When used as a pesticide on crops, on lawns and gardens, and to control termites in houses, chlordane enters the environment.
In soil, it attaches strongly to particles in the upper layers of soil and is unlikely to enter into groundwater. It is not known whether chlordane breaks down in most soils. If breakdown occurs, it is very slow. Chlordane is known to remain in some soils for over 20 years. Persistence is greater in heavy, clayey or organic soil than in sandy soil. Most chlordane is lost from soil by evaporation and is more rapid from light, sandy soils than from heavy soils. Half of the chlordane applied to the soil surface may evaporate in 2 to 3 days and when chlordane penetrates into the soil, evaporation is much slower. In water, some chlordane attaches strongly to sediment and particles in the water column and some is lost by evaporation. It is not known whether much breakdown of chlordane occurs in water or in sediment. In the atmosphere chlordane breaks down by reacting with light and with some chemicals in the atmosphere. However, it is sufficiently persistent that it may travel long distances and be deposited on land or in water far from its source. Chlordane or the chemicals that chlordane changes into accumulate in fish, birds, and mammals. Chlordane is still commonly found in some form in the fat of fish, birds, mammals, and almost all humans.