Monday, March 28, 2016

Preservatives in Cosmetics products

Preservatives in Cosmetics products

Introduction: 

Preservatives are chemical substance that is added to products such as food , pharmaceutical  products , cosmetics and other products to prevent the spoilage by microbial growth or by undesirable chemical changes. Cosmetic and beauty products are made up of ingredients that are biodegradable, and this means that microbes can easily break them down. This causes a product to become unpleasant and unsafe for consumers.  Preservatives are antimicrobial ingredients added to product formulations to maintain the microbiological safety of the products by inhibiting the growth of and reducing the amount of microbial contaminants.

Mechanism action of preservatives:

Preservatives are having limited protection against viral contamination. But it works well on bacteria and fungus.  Bactericides and fungicides may evince their effects on a variety of microbial cellular targets, for example; the cell wall, the cytoplasmic membrane or the cytoplasm.
Cell wall activity may involve lysis due to enzyme inhibition, as is the case with phenols and organo mercurials. In contrast glutaraldehyde evinces its effect by irreversible cross-linking at the cell wall.

Cytoplasmic membrane activity may be due to effects on membrane potential, membrane enzymatic function or general membrane permeability . Cetrimide, chlorhexidine, hexachlorophene, 2-phenoxyethanol, parabens and phenols affect membrane permeability allowing ‘leaking’ of essential cell constituents leading to cell death. Sorbic acid inhibits transport mechanisms across the cytoplasmic membrane and suppresses fumarate oxidation. Chlorhexidine also inhibits membrane ATPase, thereby inhibiting cellular anaerobic activity. At higher concentrations it induces precipitation of cytoplasmic nucleic acids and related proteins. Other biguanides induce phase separation and the formation of domains in the phospholipid bi-layer.

Cytoplasmic activity may concern uncoupling of oxidative and phosphorylation processes or interference with active transport mechanisms, as is the case with weak carboxylic acid and alcoholic preservatives. Other preservatives can inhibit electron transport chains, thereby inhibiting metabolic activity in aerobic bacteria [13]. Benzoic acid and the parabens inhibit folic acid synthesis . Bronopol and other organo-mercurials target thiol enzymes [3] in the cytoplasm (as do silver compounds); whereas, formaldehyde donators e.g. imidurea act on the carboxylic and amino enzymes in the cytoplasm.



Types of Preservatives in Cosmetics:

Cosmetics products are easily contaminated by microbes such as bacteria and fungi. The cosmetic formulations having water, oils , fats and vitamins are good medium for the growth of micro organisms. Cosmetics may also be contaminated during usage and handling.  So , cosmetics formulations need preservatives to preservation to ensure that products are safe to use for a long time.

Generally the following 5 types of preservatives are used in cosmetics.

  • Parabens
  • Formaldehyde releasers
  • Isothiazolinones
  • Phenoxyethanol
  • Organic acids

Parabens


Parabens are widely used preservatives in cosmetics and pharmaceutical products. they are a series of parahydroxybenzoates or esters of parahydroxybenzoic acid (also known as 4-hydroxybenzoic acid). These compounds, and their salts, are used primarily for their bactericidal and fungicidal properties. They can be found in shampoos, commercial moisturizers, shaving gels, personal lubricants, topical/parenteral pharmaceuticals, spray tanning solution, makeup, and toothpaste

Example:
  • Methylparaben
  • Propylparaben

Formaldehyde releasers

A formaldehyde-releaser is a chemical compound that slowly releases formaldehyde as it decomposes in a product formulation. Formaldehyde-releasers are used as an antimicrobial/antifungal preservative in cosmetics and hair care products.

Example:

DMDM hydantoin
Imidazolidinyl urea
Diazolidinyl urea
Quaternium-15
2-Bromo-2-nitropropane-1,3-diol (Bronopol) 
5-Bromo-5-nitro-1,3-dioxane  (Bronidox)
Sodium hydroxymethylglycinate

Isothiazolinones

Isothiazolinone is a heterocyclic chemical compound. Derivatives of isothiazolinone are used as biocides. Isothiazolinones are antimicrobials used to control bacteria, fungi, and algae in cooling water systems, fuel storage tanks, pulp and paper mill water systems, oil extraction systems, wood preservation and antifouling agents. They are frequently used in personal care products such as shampoos and other hair care products, as well as certain paint formulations.

