High Throughput Biodegradation-Screening Test To Prioritize and Evaluate Chemical Biodegradability

Comprehensive assessment of environmental biodegradability of pollutants is limited by the use of low throughput systems. These are epitomized by the Organisation for Economic Cooperation and Development (OECD) Ready Biodegradability Tests (RBTs), where one sample from an environment may be used to assess a chemical's ability to readily biodegrade or persist universally in that environment. This neglects the considerable spatial and temporal microbial variation inherent in any environment. Inaccurate designations of biodegradability or persistence can occur as a result. RBTs are central in assessing the biodegradation fate of chemicals and inferring exposure concentrations in environmental risk assessments. We developed a colorimetric assay for the reliable quantification of suitable aromatic compounds in a high throughput biodegradation screening test (HT-BST). The HT-BST accurately differentiated and prioritized a range of structurally diverse aromatic compounds on the basis of their assigned relative biodegradabilities and quantitative structure activity relationship (QSAR) model outputs. Approximately 20 000 individual biodegradation tests were performed, returning analogous results to conventional RBTs. The effect of substituent group structure and position on biodegradation potential demonstrated a significant correlation (P < 0.05) with Hammett's constant for substituents on position 3 of the phenol ring. The HT-BST may facilitate the rapid screening of 100 000 chemicals reportedly manufactured in Europe and reduce the need for higher-tier fate and effects tests.