It is important to know that no one develops beryllium sensitization unless he or she is exposed to beryllium. Beryllium sensitization may develop after an individual breathes beryllium dust or fumes. Most people who are exposed to beryllium will not experience health effects. Beryllium particle size and form, amount and duration of exposure, occupation, industry and genetics are all factors that play a role in determining why some people develop beryllium sensitization and others do not.
Studies have shown that, on average, one to six percent of exposed workers develop sensitivity, although the rates can be as high as 16 percent in workers with the highest exposures such as beryllium machinists. Some workers who are going to develop an allergy to beryllium tend to do so early, but follow-up medical surveillance continues to identify workers with beryllium sensitization years after first exposure.