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 pml studied the chemistry of the processes used for producing various pesticides in 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 ucil —Carbaryl and Aldicarb—were also tested. Five heavy metals—lead, cadmium, chromium, mercury and arsenic—were also tested.