Consequences of Prolonged Inhalation of Ozone on F344/N Rats: Collaborative Studies. Part VI: Background and Study Design

In 1987, the Health Effects Institute entered into a partnership with the National Toxicology Program (NTP) to evaluate the effects of prolonged ozone exposure on F344/N rats. The NTP studies focused on carcinogenicity, while HEI supported eight studies that addressed the biochemical, functional, and structural endpoints and a biostatistical study that developed a sample allocation design and helped to integrate the research findings. The purpose of this report is to provide a brief description of the Project protocol, to discuss the allocation strategy for the animals assigned to HEI investigators, and to present the histopathologic findings for the HEI animals.