Caprylhydroxamic Acid(in 4,478 products)
1. Antimicrobial Preservative - Actively kills and inhibits the growth of unwanted microorganisms which may be harmful.
2. Bacteriostatic Agent - Prevents, slows or inhibits bacteria growth
3. Chelating Agent (Chelants) - Binds to and removes potentially toxic or unwanted metals
4. Drug / Medicine - Treats, alleviates, cures, or prevents sickness. As officially declared by a governmental drug/medicine regulatory body
5. Fungicide / Herbicide - Kills or inhibits unwanted vegetation
6. Preservative - Prevents and inhibits the growth of unwanted microorganisms which may be harmful
Caprylhydroxamic Acid (CHA) is an amino acid derived from coconut oil. It is a white to tan crystalline solid. The hydroxamic acid functional group makes caprylhydroxamic acid an excellent chelating agent. It is known that some bacteria synthesize and use hydroxamic acids as siderophores (iron scavengers/chelators). Additionally, caprylhydroxamic acid forms strong complexes with oxidized transition metals almost instantaneously, and it may react with oxidizers and acids. Caprylhydroxamic acid is stable under normal environmental and usage conditions. 
Caprylhydroxamic acid is a natural preservative and an effective biostatic and fungistatic to prevent the growth of bacteria and fungus. It is very effective in neutral pH levels. It is compatible with most cosmetic ingredients and can be used in emulsions, anhydrous, and surfactant systems. 
In a study conducted on 39 patients in 4 Finnish dermatological clinics, patch tests showed that caprylhydroxamic acid (CHA) and its potassium salt may have caused an epidemic of allergic contact dermatitis.  Their studies are based on a moisturizer, Apobase®, where the old formulas containing methylpropanediol, or phenoxyethanol, did not cause a positive patch test result, while the new formulas containing caprylhydroxamic acid, did. "At the beginning of 2014, the parabens in Apobase® oily cream, cream and lotion were replaced with a new preservative called Phenostat™, which is a mixture of phenoxyethanol (PE), caprylhydroxamic acid (CHA), and methylpropanediol (MPD). Both Phenostat™ and CHA are widely used in different cosmetic products, such as make-up, moisturizers, and shampoos, in many countries." 
"The symptoms of patients with suspected contact allergy caused by Apobase® moisturizers appeared as acute, itchy, often sharply demarcated erythematous eczema of the exposed areas. Some patients were hospitalized because of widespread severe eczema or severe localized eczema of the face, hands, or legs. Eczema symptoms improved after discontinuation of the use of the suspected products."  In severe cases, "chronic lichenification"  and "lesions around the mouth, fingers, and groins"  was noted after the use of Apobase® moisturizers. Clobetasol ointment "provided quick relief within days" upon the negative health effects encountered by Apobase® moisturizers. 
"Since summer 2016, Phenostat™ has been omitted from all Apobase® formulations marketed in Finland."  The sudden and aggressive epidemic led to products being pulled from the shelves in Finland.
Caprylhydroxamic Acid (CHA) may potentially cause severe contact dermatitis and/or skin sensitization despite being a natural, organic compound. However, the EU has not placed any limitation or restriction on its use for the time being.
1. PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/23846
2. Safety Assessment of Caprylhydroxamic Acid as Used in Cosmetics https://www.cir-safety.org/sites/default/files/caphyd042019SLR_0.pdf
3. An epidemic of allergic contact dermatitis caused by a new allergen, caprylhydroxamic acid, in moisturizers. (Contact Derm., 77(3), 159-162. doi:10.1111/cod.12787)
4. Contact allergy to moisturizers in Finland: the tale of the lurking tube in the medicine cupboard. (Contact Derm., 78(4), 289–290. doi:10.1111/cod.12927)
Safety and Hazards (UN GHS):
1. Causes skin irritation (H315)
2. Causes serious eye irritation (H319)
3. May cause respiratory irritation (H335)