‘Elevated levels of mercury in a few samples taken outside the now defunct thermometer factory of Hindustan Unilever (HUL) in Kodaikanal’.

The latest study conducted by the National Environment Engineering Institute (NEERI) has shown elevated levels of mercury in a few samples taken outside the now defunct thermometer factory of Hindustan Unilever (HUL) in Kodaikanal, claim activists.

While they cite the study as evidence to pin the factory as the source of mercury contaminating the hill station, HUL has denied such an inference outright, citing the samples that did not show mercury contamination.

The NEERI study, the report of which was put together on October 26, was undertaken following the intervention of the Scientific Experts Committee (SEC) formed to oversee the remediation of contaminated soil at the factory. The SEC recommended on May 28 a fresh assessment of the area, after which HUL, which closed the thermometer factory down in 2001, asked NEERI to conduct the study.

According to the 10-page report, a total of 74 samples of soil, sediment and water were collected from a wide area. This included downstream off-site areas extending up to Pambar Shola forest area, Pambar River and Vaigai River.

Of these, the concentration of total mercury in sediment samples was found to be in the range between less than 0.1 to 0.507 mg/kg. In the soil samples, the range was <0.1 to 1.109 mg/kg. The table collating the analysis showed samples lifted near the place where the Pambar Shola stream joined the Pambar river, having a sediment mercury level of 0.353mg/kg. The water sample taken from the Kodaikanal Lake showed mercury Below Detectible Levels (BDL). A majority of the samples tested showed mercury BDL.

However, activists pointed out that all samples should have mercury BDL, accounting for naturally-occurring traces of mercury.

In conclusion, the report states that based on the detailed sampling and analysis of mercury levels in soil, sediment and water samples in the off-site areas of the HUL factory, the concentration of the heavy metal was insignificant. “..the concentration of mercury was well below the risk based target remediation levels of 20 mg/kg derived and validated through various studies,” the study found.

An HUL spokesperson said through email that unlike what critics claimed, the results do not indicate contamination outside the factory premises.

“All the samples taken in outside locations such as Kodaikanal Lake, Pambar river, Kumpakari falls, Vaigai river, Varaganathi and the Vaigai Dam etc. show that the levels are safe and well within the internationally accepted range. The range of <0.1mg/kg to <0.507 mg/kg refers to an area which is just adjacent to the perimeter of the factory and in a pathway,” the spokesperson contended.

However, activist Nityanand Jayaraman said the report clearly established the factory as the locus of mercury contamination in Kodaikanal.

“These reports do not indicate how much mercury will leach out of the factory site. Further, not all samples were near the factory. The factory’s vicinity includes a highly- protected and sensitive wildlife sanctuary and hence the residential standard of remediation is not enough,” he pointed out.

Target species

Agreeing with this view, T. Swaminathan, former professor of chemical engineering at IIT-Madras, said the scientific and ethical determination of clean up limits must be based on the potential risk of exposure to “target species” that are likely to be affected by the migration of the contaminant from the site. “The future use of the contaminated site after clean-up must also be considered,” he added.

However, HUL’s spokesperson said they had taken the nature of the environment into account right through.