The groundwater around the Union Carbide factory in Bhopal continues to be contaminated even 28 years after the world’s largest industrial disaster in which leak of a poisonous gas had killed more than 15,000 people, the Supreme Court was told on Tuesday.

The Indian Institute of Toxicology Research (IITR), which examined the groundwater, submitted a report to the apex court saying the levels of lead, nitrate and nickel were more than permissible levels in many samples of water taken by it.

“In nine of the 30 samples, nitrate levels exceeded its permissible Bureau of Indian Standard (BIS) limits for drinking water. Lead level in 24 samples were found to exceed its BIS permissible limit,” said the report, submitted to a bench headed by Justice Altamas Kabir.

The report, however, added there was no threat because of the groundwater contamination as the requirement for drinking water in the area was being met through piped water supply.

The water samples were to be examined by the institute on three parameters of physico-chemical, heavy metals and organics but organic analysis could not take place as it takes time.