Screening of dioxin-like compounds by complementary evaluation strategy utilising ELISA, micro-EROD, and HRGC-HRMS in soil and sediments from Montevideo, Uruguay

Abstract

Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) are persistent, toxic, and bioaccumulate in the environment. Due to their high analytical costs, these compounds are hardly regulated and mostly not monitored in the Third World. To overcome this, bioassays have been proposed as low-cost alternative methods. Two of the most established bioanalytical tools, the dioxin antibody-based enzyme-linked immunosorbent assay ELISA and the micro-EROD bioassay are evaluated and compared to high resolution gas chromatography and high resolution mass spectrometry (HRGC/HRMS) analytical methodology. The methods were tested using thirteen soils and sediment samples selected from diverse sites in Montevideo, Uruguay. The WHO₂₀₀₅ total toxic equivalent (WHO₂₀₀₅-TEQ) of soils ranged from 2.4 to 2212 (ng WHO₂₀₀₅-TEQ/kg dry sample) and from 0.14 to 9.4 (ng WHO₂₀₀₅-TEQ/kg dry sample) in sediments. This study shows significant contamination related to dioxin-like compounds, particularly in sites where uncontrolled burnings were carried out. ELISA and micro-EROD bioassay correlated well with HRGC/HRMS, R Spearman 0.773 and 0.913, respectively and were highly correlated to each other, R Spearman 0.879. Preliminary threshold values of bioassay toxic equivalents of 330 (ng/kg dry sample) for the micro-EROD bioassay and 220 (ng/kg dry sample) for ELISA are proposed.

Keywords: Cut-off values; Dioxin-like compounds; ELISA; EROD; Sediment; Soil.