Letter to the editors

Effect of Starvation and Refeeding on the Circadian Rhythms of Hematological and Clinico-biochemical Values, and Water Intake of Rats

“…Rats are usually exposed to air pollutants during the dark period when their activity is high and they eat most food, and in many inhalation studies, an intermittent exposure schedule is used [2,[11][12]15] . The present results should be useful for evaluating results observed in chronic inhalation experiments whether they are caused by the toxicities of inhaled air pollutants or by reduced food intake and/or change in the feeding pattern.…”

Current assessment of the carcinogenic hazard of diesel exhaust

“…First, several long-term animal inhalation studies were initiated, at first by EPA 17 and General Motors. 18 Other laboratories in the U.S. and abroad also initiated studies as described below, which were designed to overcome limitations of the initial bioassays. Second, efforts were initiated to make preliminary risk assessments before the bioassay data became available.…”