DEVELOPMENTAL TOXICITY EVALUATION OF ORAL ALUMINUM IN RATS Abd El- Azeim A. Khalaf; Ashraf M. Morgan; Mohey M. Mekawy and Maged F. Ali J. Egypt. Soc. Toxicol. (Vol. 37: 11-26 July 2007) WWW.estoxicology.org Toxicology and Forensic Medicine Department, Faculty of Veterinary Medicine, Cairo University, Egypt. ABSTRACT The present study was designed to elucidate the adverse effects of the orally administered aluminum (Al) on the growing fetus and consequently on the animal wealth in our country. This aim has been achieved by studying the teratogenic, perinatal and postnatal effects of aluminum chloride when administered orally at 345 mg/kg body weight to female rats during organogenesis, fetal and/ or lactation periods. The results showed that Al chloride exposure on days 6-15 of gestation produced a significantly higher percentage of postimplantation death, resorptions, morphological, visceral and skeletal anomalies in the obtained fetuses compared to the control group. In addition, the live fetuses' percentage, mean fetal body weight and placental weights were significantly decreased. The obtained data revealed also that Al chloride exposure on 6 th day of gestation till weaning induced significant increase in the percentage of dams showed delayed birth date and signs of dystocia. In addition, it induced a significant increase in the percentage of postimplantation loss, dead fetuses; fetuses showing neurobehavioral and respiratory symptoms and those born with morphological abnormalities. Moreover, it decreased the live/ birth, survival and viability indices and weight gain of these fetuses compared with control. The Al- induced effects on the obtained fetuses from Al chloride treated dams through lactation period included significant increase in the percentage of postnatal deaths, fetal stunted growth with a significantly increased percentage of nervous and respiratory symptoms prior to death. Consequently, the survival and viability indices were reduced. Moreover, the weight gain during lactation was significantly reduced. Brain examination of the obtained fetuses from all exposed dams throughout this study showed different histopathological changes. It can be concluded that Al chloride exposure of female rats during gestation and/ or lactation periods caused teratogenic, perinatal and postnatal adverse effects on their progeny. Keywords: Aluminum chloride, Teratogenicity, Perinatal, Postnatal, Rats, Lactation, Survival, Viability. INTRODUCTION The greatly increased use of metals has introduced a new noxious hazard to animals and humans. Therefore, the persistence of metals in the environment has led to growing concern about the direct and indirect exposures of pregnant females and their unborn babies. Placental transfer of most metals places the health of unborn at the highest risk. Also, the newborn can be affected through breast feeding or direct exposure (Sastray, 1995 and WHO, 1997). Therefore, prolonged exposure to some of these contaminants may induces teratogenic effects, abortion, reproductive failure and/ or immunotoxicity (Nordal et al., 1989; Piramanayagam et al., 1996; Carson, 2000 and Sharma and Mishra, 2006) both by their direct cellular toxic action and by interfering indirectly with the hypothalamo- hypophyseal function (Krause, 1977; Levine et al., 1992 and Flora et al., 2003). Nowadays, aluminum (Al) is widely used in treatment of drinking water, drugs (e.g., Antacids), deodorants and antiperspirants preparations, preservation of wood; the disinfection of stables and slaughter houses and in manufacture of alloys (Jackson, 1986; WHO, 1997 and ATSDR, 2006). Al is present also in many food products, vegetables, cereals and beverages (Filipek et al., 1987; U. S. Public Health Service, 1992; Beliles, 1994 and