Earth's threshold for chemical pollution breached: study

The release of chemicals and pollutants has accelerated to a point that a 'planetary boundary' has been crossed, threatening Earth and humanity, according to a new study.

marine litter in latvia
A crunched-up plastic bottle washed up on the shores of Latvia. Image: Bo Eide, CC BY-NC 2.0.

Thousands of human-made chemicals and synthetic pollutants are being released, with new ones being constantly produced every day. Scientists now say that we have crossed a critical threshold that threatens the Earth and poses a clear threat to humanity.

There are about 350,000 different types of artificial chemicals currently in the global market, from plastics to pesticides, to industrial chemicals such as flame retardants and insulators. While research shows that many of these chemicals have deleterious impacts on the natural world and human health, most of them have not been evaluated, and their interactions with and impacts on Earth are unknown. 

“The knowledge gaps are massive and we do not have the tools to understand all of what is being produced or released, or effects they have,” Bethanie Carney Almroth, an eco-toxicologist and microplastics researcher from the University of Gothenburg in Sweden, told Mongabay. “We just don not know. So we try to look at what we do know and add up all these little puzzle pieces to get a big picture.”

As scientists endeavor to identify and understand the impacts of chemicals and other artificial substances — referred to as “novel entities” — industries are pumping them out at a staggering rate. The global production of chemicals has increased fifty-fold since 1950, and this is expected to triple by 2050, according to a report published by the European Environment Agency. While some novel entities are regulated by governmental bodies and international agreements, many can be produced without any restrictions or controls.

The mismatch between the rapid rate at which novel entities are being produced, compared to the snail’s pace at which governments assess risk and monitor impacts — leaving society largely flying blind as to chemical threats — was what prompted Carney Almroth and colleagues to make their argument in a new paper published in Science and Technology, that we have breached the “planetary boundary” for novel entities, endangering the stability of the planet we call home.

Quantifying the novel entities boundary

The concept of planetary boundaries was first proposed by a team of international scientists in 2009 to articulate key natural processes that, when kept in balance, support biodiversity; but when disrupted beyond a certain threshold, can destabilise and even destroy the Earth’s ability to function and support life. 

Nine boundaries have been identified: climate change, biosphere integrity, ocean acidification, ozone depletion, atmospheric aerosol pollution, freshwater use, biogeochemical flows of nitrogen and phosphorus, land-system change, and of course, the release of novel chemicals.

Many of these boundaries have clear thresholds. For instance, scientists determined that humanity would overshoot the safe operating space for climate change when carbon dioxide in the atmosphere exceeded 350 parts per million (ppm), which happened in 1988. The threshold for novel entities, however, has until recently evaded definition, largely because of the knowledge gaps surrounding these substances.

Patricia Villarrubia-Gómez, a plastic pollution researcher at Stockholm University’s Stockholm Resilience Centre, who co-authored the new paper, said these knowledge gaps are not present because these chemicals and other polluting substances do not pose risks — it is because scientists are still scrambling to understand novel entities and the myriad ways they can impact the natural world.

“It is a very new field of study,” Villarrubia-Gómez told Mongabay. “It is in its infancy in comparison to other major environmental problems … most research has been done in the past seven years.”

Carney Almroth said researchers have used the Holocene, the current geological epoch that began just over 10,000 years ago, as a measuring point to quantify the thresholds of other planetary boundaries, but this approach was not appropriate for novel entities.

“This boundary is different from the others because the others are all referring back to the Holocene conditions — that was 10,000 years of a very stable Earth system and Earth climate,” Carney Almroth said. Scientists “can look back and ask, ‘What were carbon dioxide levels then and where was nitrogen and phosphorus during that time period?’ and refer back to that [as a baseline]. We could not do that because novel entities did not exist during that time period and the background baseline levels would be zero for most of them.”

Instead, the researchers gathered all of the information they could on artificial chemicals and other pollutants, looking at their impacts all along their supply chain, from extraction to production to use, and eventually, to their disposal as waste. Then they used a weight-of-evidence approach to determine that novel entities could, in fact, disrupt the planet’s stability.

“The weight of evidence indicates now that we are exceeding the boundary, but there is more work to be done,” Carney Almroth said.

Björn Beeler, the international coordinator for the International Pollutants Elimination Network (IPEN), who was not involved in this new research, called it a “very smart academic paper” that illustrates the need to act.

“We are about to enter an exponential growth period,” Beeler told Mongabay. “If you are concerned about toxic substance exposure, the amount of toxic substances [including plastic pollution] is set to grow three- [or] fourfold in the decades ahead.”

He added: “If you’re worried about it now, it’s set to get a lot worse.”

With science falling far behind in assessing risk, and governments largely failing to regulate chemicals, humanity is flying blind into a future where the unforeseen impacts of chemical pollutants could be catastrophic.

The release of novel entities isn’t the only planetary boundary that humanity has breached. Climate change, biosphere integrity, land system change and the biogeochemical flows of nitrogen and phosphorus have also pushed past the safe operating limits that keep Earth a habitable place.

