Biodegradable plastic bags are more toxic than conventional plastic bags, a new study has found.
The researchers analyzed three types of bags: a compostable bag made from plant starch, a recycled plastic bag, and a conventional plastic bag.
They exposed them to sunlight to decompose and then exposed them to fish cells.
They then also composted them and tested the toxicity of the resulting compost.
The biodegradable bags produced a ‘high level of toxicity’, damaging the fish cells, according to the authors of the Higher Council for Scientific Research (CSIC).
Researchers found a high level of toxicity in compostable plastic bags, which increases with photodegradation (the alteration of plastic material by ultraviolet light).
Cinta Porte, lead author of the study, published in the Hazardous Materials Journalstated: “We were surprised that cells exposed to conventional plastic bags did not show any trace of toxicity.”
«However, we did detect it in biodegradables, which decreased cell viability.
«Our hypothesis is that manufacturers add chemical additives to make biodegradable bags that could be especially toxic.
“In addition, recycled plastic bags also showed higher toxicity levels than conventional ones, since plastic additives would also be added to them for reuse.”
In the experiment, the aging process of the bags was simulated with ultraviolet rays (photodegradation).
The small fragments of bags left after composting and the compost resulting from the tearing of the bag were analyzed.
The study found that toxins ‘resulting in the accumulation of pollutants that can affect the environment and negatively impact the health of the population.’
The researchers analyzed three types of bags: a compostable plastic bag made from plant starch, a recycled plastic bag, and a conventional plastic bag. They exposed them to sunlight to decompose and then exposed them to fish cells.
Amparo López Rubio, co-author, states: “The toxicity observed can derive both from the additives used during processing and from the fragments of biodegradable plastics produced during composting.”
‘It is necessary to thoroughly investigate the migration and ecotoxicity of these new materials and establish a good regulatory framework, based on scientific evidence, to guarantee their safety before they reach the market.
‘We need an open and transparent interaction with companies that allows us to advance in the development of materials that, in addition to being more sustainable, are safe.’
The authors said that the specific chemical compounds added to these compostable bags could not be identified in the study, since many additives are protected by patents.
But they are likely plasticizers: compounds added to plastic to make it more flexible.
The researchers tested four different types of compostable bags: made of polybutylene adipate teraphthalate and starch, a single-use water bottle made of PET (polyethylene teraphthalate), a conventional plastic bag made of LDPE (low-density polyethylene ) and two garbage bags made of recycled polyethylene. .
Compostable bags tend to be advertised as “eco-friendly” with slogans such as “save the planet”, but their green credentials may be overstated.
Tiantian Wang, first author of the study, said: “Although each manufacturer may add different additives to their products, we have observed that all biodegradable bags have similar levels of toxicity.”
The researchers conclude: ‘This work demonstrates the elevated toxicity of recycled plastics, compostable plastics and semi-degraded compostable plastics resulting from partial disintegration, compared to conventional virgin plastic extracts.
“These findings underscore the need for additional research efforts and implementation of regulatory measures prior to the release of mature compost into the environment.”
Last year, researchers in Manchester reported that compostable bags have almost twice the impact on global warming as traditional plastic and four times more than paper.
While compostable bags can only be properly degraded at high temperatures in special processing plants, they are mostly disposed of as general waste before being sent to landfill where they release methane, experts said.
Eight million tons of plastic end up in the ocean every year
Of the 30 billion plastic bottles used by UK households each year, only 57 per cent are currently recycled.
Half of them end up in landfills and half of all plastic bottles that are recycled are wasted.
Around 700,000 plastic bottles end up in the trash every day.
This is largely due to the plastic wrappers that surround the bottles and which are not recyclable.
Bottles are a major contributor to the growing amount of plastic waste in the world’s oceans.
Researchers warned that eight million tonnes of plastic currently end up in the ocean each year, the equivalent of one truck every minute.
The amount of plastic trash in the world’s oceans will surpass that of fish by 2050 unless the world takes drastic measures to recycle it even more, a report published in 2016 revealed.
At the current rate, this will worsen to four trucks per minute by 2050 and will overtake native life to become the largest mass inhabiting the oceans.
An overwhelming 95 per cent of plastic packaging (worth between £65bn and £92bn) is lost to the economy after a single use, according to the Ellen MacArthur Foundation report.
And available research estimates that there are more than 150 million tons of plastics in the ocean today.
Plastic pollution is ruining the world’s ecosystems, both marine and terrestrial. It litters coastlines, traps animals, and suffocates entire animal populations.
Every year so much plastic is dumped into the sea that five plastic bags would be filled for every meter of coastline on the planet, scientists have warned.
More than half of the plastic waste that ends up in the oceans comes from just five countries: China, Indonesia, the Philippines, Vietnam and Sri Lanka.
The only Western industrialized country on the list of top 20 plastic polluters is the United States, at number 20.
The United States and Europe are not managing collected waste poorly, so the plastic trash coming from those countries is due to trash, the researchers said.
While China is responsible for 2.4 million tons of plastic that reach the oceans, almost 28 percent of the world’s total, the United States contributes only 77,000 tons, less than one percent, according to the study published in the journal Science. . .