Nanocrystalline titanium dioxide and magnesium oxide in vitro dermal absorption in human skin.

The dermal absorption potential of a nanocrystalline magnesium oxide (MgO) and titanium dioxide (TiO(2)) mixture in dermatomed human skin was assessed in vitro using Bronaugh-type flow-through diffusion cells. Nanocrystalline material was applied to the skin surface at a dose rate of 50 mg/cm(2) as a dry powder, as a water suspension, and as a water/surfactant (sodium lauryl sulfate) suspension, for 8 hours. Dermal absorption of nanocrystalline MgO and TiO(2) through human skin with intact, functional stratum corneum was not detectable under the conditions of this experiment.

Examining the risks and benefits of replacing traditional dose-response with hormesis.

In responding to Drs Calabrese and Baldwin's question, 'At what point, if ever, should hormesis be employed as the principal dose response default assumption in risk assessment?', we examined the benefits of replacing traditional dose-response with hormesis. In general, hormesis provides more complete useful information for risk assessment than does traditional dose-response. A major limitation of using hormesis as a default assumption in risk estimation is the difficulty of differentiating complex low-level hormetic responses from the placebo effect.

Genetically engineered corn rootworm resistance: potential for reduction of human health effects from pesticides.

Objective And Methods: Insecticide use, grower preferences regarding genetically engineered (GE) corn resistant to corn rootworm (CRW), and the health effects of using various CRW insecticides (organophosphates, pyrethroids, fipronil and carbamates) are reviewed for current and future farm practices.

Results: Pest damage to corn has been reduced only one-third by insecticide applications. Health costs from insecticide use appear significant, but costs attributable to CRW control are not quantifiable from available data.

Group learning improves case analysis in veterinary medicine.

Introduction: Group learning has become important to professional students in the healing sciences. Groups share factual and procedural resources to enhance their performances.

Methodology: We investigated the extent to which students analyzing case-based evaluations as teams acquired an immediate performance advantage relative to those analyzing them as individuals and the extent to which group work on one problem led to better performance by individual students on related problems.