Anatomy of the (known) health damage caused by plastics

If there’s one material that defines our times, it’s plastic: it’s in everything and it’s everywhere. It’s been the driving force behind major medical and technological advances, but it’s also leaving a perpetual—and dangerous—mark on human health. An international scientific review, published this Sunday in The Lancet, has compiled all the known harms caused by exposure to plastics and issued an important warning: there is now sufficient evidence that living surrounded by these polymers poses “grave, growing, and under-recognized” risks to humans at all stages of life.

Scientists are sounding this alarm while warning that the plastic pollution crisis the world is immersed in is not inevitable. Their analysis comes with the announcement of the launch of a Countdown to monitor progress toward reducing exposure to plastic and mitigating its damage to human health and the planet. However, the task will not be easy, they say. Above all, because there are three factors already working against it: global plastic production is accelerating, recycling is inadequate—only 10% is processed; 90% is burned, disposed of in landfills, or accumulates in the environment—and, unlike other materials, plastic does not biodegrade easily (it fragments into smaller particles and persists for decades).

Not everything is known about the health impact of plastics. But what is known isn’t good news. “We now know that they cause disease, disability, and premature death at all stages of their life cycle: from the extraction of gas and oil, the main raw materials for plastics, to their production, use, and subsequent disposal in the environment as plastic waste,” summarizes Philip J. Landrigan, director of the Global Observatory on Planetary Health and author of the article. The future outlook isn’t very promising either, he adds: “These harms are compounded as global plastic production continues to increase: it has increased 250-fold since 1950 and is projected to double again by 2040 and triple by 2060 if current trends are not checked.”

The damage is multifaceted and occurs in different contexts. The clearest and most direct case is that of people working in plastics production, as they are exposed to numerous toxic chemicals that can cause serious illnesses, such as cancer and neurological disorders, Landrigan points out. The Minderoo-Monaco Commission, which examined the health impact of plastics, estimated that around 32,000 premature deaths occurred worldwide among this group in 2015.

But beyond the workplace, plastic production also pollutes the air, water, and soil. And plastic disperses in tiny particles outside of factories. Indeed, an increase in illness and premature death has already been reported in communities near oil and gas wells. And one study estimated that in 2015, the emission of fine particulate matter (PM2.5) from plastics production caused 158,000 premature deaths (mostly in China and other parts of Asia).

Enigmatic chemical substances

With plastics, the source of health hazards is not only the polymer itself, but also the chemicals that accompany it. These materials can contain more than 16,000 different chemicals, many with harmful health effects of unknown magnitude. “Most of these known harms are due to the chemicals present in plastics, which leach from plastic products during use and reach people, especially children,” warns Landrigan.

A meta-analysis that reviewed studies and data from nearly 1.5 million people found “consistent evidence of multiple health effects across all life stages for many plastic chemicals,” scientists report in The Lancet. The risk is especially high for unborn babies and young children. The reported harms range from impaired reproductive potential (polycystic ovary syndrome and endometriosis) to perinatal effects (miscarriage, low birth weight), decreased cognitive function, insulin resistance, hypertension, and childhood obesity; and in adults, also diabetes, cardiovascular disease, stroke, obesity, and cancer.

One way to come into direct contact with these plastic-related chemicals is through food. Another review of nearly 1,000 studies analyzing plastic materials in contact with food revealed that 40% of the 3,700 chemicals analyzed are released into food under certain circumstances. This can be influenced, for example, by exposure to high temperatures (such as heating food in a plastic container in a microwave) or by the fat and acidity content of the food.

Microplastics can be found inside the human body.Svetlozar Hristov (Getty Images)

But there is a huge knowledge gap surrounding these chemicals: nothing is known about the risks of more than two-thirds of known plastic chemicals. And of those that do exist, approximately 75%—or some 4,200 substances—have been deemed highly hazardous due to their toxic effects, persistence, bioaccumulation, and mobility, the scientists warn in the article.

Researchers also report that, despite their widespread use in the environment and everyday life, these substances are subject to much less scrutiny and oversight than those used in other areas, such as the pharmaceutical industry.

Microplastics in the gut

The other headache for the scientific community is microplastics. These tiny particles of these polymers infest the globe and, when breathed or eaten, reach our bloodstream and seep into our guts. They have even been identified inside the human liver, kidney, intestines, and brain. They are presumed to be harmful, although the scientific community still doesn’t know the true impact of these tiny materials on health. For now, experts have evidence that they cause damage to cellular DNA and suspect they can trigger numerous ailments, from inflammation to cardiovascular disease.

Ricard Marcos, emeritus professor of Genetics at the Autonomous University of Barcelona and researcher on the European project PlasticHeal, focused on deciphering the impact of microplastics on health, explains one of the major challenges in assessing the risks of microplastics: “The levels of exposure and the population below these levels are what’s really relevant. And that’s what we don’t know. Microplastics are a segment of an entire degradation process, and the smaller the diameter of the pieces, the greater the risk because they have a greater capacity to disperse throughout the body.” The scientist, who did not participate in the research by The Lancet, admits that, when you get to the nanoscale, with increasingly tiny particles, there’s no way to quantify the levels of risk exposure.

Marcos agrees, however, that the impact of microplastics is “alarming” and this scientific article, although it “doesn’t contribute anything new,” does highlight “the urgency” of the problem.

The danger of waste

The entire life cycle of plastic takes its toll on health, as does the management of these materials as waste. Recycling workers are also at particular risk, experts warn in The Lancet. Whether due to their exposure to burning waste or sorting waste plastics that may be contaminated with other toxic chemicals, the reported health effects range from traumatic injuries and burns to respiratory illnesses, miscarriages, and cancer. A particularly dangerous practice is the open burning of PVC-coated computer cables to recover copper, which releases black smoke containing dioxins, benzene, and fine particulate matter (PM2.5) into the air, the authors emphasize.

The scientific warning comes on the eve of the final round of negotiations by UN member states, which will meet in Geneva, Switzerland, from August 5 to 14 to conclude a global plastics treaty to end plastic pollution. The scientists urge no further delay in decision-making. “States must take the plastics problem seriously and be ambitious in their efforts,” Landrigan explains.

The scientist points to a couple of key elements the treaty must contain to protect human health: a global limit on plastic production (especially to reduce single-use plastics) and regulations on the more than 16,000 chemicals found in plastics, with analyses of their toxicity and the withdrawal of the most dangerous substances from the market.

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