ANDRUP L, NIELSENBH, K0L VRAAS. Biosafety considerations in industries with production methods based on the use of recombinant deoxyribonucleicacid. Scand J Work Environ Health 1990;16:85-95. Since no occupational accidents or diseases have been attributed specifically to the use of constructions containing recombinant deoxyribonucleicacid (rDNA), this paper evaluates the occupational health risks in industries utilizinggenetically manipulated organisms mainly on the basis of theoretical considerations. Bacteria, filamentous fungi, yeasts, and mammalian cellsin culture are in use. For each of these systems the possible hazards are considered. Concerning microbial production systems, infections are regarded as the main problem, but the risk of infection is considered extremely low. As for cells in culture, only dormant viruses are regarded as problematic, but well-defined production cell lines should not contain such undetected and dangerous viruses. Overall, the additional risks posed by rDNA-modified microorganisms are minor. Only long-term observations can, however, confirm this assumption, and consequently the highest feasible containment measures should still be used in the years to come.