Interesting. The scientist swore up and down about why the process they used kept.the impurities to a Minimum and made it less toxic to your system. The impurities from what I understand make you more prone to hangovers and such. Surprised such a highly intelligent person believed the propaganda.
Scientist or not, familiarization with the definitions and requirements as relates to distilled spirits isn't something commonly understood.
Vodka is a sub-type of the TTB category "Neutral Spirits or Alcohol". The definition is:
Neutral Spirits or Alcohol: Spirits distilled from any material at or above 95% alcohol by volume (190 proof), and if bottled, bottled at not less than 40% alcohol by volume (80 proof).
Vodka: Neutral spirits distilled or treated after distillation with charcoal or other materials so as to be without distinctive character, aroma, taste or color.
Vodka differs from most other distilled spirits such as whiskey, rum and tequila in that the definitions for those spirits include the phrase, "having the taste, aroma and characteristics generally attributed to __________." Vodka must be without any of those things.
Taste, character and aroma come from two things - the cogeners present in the distilled spirit and the taste, character, aroma (and color) imparted by the wood upon which the spirit is aged. Vodka is un-aged and the requirement that it be distilled at or above 95% ABV guarantees that no cogeners are present in the finished spirit.
Without entering into the debate over the "toxicity" of cogeners, we can state with certainty that the production process of vodka - ALL vodka - renders it completely free of "toxins".