Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX5-184
Table AX5-10.9. Lead, Calcium, and Vitamin D Interactions, and Intestinal Enzymes
Compound and
Concentration Duration Species Blood Lead Effects a Authors
Ca—0.5% in diet
(low calcium)
1.2% in diet
(high calcium)
Pb—0.8% in the diet
as Pb chloride
Ca—0.1% or 1.2% in the
diet with Pb—0.1–0.8%
as Pb chloride in the diet
Ca—0.1–1.2%
Pb—0.8%
10 days White Leghorn
Cockerels
1 or 2 wks Leghorn
Cockerels
2 wks White Leghorn
Cockerels
— Dietary Pb affects intestinal Ca absorption in two different ways
depending on the dietary Ca status.
A. In chicks fed low Ca diet (0.05%), ingested Pb inhibited intestinal
47
Ca absorption, intestinal Calbindin D, and alkaline phosphatase
synthesis in a dose dependent fashion.
B. In normal calcium diets (1.2%) Pb exposure had no bearing on the
intestinal Ca absorption, or Calbindin D, or Alkaline phosphatase
synthesis and in fact elevated their levels at higher Pb concentrations.
These results indicate that the primary effects of Pb in both cases,
occur at or prior to intestinal protein synthesis involving
Cholecalciferol endocrine system.
— —Dietary Ca deficiency, initially
(1st week) stimulates Ca absorption and Calbindin D levels regardless of
dietary Pb intake.
—At 2 wks, this response is reversed by Pb.
—Intestinal Pb absorption was enhanced by Ca deficiency initially and
was inhibited by prolonged dietary Pb intake.
—Intestinal Pb absorption was increased in adequate Ca situation, but
only after 2 wks at the lower levels of dietary Pb.
— Interactions between dietary Pb and Ca-influence on serum vitamin D
levels.
—Pb ingestion and Ca deficiency alone or in combination generally
increased serum 1,25 (OH)2 D levels over the most of the range of
dietary Pb and Ca.
—In severe Ca deficiency, Pb ingestion resulted in significant decreases in
hormone concentration.
—Similarities in response profiles for 1,25 ( OH)2 D, intestinal Ca
absorption and Calbindin- D suggested major interactions between Pb
and calcium mediated changes via circulating1,25(OH)2 D
concentration.
Fullmer and Rosen
(1990)
Fullmer (1991)
Fullmer (1997)