Are We Reaching the End for Endocrine-Disrupting Chemicals?

BOSTON — Will industry finally be held accountable for the harmful health effects of plastic pollution? Quite possibly, according to various speakers at a press conference held at ENDO 2024: The Endocrine Society Annual Meeting.

Mark Newman, executive editor of the Endocrine Society’s Endocrine News, said that the organization has been working tirelessly to put “health” front and center when it comes to regulating exposures to plastic pollution and, in particular, its endocrine-disrupting chemical (EDC) by-products.

Those efforts seem to be paying off. At a 2022 meeting held in Dakar, Senegal, that launched an Intergovernmental Negotiating Committee (INC) to develop a global treaty to address the “plastic crisis,” health was “barely mentioned,” Newman said. Now, 2 years later, the INC is reshaping the conversation around this issue.

“Our job, in partnership with organizations like the Scientists’ Coalition for an Effective Plastics Treaty, the Food Packaging Forum, and a host of others is to remind the United Nations member states involved in the treaty about the importance of health and to have health as a measure for monitoring progress,” he said. “The science has to be part of the conversation in a big way.”

The Human and Economic Costs of Plastic Pollution

Leonardo Trasande, MD, of New York University, New York City, one of the Endocrine Society’s representatives to INC, spoke about the “clear and extensive body of evidence confirming that there are human health effects” of the chemicals associated with plastic pollution.

Trasande pinpointed five categories of chemicals with “substantial and profound effects for human health that run the entire lifespan from cradle to grave”:

• Bisphenols, used in polycarbonate plastics and aluminum can linings
• Phthalates, particularly those used in food packaging
• Per- and polyfluoroalkyl substances (PFASs), used in nonstick cookware fluoropolymer plastics and many other products
• Brominated flame retardants and organophosphorus esters, additives used to reduce flammability
• Dioxins, which are highly carcinogenic even at the very lowest levels of exposure and are released into the environment when plastics are burned

Trasande’s team has researched bisphenol A (BPA), a prototype obesogen that also disrupts multiple metabolic mechanisms and the function of adiponectin, a protein that protects the heart. As a low-grade synthetic estrogen, it can have sex-specific effects on body mass.

Notably, BPA is just one of about 140 bisphenols. Replacement chemicals such as bisphenol S, which make products “BPA-free,” may not reduce toxic exposures.

Trasande also touched on phthalates, noting that considerable evidence shows they contribute to placental inflammation and to preterm births. His team’s recent study associated exposure to diethylhexyl phthalate with a 45% increase in the odds of preterm birth, and in some cases, a twofold increase. Taken together with other research, this means that 5%-10% of US preterm births are linked to phthalate exposure, with direct medical costs of about $4 billion a year, Trasande said.

In addition, phthalates contribute to cardiovascular mortality, whether through disruption of androgen function — because low testosterone is a predictor of cardiovascular mortality — or potentially directly in both sexes through inflammation in the coronary arteries. They also contribute to the development of type 2 diabetes.

Studies have identified reduced male fertility and poor semen quality with multiple EDCs, including phthalates, BPA, and polyfluorinated chemicals.

Trasande presented findings highlighting the considerable economic impact on a societal scale such pollution can have.

The cost of diseases associated with plastic pollution are estimated to be $340 billion a year in the United States, about double that in the European Union, which spends €160 billion a year, or 1.2% of the gross domestic product, on the management of these diseases.

The costs are largely due to a US law in effect from 1975 to about 2013, requiring the use of brominated flame retardants in polyurethane foams and other consumer products such as furniture, Trasande said.

“As a result, we’ve had a 10-fold higher level historically of polybrominated diphenyl ethers in serum in the United States.”

“The bottom line is that there is a substantial business case for preventing the use of chemicals, and plastics in particular. We therefore need a plastics treaty that reduces plastic pollution, recognizes hazards posed particularly by recycling and use of bioplastics, and uses hazard rather than risk to evaluate chemicals used in plastic materials,” he said. “We need to expand biomonitoring globally and ultimately establish an independent scientific body to evaluate the hazards of EDCs, and particularly the 16,000 chemicals used in plastics.”

One Community’s Battle Against ‘Forever’ Chemicals

Scott Belcher, PhD, of North Carolina State University, Raleigh, North Carolina, provided a glimpse of the scientific and regulatory landscape around PFASs, also known as “forever” chemicals, and the community-based efforts to combat them.

