Subchronic Oral Toxicity Evaluation of Lanthanum: A 90-day, Repeated Dose Study in Rats / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>The present study was undertaken to evaluate the subchronic toxicity of lanthanum and to determine the no observed adverse effect level (NOAEL), which is a critical factor in the establishment of an acceptable dietary intake (ADI).</p><p><b>METHODS</b>In accordance with the Organization for Economic Co-operation and Development (OECD) testing guidelines, lanthanum nitrate was administered once daily by gavage to Sprague-Dawley (SD) rats at dose levels of 0, 1.5, 6.0, 24.0, and 144.0 mg/kg body weight (BW) per day for 90 days, followed by a recovery period of 4 weeks in the 144.0 mg/kg BW per day and normal control groups. Outcome parameters were mortality, clinical symptoms, body and organ weights, serum chemistry, and food consumption, as well as ophthalmic, urinary, hematologic, and histopathologic indicators. The benchmark dose (BMD) approach was applied to estimate a point of departure for the hazard risk assessment of lanthanum.</p><p><b>RESULTS</b>Significant decreases were found in the 144.0 mg/kg BW group in the growth index, including body weight, organ weights, and food consumption. This study suggests that the NOAEL of lanthanum nitrate is 24.0 mg/kg BW per day. Importantly, the 95% lower confidence value of the benchmark dose (BMDL) was estimated as 9.4 mg/kg BW per day in females and 19.3 mg/kg BW per day in males.</p><p><b>CONCLUSION</b>The present subchronic oral exposure toxicity study may provide scientific data for the risk assessment of lanthanum and other rare earth elements (REEs).</p>

Neurobehavioral Assessment of Rats Exposed to Yttrium Nitrate during Development / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>The aim of this study was to assess the effects of yttrium nitrate on neurobehavioral development in Sprague-Dawley rats.</p><p><b>METHODS</b>Dams were orally exposed to 0, 5, 15, or 45 mg/kg daily of yttrium nitrate from gestation day (GD) 6 to postnatal day (PND) 21. Body weight and food consumption were monitored weekly. Neurobehavior was assessed by developmental landmarks and reflexes, motor activity, hot plate, Rota-rod and cognitive tests. Additionally, brain weights were measured on PND 21 and 70.</p><p><b>RESULTS</b>No significant difference was noted among all groups for maternal body weight and food consumption. All yttrium-exposed offspring showed an increase in body weight on PND 21; however, no significant difference in body weight for exposed pups versus controls was observed 2 weeks or more after the yttrium solution was discontinued. The groups given 5 mg/kg daily decreased significantly in the duration of female forelime grip strength and ambulation on PND 13. There was no significant difference between yttrium-exposed offspring and controls with respect to other behavioral ontogeny parameters and postnatal behavioral test results.</p><p><b>CONCLUSION</b>Exposure of rats to yttrium nitrate in concentrations up to 45 mg/kg daily had no adverse effects on their neurobehavioral development.</p>