More than 16,000 chemicals are used to produce plastics — and some are silently killing us.

Particularly worrisome is di-2-ethylhexylphthalate, or DEHP, a chemical used to soften plastic products. Colorless and nearly odorless, DEHP is found in everything from shower curtains and shoes to medical tubing, and it’s long been linked to health harms like cancer. 

New research indicates the class of chemicals is also causing deaths due to heart disease, particularly in developing countries. According to a peer-reviewed study published last week in The Lancet eBioMedicine, nearly 350,000 people died in 2018 from exposure to DEHP. The research represents the first global survey of cardiovascular mortality from the chemicals, and it attributes DEHP exposure from plastics to more than 13 percent of all deaths from heart disease among adults aged 55 to 64.

One of the researchers’ most striking findings was a strong geographic disparity in DEHP exposure and related mortality rates. Residents of the Middle East and South Asia, for example, are exposed to up to six times more DEHP than their European counterparts. A greater share of these regions’ cardiovascular deaths was also attributable to the chemicals. Researchers found that in 2018, 10 percent of heart disease-related deaths in the United States and 8 percent in Europe were attributable to DEHP exposure. That figure was as high as 17 percent in the Middle East and South Asia and more than 13 percent in East Asia and the Pacific.

DEHP and other phthalates contribute to cardiovascular mortality in part because they are endocrine disruptors, meaning they interfere with the body’s hormones in ways that can increase the risk of obesity and diabetes. Phthalates also contribute to inflammation, another risk factor for heart disease, and they coexist with micro- and nanoplastics, which were shown in a groundbreaking study last year to increase people’s risk of a heart attack, stroke, or “death from any cause.” 

DEHP-laden plastics are like “a wrecking ball” on human tissues, said Leonardo Trasande, a professor of pediatrics at NYU Langone Health and one of the study’s authors. He said policymakers should do more to reduce the use of DEHP in plastic materials, potentially including restrictions on the use of polyvinyl chloride, or PVC, the type of plastic in which DEHP is most commonly found. Some typical products made of PVC include pipes, upholstery, and children’s toys, as well as — in some parts of the world — food packaging. Overuse of these products has contributed to widespread DEHP contamination in air, soil, and water.

The study suggests the geographical disparities may be attributable to regional differences in plastic production, chemical regulations, and “underdeveloped waste management sectors.” India, for example, is experiencing a surge in the manufacturing and use of plastic products, including PVC products, and it only recently began to restrict DEHP in food packaging. 

Many poorer countries also import plastic waste from abroad, creating another potential route for exposure. Countries like Malaysia, India, and Vietnam have received millions of tons of plastic waste from North America and Europe since 2021 — sometimes illegally, according to analyses of global trade data from the nonprofit Basel Action Network. In 2021, the U.S. alone exported 1.2 billion pounds of plastic waste to developing countries. Much of this plastic may be burned or dumped into unregulated landfills, where it can release chemicals such as DEHP.

The paper builds on a rapidly growing body of evidence that the manufacturing, use, and disposal of plastic creates an outsize burden for the developing world. In 2023, an analysis from the nonprofit World Wide Fund for Nature found that the life-cycle costs of plastics are at least eight times higher for low- and middle-income countries than they are for high-income ones.

To reach their conclusions, Trasande and his team of researchers modeled phthalates’ contribution to cardiovascular mortality using a survey of phthalate concentrations in urine samples combined with causes of death 10 years later reported in the U.S.’s National Death Index. Then they looked at the total number of heart disease-related deaths in particular countries and regions and determined what fraction wouldn’t have happened if it hadn’t been for DEHP.

Tracey Woodruff, a professor of reproductive sciences at the University of California, San Francisco, who was not involved in the new analysis, said the research was “consistent with what other studies have found” regarding health risks from phthalates. Last year, a study of one-third of the global population found that bisphenol A, or BPA — used in hard, clear plastic products, like food storage containers — contributed to 5.4 million cases of heart disease and 346,000 strokes in 2015. The same study found that polybrominated diphenyl ethers, or PBDEs — used as a flame retardant in electronics and some textiles — caused the loss of 11.7 million IQ points.

DEHP is inconsistently regulated globally. The European Union restricts DEHP, along with several other phthalates, to no more than 0.1 percent by weight in children’s toys and clothing, and strictly limits its use in food-contact materials and cosmetics. China has similar restrictions, and Japan has banned DEHP from food packaging and children’s products since 2003. India passed legislation in 2022 limiting the amount of DEHP that’s allowed to leach from food packaging.

The U.S. restricts DEHP in children’s toys and some food packaging but not in cosmetics. In 2022, the federal Food and Drug Administration denied a petition from 11 public health and environmental groups to ban DEHP and seven other phthalates in food-contact materials outright. 

“There’s no evidence for a threshold at which phthalate exposures are safe,” Trasande emphasized.

Trasande said his research could influence ongoing negotiations for the United Nations’ global plastics treaty, set to resume this August. The treaty’s mandate is to “end plastic pollution,” but delegates have increasingly turned their attention to hazardous chemicals in plastic products. Many scientists want the treaty to include lists of plastic types and plastic-related chemicals that must be limited or phased out. Both PVC and phthalates are top contenders for such lists.

Woodruff said research like Trasande’s should also drive home the need to limit overall plastic production, not just the chemicals used in plastics. “That there are important health benefits from capping the amount of plastic production,” she said. “Lowering our exposure to these chemicals in plastics is going to be a critical part of reversing the trend of chronic disease in the U.S.”