Fetal toxicity and teratogenicity of arsenic (7440382) exposure were investigated in hamsters. Female golden-Syrian-hamsters were administered sodium-arsenite (7784465) by gavage in a single dose of 25 milligrams per kilogram (mg/kg) on gestation days 8, 11, or 12 or a dose of 20mg/kg on days 9 and 10. An intraperitoneal injection of 5mg/kg sodium-arsenite was given on gestation days 8, 11, or 12 or a dose of 2.5mg/kg on days 9 or 10. Females were killed on day 15 and litters were examined for prenatal mortality, malformations, and fetal weight. Maternal liver and body weights were also obtained. Treatment with 20mg/kg on days 9 or 10 or with 25mg/kg on day 11 had no significant effect on fetal growth or survival; however, treatment with the higher dose on days 8 or 12 increased prenatal deaths and inhibited growth in day 12 treated fetuses. No morphological effects were seen in day 12 treated fetuses. No morphological effects were seen in orally treated mothers. Seven of 57 gavaged mothers died. Intraperitoneal injection inhibited fetal growth only by treatment on days 11 or 12. Prenatal mortality was significantly increased following maternal dosing on days 8 or 11 only. Gross malformations were seen only in fetuses exposed on days 8 or 9. Micromelia, syndactyly, micrognathia, and encephalocoel (day 8) and micromelia, facial malformation, and twisted hindlimb (day 9) were seen. There were no deaths among intraperitoneally dosed females. No changes of maternal liver/body weight ratios were found with the exception of increased liver weights in the orally treated day 12 group. The authors conclude that the hamster fetus can be affected by oral and intraperitoneal treatment to the mother with inorganic trivalent arsenic; however, oral dosing is significantly less damaging.