Cosmetic Preservatives Encyclopedia Antimicrobials COPYRIGHT 1990 Allured Publishing Corp.

1. Alcohols

1.1 Benzyl Alcohol

CAS number: 100-51-6 Activity spectrum: Bacteria Use concentration: 1.0-3.0% Solubility: 1g/25 grams water Optimum pH: Above 5 Stability: Slowly oxidizes to benzaldehyde; dehydrates at low pH Compatibility/Inactivation: May be inactivated by nonionic surfactants Toxicity: Acute oral [LD.sub.50]:2.08; 1.23g/kg (rats); 1.94g/kg (rabbits); 1.58g/kg (mice); acute dermal [LD.sub.50] [is less than] 5.0 ml/kg (guinea pigs). Metabolized to hippuric acid Regulatory status: Permitted in Argentina up to 1.0% (cosmetics). Permitted in Japan Comments: Bacteriostat; used in injectable drugs and ophthalmic products Suppliers: Ashland Chemical, Haarmann & Reimer, Kalama Chemical, Quest International Fragrances

1.2 Chlorobutanol

Chemical name: 1,1,1-Trichloro-2-methyl-2-propanol CAS number: 57-15-8 Activity spectrum: Bacteria, fungi Use concentration: Up to 0.5% Solubility: Soluble in hot water, very soluble in ethanol Optimum pH: Acid pH (up to 4.0) Stability: Decomposed by alkalies, heat Compatibility/Inactivation: Incompatible with some nonionic surfactants Regulatory status: EEC--acceptable up to 0.5%.Permitted in Japan Comments: Camphor odor Supplier: Aldrich Chemical

1.3 Dichlorobenzyl Alcohol (2)

Chemical name: 2,4-Dichlorobenzyl alcohol CAS number: 1777-82-8 Activity spectrum: Broad spectrum, most effective against yeasts and fungi Use concentration: 0.05-0.5% Solubility: Sparingly soluble in water, soluble in propylene glycol Optimum pH: Wide pH range (4-10) Stability: Stable at normal temperatures Compatibility/Inactivation: Compatible with most commonly used pharmaceutical and cosmetic ingredients. Some surfactants can reduce activity Toxicity: Nontoxic at use levels. See K. D. Brunt et al, Cosm. Technol. 3,25 (April 1981) Regulatory Status: EEC Directive 86/199/EEC--fully listed for use as a cosmetic preservative up to 0.15%. Registered in many countries as an active ingredient in lozenge formulations for mouth and throat infections Suppliers: Boots MicroCheck (Myacide SP), Induchem (Unikon A-22), Inolex Chemical (Myacide SP)

1.4 Phenethyl Alcohol

CAS number: 60-12-8Activity spectrum: Primarily effective against gram-negative bacteria Use concentration: Usually 1-2% Solubility: Up to 2% in water Compatibility/Inactivation: May be inactivated by some nonionic surfactants Regulatory status: GRAS on FEMA list; approved by FDA in foods 121:1164 Comments: Floral (rose) odor / Suppliers: Aldrich Chemical, IFF

1.5 Propylene Glycol

Chemical name: 1,2-Propanediol CAS number: 57-55-6 Activity spectrum: Bacteria, fungi Use concentration: 16% or higher Solubility: Miscible with water Stability: Oxidizes at high temperatures Regulatory status: Approved for use in some drugs. Permitted in Japan Comments: GRAS Suppliers: Aldrich Chemical, Olin Chemical, Union Carbide

2.Amides and Amines

2.1 Chloroacetamide

Chemical name: 2-chloroacetamide CAS number: 79-07-2 Solubility: Soluble in 10 parts water, 10 parts abs. alcohol Regulatory Status: Permitted in Argentina up to 0.3% Supplier: Aldrich Chemical

2.2 Disodium EDTA

Chemical name: Disodium ethylene diamine-tetraacetate CAS number: 139-33-3 Use concentration: 0.1-0.5% Solubility: Over 5% Optimum pH: 4.0-8.0 Stability: Very stable Regulatory status: 21 CFR 121.271, 121.1056, 121.2507, 121.2520, 121.2535 Supplier: International Sourcing (Disodium EDTA)

2.3 Formaldehyde Donors and Aldehyde Derivatives

2.3.1 5-Bromo-5-nitro-1,3-dioxane

CAS number: 30007-47-7 Activity spectrum: Broad spectrum (bacteria and fungi) Use concentration: 0.2-0.5% (10% solution) Solubility: Soluble in water Optimum pH: 5-8 Stability: Stable at pH 5-8 below 40 [degrees] C (no formaldehyde split off) Compatibility/Inactivation: Extreme inactivation and incompatibility of Bronidox L with other cosmetic raw materials are not know Toxicity: See literature references: (1) M Potokar, W Greb, H Ippen, H I Maibach, K H Schulz, P Lorenz, Chr Gloxhuber, Fette, Seifen, Anstrich 7,269, 1976; (2) P Lorenz, Cosm Toilet, 92(3), 89, March 1977 Regulatory status: Included in the positive list of the EEC guidelines. Also permitted in Argentina up to 0.1% (wash-offs). Permitted in Venezuela in hair products (up to 0.5%) Comments: Recommended for rinse-off products. Supplied in propylene glycol solution Supplier: Henkel (Bronidox L)

2.3.2 7-Ethyl bicyclooxazolidine

Chemical name: 1-Aza-3,7-dioxa-5-ethylbicyclo (3,3,0)octane CAS number: 7747-35-5 Type of compound: Oxazolidine

Activity spectrum: Broad spectrum, most effective against bacteria Use concentration: 0.05 to 0.2% Solubility: Water, oil, alcohols Optimum pH: Above 6.0 Stability: Unstable under acid conditions Compatibility/Inactivation: Compatible with all ionic surfactant types Toxicity: Nontoxic at use levels Suppliers: ANGUS Chemical (Oxaban-E)

2.3.3 2-Bromo-2-nitropropane-1,3-diol (3)

Other name: Bronopol CAS number: 52-51-7 Type of compound: Substituted aliphatic diol Activity spectrum: Broad spectrum, most effective against bacteria Use concentration: 0.01-0.1% Solubility: Soluble in water, alcohol Optimum pH: Broad range 4-10 Stability: Unstable under alkaline conditions. Unstable at high temperature Compatibility/Inactivation: Compatible with most surfactants; inactivated by compounds containing sulphydryl (-SH) groups. Inactivated by cysteine, aluminum Toxicity: Nontoxic at use levels. Nonirritant at 0.1% or less and nonsensitizing to humans. Safe as a cosmetic ingredient up to and including 0.1% except under circumstances where its action with amines and amides can result in the formation of nitrosamines or nitrosamides Regulatory Status: FDA Drug Master File No. DMF 1673; CTFA CIR Final Safety Assessment Report with Addendum published; EEC Directive 86/199/ECC--fully listed for use as a cosmetic preservative up to 0.1%. Also permitted in Argentina up to 0.1%. Permitted in Venezuela in products containing no amines or amides. Not permitted in Japan in cosmetics Suppliers: ANGUS Chemical Co. Boots MicroCheck, Costec, Inc. (CoSept BNP), Inolex Chemical, Tri-K Industries (Tristat BNP)

2.3.4 Diazolidinyl Urea (4)

Chemical name: N-(Hydroxymethyl)-N-(1, 3-dihydroxymethyl-2,5-dioxo-4-imidazolidinyl-N'-(hydroxymethyl) urea CAS number: 78491-02-8 Type of compound: Heterocyclic nitrogen compound Activity spectrum: Broad spectrum with special activity against gram-negative bacteria Use concentration: 0.03-0.3% Solubility: Very water soluble Optimum pH: 3-9 Stability: Stable Compatibility/Inactivation: Compatible with essentially all cosmetic ingredients Toxicity: [LD.sub.50]: 2570 mg/kg (oral rat) at 100% Draize eye irritation index: 0 at 5% Supplier: Sutton Laboratories (Germall II)

2.3.5 DMDM Hydantoin (4)

Chemical name: Dimethylol dimethyl hydantoin CAS number: 6440-58-0 Type of compound: Nonionic cyclic Activity spectrum: Broad spectrum, less effective vs yeast Use concentration: 0.15-0.4% Solubility: Soluble in water, ethanol Optimum pH: 3-9 Stability: Stable over wide pH range and temperature conditions, up to 80 [degrees] C Compatibility/Inactivation: No incompatability known Toxicity: [LD.sub.50]: 3.8 [+ or -] 0.5 gms/kg at 1-15 gms/kg Draize eye irritation index; 0 at 0.10%

Skin primary irritation index; 1.5 at 0.25% Other: 28 Dermal toxicity, [LD.sub.50] is greater than 800 mg/kg, no behavioral or gross pathology noted 90 Day Oral, [LD.sub.50] is greater than 600 mg/kg, safe, no behavioral or gross pathological changes noted during study or at necropsy Mutagenicity--negative Phototoxicity--negative Regulatory status: Permanently listed in EEC. Permitted in Argentina up to 0.2%. Not permitted in Japan Comments: Formaldehyde donor Suppliers: Lonza, (Glydant), McIntyre Chemical (Mackgard DM), Nipa Laboratories (Nipaguard DMDMH)

