3,3′-Dichlorobenzidine: a candidate for inclusion in marine monitoring programmes?

3,3′-Dichlorobenzidine (DCB) is used as an intermediate in the industrial manufacture of dyes and pigments. It is classified as a human carcinogen in the United Kingdom, and as a probable human carcinogen in Canada. World production of this chemical in 1983 was 7 to 10 ktpa, with an estimated loss to the environment of 0.1% of usage (7 to 10 tpa). Owing to the relatively short half-life of DCB in water, soil and air, it is not expected to persist in the environment. DCB is only moderately toxic to fish and crustacea, but some bioaccumulation may occur. DCB has not been detected, however, in fish sampled from the vicinity of dye or textile manufacturing plants, nor have high concentrations been found in the waters downstream of such installations. No monitoring of DCB in marine waters is warranted at the present time.