Plastics contain and leach hazardous chemicals, including endocrine-disrupting chemicals (EDCs) that threaten human health. An authoritative new report, Plastics, EDCs, & Health, from the Endocrine Society and the IPEN (International Pollutants Elimination Network), presents a summary of international research on the health impacts of EDCs and describes the alarming health effects of widespread contamination from EDCs in plastics.
Plastic in Galapagos seawater, beaches and animals
At the worst "hotspots" - including a beach used by the rare "Godzilla" marine iguana - more than 400 plastic particles were found per square metre of beach.
Plastic was also found inside more than half of the marine invertebrates (such as barnacles and urchins) studied, and on the seabed.
The findings suggest most plastic pollution in Galapagos - a world-famous biodiversity haven - arrives on ocean currents.
The study also identifies Galapagos marine vertebrates most at risk from swallowing plastic or getting entangled - including scalloped hammerheads, whale sharks, sea lions and sea turtles.
"The pristine image of Galapagos might give the impression that the islands are somehow protected from plastic pollution, but our study clearly shows that's not the case," said Dr Ceri Lewis, of Exeter's Global Systems Institute. "The highest levels of plastic we found were on east-facing beaches, which are exposed to pollution carried across the eastern Pacific on the Humboldt Current.
"These east-facing beaches include Punta Pitt, a highly polluted site that is home to Godzilla marine iguanas which - like so much Galapagos wildlife - are found nowhere else in the world.
"There are less than 500 Godzilla marine iguanas in existence, and it's concerning that they are living alongside this high level of plastic pollution." Speaking about microplastic particles found inside marine invertebrates, lead author Dr Jen Jones, of GCT, said: "These animals are a crucial part of food webs that support the larger species that famously live on and around the Galapagos Islands.
"The potential health effects of plastic ingestion on marine animals are largely unknown, and more research is needed."
Source: University of Exeter
Can Faster degrading plastic promise cleaner seas?
“We have created a new plastic that has the mechanical properties required by commercial fishing gear. If it eventually gets lost in the aquatic environment, this material can degrade on a realistic time scale,” said lead researcher Bryce Lipinski, a doctoral candidate in the laboratory of Geoff Coates, professor of chemistry and chemical biology at Cornell University. “This material could reduce persistent plastic accumulation in the environment.”
Commercial fishing contributes to about half of all floating plastic waste that ends up in the oceans, Lipinski said. Fishing nets and ropes are primarily made from three kinds of polymers: isotactic polypropylene, high-density polyethylene, and nylon-6,6, none of which readily degrade.
“While research of degradable plastics has received much attention in recent years,” he said, “obtaining a material with the mechanical strength comparable to commercial plastic remains a difficult challenge.”
Coates and his research team have spent the past 15 years developing this plastic called isotactic polypropylene oxide, or iPPO. While its original discovery was in 1949, the mechanical strength and photodegradation of this material was unknown before this recent work. The high isotacticity (enchainment regularity) and polymer chain length of their material makes it distinct from its historic predecessor and provides its mechanical strength.
Lipinski noted that while iPPO is stable in ordinary use, it eventually breaks down when exposed to UV light. The change in the plastic’s composition is evident in the laboratory, but “visually, it may not appear to have changed much during the process,” he said.
The rate of degradation is light intensity-dependent, but under their laboratory conditions, he said, the polymer chain lengths degraded to a quarter of their original length after 30 days of exposure.
Ultimately, Lipinski and other scientists want to leave no trace of the polymer in the environment. He notes there is literature precedent for the biodegradation of small chains of iPPO which could effectively make it disappear, but ongoing efforts aim to prove this.
Source: Cornell University
How Microplastics Impact in Land and Sea?
“We found a lot of legacy plastic pollution everywhere we looked; it travels in the atmosphere and it deposits all over the world,” Brahney said. “This plastic is not new from this year. It’s from what we’ve already dumped into the environment over several decades.”