2.3.6 Formaldehyde (4)

CAS number: 50-00-0 Type of compound: Aldehyde Activity spectrum: Broad spectrum (fungicide and bactericide) Use concentrations: 0.05-0.2% (equals 0.125-0.5% formalin) Solubility: Soluble in water Optimum pH: Broad range (3-10) Stability: Highly reactive, may volatilize Compatibility/Inactivation: Generally unaffected by different types of ionic emulsifiers. Inactivated by gelatin, proteins Toxicity: Irritant to mucous membranes Regulatory status: EEC-acceptable up to 0.2%; 0.1% in oral hygiene products. In Argentina permitted up to 0.2% (0.1% for oral hygiene products), not permitted in baby products. Permitted in wash-offs in Venezuela (hair products). Not permitted in Japan Comments: Sensitizer in some subjects. Use in wash-off products Supplier: J.T. Baker

2.3.7 Glutaral

Chemical name: Glutaraldehyde CAS number: 111-30-8 Type of compound: Dialdehyde Activity spectrum: Broad spectrum Use concentration: 0.02-0.2% of 50% solution Solubility: Water soluble Optimum pH: 3.5-9 Stability: Excellent storage stability, avoid storage at elevated temperatures Compatibility/Inactivation: Inactivated by ammonia or primary amines at neutral to basic pH Toxicity: Toxic orally or dermally as supplied in 25% or 50% solutions Regulatory Status: Listed on the EEC positive list. EPA reg. no 10352-39 for Ucarcide preservative 225, EPA reg. no. 10352-38 for Ucarcide 250. FDA status: component in adhesives used in articles intended for packaging, transporting or holding food, FDA 175.105; crosslinking agent for insolubilizing a coacervate of gum arabic and gelatin used for encapsulating flavoring oils, FDA 172.230; component of paper and paperboard in contact with aqueous and fatty food, FDA 176.170; with dry food, FDA 176.180 Comments: Excellent disinfectant Supplier: Union Carbide (Ucarcide Antimicrobials)

2.3.8 Imidazolidinyl urea (4)

Chemical name: N,[N.sup.1]-methylenebis ([N.sup.1]-(1-(hydroxymethyl)-2,5-dioxo-4-imidazolidinyl) urea) USP XXI/NF XVI name: Imidurea NF CAS number: 39236-46-9 Type of compound: Heterocyclic substituted urea Activity spectrum: Broad spectrum especially when used in combination with the parabens

Use concentration: 0.50-0.5% Solubility: Water soluble Optimum pH: 3-9 Stability: Stable Compatibility/Inactivation: Compatible with all cosmetic ingredients including proteins, soluble collagens, aloe and plant extracts Toxicity: Low toxicity; no irritation or sensitization [LD.sub.50]: 5200 mg/kg (oral rat) at 100% Draize eye irritation index: 0 at 5% Skin primary irritation index: 0 at 5% See: CIR Expert Panel Safety Assessment Final Report: Environ Path and Tox 4 (4), 133-146 (October 1980) Regulatory status: Permitted everywhere in the world except Japan Comments: Germall yields low levels of formaldehyde when destructive methods are used. Under normal conditions there is no free formaldehyde by the USP silver method assay. Suppliers: Ashland Chemical, Costec (CoSept 115), Induchem (Unicide U-13), International Sourcing, Lipo Chemical, Sutton Laboratories (Germall 115), Tri-K Industries (Tristat I U)

2.3.9 MDM Hydantoin

Chemical name: Monomethylol dimethyl hydantoin CAS number: 116-25-6 Type of compound: Nonionic cyclic Activity spectrum: Broad, weakest vs yeast Use concentration: 0.25% Solubility: Water soluble Optimum pH: 4.5-9.5 Stability: Temperature stable to 85°C Toxicity: Nontoxic at use levels Regulatory status: Permitted in Argentina up to 0.2% (wash-offs). Not permitted in Japan Comments: Formaldehyde donor Supplier: Lonza

2.3.10 Quaternium-15 (4)

Chemical name: Cis-iomer of 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride CAS number: 51229-78-8 Type of compound: Hexamine derivative Activity spectrum: Active against gram-positive and -negative bacteria, including Ps. aeruginosa and Ps. cepacia, mold and yeast Use concentration: 0.02-0.3% Solubility: Water soluble (127 g/100g) Optimum pH: Broad range (4-10) Stability: May be unstable above 60 [degrees] C Compatibility/Inactivation: Compatible with anionic, nonionic, cationic and amphoteric surfactants and proteins Toxicity: Not a primary skin irritant. Oral [LD.sub.50]: 940-1500 mg/kg (rats). Nonmutagenic (via Ames test and

unscheduled DNA synthesis) Regulatory status: Permitted in Argentina up to 0.2%. Permanently listed by EEC up to 0.2% Comments: Analytical data are available that show, contrary to results obtained using conventional nonspecific analytical techniques, this product does not release gaseous formaldehyde Suppliers: Costec (CoSept 200), Dow Chemical (Dowicil 200 Preservative)

3. Inorganic Compounds

3.1 Boric Acid

CAS number: 10043-35-3 Activity spectrum: Very effective vs yeasts Use concentration: 0.01-1.0% Solubility: 1 gm/18 gms water Optimum pH: 5.0-7.0 Compatibility/Inactivation: Incompatible with alkali carbonates and hydroxides Regulatory status: Permitted in Argentina up to 2.0% except in baby products. Not permitted in oral products or cosmetics with pH below 6 in Venezuela Supplier: Aldrich Chemical

4. Metal Compounds

4.1 Phenylmercuric Acetate

CAS number: 62-38-4 Activity spectrum: Bacteria and fungi Use concentration: Up to 65 ppm permitted (0.0065%) Solubility: Poorly soluble in water, soluble in hot ethanol Optimum pH: Neutral pH Compatibility/Inactivation: Inactivated by sulfides, thioglycollates Toxicity: Toxic orally and can cause a dermatitis Regulatory status: Permitted in Argentina up to 0.007% as mercury in eye products only. Not permitted in Japan and Venezuela Comments: Limited to eye cosmetics and pharmaceuticals Supplier: Centerchem

5. Organic Compounds

5.1 Benzoic Acid (1)

CAS number: 65-85-0 Activity spectrum: Good on molds and yeasts, fair on bacteria Use concentration: 0.05-0.10% Solubility: Below 1% in water Optimum pH: Under 4.5 Stability: Do not store at elevated temperatures Compatibility/Inactivation: Incompatible with elevated pH Regulatory status: 0.1% max (USA), 21 CFR 121.101 Supplier: International Sourcing (Benzoic Acid)

5.2 Chloromethyl Isothiazolinone and Methyl Isothiazolinone (3)

Chemical name: Mixture of 5-chloro-2-methyl-4-isothiazoline-3-one and 2-methyl-4-isothiazoline-3-one CAS number: 26172-55-4 and 2682-20-4 Type of compound: Two isothiazolinones plus magnesium salts in water Activity spectrum: Bacteria, yeast, fungi Use concentration: 0.02-0.1% (as supplied); 3-15 ppm active ingredient Solubility: Miscible with water, lower alcohols, glycols Optinum pH: 2 to approximately 9, higher pH in conjunction with some ingredients may inactivate Stability: At least one year at RT; at least 6 months at 50 [degrees] C; good freeze-thaw stability Compatibility/Inactivation: May be inactivated by amines, sulfites, mercaptans and strong reducing agents. Compatible with surfactants and emulsifiers of all ionic types Toxicity: Oral toxicity [LD.sub.50]: 3350 mg/kg; 1.5% conc

Draize eye irritation index: corrosive; 1.5% conc Skin primary irritation index: severely irritating; 1.5% Nontoxic at use levels (0.02-0.1%) See Kathon CG product bulletin Regulatory status: On EEC positive list and on file with FDA. Permitted in Argentina up to 0.005%. Approved for rinse-off applications in Japan Supplier: Rohm and Haas (Kathon CG)

5.3 Dehydroacetic Acid (1)

Chemical name: 3-Acetyl-6-methyl-2H-pyran 2,4(3H)-dione CAS number: 520-45-6 Type of compound: Organic acid Activity spectrum: Bacteria, yeasts, fungi Use concentration: 0.02-0.2% Solubility: Sodium salt is quite water soluble, acid is not Optimum pH: 5-6.5 Stability: Activity decreases with high pH Compatibility/Inactivation: Discoloration with iron compounds Regulatory status: Permitted in Argentina up to 0.6% as the acid; permitted in Japan, Venezuela (up to 0.5%) Comments: Bacteriostat, fungistat Suppliers: Ganes Chemical Works, International Sourcing

5.4 Dimethylhydroxymethylpyrazole

Chemical name: 1-Hydroxymethyl-3, 5-dimethylpyrazole CAS number: 85264-33-1 Type of compound: Pyrazole derivative Activity spectrum: Broad spectrum preservative effective against bacteria, mold and yeast Use concentration: 0.01-0.1% Solubility: Water soluble (4% at 25 [degrees] C) Optimum pH: Broad range (3-11.5) Stability: Stable to 100 [degrees] C Compatibility/Inactivation: Compatible with anionic, cationic, nonionic and proteinaceous materials Toxicity: Not a primary skin irritant. Oral [LD.sub.50] 2600 mg/kg (rats). Not a mutagen via Ames (Salmonella). Not a teratogen Regulatory status: Registered in Brazil. U.S. EPA registration pending Comments: Analytical methods and data available for vertification of active ingredient in product and formulations Supplier: Buckman Laboratories (Busan 1504)

