Toxicological Sciences, Vol 52, 248-257, Copyright © 1999 by Society of Toxicology
RW Tyl, LC Fisher, DE Dodd, IM Pritts, MF Kubena, PE Losco, CM Troup, JP Lyon and TD Landry
Mated female CD (Sprague-Dawley) rats, 25/group, were exposed to toluene
diisocyanate (TDI) vapor, for six h/day on gestational days (gd) 6 through
15, at 0.00, 0.02, 0.10, or 0.50 p.p.m.. Maternal clinical signs, body
weights, and feed and water consumption were recorded throughout gestation.
At termination (gd 21), maternal body, gravid uterine, and liver weights
were recorded. Corpora lutea were counted, and implantation sites were
identified: resorptions and dead and live fetuses. All live fetuses were
examined for external alterations. One-half of the live fetuses/litter were
examined for visceral (including craniofacial) alterations. The remaining
intact fetuses/litter were stained with alizarin red S and examined for
ossified skeletal alterations. Maternal toxicity at 0.50 ppm consisted of
reduced body weights, body weight gains, feed consumption, and clinical
signs of toxicity. Water consumption was unaffected. Gestational parameters
exhibited no significant treatment-related changes, including pre- and
postimplantation loss, sex ratio/litter, or fetal body weights/litter.
Incidences of individual malformations, malformations by category
(external, visceral, and skeletal), total malformations, individual
external and visceral variations, variations by category, and total
variations were unaffected. Of 111 skeletal variants observed, only 1,
incidence of poorly ossified cervical centrum 5, was increased at 0.50 ppm,
indicating possible minimal fetotoxicity, although it occurred in the
absence of any other indications of developmental toxicity. Therefore,
exposure to TDI vapor by inhalation, during major organogenesis in CD rats,
resulted in maternal toxicity and minimal fetotoxicity at 0.50 ppm no
observed adverse effect level (NOAEL) for maternal and developmental
toxicity was 0.10 ppm. No treatment-related embryotoxicity or
teratogenicity was observed.
ARTICLES
Developmental toxicity evaluation of inhaled toluene diisocyanate vapor in CD rats
Bushy Run Research Center, Export, Pennsylvania, USA. rwt@rti.org
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