Toxic chemicals in recycled plastic can affect hormone system, finds study

A new study sheds light on the potential human health risks associated with recycled plastics. The research reveals that toxic chemicals found in plastic pellets can affect hormone and lipid metabolism in zebrafish larvae. The scientists urge for greater transparency in the lifecycle of recycled plastics to reduce the use of toxic chemicals in plastics.

Researchers from the University of Gothenburg, Sweden, and Leipzig, Germany, published a study in the Journal of Hazardous Materials that found a single pellet of recycled plastic can contain over 80 different chemicals. 

Packaging Insights speaks to Dr. Bethanie Carney Almroth, co-author of the study, about the potential implications of recycled plastics on human health.

“Some of the chemicals we have identified in our samples in the current publication have known negative impacts on human health. While the chemicals were present in the water samples at low concentrations, many of which are below known toxicity values, our results show that the sum of the exposure to this cocktail of chemicals did affect the hormone systems and metabolism of the fish,” says Carney Almroth. 

“The genes we measured are similar to those known to be impacted in humans. Recycled plastics should not be used in products that will lead to direct exposure to humans, including but not limited to food contact materials, toys, and childcare products.”

The researchers collected recycled plastic pellets from India, Nigeria, and Taiwan. They let them soak in water for 48 hours until water leachates — a solution that has leached out some of its constituents — formed. 

Recycled plastics not to be used in products like food contact materials and toys, says Carney Almroth.Zebrafish embryos and larvae were exposed to the water leachates. The experiment revealed that the water leachates affected the organisms’ “mRNA expression in genes associated with endocrine regulation including thyroid hormone systems as well as adipogenesis and lipid metabolism.”

Carney Almroth says: “As we have previously conducted research on the chemicals in recycled plastics, we wished to assess whether the chemicals leached out from the plastics into water and whether they would impact a model organism, zebrafish.”

Chemical analysis of the water identified 84 different substances in the leachates, including plastic additives and other non-intentionally added substances such as pesticides and pharmaceuticals.

Human health impact 

The researchers highlighted that the discovery of toxic chemicals and their impact on Zebrafish could indicate particular health risks for humans. 

Carney Almroth says: “At the use phase, we know that chemicals will migrate out of plastics, leading to exposure via food, inhalation, and uptake via the skin. Some 4200 of the 16,000 chemicals used or present in plastics have hazardous properties.”

Recent research observed microplastics leaking into food from plastic packaging, while microplastics in agricultural soils accumulate more than in oceans. 

She also highlights that exposure to chemicals associated with plastics — from extraction and production to use and waste — affects various groups in society. 

Workers, frontline and fenceline communities, consumers, and waste pickers are all exposed. 

Carney Almroth argues that the “burden” of chemical exposure to recycled plastic is unequally shared across these groups: “there are issues of gender and socioeconomic nature involved.”

A single pellet of recycled plastic can contain over 80 different chemicals, according to the study.The study concludes that the mixture of chemicals in recycled plastics reveals the need for transparency and traceability across the plastics lifecycle and the “importance of limiting the use of hazardous chemicals in plastics.”

Plastic “not truly circular”

The researchers highlight how plastic recycling is often presented as the solution to plastic pollution. Still, the process is associated with “several challenges” due to the complex mix of polymers, additives, and contamination in waste streams. 

“Most plastics can be only recycled a limited number of times and are not truly circular. As we explain in our work, the issues of chemicals in plastics are not fully addressed,” adds Carney Almroth. 

In further response to the use of recycled plastics, she also notes that the degradation of material quality of mechanically recycled plastic requires using virgin plastics.

“Using recycled plastics also locks us into the continued production of primary plastic polymers. Science shows us that production reduction is necessary to solve the plastics crisis.”

Plastic policy gaps 

Carney Almroth notes that there are few regulatory or reporting requirements regarding chemicals present and added to plastics. 

“It is currently impossible to assess and control chemicals in recycled materials, nor mitigate harm. Furthermore, policy and financial mechanisms lifting recycling as a “solution” divert attention and efforts away from upstream measures addressing production, design, and use of materials and products.”

In April, the EU Council and the European Parliament provisionally agreed on a regulation to tackle environmental pollution with plastic pellets — an industrial raw material used in plastic products.

Carney Almroth notes that addressing upstream processes in plastic production, like reuse and refill systems, is “essential” to ending plastic pollution, alongside developments in infrastructure and materials. 

Recently, GoUnpackaged indicated in its refill and reuse trial report that consumers prefer refillable systems across UK supermarkets.