5.5 Polyaminopropyl Biguanide

Chemical name: Polyhexamethylene biguanide hydrochloride Activity spectrum: Broad spectrum Use concentration: 0.2-1.0% of 20% solution Solubility: Water soluble, alcohol soluble Optimum pH: 4.0-8.0 Stability: Stable below 80 [degrees] C Compatibility/Inactivation: Incompatible with anionic surfactants Toxicity: Low toxicity Comments: Supplied as a 20% solution Supplier: ICI Americas (Cosmocil CQ)

5.6 Potassium Sorbate (Sorbic acid, 1)

Chemical name: 2,4-Hexadienoic acid, potassium salt CAS number: 590-00-1

Activity spectrum: Molds and yeasts primarily Use concentration: 0.025-0.2% Solubility: Good water solubility Optimum pH: Up to 6.5 Stability: Unstable at temperatures above 38 [degrees] C or in strong light Compatibility/Inactivation: Slightly incompatible with nonionic surfactants Toxicity: Nontoxic Regulatory status: Permitted in all countries of the world for preservation of food. EEC--acceptable up to 0.6%; Argentina up to 0.6%. Permitted in Japan Comments: GRAS Supplier: International Sourcing, Pfizer Inc., Tri-K Industries (Tristat K)

5.7 Sodium Dehydroacetate (Dehydroacetic acid, 1)

Chemical name: 3-Acetyl-6-methyl-2H-pyran-2,4(3H)-dione, ion(1-), sodium CAS number: 4418-26-2 Activity spectrum: Bacteria and fungi Use concentration: 1% or less Solubility: Good water solubility Optimum pH: 2-6, activity decreases with higher pH Toxicity: See CIR Expert Panel Final Report on Safety Assessment; J American College of Toxicology, 4(3) (1985). CIR concluded safe as used Regulatory status: EEC maximum 0.6% Comments: Useful in combination with parabens, sodium benzoate, phenoxyethanol Suppliers: International Sourcing, Tri-K Industries (Trisept SDHA)

5.8 Sodium Hydroxymethylglycinate

Chemical name: Sodium hydroxymethylaminoacetate CAS number: 70161-44-3 Activity spectrum: Broad spectrum Use concentration: 0.03-0.5% Solubility: Water soluble Stability: Stable Compatibility/Inactivation: No incompatibilities known Toxicity: Low Comments: Supplied as 50% solution in water Supplier: Sutton Laboratories (Suttocide A)

5.8 Sorbic Acid (1)

Chemical name: 2,4 Hexadienoic acid CAS number: 110-44-1 Activity spectrum: Molds and yeasts Use concentration: 0.10 to 0.30 Solubility: Water--slight; soluble in many organics Optimum pH: 2.5-6.0 Stability: Stable Compatibility/Inactivation: Inactive above pH 6.2 Toxicity: Nontoxic Regulatory status: EEC-acceptable up to 0.6%. Permitted in Argentina up to 0.6%. Permitted in Japan Comments: GRAS / Suppliers: Ashland Chemical, International Sourcing, Tri-K Industries (Tristat) 6. Paraben Esters

6.1 Parabens (Methyl, 3; Propyl, 3)

CTFA label name: Parabens (various) esters

Chemical name: Hydroxybenzoates (methyl, ethyl, propyl, butyl) CAS numbers: Methyl paraben 99-76-3; propyl paraben 94-13-3; butyl paraben 94-26-8; ethyl paraben 120-47-8 Type of compound: Benzoic acid esters Activity spectrum: Primarily fungi and gram-positive bacteria, poor vs pseudomonads Use concentration: Use at maximum solubility (0.3% methyl, etc.) Solubility: Poorly water soluble Optimum pH: Up to ca 8.0 (3.8) Stability: Good Compatibility/Inactivation: Incompatible with nonionic (eg. cocamide DEA) and anionic surfactants (eg. Sodium laureth sulfate), which reduces their efficacy. Possess unfavorable partition coefficients between the oil and water phases of emulsions. Some sequestering agents (EDTA, citric acid, etc.), which form soluble complexes with metal ions, are introduced to improve the activity of antimicrobial agents and to avoid discoloration of the product. There is a marked synergistic effect of parabens in combination with EDTA.Toxicity: Nontoxic, nonirritating, [LD.sub.50]:8g/kg (methyl, propyl and ethyl paraben); 5 g/kg (butyl paraben) Regulatory status: EEC-acceptable up to 0.4% (one ester), 0.8% for mixtures of esters Permitted in Argentina, Japan and Venezuela Comments: GRAS Suppliers: Ashland Chemical, Costec (CoSept), Inolex Chemical, International Sourcing, Kalama Chemical, Napp Chemicals, Nipa Laboratories, Protameen Chemicals, Tri-K Industries, Van Dyk

6.2 Sodium Benzoate (Benzoic acid, 1)

Chemical name: Benzene carboxylic acid, sodium salt CAS number: 532-32-1 Type of compound: Organic acid salt Activity spectrum: Especially good vs yeasts, some activity vs molds and bacteria Use concentration: 0.1%-0.2% Solubility: Water soluble Optimum pH: 2.5-4.0 Stability: Stable at low pH Compatibility/Inactivation: Incompatible with nonionics Toxicity: Nontoxic Regulatory status: EEC--acceptable up to 0.5%; permitted in Argentina and Venezuela up to 0.5%; permitted in Japan Comments: GRAS Suppliers: International Sourcing, Kalama Chemical, Pfizer, Tri-K Industries

7. Phenol Derivatives

7.1 Chloroxylenol

Chemical name: p-Chloro-meta-xylenol CAS number: 88-04-0 Activity spectrum: Bacteria, fungi and yeasts Use concentration: 0.2-0.8% Solubility: Poorly soluble in water, soluble in alcohol and glycols Optimum pH: 4-9 Stability: Stable over wide range of physical and chemical conditions Compatibility/Inactivation: Incompatible with some cationics, inactivation by some nonionics Toxicity: [LD.sub.50] in rats: 3.94 gm/kg at 100% activity Regulatory status: Permitted in Argentina up to 0.5%. Permitted in Venezuela Comments: Listed in B.P., 1976 Edition. Registered with EPA and FDA, CIR review complete Suppliers: Nipa Laboratories (Nipacide PX), Ferro (Ottasept)

7.2 2-Isopropyl-5-methylphenol

CAS number: 89-83-8 Solubility: Ethanol soluble, mineral oil soluble, 0.1% in water Optimum pH: In water, 8-14, in organic solvents, 2-7 Stability: Two years Toxicity: Rat [LD.sub.50]: 980 mg/kg Regulatory status: 21 CFR 172.515 Suppliers: Haarmann & Reimer (Thymol Crystals)

7.3 Phenoxyethanol (1)

Chemical name: Ethylene glycol monophenyl ether; 2-phenoxyethanol CAS number: 122-99-6 Activity spectrum: Especially effective vs gram-negatives, including P. aeruginosa; broad range Use concentration: 0.5-2.0% Solubility: 2.4% in water; miscible with alcohols, propylene glycol, glycerin Optimum pH: Wide pH tolerance Stability: Fully stable Compatibility/Inactivation: May be inactivated somewhat by nonionic surfactants; compatible with anionic and cationic surfactants Toxicity: [LD.sub.50] in rats: 1.3 g/kg. See CIR Final Report on Safety Assessment; CIR concluded safe as used. Regulatory Status: Permitted in Argentina up to 1.0%; included in EEC positive list; listed with Japanese MHW as an approved traditional cosmetic ingredient. Comments: Useful in combination with parabens, sodium dehydroacetate, sorbic acid Suppliers: Henkel/Emery Group (Emeressence 1160 Rose Ether Phenoxyethanol), Induchem (Uniphen P-23), Lipo Chemical, Nipa Laboratories (Phenoxetol), Tri-K Industries

7.4 o-Phenylphenol

Chemical name: ortho-Phenylphenol CAS number: 90-43-7 Activity spectrum: Broad spectrum; moderate activity against most types of microorganisms Use concentration: 0.05-0.5% by weight Solubility: Soluble in organic solvent, poorly soluble in water, soluble as Na + salt Optimum pH: 6-10 Stability: Stable over a wide range of physical and chemical conditions Compatibility/Inactivation: Activity will be reduced by most nonionic, cationic or amphoteric surfactants; fairly tolerant of organic matter such as proteins Regulatory status: EEC and Argentina--acceptable up to 0.2% expressed as phenol; permitted in Japan Comments: Water solubility is a function of pH (pKa = 10.0) Supplier: Ashland Chemical, Dow Chemical (Dowicide 1 Antimicrobial)

7.5 Sodium o-Phenylphenate

Chemical name: Sodium ortho-Phenylphenate CAS number: 132-27-4 Activity spectrum: Broad spectrum; moderate activity against most types of microorganisms Use concentration: 0.05-0.5% by weight Solubility: Water soluble; slightly soluble in organics Optimum pH: 6-10 Stability: Stable over a wide range of physical and chemical conditions Compatibility/Inactivation: Activity will be reduced by most nonionic, cationic or amphoteric surfactants; fairly tolerant of organic matter such as proteins Comments: Water solubility is a function of pH (pKa = 10.0) Supplier: Ashland Chemical, Dow Chemical (Dowicide A Antimicrobial)