“These compounds are essentially everywhere and in everything — they’re man-made pollutants,” Belcher said. “They have many, many uses because of their chemical structures and properties. They are resistant to degradation, which is a good thing for industrial applications but a very bad thing when these chemicals are released out into the environment, and are there, essentially, until the end of time in some form or another.”

In addition to being EDCs, “PFASs are also toxic in many organ systems and accumulate in protein-rich compartments of the body,” he said. “They are persistent, they are bioaccumulative, and they’re also mobile in the environment. That means once they get into soil or water, their chemical properties allow them to be distributed into groundwater, into the air, and into surface vapor on ocean foam; they are essentially global contaminants.”

Focusing on one PFAS named GenX, Belcher described the efforts and findings of an experimental working group in North Carolina. The group analyzed samples downstream of wastewater treatment facilities and found that GenX, along with other PFASs, were identified in those obtained from a factory owned by The Chemours Company and previously owned by DuPont.

GenX is a by-product of the company’s production of vinyl ethers, manufactured since 1980 and released into the Cape Fear River, which supplies drinking water to surrounding communities. In addition, PFASs were being released from the company’s chemical manufacturing of Nafion, a fluoropolymer that is a backbone of Teflon.

In 2020, the group investigating the contamination worked with a local veterinarian and collected blood samples from dogs and horses in Wilmington, North Carolina.

“Nafion by-products were found in 100% of the tested residents of Wilmington, as well as in their dogs and horses,” said Belcher, whose group reported the findings in a recent article in Environmental Science & Technology. Because it was present in the horses, the researchers concluded that much of the exposure, consistent with other research done by the group, was probably coming from food and other components of the outside environment, rather than in the home.

The impact of these chemicals on people in the community and on their pets helped spawn a novel approach to managing the contamination called “One Health” — a holistic approach that integrates human, environmental, and domestic and wild animal health into community-engaged research and education within areas that are most affected by plastic pollution.

“Anecdotally, we’re finding that about 15%-20% of people living in contaminated areas have no knowledge about what’s happening, maybe because of bad news burnout or some other combination of effects,” Belcher said. “We’ve been working very hard by talking with and educating people in affected communities one on one, bringing the science to them and asking them to help us ask the best and most impactful scientific questions for our research.”

The group has been working on some of the “more blatant environmental justice issues,” he said, “getting to the most impacted communities that are the least likely to be able to change behaviors by buying water filters and other strategies.”

The US Environmental Protection Agency’s recent guidelines on PFAS pollution involving six different PFAS chemicals “is a huge step forward,” he noted. The rule sets limits for five individual PFASs: PFOA, PFOS, PFNA, PFHxS, and HFPO-DA (also known as “GenX Chemicals”).

“It’s the first major regulation we’ve had on these chemicals, especially in drinking water, based on the Clean Drinking Water Act.”

That said, he added, “PFAS is not a single chemical or six chemicals but thousands of different chemicals, which is why our community-based approach is so important. The published results of our study are now in the 10th through 12th grade curriculum in the state of North Carolina in about 35 different high schools. Working with colleagues, we’ve developed good examples that people can relate to, whether it’s to understand that these chemicals are in the water you’re drinking, the fish you’re eating, and the alligators that are sometimes in your front yard.”

The Treaty to End Plastic Pollution: What’s Next?

Marina Fernandez, PhD, Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina, and an Endocrine Society representative to INC, brought the audience up to date on the treaty to end plastic pollution.

Work on the treaty began in 2022. It was mandated by the United Nations Environment Assembly, establishing INC with the goal of developing an international, legally binding instrument on plastic pollution, with the ambition to end the work by the end of 2024.

“The process will end this year, and in 2025, we will have a treaty that will be signed, and then another process will start to work on implementing the treaty, led by governments of the UN members states,” Fernandez said.

The committee is now in an intersessional period during which they will work on criteria for chemicals and problematic plastic products, she added.

Fernandez then summarized the key messages that have emerged thus far from the INC’s work:

• We need a strong, legally binding instrument that protects human and environmental health by limiting plastic production because when we limit plastic production, we also limit the use of chemicals for its production and reduce exposure to harmful chemicals in plastic.
• We need restrictions and prohibitions on hazardous chemicals, including EDCs, based on internationally defined, science-based criteria.
• We need engagement of the academic research community in the identification of hazardous chemicals of concern and in the monitoring and evaluation of the treaty, including through biomonitoring capacity to measure reductions in exposure.
• We need to establish an independent advisory body to provide relevant scientific information, which includes academic scientists free of conflicts of interest, who are actively publishing and engaged in endocrine research to provide advice on measures to minimize exposures to EDCs.

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.