Tag: microplastics

Categories : Environmental Effects PaediatricsTags :

Microwaving Plastic Baby Food Container Releases Billions of Plastic Nanoparticles

On By ModernMedia
Photo by Burst on Pexels

Experiments have shown that microwaving plastic baby food containers available on the shelves of US stores can release huge numbers of micrometre or smaller-sized plastic particles – in some cases, more than 2 billion nanoplastics and 4 million microplastics for every square centimetre of container.

Though the health effects of consuming micro- and nanoplastics remain unclear, the University of Nebraska-Lincoln researchers further found that three-quarters of cultured embryonic kidney cells had died after two days of being introduced to those same particles. A 2022 report from the World Health Organization recommended limiting exposure to such particles.

“It is really important to know how many micro- and nanoplastics we are taking in,” said Kazi Albab Hussain, the study’s lead author and a doctoral student in civil and environmental engineering at the University of Nebraska-Lincoln. “When we eat specific foods, we are generally informed or have an idea about their caloric content, sugar levels, other nutrients. I believe it’s equally important that we are aware of the number of plastic particles present in our food.

“Just as we understand the impact of calories and nutrients on our health, knowing the extent of plastic particle ingestion is crucial in understanding the potential harm they may cause. Many studies, including ours, are demonstrating that the toxicity of micro- and nanoplastics is highly linked to the level of exposure.”

The team embarked on its study in 2021, the same year that Hussain became a father. While prior research had investigated the release of plastic particles from baby bottles, the team realised that no studies had examined the sorts of plastic containers and pouches that Hussain found himself shopping for, and that millions of other parents regularly do, too.

Hussain and his colleagues decided to conduct experiments with two baby food containers made from polypropylene and a reusable pouch made of polyethylene, both FDA-approved plastics. In one experiment, the researchers filled the containers with either deionised water or 3% acetic acid (the latter intended to simulate dairy products, fruits, vegetables and other relatively acidic consumables) then heated them at full power for three minutes in a 1000-watt microwave. Afterward, they analysed the liquids for evidence of micro- and nanoplastics: the micro- being particles at least a micrometre in diameter, the nano- any particles smaller.

The actual number of each particle released by the microwaving depended on multiple factors, including the plastic container and the liquid within it. But based on a model that factored in particle release, body weight, and per-capita ingestion of various food and drink, the team estimated that infants drinking products with microwaved water and toddlers consuming microwaved dairy products are taking in the greatest relative concentrations of plastic. Experiments designed to simulate the refrigeration and room-temperature storage of food or drink over a six-month span also suggested that both could lead to the release of micro- and nanoplastics.

“For my baby, I was unable to completely avoid the use of plastic,” Hussain said. “But I was able to avoid those (scenarios) which were causing more of the release of micro- and nanoplastics. People also deserve to know those, and they should choose wisely.”

With the help of Svetlana Romanova from the University of Nebraska Medical Center, the team then cultured and exposed embryonic kidney cells to the actual plastic particles released from the containers – a first, as far as Hussain can tell. Rather than introduce just the number of particles released by one container, the researchers instead exposed the cells to particle concentrations that infants and toddlers might accumulate over days or from multiple sources.

After two days, just 23% of kidney cells exposed to the highest concentrations had managed to survive – a much higher mortality rate than that observed in earlier studies of micro- and nanoplastic toxicity. The team suspects that kidney cells might be more susceptible to the particles than are other cell types examined in prior research. But those earlier studies also tended to examine the effects of larger polypropylene particles, some of them potentially too large to penetrate cells. If so, the Hussain-led study could prove especially sobering: Regardless of its experimental conditions, the Husker team found that polypropylene containers and polyethylene pouches generally release about 1000 times more nanoplastics than microplastics.

The question of cell infiltration is just one among many that will require answers, Hussain said, before determining the true risks of consuming micro- and nanoplastics. But to the extent that they do pose a health threat – and that plastics remain a go-to for baby food storage – parents would have a vested interest in seeing that the companies manufacturing plastic containers seek out viable alternatives, he said.

“We need to find the polymers which release fewer (particles),” Hussain said. “Probably, researchers will be able to develop plastics that do not release any micro- or nanoplastics – or, if they do, the release would be negligible.

“I am hopeful that a day will come when these products display labels that read ‘microplastics-free’ or ‘nanoplastics-free.'”

Source: University of Nebraska-Lincoln

Categories : Environmental Effects Medical IndustryTags :

Can Fungi Transform Plastic Waste into Drug Components?

On By ModernMedia
Photo by Louise Reed on Unsplash

Research on fungi has helped transform tough-to-recycle plastic waste from the Pacific Ocean into key components for making pharmaceuticals, using a genetically altered version of an everyday soil fungus, Aspergillus nidulans. The researchers described their chemical-biological approach in Angewandte Chemie, a journal of the German Chemical Society.

“What we’ve done in this paper is to first digest polyethylenes using oxygen and some metal catalysts – things that are not particularly harmful or expensive – and this breaks the plastics into diacids,” said co-author Berl Oakley, professor at the University of Kansas.

Next, long chains of carbon atoms resulting from the decomposed plastics were fed to genetically modified Aspergillus fungi. The fungi, as designed, metabolised them into an array of pharmacologically active compounds, including commercially viable yields of asperbenzaldehyde, citreoviridin and mutilin.

Unlike previous approaches, Oakley said the fungi digested the plastic products quickly, like “fast food.”

“The thing that’s different about this approach is it’s two things – it’s chemical, and it’s fungal,” he said. “But it’s also relatively fast. With a lot of these attempts, the fungus can digest the material, but it takes months because the plastics are so hard to break down. But this breaks the plastics down fast. Within a week you can have the final product.”

The KU researcher added the new approach was “bizarrely” efficient.

“Of the mass of diacids that goes into the culture, 42% comes back as the final compound,” he said. “If our technique was a car, it would be doing 200 miles per hour, getting 60 miles per gallon, and would run on reclaimed cooking oil.”

Previously, Oakley has worked with corresponding author Clay Wang of the University of Southern California to produce about a hundred secondary metabolites of fungi for a variety of purposes.

“It turns out that fungi make a lot of chemical compounds, and they are useful to the fungus in that they inhibit the growth of other organisms – penicillin is the canonical example,” Oakley said. “These compounds aren’t required for the growth of the organism, but they help either protect it from, or compete with, other organisms.”

Oakley’s lab at KU has honed gene-targeting procedures to change the expression of genes in Aspergillus nidulans and other fungi, producing new compounds.

The researchers focused on developing secondary metabolites to digest polyethylene plastics because those plastics are so hard to recycle. For this project, they harvested polyethylenes from the Pacific Ocean that had collected in Catalina Harbor on Santa Catalina Island, California.

“There’ve been a lot of attempts to recycle plastic, and some of it is recycled,” Oakley said. “A lot of it is basically melted and spun into fabric and goes into various other plastic things. Polyethylenes are not recycled so much, even though they’re a major plastic.”

The KU investigator said the long-term goal of the research is to develop procedures to break down all plastics into products that can be used as food by fungi, eliminating the need to sort them during recycling.

“I think everybody knows that plastics are a problem,” Oakley said. “They’re accumulating in our environment. There’s a big area in the North Pacific where they tend to accumulate. But also you see plastic bags blowing around – they’re in the rivers and stuck in the trees. The squirrels around my house have even learned to line their nest with plastic bags. One thing that’s needed is to somehow get rid of the plastic economically, and if one can make something useful from it at a reasonable price, then that makes it more economically viable.”

Source: University of Kansas