Copper Silver Effectiveness Study
"Individual and combined effects of copper and silver
and silver ions on inactivation of Legionella Pneumophila"
Lin Y S E, Vidic R D, Stout J E, Yu V L. Water Research
Copper/Silver ionization is a new disinfection method that is
being used to eradicate Legionella pneumophila from hospital
hot water recirculating systems. The objective of this study was to
determine the susceptibility of L. pneumophila serogroup 1 to
copper and silver ions alone and in combination. L. pneumophila
serogroup (L. p. sg-1) was completely inactivated (6-log reduction) at
copper concentration of 0.1mg/l within 2.5 h, whereas more than 24 h
was required to achieve a similar reduction at the highest silver ion
concentration tested (0.08 mg/l). Checkerboard method and Gard
additive model prediction demonstrated that copper and silver ions in
combination could result in additive and synergistic effect depending
on the concentration of copper and silver ions. Under the experimental
conditions used in this study, synergism of copper/silver ions in
eradicating L. p. sg-1 was observed at higher concentration
combinations of copper/silver ions (e.g. 0.04/0.04 mg/l) while only an
additive effect was observed at lower concentration combinations (e.g.
0.02/0.02 mg/l). This study suggested that both copper and silver ions
are effective in inactivating Legionella pneumophila and the
combined effect is greater than that seen with either ion alone.