Scientists have begun working on this issue.
They have made it easier to evaluate how to use biodegradation rates determined in laboratory conditions to what that actually means for diverse, real world marine conditions.
The goal of a recent study conducted by a team at the University of Queensland was to determine the rate of biodegradation of PHA in the natural marine environment and apply this to the lifetime estimation of various PHA products.
According to the study authors, “this provides the clarification required as to what ‘marine biodegradation of PHA’ means in practicality and allows the risks and benefits of using PHA to be transparently discussed.”

Source: “The rate of biodegradation of PHA plastics in the marine environment: A Meta-Study”, Dilkes-Hoffman,et al, The University of Queensland, Marine Pollution Bulletin 142 (2019) 15-24.

Lifetime values estimated using the 95% confidence interval for the mean of the rate of biodegradation (in years) of PHA in the marine environment.

PHA Straw – 3.6 – 8.4 months

The proper way to dispose of a phade straw is through composting. A phade straw is home and industrial compostable, so it will completely biodegrade in either environment. A phade straw should NEVER be disposed of in a marine environment; however, it was designed to be consumed by bacteria, so in the unfortunate circumstance where a phade straw might end up in an ocean, it will biodegrade because it will be consumed by the bacteria in the ocean.

If phade should mistakenly end up in a marine environment, it is preferred to traditional fossil fuel based plastics and even some “natural” alternatives because:

• phade will sink and be far less likely to be ingested by, or harmful to, marine life, and
• It does not result in microplastics.

A University study conducted in 2019 testing small quantities of PHA introduced to both fish and livestock found that fish actually grew larger, faster and with better overall digestive health than marine life that did not ingest PHA.

Source: Microbial Poly-3-Hydroxybutyrate (PHB) as a Feed Additive for Fishes and Piglets, May 2019, Biotechnology Journal 14(12):1900132 DOI:10.1002/biot.201900132

• PHA is denser than water, so it is not expected to be found on the surface in a marine environment.
• PHA contains heteroatoms in its backbone and is denser than water, meaning it is more likely to sink than a conventional polymer.
• This suggests that PHA is likely to be in contact with sediment rather than be free-floating, and that its dispersal via ocean currents will be different to a conventional polymer (potentially remaining closer to its point of entrance to the ocean versus being distributed to the open ocean).
• The fact that phade sinks will generally help speed the process of biodegradation.
• Contact with sediment plays a significant role in influencing rates of biodegradation.
• Biodegradation with sediment contact is faster than just in water. Sediment, and in particular deeper sediment layers, are suggested to host a larger consortium of microorganisms and will have low dissolved oxygen concentrations.
• Furthermore, if PHA remains close to shore it would likely be exposed to higher temperatures and more active bacterial populations.

Source: “The rate of biodegradation of PHA plastics in the marine environment: A Meta-Study”, Dilkes-Hoffman,et al, The University of Queensland, Marine Pollution Bulletin 142 (2019) 15-24.

• Not only are PHA based products far more biodegradable than other biopolymers, in some environments, they are also more biodegradable than some of the non-plastic alternative products that are allowed under the straw bans that favor so-called “natural” products.
• In one study, PHA experienced significant disintegration in a simulated marine environment but sugar cane lids, among other products, did not exhibit disintegration in the marine environment.
• Other “natural” alternatives, such as bamboo, are designed to be reusable and will not break down in a marine environment.
• Paper straws are often chemically treated (coated with wax or other materials), or made with adhesives, which impact their biodegradability.

Sources: “Biodegradation of Biodegradable and Compostable Plastics under Industrial Compost, Marine and Anaerobic Digestion.” Greene, J., California State University, Ecology, Pollution and Environmental Science Open Access (2018). “Banning Plastic Straws: The Beginning of the War Against Plastics .“ Mosquera, M.R.. Environmental and Earth Journal (2019).

Microplastics in our oceans and our food chain are a reason for all of us to be concerned. However, marine biodegradable PHA based products, such as our phade straw, do not result in microplastics.

• When synthetic (traditional fossil fuel based) non-biodegradable plastics are littered in the ocean or on land, they break down and result in microplastics.
• These materials break into smaller and smaller pieces until finally only tiny pieces of plastic (less than 5mm long) remain – these are “microplastics.”
• In this context, “break down” simply means breaking apart.
• The “breaking apart” of a product is not the same as the “biodegradation” of a product.
• Biodegradation is a multi-step process in which microorganisms use a material as a source of carbon and energy. It is a biological process that consumes the entire material and results only in CO2, water and biomass (or methane if conditions are anaerobic).