Physiologically based modeling of lead kinetics: a pilot study using data from a Canadian population

Area of Science:

• Environmental Health
• Toxicology
• Biomathematics

Background:

• Low-level chronic lead exposure poses risks to Canadian population health.
• Physiologically based modeling offers a method to approximate lead exposure when direct measurement is challenging.
• Lead's affinity for bone makes bone turnover rates crucial in kinetic models.

Purpose of the Study:

• To evaluate the O'Flaherty model's applicability for analyzing low, chronic lead exposure in a general Canadian population.
• To calibrate and revise model parameters for improved accuracy in predicting lead kinetics.
• To assess the model's utility for understanding population-level lead body burden.

Main Methods:

• Utilized the O'Flaherty lead kinetics model, incorporating age-dependent growth and bone turnover.
• Calibrated model input lead exposure to match output cortical bone lead with measured tibia lead in 263 individuals.
• Compared model outputs for trabecular bone, blood, and plasma lead with corresponding subject measurements (calcaneus, blood, serum).

Main Results:

• Initial model calibration indicated a need for parameter revision, particularly for blood lead binding and blood-to-bone clearance.
• Revised model parameters showed improved general trends for blood and plasma lead concentrations compared to measurements.
• Model predictions for trabecular lead concentration did not align with calcaneus measurements, and individual blood/plasma predictions showed scatter.

Conclusions:

• Revisions to blood lead binding and clearance parameters show promise for future studies on low lead exposure.
• The adapted O'Flaherty model, with discussed revisions, is a potentially useful tool for analyzing human lead kinetics and body burden in low-exposure populations.
• Further refinement may be needed for accurate prediction of specific tissue lead concentrations, especially in bone.