Toxicological Sciences, Vol 51, 87-97, Copyright © 1999 by Society of Toxicology
JF Holson, DG Stump, CE Ulrich and CH Farr
A review of the literature revealed no published inhalational developmental
toxicity studies of arsenic performed according to modern regulatory
guidelines and with exposure throughout gestation. In the present study,
inorganic arsenic, as arsenic trioxide (As(+3), As2O3), was administered
via whole-body inhalational exposure to groups of twenty-five Crl:CD(SD)BR
female rats for six h per day every day, beginning fourteen days prior to
mating and continuing throughout mating and gestation. Exposures were begun
prior to mating in order to achieve a biological steady state of As(+3) in
the dams prior to embryonal-fetal development. In a preliminary exposure
range-finding study, half of the females that had been exposed to arsenic
trioxide at 25 mg/m3 died or were euthanized in extremis. In the definitive
study, target exposure levels were 0.3, 3.0, and 10.0 mg/m3. Maternal
toxicity, which was determined by the occurrence of rales, a decrease in
net body weight gain, and a decrease in food intake during pre- mating and
gestational exposure, was observed only at the 10 mg/m3 exposure level.
Intrauterine parameters (mean numbers of corpora lutea, implantation sites,
resorptions and viable fetuses, and mean fetal weights) were unaffected by
treatment. No treatment-related malformations or developmental variations
were noted at any exposure level. The no-observed-adverse-effect level
(NOAEL) for maternal toxicity was 3.0 mg/m3; the NOAEL for developmental
toxicity was greater than or equal to 10 mg/m3, 760 times both the
time-weighted average threshold limit value (TLV) and the permissible
exposure limit (PEL) for humans. Based on the results of this study, we
conclude that arsenic trioxide, when administered via whole-body inhalation
to pregnant rats, is not a developmental toxicant.
ARTICLES
Absence of prenatal developmental toxicity from inhaled arsenic trioxide in rats
WIL Research Laboratories, Inc., Ashland, Ohio 44805, USA.
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