Pesticides : (1) These are basically synthetic toxic chemicals with ecological repercussions.
(2) Earlier DDT was used to control insect borne disease in crops, later, as insect resistance of DDT was increased other organic toxins, such as Aldrin and Dieldrin were used as pesticides.
Herbicides : (1) These are sodium chlorate and sodium arsinite.
(2) Most are toxic to mammals but are not as persistent as organo chlorides.
(3) These chemicals decompose in few months.
(4) Some herbicides cause birth defects.