A global study has revealed that free-range chicken eggs collected near waste sites contain “alarming” levels of toxic flame retardant chemicals, including brominated dioxins (PBDD/Fs) and brominated flame retardants (BFRs). The research was published in Emerging Contaminants and was led by the International Pollutants Elimination Network (IPEN) and Czech nonprofit Arnika.

With the assistance of a global network of nonprofit organizations, IPEN and Arnika facilitated chemical analyses of free-range eggs collected from 15 countries across Asia, Africa, Europe, and the Americas. Sampling was targeted in areas at a high risk for contamination by persistent organic pollutants (POPs), such as electronic waste (e-waste) recycling sites, dumpsites, waste incinerators, and metallurgical facilities.

Samples were tested for a range of POPs, including substances banned or under review by the Stockholm Convention. Chemical analyses were performed by accredited laboratories in the Czech Republic, the Netherlands, and Germany using advanced instrumental methods and the DR CALUX bioassay, which the authors describe as a cost-effective screening tool for total dioxin-like toxicity.

Importantly, extreme contamination by brominated dioxins were found in eggs collected near e-waste sites. For example, eggs from an e-waste area in Ghana contained 503 picograms toxic equivalent per gram of fat (pg TEQ/g) fat of brominated dioxins, exceeding food safety standards for closely related chlorinated dioxins by 200 times. Additionally, the Ghanan eggs contained 1,200 nanograms per gram of fat (ng/g fat) of polybrominated diphenyl ethers (PBDEs), a type of BFR.

In Kazakhstan, eggs were found with more than 18,000 ng/g fat of hexabromocyclododecane (HBCDD), another BFR, representing some of the highest concentrations ever recorded globally.

While the use of BFRs has been largely phased out, industry has adopted the use of closely related chemicals, called “novel BFRs” (nBFRs), which are not proven to be safer than traditional BFRs. Certain nBFRs, 1,2-Bis (2,4,6-tribromophenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE), were frequently detected in eggs, with BTBPE levels reaching 221 ng/g fat in some samples. The highest levels of BTBPE and DBDPE were detected in eggs from free range chickens near hospital waste incinerator sites in Kenya.

BFRs and brominated dioxins are linked to endocrine disruption, reproductive toxicity, neurodevelopmental impairment, immune system damage, and cancer.

“Brominated dioxins and flame retardants are a global threat to human health and the environment,” said lead author Jindrich Petrlik, R.N.Dr. of Arnika and IPEN. “The evidence is overwhelming—these chemicals must urgently be listed under the Stockholm Convention, and recycling of waste containing them must stop.”

Study authors and environmental experts from Thailand and Kenya explained the importance of listing BFRs under the Stockholm Convention to guide national restrictions on these chemicals, protecting communities that live and produce food near waste sites, such as those within their respective countries. Eggs are a cheap and essential source of protein, and in contaminated areas, frequent consumption can pose critical health risks.

The Stockholm Convention is a global treaty to protect human health and the environment from POPs. It requires participating countries to take measures to eliminate or reduce the release of POPs into the environment.

The study’s authors specifically call for listing PBDD/Fs and mixed brominated-chlorinated dioxins (PXDD/Fs) under the Stockholm Convention. When flame-retarded plastic is incinerated, high amounts of POPs are released, and PBDD/Fs are formed from PBDEs and other BFRs. The Stockholm Convention’s POP Committee are considering PBDDFs and PBDD/Fs for inclusion in the treaty by 2027.

The authors also recommend stronger global controls on BFRs and their wastes, including the evaluation of nBFRs for potential regulation; banning exports of e-waste and plastic waste to developing countries; environmentally sound management of incinerator ash and contaminated materials; and substitution of brominated flame retardants with safer alternatives.

Finally, the authors advocate for broader use of comprehensive and cost-effective bioassay screening methods like DR CALUX to monitor total dioxin-like toxicity in food, especially in resource-limited settings.