Acute inhalation study in the rat of comparative uptake, distribution and excretion for different cadmium containing materials.

Single 2-hr inhalation exposures were conducted at levels of approximately 100 mg/m3 (based on cadmium content) with the use of two cadmium pigments (cadmium red and cadmium yellow), a dust of cadmium carbonate, and a cadmium fume. An air exposed control group also was included. The rate of elimination of cadmium in the urine and feces, and the cadmium levels in selected tissues were measured at several intervals following the exposure. In addition, observations of the animals for clinical signs of toxicity and mortality and measurements of organ weights and body weight were performed. There was no mortality in the control, cadmium red or cadmium yellow exposed groups. In the cadmium carbonate exposed group, 3 out of 52 rats died, and in the cadmium fume exposed group, 25 out of 52 rats died. Cadmium blood levels indicated that cadmium from the cadmium carbonate and fume was absorbed to a greater degree than cadmium from the red and yellow pigments. The major route of elimination of cadmium following exposure to the two pigments was via the feces, with 80% being cleared within 24 hr. Elimination was slower following exposure to the carbonate. The levels of cadmium in the liver and kidneys were much higher following exposure to the carbonate than following exposure to the red and yellow pigments. It appeared that these cadmium compounds were not equivalent with respect to toxicity, absorption, distribution or excretion. Exposure to the two insoluble compounds, cadmium red and cadmium yellow, did not produce mortality and resulted in rapid elimination in the feces with lower tissue levels of cadmium than observed following exposure to the cadmium carbonate.

A method for repeated evaluation of benzene uptake in rats and mice during a six hour inhalation period.

Benzene uptake measurements and respiratory minute volume (RMV) were assessed in rats and mice during a 6-hour inhalation exposure to 300 ppm (v/v) of benzene vapor. The values for benzene uptake and RMV were used to compare predictions of inhaled dose in both species. The theoretical prediction assumed an unchanging RMV. The next prediction allowed adjustments for changes in RMV during exposure. The final prediction addressed benzene uptake directly. The uptake characteristics of benzene in both species were different from the theoretical prediction, from the prediction adjusted for changing RMV and from each other. The greatest difference was seen in rats where the observed benzene dose was only 28% of the theoretical value. The experiment was not designed to elucidate the causes for the difference between the predictions, nor was the data sufficient to suggest whether the rat or the mouse was a suitable model of benzene uptake in humans.

Whirling disease Myxosoma cerebralis spore concentration using the continuous plankton centrifuge.

A method for concentrating and detecting the spores of the cause of whirling disease (Myxosoma cerebralis) of salmonids is described. The method involves homogenization of head skeletons, screening out tissue shreds, and concentrating with a continuous plankton centrifuge.