The Southern Bench of the National Green Tribunal (NGT) has directed the Tamil Nadu Pollution Control Board (TNPCB) to issue the Terms of Reference (ToR) to IIT-Madras and fix a timeline for a comprehensive scientific study into pollution in Neyveli, after differences emerged among members of a technical committee constituted to examine the issue.

The direction was issued by the Bench comprising Justice Pushpa Sathyanarayana and expert member Prashant Gargava on August 12 while hearing two suo motu cases based on news reports concerning alleged pollution around Neyveli Lignite Corporation (NLC) India and the presence of mercury in water. The Bench noted that the internal technical committee constituted by the TNPCB had submitted individual reports, but there were differences of opinion among its members on preparing a comprehensive report.

The TNPCB later decided to entrust the study to IIT-Madras. However, the Bench observed that the TNPCB was yet to issue the ToR to IIT-Madras or fix a timeline for completing the study.

In its earlier order dated July 15, the Bench had recorded that the TNPCB’s sampling and analysis had produced differing findings. While private laboratory reports found mercury and selenium below the level of quantification in the second cycle of analysis, the TNPCB’s own laboratory found mercury in six of 19 surface water samples, ranging from 0.01 mg/l to 0.027 mg/l. The Bench had noted that the heavy metals were within prescribed standards.

High-level committee

A high-level technical expert committee inspected the study area in July 2025 and collected four samples. Its members submitted individual reports but differed on the preparation of a comprehensive report. The committee had also stated that the exact source of contamination could not be established with the available data and that a detailed investigation of hydrogeology, wind patterns, and nearby industries, including NLC, TAQA, and IL&FS, would be necessary.

The Bench has asked the TNPCB to file a status report covering the ToR issued to IIT-Madras, the timeline fixed for submission of the study, and other relevant details. The matter has been posted to September 25. The Bench said that once the IIT-Madras report was filed, it could consider giving a quietus to the applications and further directions depending on the findings.