Recent studies suggested that the presence of elevated levels of 2,4,6,8-tetrachlorodibenzothiophene (2,4,6,8-TCDT) in sediments collected from the lower Passaic River in Newark, New Jersey is due to operations at a former 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) manufacturing facility. This paper reviews the scientific literature to determine if 2,4,6,8-TCDT is commonly found in the aquatic environment and evaluates whether 2,4,6,8-TCDT is associated with the production of 2,4,5-T. Polychlorinated dibenzothiophenes (PCDTs) are generated by chemical processes that are similar to those that result in the formation of polychlorinated dibenzofurans (PCDFs). PCDTs have been found in pulp and paper mill effluents and waste incineration fly ash, and are associated with metal reclamation processes and incineration of PCBs (Peterman et al., 1986; Buser et al., 1991; Rappe, 1992; Sinkkonen et al., 1991, 1992a,b, 1993). Chemical processes similar to those that have resulted in the formation of PCDFs, such as dye, pigment, paint, pesticide, and raw chemical production, are likely significant sources of PCDTs if sulfur-containing organic chemicals are used in the manufacturing process. It has been estimated that there are over 300 PCDD and PCDF sources within the Newark Bay estuary, many of which are likely to have discharged PCDT-containing effluents to the Passaic River (Paustenbach, 1993). Chlorinated thiophenols and other sulfur-containing compounds such as sulfonated benzenes, chlorinated in the 2, 4, and 6 positions, and 2,3,5,2′,3′,5′-hexachlorobiphenyl, present in commercial PCB mixtures (Ballschmitter and Zell, 1980), have precisely the correct configuration of chlorine substitution for 2,4,6,8-TCDT formation. Elevated levels of both 2,4,6,8-TCDT (Pruell et al., 1993) and PCBs (Wenning et al., 1992c) in lower Passaic River sediments suggest that PCDT contamination of these sediments may be related to several sources, most notably, a known PCB contaminated site approximately one mile downstream of the former 2,4,5-T facility. The scientific literature provided no evidence to support the assertion that the presence of 2,4,6,8-TCDT in the environment was related to 2,4,5-T production. The reported presence of 2,4,6,8-TCDT in Passaic River sediments cannot be explained by production practices at the former 2,4,5-T facility.