A comprehensive analysis and risk evaluation of microplastics contamination in Australian commercial plant growth substrates: Unveiling the invisible threat

Abstract

In Australia, quality standards for composts and potting mixes are defined by AS4454–2012 and AS3743–2012. These standards outline key parameters, including physicochemical properties, nutrient content, and plant toxicity. However, they do not address emerging pollutants like microplastics (< 1 mm). This study investigates the prevalence and characteristics of MPs in commercial plant growth substrates (PGS), including nineteen potting mixes and five composts, revealing a significant occurrence of MPs, with concentrations ranging from 233 to 7367 particles Kg−1 and an average of 1869 ± 109 particles Kg−1. MPs categorized by shape, size, and color, with fragments (491 ± 34 particles Kg−1), whi..