Subchronic lead feeding study in male rats and micropigs.

This study compared the lead uptake from contaminated test soil of known lead concentration with a soluble lead acetate standard, which was considered to be 100% bioavailable. This study also compared the lead bioavailability from this lead-contaminated soil between rats and micropigs. Harlan Sprague-Dawley rats and Yucatan micropigs were fed lead-contaminated soil as a 5% (w/w) mixture with their diet. The lead-contaminated soil was either a specific test soil of known lead concentration (1000 microg/g) or basal low concentration lead soil ( approximately 135 microg/g), which was spiked with lead acetate to match the lead content of the test soil. The effective diet lead concentration was 50 microg Pb/g diet. Results demonstrated that rats reached steady-state concentrations of blood lead by week 2, whereas micropigs did not reach steady state until week 4. In addition, final blood lead concentrations in micropigs were four-fold higher than those in rats. In the micropigs, the final blood lead levels in the test soil study group were significantly lower than those in the lead acetate study group, although there was no significant difference between study groups in the rats. Tissue lead concentrations were significantly higher in micropigs than those in the rats, although the diet lead concentrations in both sets of animals were the same. In summary, because of the greater sensitivity in demonstrating higher tissue lead incorporation in micropigs as compared to rats, the micropig is a better animal model for demonstrating the differences in relative lead bioavailability when testing different sources of lead-contaminated soils.

Subchronic lead feeding study in male rats.

This study was done to establish baseline information on the bioavailability of low levels of different species of lead by oral feeding in young rats and to compare this with lead-contaminated soils of similar dosage. These results can be used to help establish low-level risk assessments for lead exposure in children. Lead acetate was used in this study as a point of reference because it was considered to be 100% bioavailable. The required amounts of either lead acetate or lead nitrate were added to the control soil of 135 mg/kg lead to match the targeted test soil lead concentrations of 375, 750, 1500, and 3000 mg/kg lead. This lead-contaminated soil was mixed 5% (soil/diet) by weight with a semipurified lab chow diet, which resulted in final dietary lead concentrations of 6.75, 18.75, 37.5, 75, and 150 microg Pb/g diet. Results from this study indicated that (1) the dietary lead concentrations used did not result in any overt signs of lead toxicity (i.e., no significant effect on body weight gain, food consumption, or fecal output), (2) there were significant dose-dependent increases in fecal lead concentration and total fecal lead output, although there were no significant differences among study groups, (3) there was a time-dependent decrease in net whole-body lead uptake from a total group average of 65% at week 1 down to approximately 40% by week 5, and (4) there were no significant differences in terminal blood lead levels among study groups. Results from this study demonstrated a significant dose-dependent increase in tissue lead concentrations (mug Pb per g tissue weight) for bone, kidney, and liver for all study groups. There were no significant differences between the lead acetate and the test soil study groups at any lead dosages; however, there was a significantly increased lead incorporation into the bones from the lead nitrate study group. In summary, these results demonstrate that rats metabolize and handle lead of relatively small particle size from different soils and from different sources in a similar manner, although the use of lead acetate as the standard for 100% bioavailability might need to be reevaluated.

Telepsychiatry in juvenile justice settings.

Telepsychiatry is emerging as a valuable means of providing mental health care in juvenile justice settings. Youth in the juvenile justice system have high levels of psychiatric morbidity. State and local juvenile justice systems frequently struggle to provide specialized psychiatric care, as these systems have limited resources and often operate in remote locations. Case studies in the use of telepsychiatry to provide improved care in juvenile corrections in 4 states are described, along with a review of advantages and disadvantages of telepsychiatry in these settings.