Developmental toxicity of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). II. Multireplicated dose-response studies with technical and analytical grades of 2,4,5-T in four-way outcross mice.
A series of multireplicated developmental toxicity studies were conducted in four-way outcross mice and CD-1 outbred mice administered either analytical or technical grades of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) by gavage on Gestational Days 6 through 14. The formulations of 2,4,5-T differed by a factor of 10-fold in 2,3,7,8-tetrachlorodibenzo-p-dioxin levels. Reduced fetal weight and increased incidences of cleft palate and embryolethality were the most significant prenatal effects of both formulations of 2,4,5-T observed in all strains/stocks of mice. Both the outcross and outbred mice exhibited a dose-response relationship with each of the above endpoints and the dose-response curves were parallel. There were no embryotoxic or fetotoxic differences between the technical and analytical grades of 2,4,5-T with regard to extent of fetal weight reduction, resorption rate, or cleft palate incidence. There was little difference in the results between the four-way outcross mouse and the CD-1 outbred mouse.
Nelson
C J
CJ
USEPA (MD-56), Research Triangle Park, North Carolina 27711.
Holson
J F
JF
Gaines
T B
TB
LaBorde
J B
JB
McCallum
W F
WF
Wolff
G L
GL
Sheehan
D M
DM
Young
J F
JF
D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000633:toxicity*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D007044:Hysterectomy; D051379:Mice; D011247:Pregnancy; D013045:Species Specificity; D013723:Teratogens / Q000633:toxicity*
D013723:Teratogens; D015085:2,4,5-Trichlorophenoxyacetic Acid