Distinction between heavy metal and organic toxicity using EDTA chelation and microbial assays

Use of the EDTA chelation test in conjunction with microbioassays for general toxicity (Microtox) and heavy metal toxicity (β‐galactosidase activity) allowed us to identify the presence of heavy metal toxicity, and to distinguish between cases in which toxicity was due solely to either heavy metals, organic compounds, or a mixture of these chemicals. The technique is effective over a wide range of water hardness and pH. Screening of industrial wastewater samples by the EDTA‐microbioassay technique gave results that were consistent with chemical analysis of samples by atomic absorption.