A population of 3185 workers from nine aluminium smelters owned by four different aluminiumproducing companies were determined to have significant beryllium exposure. Of these, 1932 workers participated in medical surveillance programmes that included the serum beryllium lymphocyte proliferation test (BeLPT), confirmation of sensitization by at least two abnormal BeLPT test results and
further evaluation for chronic beryllium disease in workers with BeS.