Environmental concerns: It's not just landfills & oil-based packaging anymore
By Dr. Charles A. Bishop
Sustainability is increasingly high on the agenda for polymer packaging, and it is likely to remain under intense scrutiny for the foreseeable future. Much of the focus has been on the volume of packaging derived from oil that ends up in landfills, and while will from petroleum sooner or later run out as a resource. Looking at a couple of other items, we may get an early warning of another problem we need to consider when thinking about how we change to more sustainable packaging.
Nanomaterials are currently of interest and seeing greater applications. Particle sizes are reduced into the nano range where the surface area to volume is much higher. This same activity also is a cause of concern as some nanoparticles have been found to easily absorbed into the body and are able to pass into various organs. This can be either good or bad. For example, medical research is studying the use of some nanoparticles for cancer treatments, whereas elsewhere uncontrolled exposure to other nanoparticles may be the cause of the cancer.
Microbeads were developed just over 50 years ago, but it was only 30 years ago that they became widely used in personal-care products. Their function varies from bulking agents, abrasives as exfoliants or polishers, and absorbers of degradable ingredients that would otherwise reduce product shelf life, to lubricants that make pastes or creams have a more silky texture. It was only 10 years later that the first reports appeared about the rapidly increasing pollution of the oceans with microbeads. The beads in many personal-care products are washed off and are small enough to pass through the filters in sewage-water filtration plants and end up in water courses and ultimately into the oceans. This gained a large amount of publicity in nature/science TV programs such as “The Blue Planet.” Along with the scientific pressure, this has resulted over the last five years in legislation in many countries to restrict microbead use. The beads were a more convenient and probably cheaper alternative to the natural products they replaced (ground almonds, apricot stones, cocoa beans, pumice or oatmeal), all of which biodegrade when released into the environment.
One thing leads to another
This brings me back to packaging. We all see packaging that has been discarded that litters the roadside and know about much that reaches landfills, but we may not be aware of the amount that reaches everywhere else [1,2]. 1,2. In a recent study in some US conservation areas, it was found that there was an average of 132 plastic fragments per square meter per day that equates to more than 1,000 tonnes of plastic deposited over the 11 protected areas annually. Similarly, in the Pyrenees, it was found that 365 microplastic particles per square meter per day were being deposited.
There are many sources of this plastic debris, not just packaging. The original plastic degrades, and there is progressive fragmentation toward small particles that are able to enter the atmosphere. These small fragments with their increased surface area to volume ratio have a greater ability to absorb and concentrate organic pollutants, making them of more concern than if they remained as pure polymer particles. The microfragments entering the atmosphere can be blown long distances. In one study, the plastics found were of a type that had no source within a 60-mile radius. These visible plastic fragments are the tip of the iceberg as there are many orders of magnitude more of even smaller fragments. Plastics less than 25 microns can enter the body when breathing and particles less than 5 microns can enter the lung tissue.
We have long been aware of the advantages of the plastics we use in packaging and hence the increase in their use. What we are only starting to learn is the fine detail of their life cycle and how any debris may not only be a pollutant but also a health risk. Given the legislative and regulatory response to the pollution problem of microbeads, it can be expected that sooner or later there will be action taken on plastic packaging. Looking ahead, changing packaging from oil-based materials to natural materials looks to have advantages far beyond replacing petroleum as the source of the packaging.
1. Leahy S. “Microplastics are raining down from the sky.” National Geographic, April 15, 2019. www.nationalgeographic.com/ environment/2019/04/microplastics-pollution-falls-from-air-even-mountains/
2. Brahney J., Hallerud M., Heim E., Hahnenberger M., Sukumaran S. “Plastic rain in protected areas of the United States.” Science, 12 June 2020: Vol. 368, Issue 6496, pp. 1257-1260 DOI: 10.1126/science.aaz5819