A wide-ranging review of more than 900 studies of five plastics additives says they all have statistically significant links to human health problems, and it's urging negotiators for the plastics treaty to adopt a precautionary approach to regulating them.
The Aug. 20 study from the Minderoo Foundation and researchers at the University of Adelaide in Australia said it's the first to use so many systematic reviews to look at bisphenol A, phthalates, two classes of flame retardants and fluorinated "forever" chemicals.
"This research categorically proves that none of the examined chemicals — which are found in plastic items people use every single day and are known to infiltrate our bodies — can be considered safe," said Sarah Dunlop, head of plastics and human health at Minderoo and one of the study's authors.
"This is a red flag for the world," she said. "We must minimize our exposure to these plastic chemicals, as well as many that haven't yet been assessed for human health outcomes, but are known to be toxic."
An industry group, however, said the Minderoo study has significant flaws.
Kimberly Wise White, vice president of regulatory and scientific affairs at the American Chemistry Council, said the study "cherry picks" some research to highlight while ignoring others in their review where results work against their conclusions.
"The study is best characterized as tertiary science, a review of other's reviews of primary science," she said. "The distance of this report from the original authors' conclusions in the primary science has led to numerous dubious assumptions, and the authors themselves rated the quality of the systematic reviews they cited as low or moderate quality."
She said the studies summarized are observational and could only establish potential correlation rather than a causal relationship.
"However, even the mere correlation between chemical exposure and adverse outcomes is largely unobserved," Wise White said. "The latest 'Umbrella Review' by Minderoo on the association between human health exposure to chemicals in plastics has significant flaws that are only apparent when reading beyond the abstract, summary and press release."
The study said it synthesized 52 systematic reviews, which in turn had looked at more than 900 individual studies covering more than 1.5 million people. The systematic reviews were published through 2020.
The Minderoo study, known as an umbrella review, said it found links between exposure to the studied chemicals and miscarriages as well as impacts in children such as asthma, irregular blood pressure and early puberty, and in adults, conditions such as diabetes, hypertension and cardiovascular disease.
"Consistent, statistically significant (95 percent) evidence was found for harm across a wide range of health outcomes for each of the chemical classes," said Edoardo Aromataris, an associate professor of public health at the University of Adelaide and a co-author, in a statement.
"None of the plastic-associated chemicals examined in the umbrella review can be considered safe, with multiple harmful effects linked to each chemical class," said Aromataris.
A Minderoo official said the study shows that the plastics treaty needs to urge a precautionary stance on regulation.
"When faced with similar discoveries from other chemicals, including mercury, the world has come together and agreed to a framework to protect human health," said Jay Weatherill, director of the Minderoo Foundation. "This is a chance for countries to do the same and protect the health of their citizens by agreeing [on] a list of chemicals to be included in the treaty."
Minderoo said it wants the treaty to restrict harmful chemicals used in plastics production.
The study comes less than a week after the U.S. government made a public shift in its plastics treaty negotiating positions, including agreeing to support the treaty including a global list of chemicals to develop obligations around and having global criteria for avoidable plastic products.
Minderoo said many other plastics-related chemicals have not been properly studied.
"The umbrella review found that most plastic chemicals, as well as polymers and microplastics, have been insufficiently or never studied for human health effects," it said in a statement on the report's website. "Considering the evidence of harm found for the few chemicals that have been examined, we should take a precautionary approach, and not assume safety for the rest."
How to regulate chemicals in plastics has been a significant topic in plastics treaty talks.
Technical experts from countries in the talks will convene at a United Nations meeting in Thailand Aug. 24-28, with discussions of how the treaty should address chemicals of concern in plastics as one item on the agenda.
Industry groups have stepped up their research on the health impacts of additives in plastics.
The International Council of Chemical Associations has said it's building a public database of additives used in plastics, including information on their function and hazard classification, as well as the chemical management laws that regulate them.
ICCA said additives provide significant benefits for the use of plastics, but the website for the project said it "understands there are questions and concerns."
As well, a group of scientists and food packaging organizations earlier this year presented the treaty negotiators with a framework for evaluating the thousands of chemicals used in manufacturing plastics, including additives and processing aides.
Minderoo has helped to fund previous plastics and human health studies, including a report last year that urged the plastics treaty negotiators to set tough benchmarks to regulate plastics.
Industry officials criticized that report, saying it was making irresponsible claims, equating the presence of chemicals with harm, and they said that chemicals in plastics are highly regulated for safety.