Health Stream Literature Summary - Issue 50 - June 2008

Chemical contamination of potable water in ship tanks.
Oldenburg, M., Huesing, U.P., Kalkowski, M., Baur, X. and Schleich, K. (2007) International Maritime Health, 58(1-4); 79-91.

An increasing rate of problems relating to unpleasant odours from drinking water in newly built ships has been observed by the German Port Health Authority. A suspected cause of such problems is leaching of solvent-based tank coatings (intended to protect against corrosion) due to the non-observance of required specifications, especially the drying periods. This study was conducted to explore the frequency of drinking water contamination by chemicals in a selected sample of vessels and to assess the effect of specific interventions to reduce these concentrations. Drinking water samples were collected and analysed for 22 different volatile halogenated hydrocarbons. This paper reports tests performed on 21 vessels between 2004 and July 2007 due to aromatic odours of the potable water. Water samples were either taken from the tanks (70.6%) or the galley (29.4%) depending on the accessibility of the ships water supply system. Microbiological quality tests (not specified) were also undertaken.

The vessels analysed ranged from 2 to 24 months of age. Unpleasant odours were mostly perceived by crew members within a few weeks of initial operation and often increased in stays in warmer climatic zones. The microbiological quality of potable water samples complied with German guideline values for drinking water. The guideline values (GVs) of chemical substances in drinking water were exceed on five ships: Ship no 1 - xylene 770 micro g/l (GV 500 micro g/l), ethyl benzene 590 micro g/l (GV 300 micro g/l), vinyl chloride 0.6 micro g/l (GV 0.5 micro g/l); Ship no 2 - xylene 510 micro g/l, ethyl benzene 400 micro g/l; Ship 3 - xylene 860 micro g/l; Ship 4 - xylene 540 micro g/l; Ship 5 - benzene 1.0 micro g/l (GV 1.0 micro g/l). The highest chemical concentrations in ship tanks were found within the first 12 months after initial operation. Most other chemicals investigated were below the respective detection limit in potable water. In most cases chemical levels were reduced by complete discharge and ventilation of the tanks for at least 14 days.

This study showed that an aromatic odour in water supplies on newly built ships represents a potential hazard to the health of those on board due to chemical solvents. It is recommended that suitable codes of practice in the application of coatings need to be observed by water tank producers. Public Health officers, ship masters and other people responsible for health and safety on board need to be aware of the problem and initiate appropriate surveillance and control measures if required. The authors make specific recommendations about remedial measures based on their experiences.