the evil, vile, repugnant grapefruit seed extract (GSE)

There are certain topics that make me rant, pretty much every time they come up... one of these is GSE - grapefruit seed extract.  It's sold as a "natural antimicrobial/preservative" but in truth is adulterated with horrible, awful, dreadful, deplorable, revulsive chemicals that are carcinogens, endocrine disrupters, allergy sensitizers, and environmental pollutants. 

GSE is not safe to ingest, it's not safe to put on your skin, and it's not even safe to use in any manner where it will be released into the environment.  Please don't use it for parasites, don't use it as an ingredient in "natural detergents" (Bio-Kleen uses GSE), in soaps and by no means expose your infants to it to "fight thrush".  Most GSE is more heavily laden with chemicals than Lysol (thanks to Todd Caldecott for that tidbit).

GSE Overview (todd caldecott)
"While on the one hand the marketing of GSE could be nothing more than a kind of charlatanism, there are additional concerns about the long term safety of ingesting the aforementioned preservatives. I am quite sure that many of the people currently using GSE, who espouse the value of natural alternatives over commonly used synthetic drugs and spend their hard earned money to buy “all-natural” products, would be shocked to learn the mechanism of GSE’s biological activity."

Grapefruit Seed Extract Explained (kathy abascal)

"The main active components in the finished product are a group of quarternary ammonium chlorides including benzethonium chloride that make up 8-17% of the product.  Benzethonium chloride is not a substance that occurs naturally in grapefruit seeds. It is a manufactured chemical that is lacking in safety data but may be an endocrine and skin toxicant.  Endocrine toxicants are chemicals that have the ability to disrupt our hormones.  Commonly encountered endocrine toxicants include PCBs and DDT.  “Not to worry,” assures the manufacturer of Citricidal: “Benzethonium chloride is a well-known synthetic antiseptic agent; it is not added to the grapefruit extract, but if formed from the orginal grapefruit flavonoids during the ammoniation process.”  Using grapefruit seed extract is about the same as going to a pharmacy and buying triclosan or any other synthetic antimicrobial chemical.  They may work. They may be safe.  Or they may not be safe."

The Adulteration of Commercial “Grapefruit Seed Extract” with Synthetic Antimicrobial and Disinfectant Compoundsby (john cardellina)

"Tests conducted in multiple laboratories over almost 20 years indicated that all commercial GFSE preparations that exhibited antimicrobial activity contained one or more synthetic microbicides/disinfectants, while freshly-prepared extracts of grapefruit seeds made with a variety of extraction solvents neither exhibited antimicrobial activity nor contained the antimicrobial synthetic compounds found in the commercial ingredient materials. Furthermore, over the course of the 18 years covered by the various analyses, the actual antimicrobial compounds found in the putative grapefruit seed extracts changed from triclosan and methyl p-hydroxybenzoate in early samples to benzethonium chloride in the middle years to mixtures of benzalkonium and/or alkonium chlorides in more recent years. The suggestion on a commercial website4 that these antimicrobial compounds are formed from the phenolic compounds naturally occurring in grapefruit seed and pulp by heating them with water, ammonium chloride, and hydrochloric acid is not supported by chemical evidence, or any known organic chemistry pathway."

Grapefruit Seed Extract. Natural or synthetic? (rob mccaleb)
"The presence of preservatives, harmful to human health, has been reported [in] cosmetic and medicinal GSE products.” We created a method “to quantify all GSE-relevant preservatives in one analytical run by a fully validated assay” and found preservatives “commonly used (as) synthetic antimicrobial agents whose formation in the plant or during the extraction process is very unlikely."

Simultaneous identification and quantification by liquid chromatography of benzethonium chloride, methyl paraben and triclosan in commercial products labeled as grapefruit seed extract (Avula B, Dentali S, Khan IA)
"A HPLC method has been developed which permits the quantification of methyl paraben, benzethonium chloride and triclosan in various samples of grapefruit seed extract (GSE). The best results were obtained with a Phenomenex Gemini C18 column using gradient mobile phase of water (0.1% acetic acid) and acetonitrile (0.1% acetic acid) with a flow rate of 1.0 mL per minute. The detection wavelength was 254 nm for methyl paraben, and 275 nm for benzethonium chloride and triclosan. The main synthetic antimicrobial agent identified in commercial GSE samples was benzethonium chloride in concentrations from 0.29-21.84%. Positive ion electrospray MS of a commercial GSE sample showed a molecular ion at m/z 412 [M+], which matched that of a standard of benzethonium chloride. Triclosan was detected in two samples at 0.009 and 1.13%concentrations; while methyl paraben was not detected in the samples analyzed"

Several more scientific references on adulteration...
http://www.yesyesyes.org/GSE.htm ...yes, I know that's a sex lube site, but no, I have no idea whether it's good or not.  I encourage you experiment to your hearts delight (and with your hearts delight)