Aldicarb is manufactured by the addition of 2-methyl-2-(methylsulfanyl)propanaldoxime to methyl isocyanate . In 1984, a leak of methyl isocyanate at a Union Carbide factory in Bhopal , India, making aldicarb and the related pesticide carbaryl for the Indian cotton crop, killed over 3,000 local residents; some estimates of the death toll