8. Pyridine Compounds

8.1 Sodium Pyrithione

Chemical name: Sodium 2-pyridinethiol-oxide CAS number: 15922-78-8 Type of compound: Cyclic thiohydroxamic acid (salt) Activity spectrum: Fungi, yeast, gram-positive and -negative bacteria Use concentration: 250-1000 ppm (active basis) Solubility: Water, 53%; ethanol, 19%; PEG 400, 12% Optimum pH: 7-10 Stability: Unstable in light and oxidizing agents. Light stability can be enhanced by formulating with UV stabilizers. Compatibility/Inactivation: Slight inactivation by nonionic surfactants. Compatible with most other preservatives Toxicity: Acute oral [LD.sub.50] (rats) 1.5g/kg Regulatory status: Permitted in Argentina up to 0.5% Comments: Useful in "clear" formulations, thin lotions, or any neutral to alkaline formulation. Available as a 40% aqueous solution Supplier: Olin Chemical (Sodium Omadine)

8.2 Zinc Pyrithione

Chemical Name: Zinc bis(2-pyridinethiol-1-oxide) CAS number: 13463-41-7 Type of compound: Cyclic thiohydroxamic acid (zinc complex) Activity spectrum: Fungi, yeasts, gram-positive and -negative bacteria Use concentration: 250-1000 ppm (active basis) Solubility: Water, 15 ppm; ethanol, 100 ppm; PEG 400, 2000 ppm Optimum pH: 4.5-9.5 Stability: Unstable in light and oxidizing agents. Light stability can be enhanced by formulating with UV stabilizers. Compatibility/Inactivation: Incompatible with EDTA, slight inactivation by nonionic surfactants. Compatible with most other preservatives Toxicity: Acute oral [LD.sub.50] (rats) 560 mg/kg, 48% dispersion; 269 mg/kg, Powder Regulatory status: EEC--acceptable up to 0.5%. Permitted in Argentina up to 0.5% in wash-off products Comments: Useful in gels, creams, heavy lotions and talcum powder. Available as powder or 48% aqueous dispersion Suppliers: Olin Chemical (Zinc Omadine), Ruetgers--Nease Chemical Weyl

9. Quaternium Compounds

9.1 Benzalkonium Chloride

Chemical name: Mixture of alkyl dimethylbenzyl ammonium chlorides CAS number: 68391-01-5 Activity spectrum: Gram-positives primarily; also gram-negatives Use concentration: 0.1%-0.3% Solubility: Soluble in water, alcohol Compatibility/Inactivation: Incompatible with anionic surfactants Toxicity: Can cause occasional allergic responses with chronic use Regulatory Status: Approved prescription drug ingredient. Permitted in Japan. Permitted in Venezuela in dentifrices and mouthwashes Comments: Pseudomonas resistance is known Suppliers: Stepan Chemical, Lonza

9.2 Benzethonium Chloride

CAS number: 121-54-0 Activity spectrum: Bacteria (gram-positive primarily), fungi, algae

Use concentration: 1,000 ppm Solubility: Water, lower alcohols, glycols, chlorinated hydrocarbons Stability: Stable to melting point (about 160 [degrees] C) Compatibility/Inactivation: Action retarded by hard water salts, precipitated by anionic surfactants, dyes, chelating agents overcome inhibition in hard water Toxicity: Safe at concentration of 0.5% in cosmetics applied to skin Regulatory status: Permitted in Argentina up to 0.1% (cosmetics). Approved prescription drug ingredient. Permitted in Japan. Permitted in Venezuela in dentifrices and mouth washes Suppliers: Aldrich Chemical, Lonza (Hyamine 1622)

9.3 Methene ammonium chloride

Chemical name: 1-Methyl-3,5,7-triaza-1-azoniatricyclo-([3.3.1.1.sup.3,7]) decane chloride CAS number: 76902-90-4 Activity spectrum: Broad spectrum preservative effective against bacteria, mold and yeast Use concentration: 0.025-0.5% Solubility: Soluble with water at all proportions Optimum pH: Broad range (3-11) Stability: Stable to 80 [degrees] C Compatibility/Inactivation: Compatible with anionic, cationic and nonionic materials Toxicity: Not a primary skin irritant. Oral [LD.sub.50] 5000 mg/kg (rats). No incidence of human sensitization at 2.0%. Non-mutagenic via Ames (Salmonella). Not a teratogen. 90-day dermal--nonirritant, nontoxic. Regulatory status: US EPA registered microbicide No. 1448-92 Comments: Analytical methods and data to determine active ingredient in product and formulations Supplier: Buckman Laboratories (Busan 1500)

Mixtures

1. Emercide [R] 1199

CTFA label name: Phenoxyethanol (and) chloroxylenol Chemical name: 2-Phenoxyethanol (and) p-Chloro-meta-xylenol CAS number: 122-99-6 and 88-04-0 Activity spectrum: Broad spectrum Solubility: Dispersible in water Optimum pH: Wide pH range Stability: Fully stable Compatibility/Inactivation: May be somewhat inactivated by cationic, nonionic surfactants Use concentration range: 0.3-0.5% Toxicity: [LD.sub.50]:2.6 g/kg at 100%; Draize eye irritation index: not an irritant; Skin primary irritation index: 2.7 at 1% in IPM; Acute dermal [LD.sub.50]:2.0 g/kg at 100% Comments: The Emercide 1199 liquid preservative system can be used in combination with parabens Supplier: Henkel/Emery Group

2. Euxyl K 100 [TM]

CTFA label name: Benzyl Alcohol (and) Methylchloroisothiazolinone (and) Methylisothiazolinone Chemical name: Benzyl Alcohol, 5-Chloro-2-methyl-4-isothiazolin-3-one, 2-Methyl-4-isothiazolin-3-one CAS number: 100-51-6 and 26172-55-4 and 2682-20-4 Type of compound: liquid mixture Activity spectrum: broad spectrum activity against gram-positive and gram-negative bacteria, yeast and mold Use concentration: 0.03-0.15%

Solubility: easily soluble in formulated products Optimum pH: 4.0-8.0 Stability: avoid prolonged exposure to temp. above 40 [degrees] C Compatibility/Inactivation: direct contact with alkalines, amines and sulfites should be avoided Toxicity: nontoxic at use levels Regulatory status: Approved for leave-on and rinse-off products; on the EEC positive list Suppliers: Calgon, Schulke & Mayr

3. Euxyl K 400 [TM]

CTFA label name: Methyl dibromoglutaronitrile (3) (and) phenoxyethanol (1)Chemical name: 1,2-Dibromo-2,4-dicyanobutant (and) 2-phenoxyethanol CAS number: 35691-65-7 and 122-99-6 Type of compound: Liquid mixture Activity spectrum: Broad spectrum activity against Gram-positive and -negative bacteria, yeast and mold Use concentration: 0.03 to 0.3% Solubility: Easily soluble in formulated products Optimum pH: 4.0 to 8.0 Stability: Avoid prolonged exposure to temperature above 60 [degrees] C Compatibility/Inactivation: Direct contact with alkalines, amines and sulfites should be avoided Toxicity: Nontoxic at use levels Regulatory status: Approved for leave-on and rinse-off products; on EEC positive list; approval in Japan pending Suppliers: Calgon, Schulke & Mayr

4. Germaben II [R]

CTFA label name: Diazolidinyl urea (and) methylparaben (and) propylparaben (and) propylene glycol Type of compound: Liquid synergistic mixture of preservatives in optimum proportions Activity spectrum: Effective against bacteria, yeast and mold including troublesome mutated ("house") species Use concentration: 0.25-1.0% Solubility: Soluble in water or emulsion systems at use concentrations Stability: Stable Compatibility/Inactivation: Compatible with all cosmetic ingredients, so useful in preserving cosmetics containing proteins, soluble collagens, aloe, plant and herbal extracts Toxicity: Highly concentrated paraben solution is skin irritant and severe eye irritant. Safe at use levels. Comments: Its liquid form permits cold formulation of shampoos, liquid soaps and other cosmetic products.

Germaben II-E is composed of the same ingredients as Germaben II, but in somewhat different proportions. Germaben II-E is especially useful for creams, lotions, and shampoos that present special susceptibility to yeast or mold contamination. Supplier: Sutton Laboratories

5. Glydant [R] Plus

Chemical name: DMDM hydantoin (4) (and) Iodo propynyl butyl carbamate (3) CAS number: 6440-58-0 and 55406-53-6 Type of compound: Nonionic cyclic and nonionic acyclic Activity spectrum: Broad spectrum, very effective fungicide Use concentration: 0.04-0.25% Solubility: Soluble in surfactants, alcohols, glycols Optimum pH: 3-9 Stability: Stable over a wide pH range and temperature up to 80 [degrees] C Compatibility/Inactivation: No compounds known to be incompatible Toxicity: Components of Glydant Plus have been the subject of extensive toxicological testing. The studies indicate that these components are safe and present minimal hazards at recommended use levels. Regulatory status: Both ingredients are EPA registered.

