Decontamination of Cosmetic Products and Raw Materials by Gamma Irradiation

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Decontamination of Cosmetic Products and Raw Materials by Gamma Irradiation

Summary

Decontamination of Cosmetic Products and Raw Materials by Gamma Irradiation

In this study, we aimed to use gamma irradiation for decontamination of cosmetic products in order to achieve the acceptable microbiological limits. Cosmetic products and raw materials were irradiated (5-7.5-10 kGy) and physicochemical, microbiological and biological properties of these samples were evaluated in normal and stress storage conditions.

It was found that the physicochemical properties of samples tested were changed after irradiation. No change was observed in skin irritation properties of all samples tested. Decontamination dose for all samples, excluding starch, was found to be about 5 kGy or below.

Key Words: Decontamination by gamma radiation, cosmetic products, cosmetic raw materials.

Received : 03.03.2008 Revised : 27.03.2008 Accepted : 29.05.2008

* Hacettepe University, Faculty of Pharmacy, Department of Radiopharmacy, 06100, Ankara,Turkey.

** Hacettepe University, Faculty of Pharmacy, Department of Pharmaceutical Microbiology, 06100, Ankara, Turkey.

*** Hacettepe University, Faculty of Medicine, Department of Dermatology, 06100, Ankara, Turkey.

**** Hacettepe University, Faculty of Engineering, Department of Physics Engineering, 06532, Ankara, Turkey.

° Corresponding author e-mail : ayozer@hacettepe.edu.tr

INTRODUCTION

Gamma irradiation has an increasingly important role in the manufacture of cosmetic products [1]. The use of gamma rays is an alternative method for sterilization/decontamination of products and raw materials [2]. However, one of the major problems of irradiation is the occurrence of new radicals during the process [3]. Irradiation is never a substitute for poor compliance to Good Manufacturing Practice (GMP) guidelines. In fact, it should be a part of GMP [4]. The gamma radiation process cannot make some-

thing radioactive or leave any residual radioactivity.

Microorganisms are killed either as a result of the destruction in a vital molecule or by chemical reaction of compounds resulting from radiation. The most widely used application of gamma radiation processing is in the control of microbial contamination levels [1].

Topically applied preparations must not contain mi- crobials exceeding the permissible limits. This is

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achieved through the decontamination and sterilization process [5]. In many cases, the offending organ- isms in a cosmetic product are Escherichia coli (E.

coli) or Pseudomonas aeruginosa (P. aeruginosa).

Both are especially susceptible to radiation energy at very low doses, which often means that the radiation effect on the product is negligible [6]. Cosmetic products may be contaminated during manufacturing by microorganisms existing in the environment or in the raw materials. Raw materials, especially water, found in most of the cosmetic preparations form an appropriate media for microbial growth. There is no certain radiation dose level in pharmacopoeia and guidelines for decontaminating cosmetic preparations and cosmetic raw materials. However, acceptable microbiological limits are recommended in guidelines for a variety of cosmetic preparations. These limits are between 102 and 103. Generally, the gamma radiation dose preferred to achieve these levels ranges between 5 and 15 kGy. 60Co source, which is commonly used for gamma irradiation, can be used for cosmetic raw materials and finished products. Aiming at the reduc- tion in microbiological content, the method does not leave any residues that may be harmful to the em- ployees or consumers. Gamma radiation can penetrate the packaging materials and sealed packages contain- ing the finished products, thus destroying the existing microorganisms. Decontamination by gamma radiation is gaining increasing attention in cosmetic production.

MATERIALS and METHODS

Materials used in the experiments are coded in Table 1. A, B, and C were kindly provided from Colgate- Palmolive, D from Canan Kozmetik, E, F, G, H, I, J,

K, L from Eczac›bafl›-Beiersdorf, M from Evyap, N, O, P from Eczac›bafl›-Avon, R from Johnson & Johnson, S, V, Y from Merck, T from Roquette Freres, and U from Çapamarka.

Statistics

Physicochemical test results are given as the mean of 6 experiments; whereas, n = 3 was applied for biological and microbiological tests. Kruskal-Wallis and non-parametric Mann-Whitney U tests were used as the significance tests and SPSS computer software program was employed for analyses.

Irradiation Process

Irradiation was performed at room temperature using a 60Co Gamma Cell 220 available at the Turkish Atomic Energy Agency (TAEK) at a dose rate of 2.84 kGy h- 1. All samples in glass vials were irradiated at doses of 5, 7.5, 10 kGy. Bioburden and irritation tests were carried out for sample K.

Unirradiated samples were used as controls to detect physicochemical, biological and microbiological changes resulting from the action of ionizing radiation on the cosmetic products and raw materials investigated. Experiments performed on cosmetic samples are summarized in Table 2.

Physicochemical Properties

All tests were performed on unirradiated samples and samples irradiated at doses of 5, 7.5 and 10 kGy (Table 2). Results were analyzed statistically.

