# Maternal–Fetal Transfer and Toxicokinetics of 2,2′,5,5′-Tetrachlorobiphenyl, [14C]-PCB52, Following Intratracheal Administration

## TL;DR

This study examines how a type of PCB chemical moves through a pregnant rat's body and into the fetus after being inhaled, showing where it accumulates and how long it stays.

## Contribution

The study provides the first comprehensive whole-body disposition analysis of PCB52 in dams and fetuses following lung exposure during gestation.

## Key findings

- PCB52 was rapidly distributed to maternal serum, lung, heart, and liver, with accumulation in ovaries, brain, and mammary glands.
- The peak concentration of PCB52 in the placenta, fetus, and amniotic fluid was reached 1.7 hours after exposure.
- Maternal serum levels were significantly correlated with levels in amniotic fluid, placenta, and fetus.

## Abstract

Despite increased recognition of the adverse impacts
of PCB exposure
on human health, comprehensive risk assessments, particularly regarding
inhalation exposure and effects on the developing fetus, are lacking.
Out of all PCB congeners, lower-chlorinated PCBs have been more prevalent
in indoor and outdoor atmospheres. Thus, we investigated in
vivo toxicokinetics and placental transfer of radiolabeled
[14C]-PCB52 (0.157 mg/kg administered intratracheally)
in Sprague–Dawley rats at gestational day 11 ± 1. Following
dosing, 99.4 ± 0.5% of the administered dose was distributed
to the systemic circulation. Radioactivity disappeared biexponentially
following lung exposure, with 41.1% of the dose retained after 96
h. PCB52 was rapidly distributed to the maternal serum, lung, heart,
and liver, with subsequent accumulation in the ovaries, brain, white
and brown adipose, muscle, and mammary glands. The time to reach a
maximum concentration in the maternal serum was 0.21 h, with an apparent
terminal elimination half-life of 40.7 h. The peak concentration of
[14C]-PCB52 and its metabolites in the placenta, fetus,
and amniotic fluid was achieved 1.7 h after exposure, with a fetal
half-life of 34.8 h. The maternal serum level was significantly correlated
with levels in amniotic fluid, placenta, fetus, and the maternal brain.
However, PCB52 exposure in the placenta, fetus, and amniotic fluid
was limited with their respective maternal serum exposure ratio values
of 0.5, 0.27, and 0.05. These results demonstrate for the first time
a comprehensive whole-body disposition of PCB52 in dams and fetuses
after lung exposure during gestation. PCB52 and its metabolites accumulate
predominantly in the ovaries, brain, and mammary glands. The apparent
half-life of PCB52 in developing fetuses and placenta is comparable
to that of maternal serum. This study provides novel quantitative
foundations for the development and evaluation of physiologically
based toxicokinetic modeling to inform the exposure and risk assessment
for public health decisions.