Table 1 . Chemicals measured in NOAA's National Status and Trends Program. 



Trace Metals 



Cadmium (Cd) 

 Chromium (Cr) 

 Copper (Cu) 

 Lead (Pb) 

 Mercury (Hg) 

 Silver (Ag) 

 Zinc (Zn) 



Organic Compounds 



Total DDT (tDDT) 



The sum of concentrations of DDT (dichloro-diphenyl-trichloroGthane) and its metabolites 

 DDE (dichloro-diphenyl-trichloroethylene) and DDD (dichloro-diphenyl-dichloroethylene). 



Total chlordane (tCdane) 



The sum of concentrations of two major constituents of chlordane mixtures: alpha- 

 chlordane and trans-nonachlor. 



Total polychlorinated biphenyls (tPCB) 



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

 chlorobiphenyls. 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). 



is also attributable to human activity be- 

 cause they are produced when organic 

 matter is burned. A multitude of human 

 activities, from burning coal and wood to 

 incineration of wastes, create PAH 

 compounds in excess of those that would 

 exist naturally. Often, the lower molecu- 

 lar weight compounds (2- and 3-ring 



compounds in Table 1) are classified 

 separately from the higher-weight com- 

 pounds (4- and 5-rings) because the 

 lower-weight compounds have a higher 

 association with petroleum and the 

 higher-weight compounds with combus- 

 tion products. Since high concentrations 

 of both types of compounds tend to be 



