Biodegradation
A standard for biodegradability used by the European Union is that greater than 90% of the original material must be converted into CO2, water and minerals by biological processes within 6 months.
[12] It's important to note factors that affect biodegradation rates during product testing to ensure that the results produced are accurate and reliable.
Several materials will test as being biodegradable under optimal conditions in a lab for approval but these results may not reflect real world outcomes where factors are more variable.
The development and use of accurate standard test methods can help ensure that all plastics that are being produced and commercialized will actually biodegrade in natural environments.
[16] The term Biodegradable Plastics refers to materials that maintain their mechanical strength during practical use but break down into low-weight compounds and non-toxic byproducts after their use.
Starch-based plastics will degrade within two to four months in a home compost bin, while polylactic acid is largely undecomposed, requiring higher temperatures.
Oxo-biodegradation is defined by CEN (the European Standards Organisation) as "degradation resulting from oxidative and cell-mediated phenomena, either simultaneously or successively."
[18] The Clean Technology Group is exploiting the use of supercritical carbon dioxide, which under high pressure at room temperature is a solvent that can use biodegradable plastics to make polymer drug coatings.
The coating is designed for controlled release over a period of time, reducing the number of injections required and maximizing the therapeutic benefit.
Professor Steve Howdle states that biodegradable polymers are particularly attractive for use in drug delivery, as once introduced into the body they require no retrieval or further manipulation and are degraded into soluble, non-toxic by-products.
Biodegradable material is capable of decomposing without an oxygen source (anaerobically) into carbon dioxide, water, and biomass, but the timeline is not very specifically defined.
[37] Additionally, the end product of composting not only returns to its previous state, but also generates and adds beneficial microorganisms to the soil called humus.
Commercial composting is capable of breaking down more complex plant-based products, such as corn-based plastics and larger pieces of material, like tree branches.
The third and final study reviews European standardization of biodegradable and compostable material in the packaging industry, again using the terms separately.
[43] The distinction between these terms is crucial because waste management confusion leads to improper disposal of materials by people on a daily basis.
Slow-degrading chemicals, like polychlorinated biphenyls (PCBs), nonylphenol (NP), and pesticides also found in plastics, can release into environments and subsequently also be ingested by wildlife.
[46] These chemicals also play a role in human health, as consumption of tainted food (in processes called biomagnification and bioaccumulation) has been linked to issues such as cancers,[47] neurological dysfunction,[48] and hormonal changes.
A well-known example of biomagnification impacting health in recent times is the increased exposure to dangerously high levels of mercury in fish, which can affect sex hormones in humans.
[49] In efforts to remediate the damages done by slow-degrading plastics, detergents, metals, and other pollutants created by humans, economic costs have become a concern.
[50] Researchers at the World Trade Institute estimate that cleanup initiatives' cost (specifically in ocean ecosystems) has hit close to thirteen billion dollars a year.
[51] The main concern stems from marine environments, with the biggest cleanup efforts centering around garbage patches in the ocean.
While the patch contains more obvious examples of litter (plastic bottles, cans, and bags), tiny microplastics are nearly impossible to clean up.
[52] National Geographic reports that even more non-biodegradable materials are finding their way into vulnerable environments – nearly thirty-eight million pieces a year.
[55] Similarly, coastal communities which rely heavily on ecotourism lose revenue thanks to a buildup of pollution, as their beaches or shores are no longer desirable to travelers.
The World Trade Institute also notes that the communities who often feel most of the effects of poor biodegradation are poorer countries without the means to pay for their cleanup.