Results from their study, “Constraining the Atmospheric Limb of the Plastic Cycle,” suggest that atmospheric microplastics in the western United States are primarily derived from secondary re-emission sources.
From December 2017 to January 2019, researchers collected atmospheric microplastic data from the western U.S., where 84% of microscopic shards came from road dust – cars and trucks agitating the plastic. About 11% entered the atmosphere from sea spray, and 5% was derived from agricultural soil dust.
As large clusters of refuse plastic merge into pods of plastic islands on the oceans, the oceanic action grinds them into mere micron-size particles, where the winds ferry them into the atmosphere – for as little as an hour, or as long as six days.
In the process of conducting other scientific research, Brahney had discovered bits of microplastic everywhere she went. Mahowald developed a microplastic transport model to determine the tiny plastics’ origins.
“We did the modeling to find out the sources, not knowing what the sources might be,” said Mahowald, a fellow at the Cornell Atkinson Center for Sustainability. “It’s amazing that this much plastic is in the atmosphere at that level, and unfortunately accumulating in the oceans and on land and just recirculating and moving everywhere, including remote places.
“Using our best estimate of plastic sources and modeled transport pathways, most continents are net importers of microplastics from the marine environment,” she said. “This underscores the cumulative role of legacy pollution in the atmospheric burden of plastic.”
Microplastics are landing and accumulating in all sorts of places, Mahowald said. “It’s not just in the cities or the oceans,” she said. “We’re finding microplastics in national parks.”
Source: Cornell University
Designing plastic to break down in the ocean is possible, but is it practical?
In a study, the researchers used a machine learning algorithm to classify more than 110 types of plastics, including commercial and lab-made varieties, to better understand how they might degrade in the ocean, said Robert Mathers, professor of chemistry.
“One of the things we were interested in finding out is what is going to happen to the large quantity of plastic that is in the ocean,” said Mathers. “This study took a wide range of physical property data, in combination with a metric that would quantify the composition of molecular structures and used that to try to figure out the most important aspects of plastic degradation in the ocean.”
According to the Ocean Conservancy, there are more than 150 million metric tons of plastic in the ocean, with 8 million metric tons more entering the ocean each year. The researchers, who released their findings in a recent issue of Nature Communications, said a number of factors in the ocean can help break down this plastic, including ultraviolet radiation from the sun, wind, waves, seawater, water temperature and bacteria. They found that certain types of plastics did break down quicker than others when subjected to these conditions.
While knowing the molecular structure of the more susceptible plastics could give engineers a chance to develop plastics with less environmental impact, Mathers said that economics of producing those plastics at scale would still be an issue.
“Others have suggested the possibility of putting a weak link in the molecular structure of a plastic that could accelerate the degradation of that strand of atoms,” said Mathers. “Now, that is a great idea, but, right now, it may not be an economically feasible option. It’s just hard to economically compete with polyethylene and polypropylene, which are the most-used plastics in the world. So, we probably want to keep focusing on recycling because that offers the most immediate help.”
The team approached the problem of plastic in the ocean by gathering as much data on the molecular structure of the various plastics and information on how these plastics behave in sea water, both in the field and in laboratory conditions.
“From the literature, we were able to get information about the physical properties of the plastic that are in the ocean, for instance, molecular weights, the glass transition temperature, the amount of crystallinity, but considering the molecular composition was an overlooked opportunity. In this regard, we figured out how to translate molecular structure into a metric that we called hydrophobicity, which is how much is the material likely to absorb water or want to be in contact with water,” said Mathers.
There are so many types of plastics and so many experimental conditions, machine learning became instrumental in helping the researchers both sort through the large amount of data, as well as classify that information.
“We started with basic data analysis to explore and sort through the data, then we moved on to predictive machine learning to help us elucidate patterns and trends,” said Cuiffi. “The machine learning helped us to determine key relationships and to develop rules for predicting plastic behavior.”
After experimenting with a few different models of machine learning, the researchers opted for a decision tree, machine learning approach. Members of the Institute for Computational and Data Sciences and Materials Research Institute helped the team by providing access to machine learning tools.
