Development of an eDNA-Based Toxicity Test as a Screening Tool for Assessing Pollutant Impacts in Soil: A Case Study of Metal Toxicity in Allonychiurus kimi (Collembola)

초록

The increasing prevalence of emerging chemicals poses a significant global threat to ecosystems, emphasizing the urgent need for efficient methods to assess pollutant impacts. Environmental DNA (eDNA) analysis has been employed as a rapid, labor-saving biomonitoring tool. However, its application in pollutant toxicity testing has not yet been established. This study aimed to develop a soil toxicity test protocol using species-specific eDNA from Allonychiurus kimi (Collembola). Quantity of DNA in quantitative polymerase chain reaction (qPCR) was determined by the semi-quantitative measurement of the threshold cycle (Ct). To validate the effectiveness of this method in reflecting ecotoxicological endpoints, eDNA concentrations were measured across various age structures of A. kimi populations. Ct-values decreased with increasing age and adult proportion, demonstrating that this approach can accurately detect demographic variations. Conventional (28-day reproduction toxicity test) and eDNA-based toxicity tests were conducted to compare their sensitivity for four heavy metals: arsenic, lead, cadmium, and copper. Both methods exhibited dose-dependent responses to the tested heavy metals and yielded identical no observed effect concentration (NOEC) values for each metal. The eDNA tests indicated median effect concentration (EC50) values of 45.73, 684.70, 35.04, and 147.53 mg kg−1 for As, Pb, Cd, and Cu, respectively. Except for Cu, these values showed no statistically significant differences compared with those of conventional tests. Furthermore, the eDNA method produced a consistent EC50 equivalent Ct-value of 29.91 across all the tested metals, suggesting its potential use as a benchmark in ecotoxicological risk assessment. These findings indicate that the eDNA-based toxicity test offers sensitivity comparable to that of the conventional method and holds promise as an effective screening tool for assessing pollutant impacts on ecosystems. © 2026 The Author(s). Environmental DNA published by John Wiley & Sons Ltd.

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