Exposure to a trio of chemicals found in many everyday household and industrial items may have contributed to millions of cases of heart disease, stroke, and deaths over the years according to estimations of the health and economic impacts of common plastic additives.
An international team of researchers pooled findings from over 1,700 existing studies from 38 different countries investigating links between people's exposure to the chemicals and certain health impacts.
The researchers argue the results are concerning enough to warrant global action, but critics say we still need conclusive proof that these chemicals are the true cause.
The suspects in question – BPA (bisphenol A), DEHP (di(2-ethylhexyl) phthalate) and PBDEs (polybrominated diphenyl ethers) – have been previously associated with serious health issues.
The safety of BPA has been questioned for a while: widespread in our food packaging, especially in the form of the epoxy that lines some food and drink cans and bottles, exposure to this compound has been linked to higher rates of ischemic heart disease and stroke.
This latest study found 5.4 million cases of ischemic heart disease and 346,000 cases of stroke in 2015 could be associated with BPA exposure. That suggests BPA exposure could be associated with 431,000 deaths. An estimate on the total economic impact suggests the resulting loss in health could have cost nations an equivalent of US$1 trillion in purchasing power.
DEHP is present in the flexible plastics of garden hoses, shower curtains, medical tubing, and synthetic leathers.
Animal studies have shown its potential as an endocrine disruptor, affecting pregnancy in mice and puberty in rats. A study published back in 2022 found a significant link between increased DEHP metabolites in the urine samples of 5303 US adults and an increase in mortality rate. This recent study calculates 164,000 deaths worldwide could be related to DEHP exposure, with an estimated US$398 billion in equivalent economic losses.
PBDEs are a class of brominated flame retardants controversially behind advice to throw out your black plastic spatula. Common in materials that are exposed to high levels of heat, they're also present in electronics, car parts, aircraft, and certain textiles.
They can enter your body by inhalation, dermal absorption, or via your food – a seemingly unlikely route, but they've turned up in utensils, food packaging, and children's toys made from recycled black plastic.
A correlation between PBDE exposure and measures of intelligence suggests almost 12 million collective IQ points may have been lost due to maternal PBDE exposure.
The cumulative impact, it seems, is damning. BPA and DEHP may be eliminated from the body relatively quickly over a course of days, but the continuous stream of plastics in our lives means we have little relief from their exposure. The 'stickiness' of PBDE in our bodies is less clear, and depends on the specific chemical makeup.
"Our reason for quantifying these health effects was to focus on the damages associated with three of the best studied chemicals in plastics and to estimate exposures in as many countries as we could," says Maureen Cropper, an economist from the University of Maryland.
All of the study's estimates lean heavily on the data from existing observational studies, making causation difficult to confirm. Some unrelated factor might increase people's exposure to the chemicals as well as their health problems – a diet high in fast food, for instance, would increase a person's exposure to plastics and is also known to increase the risk of cardiovascular disease.
Statistician Kevin McConway, who was not involved in the research, urges caution in how the results are interpreted.
"I'm not trying to say that these plastics can't present important health hazards, but only that this research can't clearly establish the extent to which they do cause extra ill health and higher death rates," McConway says.
But Cropper and team think there's more than enough data to warrant global action, though there's a need for much more data on our exposure to these substances. If these plastic additives are in fact making people sick, the estimates suggest they might already have killed half a million people.
"Protection of human health against the hazards of chemicals in plastics will require a paradigm shift in national chemical law in multiple countries including the United States, Canada, and the EU," the team writes, urging producers of plastics to take on the onus of proof.
This, they note, has been the norm in pharmaceutical regulation since the 1970s.
"It will require a more precautionary approach that prioritizes the protection of human health and no longer presumes that chemicals are safe."
The paper is published in PNAS.