“We tried regression models at first, but the inconsistencies in experimental conditions across our dataset made that difficult,” said Cuiffi. “Classification learners worked much better, and decision trees, specifically, were helpful because they provided visibility into the learned rules, which provided insights to chemical and physical behavior.”
Where does the information on the lifetime expectancy of plastic goods come from, and how reliable is it?
It turns out, getting a true read on how long it takes for plastic to break down in the environment is tricky business, says Collin Ward, a marine chemist at Woods Hole Oceanographic Institution and member of the its Microplastics Catalyst Program, a long-term research program on plastics in the ocean.
“Plastics are everywhere, but one of the most pressing questions is how long plastics last in the environment,” he says. “The environmental and human health risks associated with something that lasts one year in the environment, versus the same thing that lasts 500 years, are completely different.”
Knowing the fate of plastics may be tricky, but it’s critical. Consumers need the information to make good, sustainable decisions; scientists need it to understand the fate of plastics in the environment and assess associated health risks; and legislators need it to make well-informed decisions around plastic bans.
The long-standing mystery around the life expectancy of plastic goods has prompted a new study from Woods Hole Oceanographic Institution looking at how the lifetime estimates of straws, cups, bags, and other products are being communicated to the public via infographics. Ward, the lead author of a new paper published in the journal, along with WHOI marine chemist Chris Reddy, analyzed nearly 60 individual infographics and documents from a variety of sources, including governmental agencies, non-profits, textbooks, and social media sites. To their surprise, there was little consistency in the lifetime estimates numbers reported for many everyday products, like plastic bags, among the materials.
“The estimates being reported to the general public and legislators vary widely,” says Ward. “In some cases, they vary from one year to hundreds of years to forever.”
On the other end of the spectrum, certain lifetime estimates seemed far too similar among the infographics. Of particular interest, Ward notes, were the estimates for how long fishing line lasts in the ocean. He says that all 37 infographics that included a lifetime for fishing line reported 600 years.
“Every single one said 600 years, it was incredible” he says. “I’m being a little tongue-in-cheek here, but we’re all more likely to win the lottery than 37 independent science studies arriving at the same answer of 600 years for fishing line to degrade in the environment.”
In reality, these estimates didn’t stem from actual scientific studies. Ward said he did a lot of digging to find peer-reviewed literature that was either funded, or conducted, by the agencies putting the information out there and couldn’t find a single instance where the estimates originated from a scientific study. He and Reddy believe that while the information was likely well intentioned, the lack of traceable and documented science behind it was a red flag.
“The reality is that what the public and legislators know about the environmental persistence of plastic goods is often not based on solid science, despite the need for reliable information to form the foundation for a great many decisions, large and small,” the scientists state in the paper.
In one of their own peer-reviewed studies on the life expectancy of plastics published last year, Ward and his team found that polystyrene, one of the world’s most ubiquitous plastics, may degrade in decades when exposed to sunlight, rather than thousands of years as previously thought. The discovery was made, in part, by working with researchers at WHOI’s National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility to track the degradation of the plastic into gas and water phases, and with the aid of a specialized weathering chamber in Ward’s lab. The chamber tested how environmental factors such as sunlight and temperature influenced the chemical breakdown of polystyrene, the first type of plastic found in the coastal ocean by WHOI scientists nearly fifty years ago.
Reddy feels that one of the biggest misconceptions surrounding the fate of plastics in the environment is that they simply break down in to smaller bits that hang around forever.
“This is the narrative we see all the time in the press and social media, and it's not a complete picture,” says Reddy. “But through our own research and collaborating with others, we’ve determined that in addition to plastics breaking down into smaller fragments, they also degrade partially into different chemicals, and they break down completely into CO2.” These newly identified breakdown products no longer resemble plastic and would be otherwise missed when scientists survey the oceans for missing plastics.
Understanding the various forms of plastic degradation will be key to solving one of the enduring mysteries of plastic pollution: more than 99 percent of the plastic that should be detected in the ocean is missing.