The latest science indicates that plastics are entering our oceans at the rate of 8 to 12 million metric tonnes per year, according to an article in Science Advances published last year. The Ellen McArthur Foundation estimates that there will be more plastic in the oceans by weight than fish by 2050, a mere 32 years from now.
The reasons for this are many, from litter, storm debris, and lost fishing gear to inadequate solid waste infrastructure and poor consumer practices. The major sources of marine plastics are several countries in Southeast Asia, Asia, and Africa, but all countries contribute to some degree.
Science-based life cycle assessments (LCA) indicate that plastics are a resource efficient material with many upstream benefits and therefore a preferred alternative to other materials. But it is clear that LCAs do not provide the whole story when we face a future with more plastics than fish in our oceans. A typical product and packaging LCA does not provide information on the loss or mismanagement of material along the life cycle. As the accumulation of plastic in our environment shows, these losses can be profound. So why are mismanaged materials missing from LCAs and how do we address it?
LCA is the preferred tool to evaluate the environmental impacts of products and packaging materials throughout their life cycle. It is used to help design products, select materials, form environmental strategies, and make claims. One of the powerful aspects of LCA is that it allows material comparisons for products that provide a similar function in relation to a common set of environmental indicators. However, LCA is a data driven methodology and the results are only as good as the data that underlies the analysis and the categories of impact evaluated.
Understanding the role of data, or lack thereof, in LCA is a critical area to solve if the blind spots in LCA are to be addressed to capture the impact of mismanaged materials. There is typically good data to describe the extraction and manufacture of raw materials. The extraction, refining, and conversion processes for commodity materials is well understood and the processes do not vary dramatically from market to market. So, it is relatively simple to generalize the life cycle inventory data to model these processes in an LCA.
The case is very different for end-of-life management processes. Waste management systems are very different from one region of the world to the next. It is not valid to generalize about end-of-life, solid waste management models or consumer behavior. Some of the most heavily populated regions of the world, like China, India and Indonesia, depend heavily on poorly managed landfills and dumps, yet have high recycling rates for select materials in urban areas through waste picking and the informal sector.
Other parts of the world rely on engineered landfills and have mediocre to average recycling rates for many materials through widespread curbside recycling. In both cases, there are losses both intentional and unintentional throughout the life cycle. It is important that LCA capture the difference in these end-of-life waste management systems and the fraction of waste not captured if LCAs are to more accurately reflect the true impact of materials. The same data-driven coverage and assessment that LCA provides for many important aspects of product life cycles must be brought to bear on the vital topic of mismanaged wastes and its consequences.
Today, LCA uses end-of-life, solid waste management models that have been developed to characterize the impacts of managing wastes in engineered landfills, waste-to-energy facilities, and recycling or various organics recovery systems - all managed systems indicative of developed countries. The data in the widely-used databases for LCA generally reflect best practices for each of these management systems. The source of this data is primarily studies of systems in Western Europe. Clearly, not all waste is generated and managed in Western Europe, nor in the ways characterized by these models. The data missing from most LCA-based conclusions about product life cycles include such realities as poorly designed landfills, open dumping, low-tech incineration, open burning, storm events, accidents and spills, and just plain litter. Since waste mismanagement is not only real but also increasingly recognized as a route to major environmental and health consequences, its presence and impacts in real-world product life cycles must be addressed by LCA. This will take work to remedy.
Solutions include investment in new datasets which involves detailed research into the waste and recovery systems of individual markets and developing much more localized end-of-life models that reflect the way waste is handled in both urban and rural settings. This is not a trivial task. Organizations like EcoInvent work continually to develop more accurate data sets, but the data on material losses in some markets, like Indonesia, does not reliably exist and estimation models need to be developed until the data does exist. Recently implemented database and modeling technologies that regionalize data will greatly assist applying regionalized modeling and impact assessments of waste management once the data are developed.
The evidence is growing that there are significant human and environmental consequences of mismanaged materials, particularly plastics. Litter, aquatic trash, and marine debris have been observable phenomena for decades. But only in the last few years has rigorous research been published that attempts to quantify the amount of plastic and other materials entering the environment each year.
There are growing efforts to connect these scientific findings to LCA methodology, and it is urgent that this integration occur. To exclude the impact of litter or unintentional releases through inappropriate disposal, storm debris, or poor consumer practices in LCA is significant for any material, not just plastics. With plastics, however, this omission is magnified because plastics accumulate in the environment over time. The physical characteristics of plastics that make them efficient and lightweight during their use become particular challenges when not disposed or recycled properly. In particular, the lightweight nature of plastics means that they are easily dispersed throughout the environment via wind or water, and can fragment, float or become suspended in water. And since plastics are based on organic molecules, they attract other organic molecules when present, including persistent organic pollutants (POPs) like DDT, PCBs or hydrocarbons. In fact, numerous studies document the accumulation of POPs in the fatty tissues of higher order fish and marine mammals (see articles in Environmental Pollution and Journal of Environmental Monitoring).
In contrast, steel, aluminum, and glass if left mismanaged in the environment are less prone to dispersion due to wind and water and will eventually sink in aquatic environments so are unlikely to be taken up by animals as food. Paper can be prone to dispersion, but not when wet, and it degrades relatively rapidly. Steel and aluminum oxidize, albeit at very different rates, into materials that are compatible with the environment. Glass, on the other hand, is extremely inert in the environment and will remain largely unchanged for a very long time, and if broken or abraded will eventually degrade into sand. Clearly, the fates of mismanaged materials vary greatly by material type, which needs to be reflected in comparative LCAs.
While LCA is an effective tool for comparative analysis of products and packaging across common measures, to omit the impacts of mismanaged plastics is an important blind spot that needs urgently to be addressed. To achieve a level playing field, it needs to be a priority in the LCA community to collect the relevant data and update the modeling techniques that ensure the impacts of mismanaged materials are captured for all packaging material types. With the intense focus on marine plastics, hopefully more funds will be directed toward collecting data on solid waste and recovery systems, mismanaged materials, as well as new end-of-life models. In the meantime, it is clear that LCAs today are not providing the whole picture.
By Anne Johnson, RRS, and Greg Norris, SHINE, Harvard School of Public Health and International Living Future Institute
