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Chapter 4 CUMULATIVE EFFECTS OF COMBINATIONS OF CONSTITUENTS <br /> When several chemicals of concern are present in a particular waste,their interactive <br /> environmental/health effects—either additive, antagonistic,or synergistic-should be <br /> considered. However, data on the cumulative effects of chemicals is generally not available <br /> in the literature. As a conservative rule, the potential water quality impact of several <br /> constituents that manifest their effects in the same or similar manner should be assumed to <br /> be additive. Constituent groups for which this rule would likely apply include primary <br /> carcinogens,organophosphate and carbamate pesticides,halogenated organic pesticides, <br /> organic solvents,petroleum hydrocarbons, and heavy metals. <br /> Under the additivity assumption,the waste would be considered to be a 'designated waste' <br /> if the sum of the quotients obtained by dividing the concentration of each constituent by its <br /> Designated Level is greater than 1.W1 <br /> n (Concentration of Constituent), <br /> if Z > 1.0, then the waste is a 191 <br /> tai (Designated Level for Constituent), 'designated waste' <br /> This criterion could require the classification of a waste as 'designated'even if the <br /> concentrations of individual constituents are all below thein respective Designated Levels. <br /> This indicates that even if no potentially adverse water quality impact is posed by <br /> individual constituents, the combination of constituents does have the potential to impair <br /> beneficial uses of waters of the State. <br /> For example, consider a liquid waste that contains four-carcinogenic volatile_organic----- <br /> constituents in the following concentrations: <br /> Measured_ - — --- t Hypothetical- <br /> Concentration Designated <br /> in the Waste Level <br /> 1,2-Dichloroethane 50 gg/I 100 µg/1 <br /> Tetrachloroethylene 250 gg/l 400 gg/I <br /> Trichloroethylene 400 gg/I 500 gg/I <br /> Viny-I chloride-- - — - --- - - - 120 µ9/I -- - - 200 jig/1- - - - -- - -- -- -- <br /> Each constituent is below its individual Designated bevel, however... <br /> 50 + 250 + 400 + 120 = 2.5 [10] <br /> 100 400 500 200 <br /> On the basis of cumulative carcinogenic risk (E> 1.0),this waste should be classified as a . <br /> 'designated waste'. r <br /> r � <br /> i Designated Level Methodology page 41 <br />