Stopping exposure to beryllium in those sensitized has not been definitively shown to stop the progression to CBD.The overall prevalence of CBD among workers exposed to beryllium has ranged from 1 – 5% depending on industry and time period of study.The general population is unlikely to develop acute or chronic beryllium disease because ambient air levels of beryllium are normally very low (<0.03 ng/m3). However, a study found 1% of people living within 3/4 of a mile of a beryllium plant in Lorain, Ohio, had berylliosis after exposure to concentrations estimated to be less than 1 milligram per cubic metre of air. In the United States the Beryllium Case Registry contained 900 records, early cases relating to extraction and fluorescent lamp manufacture, later ones coming from the aerospace, ceramics and metallurgical industries. History
Since the 1920s, beryllium has been used in electronics, ceramics, research and development labs, aircraft, and the atomic energy and defense industry. Cases of bronchitis and pneumonia-like symptoms were reported in Germany and Russia in the 1930s among workers mining and refining beryllium. By 1946, a cluster of cases associated with fluorescent lamp manufacturers were apparent in the United States, and the lamp industry stopped using beryllium in 1949.
This may be due to strain and inflammation of the ligaments supporting the navicular bone, reduced blood flow and increased pressure within the hoof, damage to the navicular bursa or DDF tendon, or from cartilage erosion. Affected horses display a "tiptoe" gait - trying to walk on the toes due to heel pain. They may stumble frequently. The lameness may switch from one leg to another, and may not be consistent. Lameness usually occurs in both front feet, although one foot may be more sore than the other. Lameness is usually mild (1–2 on a scale of 5). It can be made worse when the horse is worked on a hard surface or on a circle. After several months of pain, the feet may begin to change shape, especially the foot that has been experiencing the most pain, which tends to become more upright and narrow. Treatment and prognosis
No single treatment works for all cases, probably because there is no single cause for all cases. The degenerative changes are usually quite advanced by the time the horse is consistently lame, and these changes are believed to be non-reversible. At this time, it is best to manage the condition and focus on alleviating pain and slowing the degeneration. Trimming
Putting the foot into proper neurological and biomechanical balance is crucial. Often navicular horses have long toes and underrun heels with very little inner wall depth or strength. Exposing the horse to proper stimulus to improve hoof form and structure is also vital.