Example:

Methylisothiazolinone (MIT, MI)
Chloromethylisothiazolinone (CMIT, CMI, MCI)
Benzisothiazolinone (BIT)
Octylisothiazolinone (OIT, OI)
Dichlorooctylisothiazolinone (DCOIT, DCOI)
Kathon CG ( combinations of MIT and CMIT)

Phenoxyethanol

Phenoxyethanol is a germicidal and germistatic glycol ether, phenol ether, and aromatic alcohol often used together with quaternary ammonium compounds.Phenoxyethanol is used as a perfume fixative; an insect repellent; an antiseptic; a solvent for cellulose acetate, dyes, inks, and resins; a preservative for pharmaceuticals, cosmetics and lubricants; an anesthetic in fish aquaculture; and in organic synthesis. Phenoxyethanol is effective against gram-negative and gram-positive bacteria, and the yeast Candida albicans

Example:
Optiphen, Optiphen Plus (contains phenoxyethanol combined with others for broad spectrum protection).

Organic acids

An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH.

Example:
Benzoic Acid / Sodium Benzoate
Sorbic Acid / Potassium sorbate
Levulinic Acid
Anisic Acid


List of some preservatives commonly used in cosmetics products:

S.No
Chemical Substance
Max.concentration to be used.
1
Benzoic acid and its sodium salt.
Rinse off products, except
oral care products; 2.5 %
(acid)
Oral care products; 1.7 %
(acid)
Leave-on products; 0.5 %
(acid)
2
Propionic acid and its salts
2% (acid)
3
Salicylic acid and its salts
0.5% (acid
4
Sorbic acid (hexa-2,4-dienoic acid) and its salts
0.6% (acid)
5


6
Formaldehyde and paraformaldehyde
0.2% (except for products for oral hygiene) 0.1% (for oral hygiene) expressed as free formaldehyde
7
Biphenyl-2-ol (o-phenylphenol) and its salts
0.2% expressed as phenol
8
Zinc pyrithione
Hair products; 1.0 % Other products; 0.5%
9
Inorganic sulphites and hydrogensulphites
0.2% expressed as free SO2
10
Chlorobutanol(INN)
0.5%
11
3-Acetyl-6-methylpyran-2,4 (3H)-dione (Dehydroacetic acid) and its salts
0.6% (acid)
12
Formic acid and its sodium salt
0.5 % ( Expressed as acid )
13
3,3'-Dibromo-4,4'-hexamethylenedioxydibenzamidine
(Dibromohexamidine) and its salts
( including isethionate)
0.1 %

14
Thiomersal(INN)
0.007% (of Hg)
If mixed with other mercurial
compunds authorized by this
Directive, the maximum
concentration of Hg remains
fixed at 0.007%
15
Phenylmercuric salts (including borate)
0.007% (of Hg) If mixed with other mercurial compunds authorized by this Directive, the maximum concentration of Hg remains fixed at 0.007%
16
Undec-10-enoic acid and its salts(+)
0.2% (acid)
17
Hexetidine(INN)
0.1%
18
5-Bromo-5-nitro-1,3 dioxane
0.1%
19
Bronopol(INN)
0.1%
20
2,4-Dichlorobenzyl alcohol
0.15%
21
Triclocarban(INN) (+)(5)
0.2%
22
4-Chloro-m-cresol
0.2%
23
Triclosan(INN) (+)
0.3%
24
4-Chloro-3,5-xylenol
0.5%
25
3,3’-Bis(1-hydroxymethyl-2,5-dioxoimidazolidin- 4-yl)-1,1’-methylenediurea (“Imidazolidinyl urea”)
0.6%
26
Poly(1-hexamethylenebiguanide hydrochloride)
0.3%



