Table 2. Geometric Mean and "High" concentrations 3 from analyses of mollusks collected 

 in 1990 at 214 sites (oysters collected at 107 sites and mussels at another 107). 



deep-ocean water and upwelling of this 

 water in that area (Goldberg etal., 1 983 ). 

 That supposition cannot be used to ex- 

 plain high cadmium concentrations in 

 oysters at some Gulf of Mexico sites, 

 however. Arsenic is distinctly high along 

 the Southeast Coast — an observation 

 that may be related to arsenic's natural 

 association with phosphate, and the fact 

 that phosphate deposits in that area are 



sufficient to support mining activities. 



The "high" levels have been statistically 

 derived from the NS&T data for use in a 

 relative sense to compare among sites. 

 They cannot be related to biological 

 effects. The U.S. Food and Drug Ad- 

 ministration (FDA) has issued guide- 

 lines that warn against human consump- 

 tion of shellfish with concentrations (on 



14 



