The concentrations of 2,3 ,7,8-tcdd reported by the three laboratories are plotted in Figure 26. Note that 

 the scales in Figures 25 and 26 are different. The spatial pattern in the concentrations of 2,3,7,8-tcdd in 

 all 55 samples corresponded with that for total dioxin equivalents in the 20 samples analyzed by NBS. 

 The relatively high concentrations (280-620 pg/g) of this isomer in the lower Passaic River stations 

 contrasts with the relatively low levels in the Hackensack River (62 pg/g or less). Except for station 26 

 located in central Newark Bay, the concentrations of 2,3,7,8-tcdd generally decreased down Newark 

 Bay from the mouth of the Passaic River toward Staten Island. The concentrations of this congener 

 were 100-150 pg/g in many of the samples collected near the Port Newark Terminal. 



In addition to the chemical analyses of dioxins and furans, the Midwest Science Center of NBS deter- 

 mined the concentrations of these and other compounds in H4IIE rat hepatoma bioassays, following 

 the protocols of Tillitt et al. (1991). The toxicity of whole sediment extracts (Fl) and fractions of the 

 extracts were determined and reported in units of 2, 3, 7, 8 -tcdd equivalents (pg/g). Seven fractions, 

 representing dioxins, furans, PCBs, and PAHs, were tested (Table 15). The toxicity of the F5 fraction 

 (PAHs) was considerably greater than that of all of the other fractions. In many of the samples, the 

 tcdd-equivalent concentrations of the PAHs exceeded the concentrations observed in the whole ex- 

 tracts. This observation suggests that the toxicity of these compounds may not be strictly additive, and 

 alternatively, some antagonistic effects may occur, thus reducing the cumulative toxicity of these mix- 

 tures. Also, the tcdd equivalent concentrations of the F12 fractions (dioxins, furans) were relatively 

 high. The contributions of the PCB fractions (F7 - Fl 1) to toxicity were relatively minor. 



The concentrations of the tcdd equivalents in the whole extracts were highest in the samples from the 

 lower Passaic River, particularly at stations 3, 6, 7, and 8 (Figure 27). Concentrations diminished 

 rapidly down Newark Bay and were relatively low in the Hackensack River. Concentrations were very 

 low in the sample from station 57 in the upper New York Harbor. This distribution pattern differed 

 from that observed in the chemical analyses; specifically, tcdd equivalent concentrations were rela- 

 tively low at stations 7 and 26, whereas the chemical analyses indicated that dioxin concentrations 

 were relatively high at these stations. 



The concordance between the concentrations of the planar hydrocarbons determined in chemical analyses 

 and in the rat hepatoma bioassays was very good for some fractions (Table 16). Spearman-rank corre- 

 lations were determined for the concentrations of the PCB-TEQs, dioxins/furans-TEQs, and total cu- 

 mulative TEQs (pg/g) versus the tcdd-eqs (pg/g) determined for each extract fraction in the rat hepatoma 

 bioassays. The correlations between the cumulative TEQs determined in chemical analyses and the 

 tcdd-equivalent concentrations in the F12 fraction (dioxins, furans) were particularly strong. 



74 



