Low PIN FR leaching from microplastics

Lab studies show low levels of PIN flame retardant leaching from microplastics under exaggerated artificial weathering.

Menger et al. tested leaching from 8 commercial plastics containing additives (of which 3 were PET or PVC containing FRs) after artificial UV weathering. Only five FRs were detected after leaching, of which the highest concentrations were TBBPA, with considerably lower levels of the only three PIN FRs detected (tri(butoxyethyl)phosphate TBEP, trimethyl phosphate TMP, triphenyl phosphate TPhP). The main use of TBEP is not as a flame retardant, but in polishes.

Zuo et al. tested leaching from polystyrene microplastics (ground to < 0.2 mm) in water and synthetic digestive fluids of two organo-P PIN FRs (triphenyl phosphate TPhP and tri-n-butyl phosphate TnBP). Conclusions are that only around 0.5% of the FR content in the microplastic particles, with leaching occurring in the first 24 – 30 hours. They concluded that leaching from such microparticles would not be a significant source of organophosphates, because it occurs mainly from the microplastic particle surface, but note that further leaching could occur later if the microplastic particles break down to smaller particles.

Li et al. review over 160 papers published over the last ten years, on leaching of chemicals from microplastics, scarcely mentioning PIN FR leaching. They conclude that antioxidants, flame retardant and plasticisers may leach, in particular bisphenols, and that fats and oils may accentuate leaching of liposoluble chemicals in the gut if ingested (the halogenated FRs PBDEs are severally cited). Photodegradation of plastics facilitates leaching.

Sun et al., in a modelling paper (based on published experimental data from Guo 2019, see pinfa Newsletter 132, and on theoretical diffusion coefficients), concludes that organophosphorus FR leaching from polypropylene and polystyrene microplastics contribute “minimally” in worms but leaching from polyethylene could be non-negligible. They suggest that leaching varies widely depending on the type of microplastic and that quantitative research is needed.

“Screening the release of chemicals and microplastic particles from diverse plastic consumer products into water under accelerated UV weathering conditions”, F. Menger et al., J. Hazardous Materials 477 (2024) 135256, https://doi.org/10.1016/j.jhazmat.2024.135256

“Leaching of triphenyl phosphate and tri‑n‑butyl phosphate from polystyrene microplastics: influence of plastic properties and simulated digestive fluids”, L. Zuo et al., Environmental Science and Pollution Research (2023) 30:114659–114666, https://doi.org/10.1007/s11356-023-30229-w

“Leaching of chemicals from microplastics: A review of chemical types, leaching mechanisms and influencing factors”, Y. Li et al., Science of the Total Environment 906 (2024) 167666, https://doi.org/10.1016/j.scitotenv.2023.167666

“Leaching kinetics and bioaccumulation potential of additive-derived organophosphate esters in microplastics”, B. Sun et al., Environmental Pollution 347 (2024) 123671, https://doi.org/10.1016/j.envpol.2024.123671

* “Leaching of polybrominated diphenyl ethers from microplastics in fish oil: kinetics and bioaccumulation. B. Sun et al., 2021, J. Hazard Mater. 406, 124726, http://refhub.elsevier.com/S0269-7491(24)00385-3/sref34

“The leaching of additive-derived flame retardants (FRs) from plastics in avian digestive fluids: the significant risk of highly lipophilic FRs”, H. Guo et al., 2019, J. Environ. Sci. 85, 200–207 https://doi.org/10.1016/j.jes.2019.06.013