Biodegradable plastic bags are more toxic than traditional plastic bags, a new study has found.
The researchers analyzed three types of bags – a compostable bag made from vegetable starch, a recycled plastic bag and a traditional plastic bag.
They exposed them to sunlight to make them decay, then exposed them to fish cells.
They then composted them and tested the resulting compost for toxicity.
The biodegradable bags produced a “high level of toxicity” and damaged fish cells, according to the authors from the Spanish National Research Council (CSIC).
Researchers found high levels of toxicity in compostable plastic bags, which increases with photodegradation (the change in the plastic material by ultraviolet light).
Cinta Porte, lead author of the study published in the Journal of Hazardous Materials, said: “We were surprised that cells exposed to conventional plastic bags showed no trace of toxicity.”
“However, we discovered it in biodegradable specimens, which reduced cell viability.”
“Our hypothesis is that manufacturers are adding chemical additives to create biodegradable bags that could be particularly toxic.”
“In addition, recycled plastic bags also had higher toxicity than traditional ones because plastic additives were also added for reuse.”
In the experiment, the aging process of the bags was simulated with ultraviolet rays (photodegradation).
The small bag fragments remaining after composting and the compost created when the bags decomposed were analyzed.
The study found that toxins “lead to an accumulation of pollutants that can degrade the environment and negatively impact population health.”
The researchers analyzed three types of bags: a compostable plastic bag made from vegetable starch, a recycled plastic bag and a traditional plastic bag. They exposed them to sunlight to make them decay, then exposed them to fish cells
Amparo Lopez Rubio, co-author, said: “The observed toxicity may be due to both the additives used in processing and the fragments of biodegradable plastics produced during composting.”
“It is necessary to thoroughly study the migration and ecotoxicity of these new materials and establish a good regulatory framework based on scientific evidence to ensure their safety before they enter the market.”
“We need an open and transparent interaction with companies that allows us to advance the development of materials that are not only more sustainable but also safe.”
The authors said the specific chemical compounds added to these compostable bags could not be identified in the study because many additives are protected by patents.
However, they are probably plasticizers – compounds added to plastic to make it more flexible.
The researchers tested four different types of compostable bags – made from polybutylene adipate terapthalate and starch, a disposable PET (polyethylene terapthalate) water bottle, a conventional plastic bag made from LDPE (low-density polyethylene), and two trash bags made from recycled polyethylene.
Compostable bags are often promoted as “eco-friendly” with slogans like “Save the Planet” – but their eco-friendliness may be overstated
Tiantian Wang, lead author of the study, said: “Although each manufacturer adds different additives to their products, we observed that all biodegradable bags have similar levels of toxicity.”
The researchers conclude: “This work demonstrates the increased toxicity of recycled plastics, compostable plastics and semi-decomposed compostable plastics resulting from partial decomposition, compared to new conventional plastic extracts.”
“These results highlight the need for additional research efforts and implementation of regulatory measures prior to releasing 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 as much as paper.
While compostable bags can only be properly broken down at high temperatures in special processing plants, they are usually disposed of in general waste before ending up in 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 British households each year, only 57 percent are currently recycled.
While half of it ends up in landfill, half of all recycled plastic bottles end up in the trash.
Around 700,000 plastic bottles end up in the trash every day.
This is largely due to the plastic packaging of bottles, which is not recyclable.
Bottles contribute significantly to the increasing amount of plastic waste in the world’s oceans.
Researchers warn that eight million tons of plastic are currently entering the ocean every year – that’s the equivalent of a truckload every minute.
A report published in 2016 found that the amount of plastic waste in the world’s oceans will exceed the amount of fish by 2050 unless the world takes drastic action to further recycle it.
At current rates, this will worsen to four truckloads per minute in 2050, surpassing native life and becoming the largest mass in the oceans.
According to the Ellen MacArthur Foundation report, a staggering 95 percent of plastic packaging, worth between £65 billion and £92 billion, is lost to the economy after a single use.
And available research estimates that there are more than 150 million tons of plastic in the ocean today.
Plastic pollution is ruining the world’s ecosystems, both at sea and on land. It pollutes coastlines, traps animals and suffocates entire animal populations
Scientists have warned that so much plastic is dumped into the sea every year that it would fill five carrier bags for every meter of coastline on the planet.
More than half of the plastic waste entering the oceans comes from just five countries: China, Indonesia, the Philippines, Vietnam and Sri Lanka.
The only western industrialized country on the list of the top 20 plastic polluters is the United States at number 20.
The U.S. and Europe do not mismanage their collected waste, so the plastic waste from those countries can be attributed to litter, researchers said.
While China is responsible for 2.4 million tons of plastic entering the oceans, nearly 28 percent of the global total, the United States contributes only 77,000 tons, or less than one percent, according to the study published in the journal Science.