28
2-Phenoxyethanol
1.0%
29
Hexamethylenetetramine (methenamine) (INN)
0.15%
30
Methenamine 3-chloroallylochloride (INNM)
0.2%
31
1-(4-Chlorophenoxy)-1-(imidazol-1-yl)-3,3- dimethylbutan-2-one) (+)
0.5%
32
1,3-Bis(hydroxymethyl)-5,5- dimethylimidazolidine-2,4-dione)
0.6%
33
Benzyl alcohol(+)
1%
34
1-Hydroxy-4-methyl-6-(2,4,4-trimethylpentyl)-2 pyridon and its monoethanolamine salt
1%  -- Rinse off product.
0 .5 % -- Other product
35
6,6-Dibromo-4,4-dichloro-2,2’-methylenediphenol (Bromochlorophen)
0.1%
36
4-Isopropyl-m-cresol
0.1%
37
Mixture of 5-Chloro-2-methyl-isothiazol-3(2H)- one and 2-Methylisothiazol-3(2H)-one with magnesium chloride and magnesium nitrate)
0.0015% (of a mixture in the ratio 3:1 of 5-Chloro-2- methyl-isothiazol-3(2H)-one and 2-methylisothiazol- 3(2H)-one)
38
2-Benzyl-4-chlorophenol (chlorophene)
0.2%
39
2-Chloroacetamide
0.3%
40
Chlorhexidine(INN) and its digluconate, diacetate and dihydrochloride(+)
0.3% expressed as chlorhexidine
41
1-Phenoxypropan-2-ol(+)
1.0%
42
Alkyl (C12-C22) trimethyl ammonium, bromide and chloride)
0.1%
43
4,4-Dimethyl-1,3-oxazolidine
0.1%
44
N-(Hydroxymethyl)-N-(dihydroxymethyl-1,3- dioxo-2,5-imidazolinidyl-4)-N'-(hydroxymethyl) urea)
0.5%
45
1,6-Di(4-amidinophenoxy)-n-hexane (Hexamidine) and its salts (including isethionate and p-hydroxybenzoate(+)
0.1%
46
Glutaraldehyde (Pentane-1,5-dial)
0.1%



47
5-Ethyl-3,7-dioxa-1-azabicyclo [3.3.0] octane
0.3%
48
3-(p-Chlorophenoxy)-propane-1,2-diol (chlorphenesin)
0.3%
49
Sodium hydroxymethylamino acetate (Sodium hydroxymethylglycinate
0.5%
50
Silver chloride deposited on titanium dioxide
0.004% calculated as AgCl
51
BenzethoniumChloride (INCI)
0.1%
52
Benzalkonium chloride, bromide and saccharinate(+
0.1% calculated as Benzalkonium chloride
53
Benzylhemiformal
0.15%
54
Iodopropynylbutylcarbamate (IPBC); 3-Iodo-2-propynylbutylcarbamate
(a) rinse-off products: 0.02 % (b) leave-on products: 0.01 % except in deodorants & antiperspirants: 0.0075 %
55
Methylisothiazolinone(INCI)
0.01 %




Safety:

Consumer health and safety is the main reason for including preservatives in cosmetics.
Strict rules govern the inclusion of preservatives in cosmetics. Throughout Europe, manufacturers must choose from only those preservatives listed in the EU Cosmetics Legislation. Allergy to preservatives is rare but a very small number of people could have an allergic reaction to certain substances.

The ingredients in cosmetic products are labelled in accordance with EU legislation. This means that people with sensitivities can be aware of any preservatives in product formulations that could trigger an allergic reaction.

Conclusion:

There are so many ways for cosmetics products to come into contact with microorganisms even in production or in consumer hands. Without preservatives, the cosmetics products will go to unsafe to use. Just a small amount of preservative can protect cosmetics from contamination over a long period. Most cosmetics need preservatives. There are a few exceptions—perfumes, deodorants and hair sprays with a high alcohol content, for example. For all other products, preservatives have an important and beneficial role to play. Now some natural ingredients like Neem oil, Rosemary extract are also used as preservatives.

References :





http://www.americanpharmaceuticalreview.com/Featured-Articles/38886-Antimicrobial-Preservatives-Part-One-Choosing-a-Preservative-System/