Question and Answer Discussion 
Question: Has there been any monitoring for metals in shellfish? 
Dr. Wallace: Not in any systematic way. I know of one study where metals were 
analyzed in clams taken from the Harbor. In addition, we are currently analyzing a 
limited number of clams from Boston Harbor. Incidently, one of the critical parameters 
in any of this work, and I’m sure Paul will support me in this, is proper validation of the 
methods we use. Historically, the methodology has not been properly validated. For 
example, there frequently is no reference standard analyzed. Unfortunately, we cannot 
accept concentrations in tissues with any degree of confidence unless we have that 
information. If we accept current analyses as valid, no public health problem appears to 
be associated with metal concentrations in the edible tissues of clams from the Harbor. 
Question: Do you have any insight into the amount of reduction that has resulted in 
the metals loading to sewage treatment plants? 
Dr. Wallace: Yes. For example, the reduction in copper and other metals has been 
shown in a number of reports. The best example I know where ocean disposal is involved 
is the effect of pretreatment on the municipal discharges along the southern California 
coast. Pretreatment resulted in about a 40 percent decrease in influent copper 
concentrations. Secondary treatment, in the absence of pretreatment, can increase 
removal from 25 percent for primary to 70 percent removal for secondary, or in other 
words by a factor of 2 to 3 with respect to primary. 
Question. Without pretreatment? 
Dr. Wallace: Without pretreatment. Exactly. So to accomplish dramatic decreases 
in effluent metal concentrations there has to be a rather effective pretreatment program. 
Question: Is there any data indicating a mass balance distribution between industry 
and other sources of metals? 
Dr. Wallace: Not to my knowledge. That's a difficult problem. I would defer to 
Cheryl Breen or the EPA for the answer to that question. Have you been able to identify 
individual industrial sources of the various metals in the system? 
C. Breen: No industrial sources. 
Question: I mean, that's the obvious question. 
Dr. Wallace: Exactly. I agree. 
Dr. Thomas: Do you have any gut feeling concerning, say, boat ship traffic and anti¬ 
fouling paint as sources, minor source, heavy? 
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