For the past few years, EMSL has been part of an ongoing research program sponsored by the National Toxicology Program, National Institute of Environmental Health Sciences (NTP/NIEHS), to prepare animal lung tissue for microscopy. EMSL scientists worked with the client on developing methods for the full characterization and assessment of fiber lung burden in asbestos-exposed rats. We provided comprehensive, high-quality data to help our client tackle the fundamental concerns surrounding short term and chronic asbestos exposure and toxicity.