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

AX5-35
Table AX5-3.6 (cont’d). Key Studies Evaluating Chelation of Pb in Brain
Subject Exposure Protocol Chelator Observed Effects Reference
Rat, female,
LE
Group 1: 325 µg/mL Pb
acetate maternally through
weaning, and then to 30 µg/mL
until PND 30. Chelation
treatment consisted of 7 days of
30 or 60 mg/kg/d DMSA.
Group 2: 325 µg/dL
maternally and through
PND 40 and then treated to
DMSA for 7 or 21 days.
Rat, LE Exposed gestationally to
600 µg/mL Pb acetate, then
split into high and low dose
groups.
Low dose group: 20 µg/mL
from PND 21–28, followed by
30 µg/mL from PND 29–40.
High dose group: 40 µg/mL
from PND 21–28, followed by
60 µg/mL from PND 29–40.
DMSA treatment consisted of
50 mg/kg/d for 1 wk, then
25 mg/kg/d for 2 wks. Rats
received either 1 or
2 treatments at PND 40 or
40 and 70.
DMSA Seven days of DMSA effectively removed Pb from both blood and brain.
Treatment beyond 7 days further reduced brain Pb, but not blood Pb.
Reductions in Pb were greater in the second group, which the authors attribute
to the higher exposures used. The authors also hypothesize that DMSAmediated
reduction in blood Pb are a poor indicator of reductions in brain Pb.
DMSA One treatment lowered both blood Pb and brain Pb, but the brain reductions
lagged the blood reductions both temporally and in magnitude. Following the
second DMSA treatment, they observed a rebound in blood, but not brain Pb
levels.
Smith et al. (1998)
Stangle et al. (2004)