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
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/
