[ RadSafe ] Research shows CT and nuclear imaging tests during pregnancy do not boost the risk of childhood cancer

[Howard Long]

Otto, I support Bobby in this, with what info is available to me now.

No doubt, pregnancies with x-ray were more often followed by complications, 
(Doll's study) but that is why the xrays were taken, --- expected complications! 

I did pelvimetry in my office 50 years ago and remember that women with smaller pelvis had poor nutrition -- one well known reason for fetal malformation. 


Howard Long 

On Oct 4, 2010, at 3:05 PM, "Otto G. Raabe" <ograabe at ucdavis.edu> wrote:

> At 12:51 PM 10/2/2010, Scott, Bobby wrote:
>> Research shows CT and nuclear imaging tests during pregnancy do not
>> boost the risk of childhood cancer
>> 
>> http://www.ices.on.ca/webpage.cfm?site_id=1&org_id=117&morg_id=0&gsec_id
> 
> *************************
> 
> As you surely already know, beginning in 1956 Alice Stewart  and her followers have demonstrated a strong statistical association between pre-natal X-rays and childhood cancer in the Oxford Survey of Childhood Cancer OSCC .  These data and positions received considerable prestige with the review of the data by Doll and Wakeford (The British Journal of Radiology, Vol 70, Issue 830 130-139,1997)
> 
> Risk of childhood cancer from fetal irradiation
> 
> R Doll and R Wakeford 
> Imperial Cancer Research Fund Cancer Studies Unit, Radcliffe Infirmary, Oxford, UK. 
> 
> The association between the low dose of ionizing radiation received by the fetus in utero from diagnostic radiography, particularly in the last trimester of pregnancy, and the subsequent risk of cancer in childhood provides direct evidence against the existence of a threshold dose below which no excess risk arises, and has led to changes in medical practice. Initially reported in 1956, a consistent association has been found in many case-control studies in different countries. The excess relative risk obtained from combining the results of these studies has high statistical significance and suggests that, in the past, a radiographic examination of the abdomen of a pregnant woman produced a proportional increase in risk of about 40%. A corresponding causal relationship is not universally accepted and this interpretation has been challenged on four grounds. On review, the evidence against bias and confounding as alternative explanations for the association is strong. Scrutiny of the objections to causality suggests that they are not, or may not be, valid.   A causal explanation is supported by evidence indicating an appropriate dose-response relationship and by animal experiments. It is concluded that radiation doses of the order of 10 mGy received by the fetus in utero produce a consequent increase in the risk of childhood cancer. The excess absolute risk coefficient at this level of exposure is approximately 6% per gray, although the exact value of this risk coefficient remains uncertain.
> 
> 
> **********************************************
> Prof. Otto G. Raabe, Ph.D., CHP
> Center for Health & the Environment
> University of California
> One Shields Avenue
> Davis, CA 95616
> E-Mail: ograabe at ucdavis.edu
> Phone: (530) 752-7754   FAX: (530) 758-6140
> ***********************************************