[Organohalogen contamination of a dialysis-water treatment plant]

On March 2001 the regular quality control test of the water used for dialysis in an urban centre using a reverse osmosis system revealed a high level of organo-halogenated contamination. The compounds implicated were: trichloroethylene (trielene) [M.Wt. 131 D], tetrachloroethylene, trichloromethane (chloroform) [M.Wt. 121 D], chlorodibromomethane. The dialysis unit was closed. Water samples were analysed in duplicate. The table shows the values (in ppm or microgram/l) obtained for chloroform at the given times: March 8th, altered sample; March 12th, confirmation sample; March 16th, after osmosis membranes change; March 22nd, after carbon filtration replacement; March 26th, after softener resins substitution. The AAMI doesn't recommend any value for organo-halogenated compounds in dialysis water. In the past, the European Pharmacopoeia and the Italian Health Ministry released some reference values for tap water, values which were extended to water used for dialysis. The values are 1 ppm as reference value, 30 ppm as maximum accepted value for the sum of all organo-halogenated compounds, and 10 ppm as the recommended value. In conclusion, the problem was solved by progressive replacement of the components of the water treatment system, even though the real cause remained undetermined. No clinical symptom was recorded and no level of chloroform or trielene was detected in patients' sera despite the low molecular weight and low protein binding of the compounds. A strict control of the water quality and a more comprehensive and updated reference guide are needed for better and safer dialysis delivery.