Ultrafine beryllium number concentration as a possible metric for chronic beryllium disease risk.

Beryllium is a lightweight metal which causes a chronic granulomatous lung disease among workers who become sensitized to it. Recent research has shown a persistence of the disease despite efforts at control with mean exposures below the Occupational Safety and Health Administration (OSHA) occupational exposure limit of 2 microg/m3. Results of our current research confirm a previous finding in certain plants that particle number concentrations are higher in areas where historical estimate of risk showed a high risk of disease despite relatively lower mass concentrations. By providing side-by-side measurements of both particle number and mass, this research adds support to the proposal that particle number rather than particle mass may be more reflective of target organ dose and subsequently a more appropriate measure of exposure for chronic beryllium disease. Our evidence also shows that particle mass exposure measurements and particle number exposure measurements were not correlated.