Document peZ77Zm9oxKbYqx9XZnzBNXGa

RlSiCASSESSMENT OF MONITORING DATA a. 1,1,2-trichloroethane The monitoring data shown that out of 306 samples, there are 97% non detects at 0.55 M-g/m51 There are only three values that exceed 0.55 pg/m5. Using the USEPA unit risk of 1.6 x 10* an upper bound risk, at the detection limit, is 9 x 10"*, indicating minimal risk, even at the detection limit which was exceeded in 3 out of 306 samples. b. 1,1-dichloroethylene The monitoring data shown that out of 306 samples, there are 98% non detects at 0.55 M-g/m1. There are only three values that exceed 0.6 fig/m5. Using the USEPA unit risk of 5,5 x 10J, an upper bound risk, at the detection limit, is 3 x 10"*, indicating minimal risk, even at the detection limit which was never exceeded, USEPA in the 1990 Benzene NESHAP focused on IQ"1 as a level of acceptable risk for screening analyses for air toxics. This was reinforced in the 1996 report of the Risk Management Commission which was constituted under the 1990 Clean Air Act Ammendments. Titus, rising these recommendations, and EPA's past methodology, their is no significant risk from 1,1-D and 1,1,2-T as demonstrated by over 300 24-hour average ambient air samples. E/'T'd TSt79 9)S E08T 1WDIW3HD P10CI Wd9S:0 96, 60 100 I