Effects of ultrahigh dilutions of 3,5-dichlorophenol on the luminescence of the bacterium Vibrio fischeri.

There is a great need for research in the field of homeopathy for laboratory test systems to investigate the actions of ultrahighly diluted biological effectors. With this in mind, we used the luminescent bacterium Vibrio fischeri, which is used throughout the world in testing water quality. Luminescence inhibition is utilized as a test parameter for the toxicity of a sample. We used ultrahigh dilutions (UHD) of 3,5-dichlorophenol as effector and adapted the standard test procedure for water toxicity in a way that let us evaluate very minute effects. Three groups of samples were prepared and then blinded: 45 dilutions of 3,5-dichlorophenol in steps of 10, starting with 4.2 x 10(-2) M, with vigorous shaking between dilution steps; 45 identical dilutions of 3,5-dichlorophenol without vigorous shaking; and 49 control samples of the diluent. The results of, and the discussion based on, a thorough statistical analysis led to the conclusion that an effect based on UHD, which results in an inhibition of luminescence of less than 1.5%, can be confirmed for some of the potency samples. There were both effective and ineffective samples in the three sample groups. The size of the effect was very small (ca. 1.5%), though statistically significant. The number of effective samples was significantly higher among the vigorously shaken samples than among the controls and the unshaken samples (14, 6 and 7 effective samples, respectively).