The development and validation of biomarkers that link environmental exposu
res to the pathogenesis of human disease is a leading priority in the field
of environmental research. The validation of biomarkers as early predictor
s of clinical disease can enhance health risk assessment and contribute to
effective new disease prevention policies in environmental and occupational
settings. The process of validating biomarkers involves dealing with a ran
ge of characteristics that include the intrinsic qualities of the biomarker
, its determinants, and the analytic procedure. We discuss here a three pha
se approach to validation. The final phase, consisting of longitudinal stud
ies, is reached after the biomarker has been determined to be technically r
eliable and after the effect of external variables on the association with
the outcome has been evaluated. We provide some examples of biomarkers repu
ted to be early predictors of cancer and cardiovascular disease (CVD). We t
hen present original data to support the potential of DNA adducts to predic
t cancer and show, through re-evaluation of the Italian database on cytogen
etic biomarkers, a lack of association between the frequency of chromosomal
aberrations in circulating lymphocytes and CVD mortality rates - a finding
that should not be considered conclusive. In general, whenever a biomarker
has been determined to be a valid predictor of disease, it should be used
in risk assessment and public health policy. (C) 2001 Elsevier Science B.V.
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