should be minimized both in terms quantity and toxicity, that is, the plastic should necessarily be suitable for use in a water system either for those presently available or by design. However, with the removal of potentially more damaging pharmaceuticals, the net benefit attained could easily be positive even at this stage. Moreover, a similar view needs to be taken for the disposal of the plastics after use for adsorption in that they should also be amenable to a benign method of disposal such as environmentally friendly incineration whereby the amount of toxic waste generated or released is minimized. This approach as described could be a useful adjunct to the methods already in use for the disposal and/or recycling of plastics. It would not only represent a low-tech solution and available almost immediately in some form to many entities, but would constitute an integrated approach to sustainable environmental management. 10112
dx.doi.org/10.1021/es403576t | Environ. Sci. Technol. 2013, 47, 10111−10112
