On October 29, 2009, scientists from the Central Pollution Control Board (CPCB) and Centre for Science and Environment (CSE)-Pollution Monitoring Laboratory had jointly collected soil samples from inside the former Union Carbide plant at
Both institutions had also collected groundwater samples – separately - from around the Union Carbide plant. Samples were collected with a view to check the contamination of the plant area and neighbouring localities for presence of heavy metals, pesticides, organochlorine and chlorinated benzene compounds. Collection of soil samples was done at eight locations - mostly jointly by CPCB and CSE. Subsequently, CSE had released its findings in a press conference in
A yet to be released report of CPCB has corroborated CSE’s findings by confirming high levels of contamination at the UCIL site and beyond. Both the studies show very similar trends and pattern on the presence of various contaminants that were tested. Most importantly, both studies point out that the only source of contamination is the factory site and the waste stored there.
Therefore, a comprehensive clean-up effort is needed to decontaminate the site and the affected areas.
Results: In soil in Union Carbide factory
Heavy metals: CSE found heavy metals - namely arsenic, mercury, lead and chromium - in varying concentrations in the soil. CPCB findings corroborate this and in fact find higher amounts (see table). Arsenic and chromium were detected in all the samples by both CSE and CPCB. Mercury was found in all the samples of CPCB. Heavy metal mercury was used as a sealant in the pesticide plant and chromium was used as a coolant in the cooling plant.
Pesticides: Presence of carbaryl was detected by CPCB in 75 per cent of the samples. CSE detected it in 25 per cent of the soil samples tested. Aldicarb was detected by both CPCB and CSE in varying quantities. It must be mentioned that the only source of these pesticides in the area is the factory. Both are moderately persistent, highly toxic; highly water soluble and mobile in soils.
Organochlorines: Organochlorine compounds (alpha, beta, gamma and delta HCH) were detected in fairly large amounts by both CSE and CPCB in all the soil samples. HCH and its isomers are highly persistent and toxic organochlorine pesticides and presence of different isomers of HCH is because of its processing in the plant.
Chlorinated benzene: In soil samples, 1,3 di chlorobenzene was detected by CPCB as well as CSE in all the samples. Chlorinated benzene compounds are highly persistent and were either used by Union Carbide as solvents or are degradation products of HCH.
Results: In groundwater samples around Union Carbide factory
The results of the tests performed on 14 groundwater samples by CPCB around the Union Carbide factory in
The following table reveals the extent to which some of the toxic compounds have permeated the soil.
|a-HCH||Outside pond in dump site||14679.77|
|b-HCH||Outside pond in dump site||543.04|
|g-HCH||Outside pond in dump site||2030.14|
|d-HCH||Outside pond in dump site||1157.70|
Note: All measurements are in ppm