Burnt plastic (pyroplastic) from the M/V X-Press Pearl ship fire and plastic spill contain compounds that activate endocrine and metabolism-related human and fish transcription factors

In May 2021, the M/V X-Press Pearl ship fire disaster led to the largest maritime spill of resin pellets (nurdles) and burnt plastic (pyroplastic). Field samples collected from beaches in Sri Lanka nearest to the ship comprised nurdles and pieces of pyroplastic. Three years later, the toxicity of the spilled material remains unresolved. To begin understanding its potential toxicity, solvent extracts of the nurdles and pyroplastic were screened for their bioactivity by several Attagene FACTORIAL bioassays (TF, NR, and AquaTox), which measured the activity of a combined 70 human transcription factor response elements and nuclear receptors and 6-7 nuclear receptors for each of three phylogenetically distinct fish species. Extracts of the pyroplastics robustly activated end points for the human aryl hydrocarbon receptor (AhR), estrogen receptor (ER), pregnane X receptor (PXR), peroxisome proliferator-activated receptor (PPAR), retinoid X receptor (RXR), and oxidative stress (NRF2), and the potential for several others. This bioactivity profile of the pyroplastics was most similar (similarity score = 0.96) to that of probable human carcinogens benzo[b]fluoranthene and benzo[k]fluoranthene despite the extracts being a complex mixture of thousands of compounds. The activity diminished only slightly for extracts of pyroplastic collected eight months after the spill. The AquaTox FACTORIAL bioassay measured the activation of ERa, ERb, androgen receptor (AR), PPARa, PPARy, and RXRb for human, zebrafish (Danio rerio), Japanese medaka (Oryzias latipes), and rainbow trout (Oncorhynchus mykiss), revealing species-specific sensitivities to the chemicals associated with the pyroplastics. These findings provide needed information to guide long-term monitoring efforts, make hazard assessments of the spilled material, and direct further research on pyroplastic, an emerging global contaminant.