Asbestos fibers in parenteral medication

The adequacy of current regulations for the control of particulate matter in injectable medicines has been brought into question by a recent television program which reported that asbestos fibers had been found in a number of such preparations. The fibers were identified as chrysotile, which occurs very widely as a secondary mineral in rocks, and is almost ubiquitous among minerals derived from natural erosion. Fibers are found in almost all drinking water and air samples unrelated to any contamination of fiber resulting from industrial exploitation. Because of this, even extreme laboratory precautions may fail to eliminate every fine fiber. A normal person living in an urban environment inhales about 10(5) asbestos fibers daily and ingests 10(10). There is evidence that a small proportion of these fibers regularly enters the circulation, and some fibers may be excreted in the urine. Elimination also occurs because retained chrysotile fibers fragment and disappear relatively quickly from human tissues, probably through macrophage action. Fiber length and dose are also important in disease causation. Established evidence on fiber length, durability, and quantitative exposure required for disease production does not indicate that the fibers reported to have been found in parenteral preparations constitute any hazard.