Supplier: Lonza

6. Liqua Par [TM]

CTFA label name: Isopropyl paraben (and) isobutyl paraben (and) butyl paraben Chemical name: Mixture of n-butyl, isobutyl, and isopropyl p-hydroxybenzoic acid esters Type of compound: Emulsified blend of p-hydroxybenzoic acid esters Activity spectrum: Primarily yeast, mold and gram-positive bacteria, poor vs. pseudomonads Use concentration: 0.1-0.6% active ingredient Solubility: Slightly soluble in water, soluble in alcohol and propylene glycol Optimum pH: 4-8 Stability: Stable at normal temperatures Compatibility/Inactivation: Inactivated somewhat by nonionic surfactants Toxicity: Nontoxic, nonirritating Comments: Supplied as a 50% paraben oil-in-water emulsion Supplier: Van Dyk

7. Nipastat [R]

CTFA label name: Methyl paraben, ethyl paraben, propyl paraben and butyl paraben Type of compound: Combination of esters of p-hydroxybenzoic acid Activity spectrum: Gram-positive and -negative bacteria, yeast and fungi Use concentration: 0.05-0.3% Solubility: Soluble in water to 0.13% (20 [degrees] C) Optimum pH: Up to ca 8.0 Compatibility/Inactivation: Nonionic surfactants may inactivate Toxicity: Nontoxic, nonirritating Comments: Useful in combination with phenoxyethanol to give broad spectrum activity Supplier: Nipa Laboratories

8. Phenonip [R]

CTFA label name: Phenoxyethanol, methylparaben, ethyl paraben, propyl paraben and butyl paraben Type of compound: A fluid active combination of parabens and phenoxyethanol Activity spectrum: Gram-positive and -negative bacteria, yeast and fungi Use concentration: 0.25-0.75% Solubility: Soluble in water to 0.5% (20 [degrees] C), miscible with organic solvents, surfactants and emulsifiers Optimum pH: Effective over wide pH range Stability: Fully stable Compatibility/Inactivation: Nonionic surfactants may inactivate Toxicity: Acute oral [LD.sub.50] in rats: 1.74 g/kg (at 100% Phenonip) Primary irritation index: 0.2 (rabbit at 5% Phenonip) Not considered irritant at 4% Phenonip Components not considered mutagenic by Ames test Regulatory status: A broad spectrum activity, can be used in cosmetic products in EEC, USA and Japan Supplier: Nipa Laboratories

9. Undebenzofene-C

Chemical name: Phenoxyethanol (and) methylparaben (and) ethylparaben (and) propylparaben (and) butylparaben Activity spectrum: Broad spectrum activity (gram-positive and -negative, Pseudomonas aeruginosa, molds, yeasts and fungi) Solubility: Lipidic systems, glycerol, propylene glycol, surfactants

Optimum pH: Effective over wide pH range Stability: Fully stable Compatibility/Inactivation: Nonionic surfactants may reduce its activity Use concentration range: 0.75%-1% Toxicity: [LD.sub.50]:0.31 g/kg l.p. mouse at 100% conc Draize eye irritation index: nonirritant at 2% conc Skin primary irritation index: nonirritant Component not considered mutagenic by Ames test Regulatory status: Can be used in cosmetics in EEC, USA and Japan Supplier: Vevy Europe

Miscellaneous

1. Chlorhexidine Digluconate

Chemical name: Bis(p-chlorophenyl diguanido) hexane CAS number: 14007-07-9 Activity spectrum: Bacteria primarily Use concentration: 0.01-0.1% Solubility: Water soluble (gluconate) Optimum pH: Neutrality best; 5-8 Stability: Unstable at high temperatures Compatibility/Inactivation: Compatible with cationic and nonionic surfactants; incompatible with anionic surfactants, and various gums Toxicity: Low Regulatory status: Permitted in Argentina up to 0.3%. Permitted in Japan Comments: Also known as Hibitane. More widely used in Europe than in the US. Chlorhexidine diacetate has similar characteristics Suppliers: Accurate Chemical & Scientific, ICI Americas

2. Diiodomethyltolylsulfone

Chemical Name: Diiodomethyl p-tolylsulfone CAS number: 20018-09-1 Type of compound: Halogenated sulfone Activity spectrum: Broad spectrum, most effective against fungi, yeast and gram-positive bacteria Use concentration: 0.01 to 0.2% Solubility: Alcohols, aromatics and ketones Optimum pH: 3.0 to 10.5 Stability: Stable at acid and alkaline pH and elevated temperatures. Compatibility/Inactivation: Unstable when dissolved in solvents Toxicity: Nontoxic at use levels Regulatory status: FDA direct food contact clearances (21 CFR 175.105, 175.300 and 177.2600) Suppliers: ANGUS Chemical (Amical 48)

3. Hexetidine

Chemical name: 5-Amino-1,3-bis(2-ethylhexyl)-5-methyl-hexahydropyrimidine CAS number: 141-94-6 Type of compound: Substituted hexahydropyrimidine Activity spectrum: Broad spectrum, most effective against fungi, yeasts and gram-positive bacteria Use concentration: 0.01 to 0.10% Solubility: Alcohols, polyethylene glycols, Tween 80

Optimum pH: 4.0 to 8.0 Stability: Stable at acid and moderately alkaline pH levels. Unstable at high temperatures Compatibility/Inactivation: Deactivated by some soaps; enhanced effect with certain surfactants Toxicity: Nontoxic at use levels Regulatory status: EEC Directive 87/137/EEC--fully listed up to 0.1% for use as cosmetic preservative Suppliers: ANGUS Chemical

4. Sodium Polyphosphate

Trade name: Sporix Chemical name: Sodium polyphosphate Type of Compound: Amorphous polyphosphate Activity spectrum: Effective against molds, yeasts and bacteria Use concentrations: 0.03-0.5% Solubility: Over 20% Optimum pH: 2 to 7 Stability: Very stableCompatibility/Inactivation: Inactivates above pH 8.0 Toxicity: Draize eye irritation index is 2 at 5% conc, skin primary irritation index is 2 at 5% conc Supplier: International Sourcing (Sporix)

THE SCIENTIFIC COMMITTEE ON COSMETIC PRODUCTS AND NON-FOOD PRODUCTSINTENDED FOR CONSUMERS

OPINIONCONCERNING

A CLARIFICATION ON THE FORMALDEHYDE AND PARA-FORMALDEHYDEENTRY IN DIRECTIVE 76/768/EEC ON COSMETIC PRODUCTSAdopted by the SCCNFP during the 22nd plenary meeting of 17 December 2002

Evaluation and opinion on : clarification on the Formaldehyde and para-Formaldehyde Entry in Di-rective 76/768/EEC on cosmetic products___________________________________________________________________________________________

1. BackgroundThe EU Cosmetic Directive 76/768/EC regulates the contents of formaldehyde, paraformaldehyde and formaldehyde releasers in cosmetic products. The official EU methods should be used to check the compliance of cosmetic products with the EU Cosmetic Directive. The EU Working Party (WP) on Methods of Chemical Analysis of Cosmetic Products has identified certain formaldehyde re-leasers for which it may not be possible to develop analytical method with the present state of knowledge (Annex 1). In the previous opinion (SCCNFP/586/02) it is demonstrated that benzyl-hemiformal, sodium hydroxymethylglycinate, diazolidinyl urea and imidazolidinyl urea are decom-posed in aqueous and polar solvents to release some or all of their formaldehyde content. Thus, it is not possible with present state of knowledge to develop suitable methods for the identification and quantification of these compounds, in their native forms, in cosmetic products. The decompo-sition products of benzylhemiformal are known compounds and their safety profile can be as-sessed. However, there is no information about the decomposition products of diazolidinyl urea and imidazolidinyl urea, as well as about the safety profile of the decomposition products.One of the approaches to overcome the analytical problems may be to treat such formaldehyde donors, from the legislative point of view, as formaldehyde; and regulate these formaldehyde re-leasers together with formaldehyde and paraformaldehyde (entry 5, Annex VI, part 1) on the basis of total formaldehyde content in cosmetic products.

2. Request to the SCCNFPWith reference to above-mentioned background the SCCNFP was requested to answer following questions :_ Does the SCCNFP consider it possible to amend the above-mentioned entry 5 in a way so that the maximum authorised concentration could be expressed as a concentration of total formalde-hyde without prejudicing the safety of cosmetic products?_ If so, can the SCCNFP propose maximum authorised concentration in cosmetic products as total formaldehyde?

3. Legislation on formaldehyde content of cosmetic productsAccording to Annex VI of the Cosmetic Directive 76/768/EC, the maximum authorized concentra-tion of free formaldehyde is 0.2%. In addition, the provisions of Annex VI state that, All finished products containing formaldehyde or substances in this Annex and which release formaldehyde must be labelled with the warning “contains formaldehyde” where the concentration of formalde-hyde in the finished product exceeds 0.05%.The legislation is thus dependent upon the ability of analytical methods to differentiate free formaldehyde from the bound, inert form. The official EC method (1) for analysis determines the level of free formaldehyde in the presence of its donor compound.

4. Formaldehyde releasers and analytical problemThe formaldehyde releasers for the use in the cosmetic formulations to be marketed in EU are de-scribed in the Annex. The official EU methods should be used to check the compliance of cosmetic products with the EU CosmeticDirective. The EU WP on Methods of Chemical Analysis of Cosmetic Products develops and validates methods for compliance testing. During the development of methods for the analysis of formaldehyde releasers in cosmetic products, the WP observed that imadozolidinyl urea, diazolidinyl urea, sodium hydroxymethyl glycinate and benzylhemiformal de-compose very rapidly to release formaldehyde when dissolved in aqueous/polar solvents; and therefore, identification and determination of these compounds in cosmetic products may not be possible with the present state of knowledge. The details of these 4 formaldehyde releasers and problems associated with their chemical analysis in cosmetic products are described in a previous Opinion (SCCNFP/586/02).

