We came across this post on a Singapore-focused subreddit with the title ‘dont (sic) show this to the anti weed people’:

The post claims to show the show the biodegradation process of a bottle made from cannabis plastic, with the bottle having virtually entirely decomposed within 80 days. In addition, a caption claims that ‘cannabis plastics are non-toxic and biodegradable’.

Given Singapore’s hardline stance against cannabis, the post also serves as implied criticism of the Singapore authorities’ outright ban of cannabis, hemp and derived products, regardless of their green credentials.

Cannabis plastic is made from hemp, which is derived from a variant of the Cannabis sativa plant and sometimes grown for industrial or medicinal use. The hemp variant of the plant typically has a lower concentration of the psychoactive component THC (tetrahydrocannabinol), which may mitigate the psychoactive effects associated with the cannabis drug derived from other variants of the plant.

Hemp has emerged as a prospective source of biomass for bioplastics primarily due to the 2018 US Farm Bill which made agricultural production of hemp legal by removing its designation as a drug similar to marijuana in the country. It is one use being considered for the waste byproduct of hemp after the plant had been processed for medicinal or other products.

With the industry still in its nascent stages, several companies involved in the production of cannabis products, including cannabis plastic, have sought to emphasise its green credentials.

One image, many versions

To investigate the details in the post, we did a reverse image search of it and found that it has been posted as a reference image for biodegradable hemp plastic multiple times over the last few years.

Some examples of other sites that used this image include companies in the packaging/waste industry such as an Indonesian waste management company, as well as companies operating in the recently liberalised hemp cannabis product space. More recently, in October 2021, it was used as a reference image in a European Union webpage which sought public feedback on biobased, biodegradable and compostable plastics.

What was noticeable was that there were multiple versions of the image used on the various sites with some featuring different image sections showing different stages of the bottle’s decomposition.

Different version of image as featured on sensiseeds.com

However, we were unable to track the image to its origin. The most authoritative source that used the image, the European Union webpage, chose not to include the details on the timeline for the biodegradation of the bottle. It is therefore unclear as to whether the complete biodegradation of the bottle within 80 days is accurate.

Grass not always greener

To investigate the green credentials of hemp plastics, we did some additional research into the topic. While hemp fibres, which are naturally occurring, are indeed biodegradable and non-toxic, we found that this was not always the case with bioplastics.

A study in 2020 found that most bioplastics contained just as many toxic chemicals as regular fossil-fuel plastics. One reason for this, as explained in an article in the Inside Packaging trade magazine, is that in hemp-based bioplastics, hemp fibres are often blended with other thermoplastics, which may also include fossil-fuel plastics.

Moreover, as this New Zealand Parliamentary report elaborates, biodegradable plastics require specific conditions in terms of heat, air, moisture and microbial activity in order to break down. This makes it favourable for biodegradable products to be sent to specialised waste management facilities to be treated, but such infrastructure is not always available.

If biodegradable plastics end up in landfills with the majority of other forms of waste around the world, they are likely to take much longer to biodegrade as landfills are not designed to promote biodegradation. In addition, biodegradable plastics also release greenhouse gases such as methane when they break down in landfills.

For these reasons, some transparency-focused hemp plastic manufacturers such as California-based Sana Packaging choose not to use the terms ‘biodegradable’ or ‘compostable’ to describe their products as they find them to be misleading, even if the terms are technically accurate.

Better than the alternatives

This is not to say that hemp plastic does not have its benefits. As the Inside Packaging article explains, hemp has an advantage over other bioplastic crops such as corn due to the hemp plant growing faster, requiring less water, as well as protecting the soil from sunlight and erosion. It also absorbs large quantities of carbon dioxide from the atmosphere and can create high cellulose contents that are essential for bioplastics.

The article notes that bioplastics are often non-recyclable and that commercial composting is still a fledgling industry, making the sustainability argument for hemp plastic somewhat inconclusive. It concludes by asserting that even if the environmental credentials of hemp are uncertain, the primary benefit of plant-based plastics is the reduction in the use of plastics itself.

As such, the claims in the post are partially true but potentially misleading and require context.