+----------------------------+-----------------------------------------+
| > **Lydia                  |                                         |
| > Wegman/RTP/USEPA/US**    |                                         |
| >                          |                                         |
| > 05/01/2008 12:46 AM      |                                         |
+----------------------------+-----------------------------------------+

> To
>
> \"King, Heidi R.\" \<Heidi_R.\_King@omb.eop.gov\>, \"Fraas, Arthur
> G.\" \<Arthur_G.\_Fraas@omb.eop.gov\>
>
> cc
>
> Tricia Crabtree/RTP/USEPA/US@EPA, Karen Martin/RTP/USEPA/US@EPA,
> Robert Meyers/DC/USEPA/US@EPA, Jason Burnett/DC/USEPA/US@EPA
>
> Subject
>
> Re: air-to-blood ratio section

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We\'ll plan to discuss this later this morning.

\-\-\-\-- Original Message \-\-\-\--

**From:** \"King, Heidi R.\" \[Heidi_R.\_King@omb.eop.gov\]

**Sent:** 05/01/2008 12:16 AM AST

**To:** Lydia Wegman; \"Fraas, Arthur G.\"
\<Arthur_G.\_Fraas@omb.eop.gov\>

**Cc:** Tricia Crabtree; Karen Martin; Robert Meyers; Jason Burnett

**Subject:** RE: air-to-blood ratio section

Lydia,

Thank you for this draft.  Two comments:

1\.  We failed to note additional or clarified support for the higher
ratios.  We remain somewhat uncomfortable with characterizing the
science-based support for a ratio of 1:7 as equivalently robust to the
science-based support for standards ranging up to 1:6.  I believe we'll
pick up the conversation in the morning.

2.  Questions regarding "reanalysis" and "potentially" on p 4:

More recently, a study of changes in children's blood Pb levels
associated with reduced Pb emissions and associated air concentrations
near a Pb smelter in Canada (for children through age six in age)
reports a ratio of 1:6 and **reanalysis** \<\< Did the Agency mean to
say additional analysis ??  Our conversation had not left me with the
impression that the Hilts dataset has been reanalyzed by the Agency \>\>
of the data by EPA for the initial time period of the study resulted in
a ratio of 1:7 (CD, pp. 3-23 to 3-24; Hilts, 2003).[\[1\]]{.underline} 
Ambient air and blood Pb levels associated with the Hilts (2003) study
range from 1.1 to 0.03 µg/m3, and associated population mean blood Pb
levels range from 11.5 to 4.7 µg/dL, which are lower than levels
associated with the older studies cited in the 1986 Criteria Document
(USEPA, 1986).

Sources of uncertainty **potentially**  \<\< The sentence reads well
without "potentially".  I believe these uncertainties are not
potentially related; they were identified by the author as related \>\>
related to air-to-blood ratios obtained from Hilts (2003) study have
been identified.  

Best regards,

heidi

**From:** Wegman.Lydia@epamail.epa.gov
\[mailto:Wegman.Lydia@epamail.epa.gov\]

**Sent:** Wednesday, April 30, 2008 11:25 PM

**To:** King, Heidi R.; Fraas, Arthur G.

**Cc:** Crabtree.Tricia@epamail.epa.gov; Martin.Karen@epamail.epa.gov;
Meyers.Robert@epamail.epa.gov; Burnett.Jason@epamail.epa.gov

**Subject:** Fw: air-to-blood ratio section

\-\-\-\--Forwarded by Lydia Wegman/RTP/USEPA/US on 04/30/2008 11:24PM
\-\-\-\--

To: Wegman Lydia@EPA

From: Karen Martin/RTP/USEPA/US

Date: 04/30/2008 10:28PM

Subject: air-to-blood ratio section

Karen Martin, Ph.D.

Office of Air Quality Planning and Standards

U.S. EPA (C504-06)

Research Triangle Park, NC 27711

phone: (919) 541-5274

fax: (919) 541-0237

martin.karen@epa.gov

[\[1\]]{.underline} This study considered changes in ambient air Pb
levels and associated blood Pb levels over a five-year period which
included closure of an older Pb smelter and subsequent opening of a
newer facility in 1997 and a temporary (3 month) shutdown of all
smelting activity in the summer of 2001. The author observed that the
air-to-blood ratio for children in the area over the full period was
approximately 1:6. The author noted limitations in the dataset
associated with exposures in the second time period, after the temporary
shutdown of the facility in 2001, including sampling of a different age
group at that time and a shorter time period (3 months) at these lower
ambient air Pb levels prior to collection of blood Pb levels.
Consequently, EPA calculated an alternate air-to-blood Pb ratio based on
consideration for ambient air Pb and blood Pb reductions in the first
time period (after opening of the new facility in 1997).