[CPEO-MEF] CDC perchlorate study

[Lenny Siegel <lsiegel@cpeo.org>]

Urinary Perchlorate and Thyroid Hormone Levels in Adolescent and Adult 
Men and Women Living in the United States

Benjamin C. Blount, James L. Pirkle, John D. Osterloh, Liza 
Valentin-Blasini and Kathleen L. Caldwell
Environmental Health Perspectives Online
October 5, 2006


Background:  Perchlorate is commonly found in the environment and known 
to inhibit  thyroid function at high doses.  Assessing the potential 
effect of low-level exposure to  perchlorate on thyroid function is an 
area of ongoing research.

Objectives: Evaluate the potential relationship between urinary levels 
of perchlorate and  serum levels of thyroid stimulating hormone (TSH) 
and total thyroxine (T4) in 2299 men  and women, aged 12 and older, 
participating in the National Health and Nutrition  Examination Survey 
(NHANES) during 2001-2002.

Methods: Multiple regression models of T4 and TSH that included 
perchlorate and  covariates known or likely to be associated with T4 or 
TSH levels: age, race/ethnicity,  body mass index, estrogen use, 
menopausal status, pregnancy status, premenarche status,  serum 
C-reactive protein, serum albumin, serum cotinine, hours of fasting, 
urinary  thiocyanate, urinary nitrate, and selected medication groups.

Results: Perchlorate was not a significant predictor of T4 or TSH levels 
in men.  For  women overall, perchlorate was a significant predictor of 
both T4 and TSH.  For women  with urinary iodine < 100 μg/L, perchlorate 
was a significant negative predictor of T4  (p < 0.0001) and a positive 
predictor of TSH (p = 0.001).  For women with urinary iodine  ≥ 100 
μg/L, perchlorate was a significant positive predictor of TSH (p = 
0.025), but not  T4 (p = 0.550).

Conclusions: These associations of perchlorate with T4 and TSH are 
coherent in  direction and independent of other variables known to 
affect thyroid function, but are at  perchlorate exposure levels 
unanticipated based on previous studies.


For the original version of this abstract as well as a link to download 
the entire report, go to
http://www.ehponline.org/docs/2006/9466/abstract.html

--


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org


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