Trace Metals 



Arsenic (As) Nickel (Ni) 



Cadmium (Cd) Mercury (Hg) 



Chromium (Cr) Selenium (Se) 



Copper (Cu) Silver (Ag) 



Lead (Pb) Zinc (Zn) 



Organic Compounds* 



Total DDT (tDDT) 



The sum of concentrations of DDT (dichlorodiphenyltrichloroethane) and its metabolites 

 DDE (dichlorodiphenyltrichloroethylene) and DDD (dichlorodiphenyldichloroethylene). 



Total chlordane (tCdane) 



The sum of concentrations of two major constituents of chlordane mixtures, 

 cis-chlordane and trans-nonachlor and two minor components, heptachlor and 

 heptachlorepoxide. 



Total polychlorinated biphenyls (tPCB) 



The sum of the concentrations of di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, and 

 nonachlorobiphenyls. Since 1988, the equivalent tPCB has been calculated from the 

 sum of concentrations of 18 individual PCB congeners. 



Total polycyclic aromatic hydrocarbons (tPAH) 



The sum of concentrations of 18 PAH compounds: six 2-ring compounds (biphenyl, 

 naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2,6-dimethylnaphthalene, 

 and acenaphthene); four 3-ring compounds (flourene, phenanthrene, 

 1-methylphenanthrene, and anthracene); three 4-ring compounds (flouranthene, pyrene, 

 and benz[a]anthracene); and five 5-ring compounds (chrysene, benzo[a]pyrene, 

 benzo[e]pyrene, perylene, and dibenz[a,h]anthracene). 



Total butyl tin (tBT) 



The sum of the concentrations of tributyl tin and its breakdown products dibutyl tin and 

 monobutyl tin. (Concentrations in units of ng of Sn (as tBT)/g dry tissue.) 



*The NS&T Program monitors concentrations of other chemicals, such as Dieldrin and 

 Lindane, whose concentrations were below detection at more than 10% of the 1990 

 sites. Because such results make trend identification difficult, those compounds are not 

 discussed in this report. 



Table 1 . Chemicals measured in the National Status and Trends Program. 

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