[Roentgen contrast media, source for AOX-contamination of waste water by hospitals].

Purpose: To identify the sources for the exceeding of the upper limit of the AOX (adsorbable organic halogen, X = Cl, Br, I) in hospital waste-water and to estimate the contribution of hospital waste-water to the AOX of municipal waste-water.

Methods: For several hospitals with different medical directions, the expected AOX-concentration, as far as it is caused by iodine contrast media, was ascertained by the contrast media consumption and the water consumption. The results were compared with the measured AOX concentrations.

Results: The AOX-concentration of hospital waste-water varies between 0.41 mg/l and 0.94 mg/l.

Conclusion: As a source of AOX iodine contrast media have been identified and may contribute considerably to the AOX. Hospitals with a radiological department may exceed the upper limit of the AOX which has to be observed in German municipal waste-water.