Fw: tox values for PCB congeners

[Pope.Anne@epamail.epa.gov]

Jon,

I have added these additional pollutants to the NEI pollutant code
table, but you may want to read the message from Dr. Smith below.  He
maintains the file with the UREs and RFCs that we use in NATA.  His
point is that without specific congeners of PCBs, it will not matter in
risk assessment.  So it may create more work for GLC to maintain these
pollutants rather than reporting PCBs as a group unless you revised the
list of PCBS to include congeners rather than homologues.

anne
----- Forwarded by Anne Pope/RTP/USEPA/US on 01/18/2007 06:55 AM -----
                                                                        
             Roy                                                        
             Smith/RTP/USEPA/                                           
             US                                                      To 
                                      Anne Pope/RTP/USEPA/US@EPA        
             01/17/2007 10:02                                        cc 
             AM                                                         
                                                                Subject 
                                      Re: tox values for PCB congeners  
                                      (Document link: Anne Pope)        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        



Hi, Anne:

Happy new year to you, too!

Actually, most of the proposed additions are homologs, not congeners.
On that list, only 2,4,4'-tri-, 2-mono-, and deca- are congeners.  None
of the three has any information that would support a different URE.

The rest (i.e., homologs) are mixtures of congeners with the same level
of chlorination, but with the chlorines at different positions.  There
is some information that would let us use different UREs for some of
these, but it's not possible unless you know the exact compounds within
the homologous group.  For example, 2,2',4,6,6'-pentachlorobiphenyl
would use the generic URE for PCBs, but we could assign a different URE
to 2,3,3',4,4'-pentachlorobiphenyl.  In other words, the pattern of
chlorine substitution is critical to the process.

The bottom line is if the requestors have any congener-specific data for
these homologous mixtures (e.g., exactly what congeners are included in
"total heptachlorobiphenyls), then we may be able to do something.
Otherwise there's probably no alternative to using the same old PCB URE,
which makes me wonder why they want to subcategorize.

Best,
Roy
_______________
Roy L. Smith, Ph.D.
Office of Air Quality Planning & Standards (C539-02)
US EPA, RTP, NC 27711
(919) 541-5362



                                                                        
             Anne                                                       
             Pope/RTP/USEPA/U                                           
             S                                                       To 
                                      Roy Smith/RTP/USEPA/US@EPA        
             01/10/2007 08:36                                        cc 
             AM                       Ted Palma/RTP/USEPA/US@EPA        
                                                                Subject 
                                      tox values for PCB congeners      
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        



Roy

Happy New year......

Here is list of PCB congeners that Great Lakes States wanted added to
the NEI .    Will the UREs be different for each PCB congener or will we
use the PCB URE that we used in 99 NATA?  Thanks- for looking into the
list.

anne

                                                                   
 CAS#            Pollutant                                         
                                                                   
 7012-37-5       2,4,4'-Trichlorobiphenyl                          
                                                                   
 2051-60-7       2-Monochlorobiphenyl                              
                                                                   
 2051-24-3       Decachlorobiphenyl                                
                                                                   
 2050-68-2       Dichlorobiphenyl                                  
                                                                   
 28655-71-2      Heptachlorobiphenyls, Total                       
                                                                   
 26601-64-9      Hexachlorobiphenyls, Total                        
                                                                   
 25429-29-2      Pentachlorobiphenyls, Total                       
                                                                   
 26914-33-0      Tetrachlorobiphenyls, Total                       
                                                                   
                                                                   




thanks  anne

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