Based upon separate analyses of the data from the four test end-points in Phase 1, 89.4 to 136. 1 km 2 

 were estimated to be toxic (i.e., toxicity test results were less than 80% of the control responses). These 

 areas represented approximately 25% to 39% of the total study area. Based upon a critical value of less 

 than 20% of controls (the reciprocal of 80%), the area estimated to be highly toxic ranged from to 16 

 km 2 , representing from 0% to 4.6% of the survey area. 



Table 12. Estimates of the spatial extent of toxicity* (km 2 and percent of total area) in the Hudson - 

 Ra r it an Estuary based upon the cumulative distribution functions of data from each of four test 

 end-points. 



Amphipod survival 



Bivalve larvae survival 



Bivalve larvae development 



Microtox bioluminescence 



* Based upon critical values of <80% and <20% of control responses. 

 Total survey area: 350 km 2 



Based upon the amphipod survival test performed in Phase 1, approximately 133 km 2 of the Hudson- 

 Raritan Estuary were toxic (Table 12). Since toxicity was most widespread in the amphipod tests, the 

 results of the other three end-points were compared to it to determine concordance in the estimates of 

 the spatial extent of toxicity. Toxicity was second most widespread in the microbial bioluminescence 

 test. Based upon both the amphipod and microbial bioluminescence tests (Table 13), approximately 34 

 km 2 were toxic (9.8% of the total). Based upon these data and, using the critical value of less than 80% 

 of control responses, site 7 (located near Throg's Neck), site 10 (located in the upper East River), and 

 site 30 (located in Sandy Hook Bay) were significantly toxic in all four test end-points, representing 

 about 20 km 2 (5.7% of the total area). 



Table 13. Estimates of concordance in the spatial extent of toxicity* (km 2 and percent of total 

 area) in the Hudson-Raritan estuary among the four toxicity test end-points. 



Toxic Area 

 Kilometer 2 Percent 



Amphipod survival 133.3 38.1% 



Amphipod survival and microbial 



bioluminescence 34.2 9.8 



59 