5. Regulation of formaldehyde releasers (entries 27, 46, 51, 55, Annex VI, part 1) to-gether with formaldehyde and paraformaldehyde (entry 5, Annex VI, part 1)

The maximum authorised concentrations of imidazolidinyl urea, diazolidinyl urea, sodium hydrox-ymethyl glycinate and benzylhemiformal in cosmetic products are based on the risk assessments of these compounds.

5.1 Sodium hydroxymethyl glycinateSodium hydroxymethyl glycinate in aqueous solution decomposes to sodium glycinate and formaldehyde:

Glycine is an essential amino acid, and does not appear to be harmful. So, the regulation of sodium hydroxymethyl glycinate as total formaldehyde should not give any additional safety prob-lem to consumers, as long as the maximum authorised concentration of this compound is main-tained.

5.2 BenzylhemiformalBenzylhemiformal in aqueous solution is decomposed to benzyl alcohol and formaldehyde:

Benzyl alcohol is regulated according to Annex VI, part 1 of the Cosmetic Directive as maximum authorised concentration 1%, and as a solvent for perfumes according to Annex III of the Directive. So, the regulation of benzylhemiformal as total formaldehyde should not raise any additional safety problem to consumers, as long as the maximum authorised concentrations of this com-pound in rinse-off cosmetic products is maintained. The formaldehyde content (n = 1.5) of the benzylhemiformal should also be maintained, as the risk assessment was performed only on this compound.

5.3 Imidazolidinyl urea and diazolidinyl ureaImidazolidinyl urea and diazolidinyl urea in aqueous solutions decompose to formaldehyde and some unidentified products. The release of formaldehyde from imidazolidinyl urea is dependent on temperature, pH and storage period of the solution. The decomposition products of these com-pounds have not yet been characterised. However, it is considered that the toxic profile of the de-composition products has been elucidated together with their respective parent compounds. It ap-pears that both of these formaldehyde releasers are a mixture of isomers.

6. OpinionThe amendment of entry 5 in Annex VI of the Cosmetic Directive to include formaldehyde re-leasers is not suitable, as the maximum authorised concentration of each of these preservatives is based on risk assessments of individual compounds. In the absence of analytical methods to check the compliance of cosmetic products with respect to the content of the four preservatives, con-sumer safety may be ascertained by adequately assessing the presence of formaldehyde in the cosmetic products; the total content of formaldehyde in the finished cosmetic product must not exceed 0.2%

7. Referencesec.europa.eu/food/fs/sc/sccp/out187_en.pdfPreserving Personal Care and Household Products

Jabbar MuftiWhen choosing a preservative system, the formulator must be aware of many issues.

PRESERVATIVES PLAY A vital role in product formulation. For the purpose of this review, personal care including cosmetics is defined as a chemical product having intended end uses primarily on the human body (products not intended for ingestion, with the exception of food supplements). In general, these products are designed to alter odor, appearance, touch or taste without displaying significant biochemical activity. Microbial contamination in cosmetics, toiletries and personal care products is very common and has been of great concern to the industry for many years. Bacteria, yeast or fungus all cause microbial spoilage. All of these are extremely diverse in their metabolic activities. The metabolic reactions of microorganisms can cause health hazards because of the degradation of the product that can be toxic, mutagenic and so on.[1]

Several microorganisms produce toxic waste products and render a product unfit and dangerous if they grow under conditions that support toxin production. Endotoxin, produced by gram-negative bacteria, is not, necessarily deactivated by sterilization, because it is heat stable. In order to pick an appropriate preservative system for a cosmetic product, the chemist must be familiar with the composition, morphology, ecology and diversity of microorganisms and their influences on our daily life. This knowledge enables the chemist to interpret the mechanism of action of the organism involved and effectively deal with consequential contamination.

A bacterium is structurally the simplest and most abundant of organisms and can live in soil, water, organic matter or in plants and animals themselves. Bacteria are significant to man because of their chemical effects and the role they play in the spread of disease. In fact, life on earth would not exist without bacteria, which make possible many of the essential functions of ecosystems. A bacterium of typical size is about 1-2 microns long, making it completely invisible to the naked eye. Bacteria belong to the prokaryote class because their nuclear region is not surrounded by a membrane and consists of a single DNA molecule whose division is non-mitotic.

In contrast, algae, fungi and protozoa are eucaryotes, as their nuclei are bound by a nuclear membrane, contain several DNA molecules and undergo division by the well-known process of mitosis. The algae refer to a large and diverse assemblage of eucaryotic organisms that contain chlorophyll and carry out oxygenic photosynthesis. The fungi, which lack chlorophyll, are a large and diverse group of eucaryotic microorganisms. There are three groups of fungi, having major practical importance: molds, yeasts, and mushrooms. The habitats of fungi are quite different from each other. Some are aquatic, living primarily in fresh water, though a few marine fungi have been identified. Most fungi, however, have terrestrial habitats, in soil or on dead plant matter, and these types often play crucial roles in the mineralization of organic carbon in nature. A large number of fungi are parasites of terrestrial plants. Indeed, fungi cause the majority of economically significant diseases of crop plants. A few fungi are parasitic on animals, including humans, although in general fungi are less significant as animal pathogens than are bacteria and viruses.

Infectious diseases caused by fungi are called mycosis, and three kinds have been recognized: superficial, involving only the skin; subcutaneous, in which fungal growth occurs beneath the skin's surface and systemic, which involves fungal growth in internal organs of the body. It has been estimated that only about 50 species cause human disease and many mycoses are due to infections caused by opportunistic fungi, which ordinarily are harmless. Therefore, the cosmetic chemist should not ignore their serious infectious threat while selecting a preservative that also covers fungus. Nail and skin infections are common among swimmers and beach goers, while bacteria are often maligned as the causes of human and animal diseases. A classic example is pseudomonas aeruginosa, a bacillus commonly found on human skin. While generally innocuous, it is dangerous when a person's immune system is compromised, especially in patients with severe and widespread burns.

However, certain bacteria, including actinomycetes, produce antibiotics such as streptomycin. Similarly bacteria are immensely important because they convert nitrogen into a usable form on certain plant roots or provide the tang in yogurt. Bacteria are used in the production of acetic acid and vinegar, various amino acids and enzymes, and especially in the fermentation of lactose into

lactic acid, which coagulates milk proteins and is used in the production of nearly all cheeses, yogurt and similar products. They also aid in the breakdown of dead organic matter. Today, genetic engineering methods are used to improve strains of bacteria for commercial use and hold enormous promise for the future. In cosmetics, many of the actives, such as low molecular weight proteins and peptides, anti-wrinkle ingredients and antioxidants, are being created with the use of improved specific bacterial strains.

Most bacteria may be placed into one of three groups based on their response to gaseous oxygen. Aerobic bacteria thrive in the presence of oxygen and require it for their continued growth and existence. Other bacteria are anaerobic, and cannot tolerate gaseous oxygen. The third group is the facultative anaerobes, which prefer growing in the presence of oxygen, but can grow without it. Bacteria are rod-shaped (bacilli), spherical (cocci) or spiral (spirilla) in form. Bacilli or cocci may adhere in small groups or chains.

A typical bacterium has a cell membrane surrounded by a cell wall. The lone exception to this is the mollicutes group, which includes pathogens such as the mycoplasms. The composition of the cell wall varies among species and is another important characteristic for identifying and classifying bacteria. Gram-positive bacteria have a fairly thick cell wall composed of peptidoglycan (carbohydrate polymers cross-linked by proteins) and retain a purple color when stained with a dye known as crystal violet. Gram-negative bacteria have double cell walls, consisting of a thinner wall of peptidoglycan and an outer wall of carbohydrates, proteins and lipids. They do not stain purple with crystal violet.

The most important difference between gram-positive and gram-negative organisms is the latter's additional lipopolysaccharide and protein layer. The lipopolysaccharide layer makes gram-negative bacteria more resistant to the effects of preservatives than gram-positive bacteria. Therefore, it is not only the chemical constituents that determine susceptibility to lipophilic preservatives, but also the physical structure of the wall. In fact, the effect of preservative agents on a bacterial cell varies according to the microorganisms used. In this regard, yeast and fungi have also been found in gram-positive organisms. The cell walls of yeast and fungi are composed of two or more protein polysaccharide complexes held together by a variety of covalent bonds. The presence of mannan as a cell wall component distinguishes yeasts from other fungi.[2]

When healthy, internal tissues, blood, brain and muscle are normally free of harmful microorganisms. On the other hand, the surface tissue, skin and mucous membranes are constantly in contact with environmental organisms. Literally billions of bacterial cells are present in and on the human body and most play beneficial, indeed sometimes even essential, roles in the overall health of the person. These organisms are collectively referred to as the "normal" flora, and represent species that have developed an intimate relationship with certain tissues of the human body. This balance is extremely complex and consists of more than 200 species of bacteria. Many of the normal flora are either pathogens or opportunistic pathogens.