An ‘existential’ threat to humanity

What is known about chemical substances and other pollutants has long raised alarms among experts — dating back to Rachel Carson and the publication of Silent Spring, which helped launch the modern environmental movement. Hazardous chemicals such as pesticides can damage soil health, contaminate drinking water, and even get carried on the wind, to impact a wider environment and disrupt populations of birds, mammals and fish. Many of the chemicals we ingest, such as pharmaceuticals, persist after being flushed down the toilet, with wastewater polluting rivers and oceans, or even the land when contaminated solid sewage sludge is used to fertilise crops.

Chemical persistence in the environment is a major thorny problem: Research has shown that polychlorinated biphenyls (PCBs) — highly toxic and carcinogenic substances banned by the US as far back as 1977 and once widely used in coolants and oil paints — have continued building up in the blubber of killer whales (Orcinus orca), posing a genuine threat to a species that is already struggling in many parts of the world. So called “forever chemicals” — perfluoroalkyl and polyfluoroalkyl substances (PFASs)that are highly toxic, carcinogenic and act like endocrine disruptors, are currently commonly used in disposable food packaging, cookware, cosmetics and even dental floss. A recent report also found them to be common in most of the drinking water in the US They take hundreds or thousands of years to break down, but no US limits have yet been placed on the concentration of forever chemicals in water.

“Even if we were to stop using and releasing [many novel entities], they would still be [here] for decades, or centuries, depending on what [substance] we’re talking about,” Carney Almroth said, adding that the risk of residual impacts from novel entities makes it even more imperative to stop, or at least slow down, the release of these substances.

The new paper in Science and Technology takes a specific look at plastics, which have become ever-present in daily life as food packaging, kitchenware and appliances. In recent years, much attention has been paid to the trillions of microplastics — fragments smaller than 5 millimeters, or three-sixteenths of an inch — polluting the global oceans, and the potential for larger plastic pieces to entangle or choke wildlife. New research shows that the sea breeze can even propel microplastics into the atmosphere, contaminating the very air we breathe and impacting climate change.

Plastic is highly problematic since it’s made out of a cocktail of chemicals that can leach out dangerous substances, especially when heated, cooled or scratched. A chemical compound known as bisphenol A (BPA) has been shown to act as an endocrine disruptor and interfere with hormones, impact immune systems and even promote certain cancers. One study even found that BPA can be absorbed into the human body through mere skin contact. But it’s not just BPA that’s harmful — many BPA alternatives have been found to be equally a risk to human health.

“We have been told for many, many decades that [plastics are] inert, and that they don’t release chemicals to their surroundings,” Villarrubia-Gómez said. “More and more, we’re discovering that that’s not true. Plastic leaches other chemicals … and we are in contact with [plastic] the whole day.”

Plastic isn’t just a problem in its end state. To make plastic, which uses petroleum as its base, greenhouse gases like ethane and methane need to be fracked from the ground and “cracked” into new compounds, the precursors to plastics. These industrial processes can release a number of toxic chemicals, along with various greenhouse gases, into the environment. The production of plastics is also intimately tied to the fossil fuel industry; as demand for oil drops, the petrochemical industry is ramping up its production of plastics.

“They see plastics as their next piggy bank,” Carney Almroth said. “Simultaneously, there’s a big push for an increase in plastics production and plastic use and plastic sales.”

Beeler said the release of novel entities into the environment poses a similar risk as climate change. “They’re both existential threats to humanity,” he noted. “Climate change [will determine] where you can live and how you can have a livelihood. Chemicals actually just remove your health — it’s very, very direct and personal. So I would draw them [as being at] the same crisis levels. It’s just that we’re not that socially conscious of chemicals and chemical safety, as we are of climate now.”

Determining a chemical’s risk often takes many years of methodical research, as scientists trace the causal connections between a synthetic substance and resulting environmental and health impacts. By then, that substance will often be ubiquitous, used in products across society.

‘Uptick in awareness’ 

While change is urgently needed to mitigate the impacts of novel entities, Carney Almroth said such an industrial paradigm shift would require a “massive overhaul of systemic societal structures.”

Industries that produce novel entities are “supported by the fact that we require constant economic growth,” she said. “This is one of the ways that they’ve been able to keep producing and using chemicals, even in the face of toxicity data, because they can show that it can grow economies, provide jobs, provide materials and so on and so forth.”

Despite the enormity of the problem, there may be opportunities for change in the near future. For instance, there are calls to form an international panel on chemical pollution, similar to those institutions focused on biodiversity and climate, such as the IUCN or the UN Intergovernmental Panel on Climate Change (IPCC).

In February and March, the UN Environment Assembly (UNEA) will also be meeting in Nairobi, Kenya, to discuss a number of environmental issues, including whether to mandate a new global treaty on plastics.

Beeler said that while negotiations may swing in the direction of only treating plastic as a waste issue, there are calls to address the entire plastic life cycle, taking into account all of the chemicals and pollutants plastic releases into the environment from production to waste stream.

He also said there’s also a reason for optimism in the way heightened public interest in plastic pollution has helped raise awareness of the larger problem of synthetic chemical contaminants.

“There’s been a small uptick in awareness [of] the harm from chemicals … due to the affiliation and link to plastics,” he said. “But prior to plastics, it was really [an awareness] desert — and plastics have created a little oasis of growing consciousness.”

This story was published with permission from Mongabay.com.

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