Thus, as a biological marker of dose, blood lead levels can be a reflection of acute external exposure, internal bone lead stores released into blood, but, most commonly, a steady-state mixture of both external exposure and internal stores with almost no ability to distinguish between either.
We describe two collaborative studies on tobacco smoking, in which markers of internal dose (arylamine-hemoglobin adducts) and markers of genetically-based metabolic polymorphism have been coupled.
In this framework, exposure biomarkers (e.g., markers of internal dose) and early effect markers (e.g., DNA adducts) are considered intermediate points that can be related back to exposure and forward to disease (Perera and Weinstein 2000).
Other factors causing heterogeneity include baseline 25(OH D, final 25(OH D, baseline markers of inflammation, dose of vitamin D used, type of vitamin D used (D2 or D3) and duration of treatment.
Additional studies of the genotoxic and hematologic effects of formaldehyde exposure in occupational cohorts and in experimental animals would be useful, and such studies should incorporate sensitive biological markers of internal dose.
Biological markers of internal dose are useful for improving the extrapolation of health effects from exposures to high levels of toxic air pollutants in animals to low, ambient exposures in humans.
This interpretation is consistent with the argument that established risk factors such as early menarche and late menopause can be considered markers of cumulative dose of oestrogen (Henderson and Feigelson, 2000).
Twenty-seven cohaves have measured or are measuring contaminants or their metabolites as markers of internal dose, mostly in the categories of metals, persistent organic pollutants, and tobacco smoke (Table 4).
In this paper, the KXRF method will be briefly reviewed, followed by a summary of several Superfund-supported studies (and others) of blood lead and KXRF-measured bone lead in which these measures are compared as biologic markers of lead dose.
These are generic markers of the incurred dose and indicate the physical radiation dose to the patient.