A Look at Skin

The skin, along with the respiratory tract, gastrointestinal tract and other body regions, provides a wide variety of chemical and physical conditions in which different microorganisms can grow selectively. Further, skin possesses a variety of defense mechanisms that act in concert to prevent or inhibit microbial invasion and growth. The microorganisms that have developed ways of circumventing these defense mechanisms ultimately colonize successfully. The majority of skin microorganisms are found in the most superficial layers of the epidermis and the upper parts of hair follicles. Most skin microorganisms are also associated directly or indirectly with the sweat glands, which are rather unevenly distributed over the body, with denser concentrations on the palms, finger pads and soles of the feet. They are the main glands responsible for the perspiration associated with cooling of the body.

Eccrine glands seem to be relatively devoid of microorganisms, perhaps because of the extensive flow of fluid, since when the flow of an eccrine gland is blocked, bacterial invasion and multiplication occur. The apocrine glands are more restricted in their distribution, being confined

mainly to the underarm regions. Bacterial populations on the surface of the skin in these warm, humid places are relatively high, in contrast to the situation on the smooth surface of the skin. Underarm odor develops as a result of bacterial activity on the secretions of the apocrines; aseptically collected, apocrine secretion is odorless but develops odor upon inoculation with certain bacteria isolated from the skin.

Each hair follicle is associated with a sebaceous gland, which secretes a lubricant fluid. Hair follicles provide an attractive habitat for microorganisms. A variety of aerobic and anaerobic bacteria, yeasts and filamentous fungi inhabit these regions, mostly within the area just below the surface of the skin. The secretions of the skin glands are rich in microbial nutrients. Urea, amino acids, salts, lactic acid and lipids are present in considerable amounts. The pH of human secretions is always acidic, between 4 and 6.

The microorganisms of the normal flora of the skin can be classified as either transients or residents. The skin as an external organ is continually being inoculated with transient bacteria, virtually all of which are unable to multiply and usually die. Residents are organisms that are able to multiply, not merely survive, on the skin. The normal flora of the skin consists primarily of gram-positive bacteria restricted to a few groups. These include several species of staphylococcus and a variety of both aerobic and anaerobic corynebacteria. Of the latter, propionibactrium acnes is ordinarily a harmless resident but can incite or contribute to the condition known as acne. Gram-negative bacteria are almost always minor constituents of the normal flora, even though such intestinal organisms as escherichia coli are being continually inoculated onto the surface of the skin by fecal contamination. Acinetobacter is the only other gramnegative bacterium commonly found on the skin. It is thought that the lack of success of gram-negative bacteria is due to their inability to compete with gram-positive organisms that are better adapted to the skin. If the latter are eliminated by antibiotic treatment, the gram-negative bacteria can flourish. They consist largely of micrococci (staphylococcus epidermis and micrococcus sp.) and corynebacteria. Most bacterial infections of the skin can be accounted for by three pathogens, staphylococcus aureus, streptococcus and pseudomonas.

Yeasts are uncommon on the skin surface, but the lipophilic yeast pityrosporum is occasionally found on the scalp.

Although the resident microflora remains more or less constant, various factors such as weather, with an increase of temperature and humidity, increases the density of the skin microflora. Young children have a more varied microflora and carry more gramnegative bacteria and potential pathogens than adults. Similarly, hospitalized patients have greater numbers of pathogens and antibiotic-resistant organisms than healthy people. Personal hygienic habits influence the resident microflora and unclean individuals usually have higher population densities. Organisms introduced to the skin that subsequently die, generally succumb from either the skin's low moisture content or low pH. Organisms that survive and grow are able to resist these adverse chemical conditions. The most common contaminants in a cosmetic product include bacteria such as staphylococci, pseudomonas and other opportunistic bacteria. The corynebacteria, and certain related propionic acid bacteria, are consistent skin flora and some of them have been implicated as a cause of acne.[3]

The Use of Preservatives

In order to protect the cosmetic product from decay, discoloration or spoilage, we use preservatives. A preservative is a material that protects the product from the effects of microbiological contamination. The selection of a germicidal is critical and in many cases chemicals, which are highly active against microbes, also have similar effects against mammalian cells. Therefore, a balance needs to be established with the preservative of choice between killing organisms which may attack the cosmetic product and injure the cells of the consumer who use the product.

Over the years, the list of preservatives has grown continuously and concerns regarding safety and skin's sensitization have become a big issue. Today's cosmetics are complex and need to be

preserved with efficient, safe microbial agents that perform continuously. To find the right type that fulfills all criteria such as safety and freedom from sensitivity and irritation to the skin has become quite a job. The ideal preservative system should carry the following parameters:

1. It should have a broad-spectrum antimicrobial activity against both gram-positive and gram-negative bacteria including fungi.2. It should be effective over a wide pH range and remain active during the shelf life of the product.3. It should be non-toxic and nonirritating.4. It should not react with the other ingredients in the formula and should continuously provide activity during ambient temperature or storage conditions.5. It should not react with the packaging or container.6. It must have a suitable oil/water partition coefficient to be available in an effective concentration in the aqueous phase of the product.7. It should not interfere with the color or the fragrance of the finished product.8. It should be cost-effective.

No single antimicrobial agent can possibly meet all these criteria. Therefore, a mixture of more than one chemical is required to constitute an acceptable preservative system. Among the list of preservatives, parabens are widely supported by the majority of chemists. Besides preserving the product from deterioration, the preservative system should protect the product against contamination from outside exposure, which is inflicted through frequent product usage with fingertip application. As a result, the product should pass the challenge tests employing certain procedural artifices. The preservative should also control the proliferation of microbial growth that may adversely affect the health of the consumer.

The system should be free of toxicity with minimal irritation. A great many sensitivity problems in new product formulations arise because of chemical interactions between preservatives and substances added as stabilizers or bulking excipients to improve the product's aesthetics. In fact, many interactions of preservatives were recognized years ago. The formation of preservative complexes with materials such as ethoxylated and propoxylated emulsifiers, resins and proteins are the classic examples in which the preservative activities, especially lipophilic germicides, have been drastically curtailed. Some interaction was also detected with polyethylene glycol, methylcellulose, polyvinyl pyrrolidone and gelatin, but this was considerably less than that observed with the nonionic, e.g., Tween 80. No significant interaction was observed with carboxymethylcellulose or tragacanth.[4] Sorbic acid and boric acid did not complex with glycols.[5] In reality, a compound that shows marked toxicity to microorganism cells is likely to exhibit toxicity to human cells. Selecting contaminant-free ingredients for the construction of the final product and providing bacteria-free processing equipment and environment can overcome this problem. Many of the raw materials such as certain color additives, gums, proteins, talcs and other materials from natural sources may contain indigenous microorganisms at significant levels. Similarly, many of the cosmetic products can promote microorganism growth because they are biodegradable. Therefore, cleanliness and the use of contaminantfree raw materialsmust be enforced strictly in manufacturing operations to achieve an adequately preserved product. Traditionally, there are eight major means of microbial control:

1. Chemical preservatives.2. Manipulation of pH.3. Limitation of water content.4. Use of hostile materials.5. Addition of preservative in suitable phase; e.g. oil or water6. Addition of preservative at an appropriate temperature.7. Aseptic manufacturing.8. Tamper-proof packaging.

Experience has shown that a trio of preservatives works best in cosmetic products instead of singly or in pairs. Some common cosmetic ingredients are not considered preservatives but are included in the product to create an environment hostile to the microorganism to grow in a

cosmetic product. These compounds include alcohol, propylene glycol and butylene glycol. Similarly, cationic and anionic surfactants, chelating agents (EDTA), aldehydes, phenolics other than parabens, essential oils and spices are excellent ingredients to discourage microbial growth in a product. At the appropriate concentration, glycol has preservative effects. While the inhibitory concentration of the agents would make them unacceptable in most products, at lower concentrations they do affect the favorable partition of the preservative into the aqueous phase.[6] A product is traditionally preserved in many ways to control the microbial growth; among them, the addition of chemical preservatives is the most widely used practice. These chemicals constitute an important component of any formula and are usually included at levels of less than 1%.Formaldehyde has always been one of the most effective. The two most familiar names among the formaldehyde donors include imidazole urea (Germall 115) and dimethyllol-5, 5-dimethylhydantoin (DMDMH).

DMDMH is said to be the most advanced, next generation chemical preservative that produces the lowest free formaldehyde with greater safety.[7]

Sorbates and benzoates are very effective preservatives and due to their water solubility are equally popular in cosmetics and food products. Dehydro-acetic acid is another chemical which is also frequently used as an effective cosmetic preservative. The omnipresence of parabens (esters of para-hydroxybenzoic acid) make them by far the most widely-used chemical in cosmetics and personal care products, although the acute toxicity of these compounds is very low. Routledge et al. reports that these compounds (methyl through butyl homologs) display weak estrogenic activity in several assays.[8] Although the risk from dermal applications in humans is unknown, butylparaben showed the most competitive binding to rats' estrogen, receptors at concen trations one to two orders of magnitude higher than that of nonylphenol and showed estrogenic activity in yeast estrogen screen at [10-.sup.-6]M.

Organic mercurial currently finds a limited use only in eye products unless its need is absolutely necessary due to the failure of other preservatives. Another effective way to achieve product self-preservation has been by limiting the microbial growth at the extreme pH ranges. The pH between 3-4 (acidic) and pH 9 and above has been a continuous practice to keep the product clean. However, the biggest drawback is eye and skin irritation that occurs at extreme pH. Lowering the water content to a level that does not readily support microorganism growth is another technique to keep the product clean for a longer time period. In many instances microorganisms' growth has been restricted with the inclusion of hostile materials such as alcohols, propylene glycol, 1,3-dibutylene glycol, chelating agents (EDTA) and antioxidant sodium bisulfite.

