The IUPAC name of DDT is 2,2-bis (4-chloropheny)-1,1.1-trichloroethane and tha of benzene hexachloride is 1,2,3,4,5,6-hexachlorocyclohexane.
They are banned in india because they are non-biodegradable. Instead, they get deposited and stored in fatty tissues. If this ingestion continues at a steady rate, DDT builds up within the animal over time. This will affects the reproductive system of animals.
If animals including humans are exposed to high levels of benzene hexachloride then it may cause acute poisoning. Apart from that this BHC may affect liver functioning in humans.