The Centre for Science and Environment’s Pollution Monitoring Lab (PML) tested water and soil samples from in and around the Union Carbide India Limited (UCIL) factory for the presence of toxic chemicals.
The PML studied the chemistry of the processes used for producing various pesticides in the UCIL and based on it, selected four groups of chemicals for testing soil and water samples. In chlorinated benzene compounds it tested 1,2 dichlorobenzene, 1,3 dichlorobenzene, 1,4 dichlorobenzene and 1,2,3 trichlorobenzene. In organochlorine pesticides it tested alpha, beta, gamma and delta hexachlorocyclohexane (hch). The two main products of the UCIL, Carbaryl and Aldicarb, were also tested. Five heavy metals: lead, cadmium, chromium, mercury and arsenic were also tested.
Why we tested
The UCIL used to manufacture three different kinds of pesticides Carbaryl (trade name Sevin), Aldicarb (trade name Temik), and a formulation of Carbaryl and gamma-hexachlorocyclohexane (g-hch) sold under the trade name Sevidol. g- hch was extracted from the technical grade hch, a mix of several chemical forms (isomers) of hch(mainly alpha, beta, delta and gamma hch). ucil used to buy technical grade hch, extract g-hch and throw the remaining isomers as waste.
Carbaryl and Aldicarb fall under carbamate group of insecticides; both are moderately persistent, highly toxic; highly water soluble and mobile in soils. It is therefore not surprising that pml found both these pesticides in the soil and water in and around the factory.