Biodegradable Plastics

Back in the early 1980s, a number of North American entrepreneurs began marketing the first generation of biodegradable plastic products. At the time, applications for biodegradable plastics focused on single-use disposable products, such as garbage bags, snack food wrappers and disposable plates. These applications were targeted to address litter concerns and reduce the volume of refuse sent to landfills. Initial experience with these products, however, indicated that they were not going to deliver the expected results for two reasons.





One, the majority of biodegradable waste does not break down rapidly when buried in a modern landfill. As a result, substituting biodegradable products without first separating and composting does not extend the capacity of municipal landfills.

Two, like many new, innovative products that come to market – like biodegradable plastics – they often have to go through several “evolutions” before the science behind them is perfected. This first generation of “biodegradable” plastics simply mixed a conventional polymer with starch or some other organic substance. When the starch molecules broke apart (due to natural elements or starch-eating microorganisms), the product disintegrated into minute specks of plastic and other residues that mixed into the soil. While the plastic bag or wrapper seemed to have disappeared, it hadn‘‘t really gone away. It had just broken into very tiny bits.

Biodegradable polymer bags may be considered as a possible solution. However, before they are introduced, a rigorous assessment of the potential impacts on the local environment, existing waste recovery operations, and their likely influence on social behaviour should be undertaken.



D egradable plastics offer us a limited number of uses in niche markets . Take, for example, a hospital setting. Modern health care centres generate enormous amounts of dirty linen, soiled hospital gowns, and wet towels every day. Water soluble and completely biodegradable plastic laundry bags and hamper liners are making it easier and safer for the nurses and orderlies who collect and handle these washables. The sturdy, light-weight bags are simple to use: after a load of contaminated laundry is collected, the bag is sealed shut with an adhesive strip that is designed to dissolve in cold water. The sealed bag is then placed in the washer where it will break down completely during the hot washing and disinfecting process. Any residual polymer will biodegrade during the wastewater treatment process at the local sewage treatment plant. The bags, which are impermeable to bacteria and viruses during normal use, cut the risk of contamination and protect the hospital staff, including the employees in the laundry, from infection. No one needs to handle the contents of the bags until the wash and dry cycle is complete.



Other examples of niche markets that have begun using biodegradable plastics include:



non-toxic biodegradable polymer sutures (over 125 million are being used each year by surgeons in life-saving heart operations and other procedures)

textiles for applications like wipes and geotextiles for land erosion control

personal hygiene products like diapers

bags for composting programs

plastic seeding strips and agriculture mulches that can be plowed into the soil after the harvest

biodegradable plastic bin liners for restaurants interested in composting their food scraps, peelings and unfinished meals

It is important to remember that biodegradable plastic products should not end up in the recycling stream. On the contrary, they have been designed specifically for composting applications and should be treated as such. If they were to get into the recycling stream, they could weaken a product‘‘s integrity and cause other problems down the line. So remember that biodegradable and recyclable products should go into two