I think this is one of those substances that everyone has to make up their own mind about taking or not. I found this quote:
“Citricidal® is synthesized from the polyphenolic compounds found in grapefruit seed and pulp. Numerous reactions are involved, including distillation, catalytic conversion, and ammoniation.
Every batch of Citricidal is tested and certified free from chemical and heavy metal contamination. And in an attempt to further improve the product, a source of grapefruit seed and pulp from Certified Organically Grown grapefruits has been secured.
To further show the safety of Citricidal, an Acute Oral Toxicity Study was performed(see Northview Pacific Labs Report No. X5E015G, dated 7/6/95). Results showed that Citricidal is considered non-toxic by oral ingestion with an LD50 of over 5000 mg/kg of live body weight. This is the equivalent of a 200 lb. person drinking close to 1 lb. of pure Citricidal daily for two weeks, before risking a 50% risk of fatal poisoning. (There are close to 20,000 drops in one pound of Citricidal liquid. The recommended adult dose is 5-6 drops at a time.)
According to the Association of Poison Control Centers, the AMA Physician Reporting System, and the Journal of Emergency Medicine, there have been no reports that Citricidal has ever harmed anyone. In fact, there are thousands of clinical and anecdotal reports that Citricidal has helped many, and enjoys a safety record going back more than 30 years.”