Limits...
An age-specific kinetic model of lead metabolism in humans.

Leggett RW - Environ. Health Perspect. (1993)

Bottom Line: Moreover, there is growing evidence that levels of lead intake considered inconsequential just a few years ago can result in subtle, adverse health effects, particularly in children.Transport of lead between compartments is assumed to follow linear, first-order kinetics provided the concentration in red blood cells remains below a nonlinear threshold level, but a nonlinear relation between plasma lead and red blood cell lead is modeled for concentrations above that level.The model is shown to be consistent with data on human subjects exposed to lead under a variety of experimental and natural conditions.

View Article: PubMed Central - PubMed

Affiliation: Health Sciences Research Division, Oak Ridge National Laboratory, TN 37831.

ABSTRACT
Although considerable progress has been made in recent years in reducing human exposures to lead, the potential for high intake of this contaminant still exists in millions of homes and in many occupational settings. Moreover, there is growing evidence that levels of lead intake considered inconsequential just a few years ago can result in subtle, adverse health effects, particularly in children. Consequently, there have been increased efforts by health protection agencies to develop credible, versatile methods for relating levels of lead in environmental media to levels in blood and tissues of exposed humans of all ages. In a parallel effort motivated largely by the Chernobyl nuclear accident, the International Commission on Radiological Protection (ICRP) is assembling a set of age-specific biokinetic models for calculating radiation doses from environmentally important radionuclides, including radioisotopes of lead. This paper describes a new age-specific biokinetic model for lead originally developed for the ICRP but expanded to include additional features that are useful for consideration of lead as a chemical toxin. The model is developed within a generic, physiologically motivated framework designed to address a class of calciumlike elements. This framework provides a useful setting in which to synthesize experimental, occupational, and environmental data on lead and exploit common physiological properties of lead and the alkaline earth elements. The modular design is intended to allow researchers to modify specific parameter values or model components to address special problems in lead toxicology or to incorporate new information. Transport of lead between compartments is assumed to follow linear, first-order kinetics provided the concentration in red blood cells remains below a nonlinear threshold level, but a nonlinear relation between plasma lead and red blood cell lead is modeled for concentrations above that level. The model is shown to be consistent with data on human subjects exposed to lead under a variety of experimental and natural conditions.

Show MeSH

Related in: MedlinePlus

© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC1519877&req=5


An age-specific kinetic model of lead metabolism in humans.

Leggett RW - Environ. Health Perspect. (1993)

© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1519877&req=5

Bottom Line: Moreover, there is growing evidence that levels of lead intake considered inconsequential just a few years ago can result in subtle, adverse health effects, particularly in children.Transport of lead between compartments is assumed to follow linear, first-order kinetics provided the concentration in red blood cells remains below a nonlinear threshold level, but a nonlinear relation between plasma lead and red blood cell lead is modeled for concentrations above that level.The model is shown to be consistent with data on human subjects exposed to lead under a variety of experimental and natural conditions.

View Article: PubMed Central - PubMed

Affiliation: Health Sciences Research Division, Oak Ridge National Laboratory, TN 37831.

ABSTRACT
Although considerable progress has been made in recent years in reducing human exposures to lead, the potential for high intake of this contaminant still exists in millions of homes and in many occupational settings. Moreover, there is growing evidence that levels of lead intake considered inconsequential just a few years ago can result in subtle, adverse health effects, particularly in children. Consequently, there have been increased efforts by health protection agencies to develop credible, versatile methods for relating levels of lead in environmental media to levels in blood and tissues of exposed humans of all ages. In a parallel effort motivated largely by the Chernobyl nuclear accident, the International Commission on Radiological Protection (ICRP) is assembling a set of age-specific biokinetic models for calculating radiation doses from environmentally important radionuclides, including radioisotopes of lead. This paper describes a new age-specific biokinetic model for lead originally developed for the ICRP but expanded to include additional features that are useful for consideration of lead as a chemical toxin. The model is developed within a generic, physiologically motivated framework designed to address a class of calciumlike elements. This framework provides a useful setting in which to synthesize experimental, occupational, and environmental data on lead and exploit common physiological properties of lead and the alkaline earth elements. The modular design is intended to allow researchers to modify specific parameter values or model components to address special problems in lead toxicology or to incorporate new information. Transport of lead between compartments is assumed to follow linear, first-order kinetics provided the concentration in red blood cells remains below a nonlinear threshold level, but a nonlinear relation between plasma lead and red blood cell lead is modeled for concentrations above that level. The model is shown to be consistent with data on human subjects exposed to lead under a variety of experimental and natural conditions.

Show MeSH
Related in: MedlinePlus