Haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.

Heptachlor is a highly toxic and carcinogenic termiticide banned from most applications in the U.S. since 1988.

Heptachlor epoxide is a beakdown product of heptachlor, a highly toxic and carcinogenic termiticide banned from most applications in the U.S. since 1988.

Hexachlorocyclopentadiene is an industrial pollutant discharged from chemical factories.