Mercury pollution levels show need for clean-up

Liability issues concerning pollution around the Lonza site in Valais remain to be clarified Keystone

Canton Valais has announced the first results of tests to determine just how much mercury has seeped into the ground around the town of Visp, waste from the chemical company Lonza that was produced between 1930 and 1976.

Soil analysis has shown that a minimum of 71 plots in a residential area need to be completely cleaned up, while another 104 show mercury levels pointing only to a light level of pollution. The results have come from around 4000 soil samples.

Of the 469 residential properties where the soil was analysed, 294 were judged to be unaffected by the pollution, as the mercury levels detected were too low – below 0.5mg per kg of soil.

Out of 752 samples from agricultural land, 707 were also given the all-clear. 41 sites had a reading of 0.5-20mg of mercury per kg of soil. As the upper limit for agricultural land is higher than for residential, at 20mg Hg/kg, only four plots registered beyond the acceptable level of pollution.

A laboratory analysis of produce grown in the area gave it the all-clear.

Over nearly 50 years up until the mid 1970s chemical company Lonza went through 350 tons of mercury, 50 tons of which ended up in the local canal and polluted the soil in the residential area.

Liability for pollution in the area has not been resolved, but Lonza will now carry out further tests to determine how deep into the ground the pollution goes.

Another issue that remains is how the plots of land showing light levels of pollution will be treated.

Canton Valais, Lonza, the local community and those affected want to meet for talks to discuss possible aid and support.