Tag Archives: microplastics agriculture

How Microplastics Enter Plants

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Plastic production is increasing sharply. This has raised concerns about the effects of microplastics (typically defined as plastic particles smaller than 5 millimetres in diameter) and nanoplastics (smaller plastic particles that are less than 1,000 nanometres in diameter) on human health. These concerns are partly influenced by alarming findings of the presence of microplastics in various human tissues, including the brain and placenta.

Most attention is focused on soil and water as common sources of plastics that enter the food chain. However, writing in Nature, Li et al. provide strong evidence supporting the air as being a major route for plastics to enter plants. Plants can absorb plastic particles directly from the air. Particles in the air can enter leaves through various pathways, such as through structures on the leaf surface called the stomata and through the cuticle. Stomata are small openings made of cells, and the cuticle is a membrane, covered in insoluble wax, that is well suited for absorbing microplastics…

Microplastics can also travel to and enter the plant’s water- and nutrient-transporting system (called the vascular bundle) and from there reach other tissues… Given that leaves are a key part of the food chain, microplastic particles that accumulate here can easily pass to herbivores and crop leaves, both of which can be directly consumed by humans.

Excerpt from Willie Peijnenburg, Plant Leaves Absorb Microplastics—And They End Up in Our Food, Scientific American, Apr. 18, 2025

What is the Difference between Recycling and Fake Recycling?

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Chemical companies, oil-and-gas incumbents and startups around the world are touting plans for new recycling facilities, promising to turn old bottles and bags into usable material. But policymakers are questioning whether some of these methods, broadly termed chemical or advanced recycling, should be considered recycling at all.

In 2024, Eastman Chemical began processing plastic at a new plant in Kingsport, Tenn., that it calls the largest material-to-material molecular recycling facility in the world. The company uses a chemical procedure called methanolysis to break down hard-to-recycle plastics and turn them into “virgin quality” polyesters. When operating at capacity, the facility will process 110,000 tons of plastic waste a year, the equivalent of 11 billion water bottles a year, said Mark Costa, Eastman’s chief executive. 
In July 2024, Australian company Samsara Eco announced a $65 million funding round that attracted investment from Singapore’s state-investment company Temasek and apparel company Lululemon, among others. Using a process it calls enzymatic recycling, it aims to recycle 1.5 million tons of plastic a year by 2030. 

Yet in June 2024, during last-minute negotiations on a New York state packaging bill that would have forced companies to meet ambitious recycling standards and reduce their packaging waste by 30%, state legislators agreed that technologies like Eastman’s or Samsara Eco’s would not initially be considered “recycling.”   “We had a serious concern about the pseudo solution pushed by the industry called chemical recycling,” said Judith Enck, a former Environmental Protection Agency official and founder of Beyond Plastics, an advocacy group that supported the bill. In a report published last October, Beyond Plastics raised doubts about advanced recycling plants’ yield, emissions, byproducts and energy use. The group has argued that advanced recycling amounts to little more than a marketing tactic deployed to distract decision makers from proven waste-reduction methods, like using less packaging… 

A recent ProPublica investigation found that the dominant advanced recycling technique, pyrolysis, yields 15% to 20% usable plastic materials. The rest turns into fuel and other chemicals. Traditional mechanical recycling yields 55% to 85% new plastic…

Excerpts from Claire Brown, A Fight Over the Future of Recycling Brews as Plastics Legislation Gains Traction, WSJ, July 2, 2024

Plastics, Nanoplastics and Heart Attacks

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A Landmark treaty on plastic pollution scheduled to be adopted by the end of 2024  must put scientific evidence front and center. In the run-up to the final negotiations, researchers have been publishing more reports, data sets and models about plastics than ever before….Researchers have also organized groups, such as the Scientists’ Coalition for an Effective Plastics Treaty


The treaty was originally conceived as a mechanism to end plastic pollution, which is sometimes taken to mean driving the amount of ‘mismanaged waste’ to zero by 2040. Mismanaged waste is plastic that isn’t recycled or disposed of in a well-managed landfill or incinerator, but rather ends up loose in the environment or burned in an open pit. Annual production of plastics has grown exponentially, from about 2 million tonnes in 1950 to 460 million tonnes in 2019 (current levels are on track to triple by 2060). Mismanaged waste is hard to measure–estimates put it at 74 million tonnes each year., expect to reach, by 2050, 122 million tonnes per year, under business-as-usual projections. Unless policies change, the peak of mismanaged plastic waste “is nowhere yet in sight”, he says.

A new report from environmental-policy researcher Nihan Karali and her colleagues at Lawrence Berkeley National Laboratory in California concludes that plastic production generated the equivalent of 2.24 gigatonnes of carbon dioxide in 2019, mainly from the energy-intensive process of extracting and refining the fossil fuels used to generate the petrochemicals that make up most virgin plastic.


An individual plastic typically contains hundreds of chemicals — many of which are toxic and can leach out — that make the material more flexible, water repellent, flame retardant or resistant to ultraviolet light. Last month, researchers released a report listing 16,000 chemicals associated with plastics, of which they found at least to be 4,200 hazardous… A study published in February 2024 of some 250 people undergoing surgery showed that nano- and microplastics in carotid-artery blockages were linked to increased risk of heart attacks, strokes and death.

Excerpt from Nicola Jones, Plastic pollution: three numbers that support a crackdown,  Nature, April 2024

What Do We Know about the Plastic Chemicals that Leach into Food?

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Countries are currently negotiating a global plastics treaty to end plastic pollution. It is essential that the treaty addresses plastic chemicals because all plastics, from food packaging to car tires, contain thousands of chemicals that can leach into foodstuffs, homes, and the environment. Since many of these chemicals are hazardous, they can damage human health and the environment.

