Reducing Plastic Pollution

It is one thing to describe the environmental damage caused by the production and then discarding of plastic and quite another to determine how to stop and reverse it. 

One way to begin is to determine who is doing this. We have pointed out the role of China and other Far Eastern countries in pollution of the oceans, but, according to a study by Law et al. in Science Advances [Science Advances  30 Oct 2020: Vol. 6, no. 44, eabd0288; DOI: 10.1126/sciadv.abd0288], the US was the number one source of plastic waste in 2016 (the most recent year for which data are available. ). We generated 42Mt (Million metric tons) of plastic waste. That is nearly twice the amount of the next on the list – India – which produced abut 26Mt. The US also used more plastic per capita, at 286 pounds/person according to the study.  [In blog #2, I mentioned that some of the Caribbean Islands were the leading polluters per capita, but that referred to ocean pollution only.] This estimate of plastics entering the coastal environment in 2016 was five times that of 2010, and the highest in the world. 

We do not have the waste management infrastructure to recycle all of our waste and send about half of our recyclable materials overseas. About 88% of this goes to developing countries that themselves do not have the infrastructure to manage it. These figures are misleading; only about 9% of US plastic waste was recycled in 2016.

The authors of the Science Advances study visited many countries involved in the study and documented open dumping and burning of discarded plastics. Since it was not possible to document or calculate how widespread these practices are, they applied a range estimate of 25-75% of discarded plastic imported from the US was inadequately managed in the receiving country. 

Thus, the enormous problem that we have created has been outsourced to others.  Our national problem has become a global problem. The strongest evidence that we are overwhelming the world is that China has refused to recycle any more of our waste. 

The important question is: What can we do? The obvious beginning is to produce less plastic. Especially that which is not practical to recycle. Much of this waste is packaging material, and redesigning this, even with an added cost to recycle it, is a beginning. 

Here are some simple, but important, suggestions from Iberdrola, the Spanish sustainable energy company, a leader in commercial sustainable energy and green living.

·      Avoid single-use plastics such as drinking straws, plates, and cutlery

·      If you go shopping, remember to take reusable bags (cloth, string or wicker). Europe plans to do this in 2021.

·      Recycle chewing gum. Most chewing gum contains plastic. Try to buy less chewing gum and throw it in the correct recycling container. You can also opt for natural and organic chewing gums.

·      Buy more bulk food and fewer packaged products

·      Replace plastic Tupperware with glass or steel containers. If you eat at work, a Tupperware container is part of your day. We suggest you change your routine and opt for glass or stainless-steel containers.

·      Make those around you aware of the importance of reducing the consumption of plastic. If you manage to get your family, friends and co-workers to do the same by setting an example, the impact of your actions for the good of the planet will increase exponentially.  

·      Put your plastic waste in the correct recycling container

·      Avoid using cosmetics that use micro-plastics; buy a biodegradable brush and wear natural fabrics

·      Choose to reuse and give some of the packaging a new purpose. If you have no choice but to buy a plastic bottle or a plastic container at the supermarket, reuse it instead of throwing it away. A bottle can be filled up as many times as you wish, and containers can be used to store other food.

Single-use plastics account for half the plastic we use annually. They have an average useful life of 12-15 minutes but can take up to 500 years to disappear. For example, a drinking straw can take 200 years; a toothbrush, 500 years; plastic cutlery, 400 years; plastic cup, 100 years. We must change the way we live and convince others to do the same. 

There are political activities that can help. I am not talking about marching in the street, but rather contacting your representatives locally whenever an issue of plastic use, fracking, or environmental contamination by petroleum effluents arises.  Local and state political action is important since one can influence these more easily than can be done at the federal level. You can affiliate with conservation groups wherever you live. These groups are aware of environmental issues and will know which representatives will be important in pursuing those issues. Recently, in our city, local action by concerned and engaged citizens voted five candidates on to the City Council who were opposed to the residential fracking that the City Council was allowing. This change in membership brought these fracking activities to a halt. It also made a statement locally and in the state about what was possible and destroyed the myth that oil companies could not be stopped. 

It is almost impossible to overstate the need here. Our climate and environment are changing relatively rapidly, and correspondingly rapid political action is needed to reverse this. Alternative energy is becoming more efficient and affordable. Waiting for action at the federal level will require years that we do not have. The best plan to act at the state and local levels. 

Finally, what does the future hold? Are there scientific or technological breakthroughs that can help with this problem of plastic waste. The answer is, yes, there are. In my mind, the most promising of these is microbial and insect degradation of plastics. This is in every way analogous to the use of microorganisms to breakdown oil to small, non-polluting molecules that can be metabolized by other microorganisms. This technology is over fifty years old and, after being ignored for many years, now is routinely used in managing oil spills in oceans and harbors.

There are several good sources that discuss this, but the review by Mohanan et al. [Mohanan N, Montazer Z, Sharma, PK and Levin DB (2020) Microbial and Enzymatic Degradation of Synthetic Plastics. Front. Microbiol. 11:580709. doi: 10.3389/fmicb.2020.580709] is current and comprehensive. It details the chemistry of plastics, which we will not review, as well as the biology, which we will summarize. The digestive tracts of some insects function as bioreactors, with digestive enzymes and microorganisms that accelerate the biodegradations rate of some plastics. Insect larvae of many types are capable of feeding on plastics. In the case of polystyrene, the most abundant plastic produced worldwide and found in many packaging materials, can be digested by a variety of microorganisms. Similar results have been found for polypropylene, polyvinyl chloride, and polyurethane, among others, with the same and other microorganisms. These microorganisms are living bioreactors. This is early research, and the enzyme mechanisms involved are largely unknown. However, it is a highly promising area of science with a relatively immediate application to cleaning of plastic waste from oceans and waste dumps. One does not necessarily need to know enzyme mechanisms before putting these microbes to work ridding the globe of the mess we have made.