Evaluating Toxicity of Tobacco Smoke Solutions in an In Vitro Air-Liquid-Interface Airway Model
FDA scientists from NCTR and the Center for Tobacco Products have developed an in vitro toxicity testing system. The system consists of an air-liquid-interface (ALI) human-airway tissue model and a panel of toxicity endpoints associated with human respiratory diseases. The ALI culture system was used to evaluate the toxicity of whole smoke solutions (WSS) prepared from two commercial cigarettes that differ in smoke constituents and showed time- and dose-dependent differences in mucin secretion, matrix metalloproteinase secretion, and protein carbonylation between the two WSSs.
Overall, these preliminary results suggest that using human ALI airway models to quantify disease-relevant endpoints is a potential tool for generating toxicity data that may inform tobacco regulatory activities. This study was funded by FDA's Center for Tobacco Products. A manuscript describing the study is available online at Toxicological Sciences.
For more information, please contact Xuefei Cao, Ph.D., Division of Genetic and Molecular Toxicology.
NCTR Conducting Study as Part of FDA Research on Gadolinium-Based Contrast Agents (GBCAs) for Magnetic Resonance Imaging
*Excerpt from MedWatch Safety Alert dated May 22, 2017.
An FDA review to date has not identified adverse health effects from gadolinium retained in the brain after the use of GBCAs for magnetic resonance imaging. All GBCAs may be associated with some gadolinium retention in the brain and other body tissues. However, because FDA identified no evidence to date that gadolinium retention in the brain from any of the GBCAs, including GBCAs associated with higher retention of gadolinium, is harmful, restricting GBCA use is not warranted at this time. FDA will continue to assess the safety of GBCAs and plans to have a public meeting to discuss this issue in the future.
FDA evaluated scientific publications and adverse event reports submitted to FDA. Some human and animal studies looked at GBCA use over periods longer than a year. These publications and reports show that gadolinium is retained in organs, such as the brain, bones, and skin. The publications show that linear GBCAs retain more gadolinium in the brain than macrocyclic GBCAs. However, the review did not identify adverse health effects related to this brain retention.
FDA continues to assess the safety of GBCAs. NCTR is conducting a study on brain retention of GBCAs in rats. Other research is also being conducted about how gadolinium is retained in the body. FDA will update the public when new information becomes available and we plan to have a public meeting to discuss this issue in the future.