Study population. NHANES III was a stratified,
multistage probability survey designed
to select a representative sample of the civilian
noninstitutionalized U.S. population
(National Center for Health Statistics 1994).
Overall, 18,629 adults ≥ 20 years of age completed
the NHANES III interview and examination
between 1988 and 1994. We excluded
2,577 participants missing data for urinary
cadmium, 105 participants missing data for
urinary creatinine, 382 participants missing
data for smoking history, 1,593 participants
missing data for other covariates, and
14 who did not have follow-up information.
After these exclusions, we included a total
of 13,958 NHANES III participants in the
present analyses. Participants we excluded due to missing data were older and more likely to
be non-Hispanic black or Mexican American
and to have a history of cardiovascular disease.
However, those we excluded from the present
study did not differ from those included in
sex, smoking, or history of cancer. The protocol
for NHANES III was approved by the
National Center for Health Statistics of the
Centers for Disease Control and Prevention
Institutional Review Board. All participants
gave written informed consent.