Plastic chemicals comprise all chemicals in plastics, including additives, processing aids, and impurities. A previous report by the United Nations Environment Program (UNEP) and other international institutions identified 13,000 plastic chemicals. The new PlastChem Report shows that there are more plastic chemicals than previously known, with over 16,000 chemicals included in the new PlastChem database that accompanies the report.
Further key findings of the report include:
• At least 4,200 plastic chemicals (or 26%) are of concern because of their high hazards to human health and the environment,
• More than 400 chemicals of concern can be present in each major plastic type, including in food packaging, and all tested plastics leached hazardous chemicals,

The report recommends : Increased transparency on the chemical composition of plastics is essential for closing data gaps, promoting a comprehensive management of plastic chemicals, and creating accountability across plastic value chains. A unified reporting, disclosure of the chemical composition of plastic materials and products as well as a “no data, no market” approach are recommended to ensure that essential
information about plastic chemicals becomes publicly available.

Excerpts from New Report Identifies Plastic Chemicals of Concern and Highlights
Approaches Towards Safer Plastics, Press Release of PlastChem, Mar. 14, 2024

The Curse of Nano-Plastics: Plastics in the Placenta

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A flurry of recent studies has found that microplastics are present in virtually everything we consume, from bottled water to meat and plant-based food. Now, University of New Mexico Health Sciences researchers have used a new analytical tool to measure the microplastics present in human placentas. In a study published February 17 in the journal Toxicological Sciences, a team led by Matthew Campen, reported finding microplastics in all 62 of the placenta samples tested, with concentrations ranging from 6.5 to 790 micrograms per gram of tissue.

Although those numbers may seem small (a microgram is a millionth of a gram), Campen is worried about the health effects of a steadily rising volume of microplastics in the environment. For toxicologists, “dose makes the poison,” he said. “If the dose keeps going up, we start to worry. If we’re seeing effects on placentas, then all mammalian life on this planet could be impacted. That’s not good.”…The researchers found the most prevalent polymer in placental tissue was polyethylene, which is used to make plastic bags and bottles. It accounted for 54% of the total plastics. Polyvinyl chloride (better known as PVC) and nylon each represented about 10% of the total, with the remainder consisting of nine other polymers…

Plastic use worldwide has grown exponentially since the early 1950s, producing a metric ton of plastic waste for every person on the planet. About a third of the plastic that has been produced is still in use, but most of the rest has been discarded or sent to landfills, where it starts to break down from exposure to ultraviolet radiation present in sunlight. “That ends up in groundwater, and sometimes it aerosolizes and ends up in our environment,” Garcia said. “We’re not only getting it from ingestion but also through inhalation as well. It not only affects us as humans, but all off our animals – chickens, livestock – and all of our plants. We’re seeing it in everything.”…The concentration of microplastics in placentas is particularly troubling, he said, because the tissue has only been growing for eight months (it starts to form about a month into a pregnancy). “Other organs of your body are accumulating over much longer periods of time.”

Excepts from Michael Haederle,  Microplastics in Every Human Placenta, Feb. 20, 2024

Save Time and Money but Destroy Soil and Oceans

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The images of swaths of garbage floating on the oceans’ surface have become a rallying call to address plastic pollution, but there is more to this challenge than meets the eye. While plastics and microplastics – items smaller than 5 mm – accumulate and impact marine environments, much of the problem is rooted in land contamination. Land-based plastic pollution, which often feeds into the oceans, is estimated to be at least four times higher than what is in the oceans, according to a study published in Global Change Biology. 

“Soil is the main source of microplastics reaching oceans through soil erosion and surface runoff,”  Plastics settle in soil through disposal in landfills, as well as through the use of plastic-sheets in agriculture or application of microplastic contaminated compost. “Direct disposal of plastics to ocean is relatively less pronounced compared to the transfer of microplastics from land. Microplastics, lighter than soil particles, such as sand, silt and clay, are easily lost to waterways,”…

“We contribute to plastic pollution through indiscriminate disposal of plastics in landfills and use of microbeads in cosmetics and microfibers in textiles. There are efforts to produce biodegradable plastics, which may provide some solution to plastic pollution, but bioplastic may not be the silver bullet to manage plastic pollution.” Commonly used biodegradable bioplastics “retain their mechanical integrity under natural conditions, potentially causing physical harm if they are ingested by marine or terrestrial animals.” “The fate of biodegradable bioplastics in natural and engineered environments could be potentially problematic. Methane is a product of biodegradation in anaerobic environments in landfills.” These bioplastics, furthermore, require high temperatures, controlled aeration and humidity to degrade completely.

Due to their small size, microplastics, especially nanoplastics resulting from the degradation of microplastic, can enter organisms’ internal organs, where they could potentially transfer contaminants attached to them. These can include persistent organic pollutants, like polychlorinated biphenyls (PCBs), as well as trace metals like mercury and lead. The plastics and pollutants that accumulate on or in them enter the food chain and can eventually be transferred to humans, causing growing food safety concerns.

The Joint FAO/IAEA Centre’s laboratories are equipped to research the presence of microplastics in food. “Techniques such as energy dispersive X-ray spectroscopy and infrared and Raman spectroscopy can be applied to screen for plastics in foods, enabling risk assessment and management,” said Andrew Cannavan, Head of the Joint Centre’s Food and Environmental Protection Section. 

Excerpt from Joanne Liou Out of Sight but not out of Mind: IAEA and FAO Launch R&D to Identify Sources, Impacts of Microplastic Pollution in Soil, IAEA Press Release, July 2, 2021