Dichlorodiphenyldichloroethane

Dichlorodiphenyldichloroethane (DDD) is an organochlorine insecticide that is slightly irritating to the skin. DDD is a metabolite of DDT. DDD is colorless and crystalline; it is closely related chemically and is similar in properties to DDT, but it is considered to be less toxic to animals than DDT. The molecular formula for DDD is (ClC6H4)2CHCHCl2 or C14H10Cl4, whereas the formula for DDT is (ClC6H4)2CHCCl3 or C14H9Cl5. Dichlorodiphenyldichloroethane (DDD) is an organochlorine insecticide that is slightly irritating to the skin. DDD is a metabolite of DDT. DDD is colorless and crystalline; it is closely related chemically and is similar in properties to DDT, but it is considered to be less toxic to animals than DDT. The molecular formula for DDD is (ClC6H4)2CHCHCl2 or C14H10Cl4, whereas the formula for DDT is (ClC6H4)2CHCCl3 or C14H9Cl5. DDD is in the “Group B2” classification, meaning that it is a probable human carcinogen. This is based on an increased incidence of lung tumors in male and female mice, liver tumors in male mice, and thyroid tumors in male rats. Further basis is that DDD is so similar to and is a metabolite of DDT, another probable human carcinogen. DDD is no longer registered for agricultural use in the United States, but the general population continues to be exposed to it due to its long persistence time. The primary source of exposure is oral ingestion of food. 1946 is the date of the earliest recorded use in English of the abbreviation “DDD” to stand for dichlorodiphenyldichloroethane, as far as could be determined. If one of the p-chlorines in DDD is switched to ortho-position, then we get a useful chemotherapeutic agent, mitotane. This is an example of a positional isomer.