Document ID: EPA-HQ-OAR-2006-0735-5150
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-05-01T04:00Z

"Richard Hornung" <Richard.Hornung@cchmc.org> 

04/24/2007 05:15 PM

	

To

David Svendsgaard/RTP/USEPA/US@EPA

cc

Jee-Young Kim/RTP/USEPA/US@EPA, Dennis Kotchmar/RTP/USEPA/US@EPA,
Deirdre Murphy/RTP/USEPA/US@EPA, Zachary Pekar/RTP/USEPA/US@EPA

Subject

Re: Fw: Question regarding the Lanphear et al., 2005 study

The plot begins at 1.0 ug/dL since this is essentially the lowest value
for concurrent lead index. There are 3 or 4 slightly lower values in the
entire database (n=1333), but we decided that 1.0 was the minimum Pb
value that we were comfortable using with the log-linear model since the
intercept goes to infinity as PB moves toward zero.

 

Rick

 

Professor of Environmental Health

Director, Biostatistics & Data Management Core

Div. of Gen. & Community Pediatrics

CCHMC

3333 Burnet Ave

Mail Location 7035

Cincinnati OH 45229-3039

513-636-1948

Fax: 513-636-4402

>>> <Svendsgaard.David@epamail.epa.gov> 4/23/2007 2:04 PM >>>

Hello Richard,

One of my Colleagues has a question for you.

David J Svendsgaard, PhD

Biostatistician

EPA/ORD/NCEA/RTP, Mail Drop B-243-01

Research Triangle Park, NC 27711

Phone (919) 541-4186

Fax (919) 541-1818

                                                                        

             Zachary                                                    

             Pekar/RTP/USEPA/                                           

             US                                                      To 

                                      David                             

             04/17/2007 04:15         Svendsgaard/RTP/USEPA/US@EPA      

             PM                                                      cc 

                                      Deirdre Murphy/RTP/USEPA/US@EPA,  

                                      Jee-Young Kim/RTP/USEPA/US@EPA    

                                                                Subject 

                                      Question regarding the Lanphear   

                                      et al., 2005 study                

                                                                        

                                                                        

                                                                        

                                                                        

                                                                        

                                                                        

David,

If you would forward the following question to Dr. Hornung.

Figures 3 and 4 in the Lanphear et. al., 2005 article show the

log-linear function extending down to a blood lead level in the vicinity

of 1 ug/dL. The functions in both figures are not shown to extend below

that blood lead level. I had two questions related to these figures: (a)

what is the specific blood lead level to which the figures extend down

to and (b) what is the conceptual or theoretical basis for using this

specific point of departure in the figures? In looking at the figures, I

thought it might be the lower extent of measured blood lead levels in

the pooled population (~1.0 ug/dL), but I was not sure. Thanks,

zach

Zachary Pekar, Ph.D.

Ambient Standards Group

Office of Air and Radiation, USEPA

(919)541-3704

pekar.zachary@epa.gov