Pfeiffer conducted a 12-year study which allowed him to classify behavior disorders into four categories based on trace metal patterns.^[10] Type A: high copper/zinc ratio, depressed hair sodium, potassium and lead sensitivity. These individuals exhibit episodes of fighting, oppositional behavior and mood swings. Type B: depressed hair copper, pyroluria, elevated histamine and elevated toxic metals. They exhibit assaultive behavior, absence of remorse, pathological lying, fascination with fire and cruelty towards animals.^[10] Type C: “mal absorbers”, tend to be slender, usually impulsive and oppositional.^[10] Type D: depressed manganese and chromium levels. They exhibit nonviolent delinquent behavior. ^[10]

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https://en.wikipedia.org/wiki/Carl_Pfeiffer_(pharmacologist)