Migration and phototransformation of additives in plastic products: A case study of advertising banners

Abstract

Advertising banners, as commonly used plastic materials for promotional activities, are enhanced with various additives to optimize their performance. These additives may migrate or transform, presenting potential risks to the health of human and ecosystems. However, the environmental impact of additives in advertising banners has been largely disregarded. This study examines the migration and transformation pathways of dominant additives within these banners. The results indicate that advertising banners not only release specific additives such as di-2-ethylhexyl phthalate and tris-2-ethylhexyl phosphate into the atmosphere, but also absorb external pollutants including diisobutyl phthalate and dimethyl phthalate from the surrounding environment. This dual behavior is attributed to their large surface area, which enhances both emission and adsorption potential. The polyvinyl chloride polymer used in advertising banners exhibits notable adsorption capacity for airborne pollutants, primarily driven by van der Waals interactions. The annual release of additives from advertising banners in China is estimated to exceed 1.7 × 10⁷ kg. Moreover, certain additives such as 2-ethylhexyl diphenyl phosphite (EHDPi) can undergo rapid phototransformation with a half-life of 1.4 h, yielding 2-ethylhexyl diphenyl phosphate. The transformation mechanism of EHDPi was confirmed via density functional theory calculations and high-resolution mass spectrometry, indicating that transformation byproducts of organophosphites may represent a source of organophosphate pollutants. This study highlights that advertising banners serve as a significant source of chemicals, while also acting as a conduit for atmospheric pollutants. It provides critical insights into the broader role of plastic products in the dispersion of pollutants across ecosystems.