Some of the less traditional means--freeze-drying, freezing and sterilization that create the bacteria-free environment without utilizing preservatives--can also be considered for sophisticated cosmetic products. However, these techniques, while effective, are expensive. It is also well-known that certain essential oils and fragrances have shown good preservative activity but their presence at a certain level in the product is critical and needs to be monitored.

Triclosan (Irgasan DP 300, a chlorinated biphenyl ether: 2, 4, 4'- trichloro2'-hydroxydiphenyl ether) is another antiseptic agent that has been used for nearly'30 years in a vast array of consumer products. Its use as a preservative and disinfectant continues to grow; for example, it is incorporated at [is less than] 1% in Colgate toothpaste. While triclosan is registered with the U.S. Environmental Protection Agency as a pesticide, it is freely available for use in over-the-counter products. Triclosan's use in personal care products such as hand soap, acne cream, foot deodorant cream and, rather recently, as a slowrelease product called Microban, is noticeable. The only concern to cosmetic chemists is reports of bacteria becoming resistant to triclosan.

Phytosphingosine is one of the newest biotech entries that is perceived to mimic the skin's own natural phytosphingosine to inhibit the growth of harmful skin microorganisms such as P. acnes, P. aeruginosa and S. aureus.[9]

Natural Preservatives

The concept of self-preservation and the natural preservatives is a relatively new concept in the area of cosmetics and personal care products. Tea tree oil and grapefruit seed extract are the newest entries. Grapefruit seed extract[10] is claimed to be effective on a broad spectrum of bacteria, fungi and viruses. For preservation purposes, grapefruit extract is usually recommended at 0.2 and 1.0% concentrations. However, self-preservation is a naive term mostly used for natural cosmetics. The lack of preservatives in commercial cosmetics and self-mixed preparations creates the ideal breeding ground for bacteria and fungi. Microorganisms can very easily contaminate a product through repeated consumer use. Even if a cosmetic preparation contains exquisite substances, it can turn into an unhealthy product through the inadvertent introduction of undesirable microorganisms.

Testing Procedures

As a standard procedure, many cosmetic houses use the standard microbial challenge test. In this test, samples of cosmetics are inoculated with test organisms and then inspected visually and by use of a plate count to determine if bacteria reduction has been attained. The microorganisms have been made available from the American Type Culture Consumer (ATCC), but some in-house resistant microorganisms are also tested. The most notorious strains include pseudomonas and other gramnegative microorganisms, gram-positive staphylococcus and various yeasts and molds. The testing time may run from two to three weeks to several months. The method also follows the CTFA and ASTM recommendation of two challenges, several weeks apart. Another very reliable test procedure has been the multiple challenges, whereupon all formulas are challenged to extinction; i.e. until microorganisms are routinely recovered from the test samples. A judgment is made on the minimal number of challenges that gives no recovery. Three successive positives may be considered an indication of failure with the system. The number of successful challenges required must be determined by an assessment of the overall susceptibility of the formula. This test was found useful for comparing different formulas, competitive as well as in-house. Our philosophy at Coty has been to offer consumers a well-preserved and a very safe product. Therefore, the selection of a suitable preservative system is of paramount importance in the other ingredients of the formula as well as the tamper-proof packaging.

Household Product Preservation

In household cleaning products, the most common mild-to-moderate alkalis (such as baking soda and ammonia), acids, household bleaches and detergents are used to disinfect and to do many cleaning jobs around the home and workplaces. The latest product form on the market is the wipe. Leading marketers such as Procter & Gamble and Clorox have introduced these wipes to the market with great success. In fact, according to Information Resources, Inc., Chicago, wipe sales have soared more than 900% during the past year. Clorox disinfecting wipes are made up of 0.14% dimethyl benzyl ammonium chloride, 0.145% dimethyl ethyl benzyl ammonium chloride and 99.710% "other ingredients." These wipes are used to kill staph, and salmonella without bleach, which can damage some surfaces.

The Most Popular Preservatives

Here is a look at some of the most frequently-used preservatives for personal care and household cleaning products. Parabens include the mixture of various esters of benzoic acid (methyl, ethyl, propyl and butyl). It is the most popular mixture that has been used successfully to combat fungi and grampositive bacteria. However, it shows poor activity against pseudomonas. It is effective over a wide pH range, although the optimum pH is 8. The parabens can be complemented with another preservative having special effects against gram-negative organisms.

Phenoxyethanol is a phenolic derivative that is active against predominantly gram-negative bacteria. It has a wide pH tolerance. It is water and alcohol miscible. Recommended concentration levels are 0.5-2%.

Imidazolidinyl urea is water-soluble and has a wide pH range tolerance. It exhibits broad-spectrum,

anti-microbial activity when combined with parabens. The use of this preservative is restricted because it yields low levels of formaldehyde.

Diazolidinyl urea belongs to the Germall family of preservatives. Although a broad spectrum preservative, it acts predominantly against gram-negative bacteria. It is water soluble and can perform preservation between pH 3-9. Recommended concentration levels are 0.03-0.3%. It is also a formaldehyde donor.

Ethyl alcohol has excellent antimicrobial activity against bacteria and fungi. As a preservative, 15-20% is the recommended concentration.

Benzyl alcohol is a local anesthetic and is sometimes added to relieve itching, especially in cosmetic eye products. It is an efficient bacteriostatic agent. A concentration of 1-3% is recommended as a preservative. It is water-soluble at 1g/30ml.

Dehydroacetic acid is an effective bacteriostat and fungistat. It is watersoluble and effective within a pH of 5-6.

A mixture of N-butyl, isobutyl and isopropyl parabens (Liquapar) is primarily active against yeast, molds and some bacteria. It can tolerate a wide pH range. The typical usage level is 0.50-.3%.

Potassium sorbate is primarily active against molds and yeasts. It is water-soluble with an optimum pH of up to 6.5.

Methyl, chloromethyl isothiazolinone and methyl isothiazolinone (Kathon CG) are active against bacteria, yeast and fungi. They are supplied as an aqueous solution, but for usage concentrations please contact the supplier. It can tolerate the entire pH range. The preservative is designed for rinse-off products such as shampoos and body washes.

DMDM hydantoin (Glydant) is a broad spectrum preservative, but less effective against yeasts. It is water soluble with an optimum pH 4.5-9.5.

Benzoic acid and its salt (sodium benzoate) have been used as preservatives in the food industry. Both are water-soluble with a recommended concentration of 0.1-0.2%. Their activity spectrum includes yeasts, some molds and bacteria.

Benzalkonium chloride is a quaternary compound having primary activity against gram-positives and some gramnegatives. It is soluble in water and alcohol with an optimum pH of 4-10. The usage concentration is 0.1-0.3%.

Quaternium 15 (Dowicil 200) is another quaternary broad spectrum preservative. It is water-soluble with a wide pH range (4-10).

Phenyl mercuric acetate is used in cosmetics, especially in eye products such as mascaras, where other preservatives fail. It is poorly soluble in water and soluble in hot ethanol. It is active against bacteria and fungi. As a preservative it is used in concentrations of 0.002-0.125%.

Chloroxylenol (Ottasept) is a halogenated phenolic compound with antibacterial and antifungal actions. It is alcohol soluble and poorly soluble in water. It tolerates a wide pH range. Recommended concentration is 0.2-0.8%.

Glutral (Ucarcide) is chemically glutaraldehyde. It is a broad spectrum preservative and soluble in water. Use concentration ranges from 0.02-0.2% of a 50% solution. It can remain active through a broad pH range.

Phenyl ethyl alcohol has a pleasant floral rose odor and is water soluble up to 2%. It is primarily active against gram-negative bacteria.

Sorbic acid is a mold and yeast inhibitor. It is also used as a fungistatic agent in foods, especially cheeses. It is slightly soluble in water, and soluble in alcohol. It becomes inactive above pH 6.2 and the optimum pH range is 2.5-6.

Use concentration ranges from 0.10-0.30%.

2-Bromo-2-nitropropane-1, 3-diol (Bronopol) is an efficient broad-spectrum preservative with only some activity against yeast. It is water-soluble and stable in acid environments with an optimum pH of 6. It has not been a popular preservative in the U.S., because it is pH sensitive and has been observed to impart color to the product. However, it is present in most of the cosmetic products outside the U.S.

Chlorhexidine gluconate is a cationic compound, which limits its use. It is active against bacteria. The optimum stability pH is neutral but remains active between pH 5-8. It is also unstable at high temperatures and is incompatible with anionics and many gums. Usage levels range from 0.01-0.1%.

Salicylic acid is effective against bacteria and fungi. It is poorly watersoluble and discolors products that contain traces of iron. It is used in cosmetics as a keratolytic at high concentrations. Its optimum pH is 4-6 with a usage concentration of 0.1-0.5%.

Formaldehyde is an efficient preservative with a broad-spectrum activity against bacteria and fungi. It has not been a popular preservative because of the aldehyde sensitizing reactions in some subjects. It is sometimes used in rinse-off products. It becomes inactive in the presence of proteins, especially gelatin. Optimum pH is 3-10, with use concentration ranging from 0.05-0.2%.