Table 1. Codes of materials used

Cosmetic Cosmetic Cosmetic Raw

Code Product Code Product Code Materials

A Baby powder J Concealer S Talc

B Solid soap K Mascara T Wheat starch

C Solid soap L Eye pencil U Corn starch

D Liquid soap M Solid soap V Bentonite

E Baby powder N Redness Y Gelatin

F Lush on O Lip pencil

G Compact powder P Foundation

H Foundation R Baby powder

I Eye shadow

Table 2. Tests performed on cosmetic samples under normal conditions

COSMETIC PRODUCTS Physicochemical Tests

Biological Test - Irritation test Microbiological Tests - Bioburden

- Determination of decontamination dose Solid and liquid soaps

- Organoleptic properties - pH

- Viscosity - Foam height

Other preparations - Organoleptic properties - Particle size

COSMETIC RAW MATERIALS Physicochemical Tests

Biological Test - Irritation test Microbiological Tests - Bioburden

- Determination of decontamination dose - Organoleptic properties - Particle size - ESR behavior

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-Organoleptic Properties: Solid and liquid soaps were evaluated by their color, odor and general appearance.

-pH: [5% (w/v)] solutions of unirradiated and irradi- ated soaps were prepared and pH of these solutions were measured at room temperature (25°C) and at 40°C (Sesa Model 1400).

- Viscosity: Viscosities of unirradiated and irradiated 1% (w/v) soap solutions were measured by Brookfield rheometer (DV-II model) at two different temperatures of 25°C and 40°C.

-Foam Height: To determine the foam height, 5 ml of unirradiated and irradiated 1% (w/v) soap solutions were placed in tubes and vigorously shaken for 10 min at 280 rpm.min-1. Foam height was calculated as the ratio of foam height to total height. The same procedure was repeated at 25°C and 40°C.

-Mean Particle Size and Distribution: Unirradiated samples and samples irradiated at doses of 5, 7.5 and 10 kGy were investigated. Mean particle sizes and size distributions of cosmetic samples except soaps, i.e. foundations, concealer, mascara, eye pencil and lip pencil, were measured by laser diffraction method (Sympatec Helos (H 0728) Particle Size Analyzer).

-ESR Behavior: Electron spin resonance (ESR) studies were done on cosmetic raw materials before and immediately after irradiation. These studies were carried out using a Varian 9”E-LX Band ESR Spec- trometer. Each spectrum was corrected for variation using the amount of material in the ESR tube.

Microbiological Properties

The neutralization process of antimicrobial property was not validated because the aim of this research was to determine the bioburden of cosmetic raw materials and products and to compare these findings with the limits permitted legally. The purpose was to find the reliability of cosmetic products and raw materials available on the Turkish market and in accordance with the guidelines.

In order to obtain these results, 1 g of cosmetic product

or raw material was used in the experimental part and all samples were contaminated with Bacillus pumilus spores (106 cfu.mL-1) at the beginning of the study.

-Bioburden: In order to determine the microbial load (bioburden) of samples, 1 g of each sample was weighed in sterile vials and 1 ml of sterile distilled water was then added. Each mixture was mixed for 1 min; 0.1 ml of samples were withdrawn from vials and inoculated on plates with tryptic soy agar. All plates were incubated for 24-48 h at 37°C followed by counting the number of colonies with naked eye.

-Determination of Decontamination Dose Level:

Samples were contaminated by the most radiation- resistant microorganism, Bacillus pumilus spores (106

cfu.mL-1), in order to determine the decontamination dose level. The samples were then irradiated at different dose levels of 2, 5, 7.5 and 10 kGy. Each sample was mixed for 1 min; 0.1 ml of samples were withdrawn from vials and inoculated on plate with tryptic soy agar. All plates were incubated for 24-48 h at 37°C, followed by counting the number of colonies with naked eye.

Biological Properties

-Irritation Test: Possible irritation effects of unirradi- ated and irradiated samples were evaluated using occlusive patch test. Patches were applied to the forearms of healthy volunteers. Patches were removed 24 h later, and forearms were washed with tap water.

Irritation was evaluated by a dermatologist using the scores given in Table 3. The test was repeated 3 times Table 3. Scoring of irritation

Erythema

0 No evidence of erythema 0.5 Minimal or doubtful erythema 1 Slight, spotty and diffuse redness 2 Moderate, uniform redness

3 Strong uniform redness

4 Hot redness

Dryness

0 No evidence of scaling

0.5 Dry without scaling; appears smooth and tight

1 Fine/mild scaling

2 Moderate scaling

3 Severe scaling with large flakes Edema

- Absence of edema

+ Presence of edema

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per sample. In total, 18 healthy volunteers were used for 22 samples.

5% (w/v) soap solutions were used for this test. 15 mg of samples A, E, F, G, H, I, N and R were weighed and placed in the Finn chambers. One drop of samples H and P were absorbed on special filter papers, and then placed in the chamber. For sample K, 2 ml of distilled water was added to the original package and mixed for 2 min; then, one drop of mixture was put on special filter paper and then placed in the chamber. A certain amount of samples J, L and O were placed in chambers. At the end of the test, the score table (Table 3) [7] was used for evaluating the results.

Stability Studies

In this part of the study, tests performed for samples under normal environmental conditions were repeated with samples stored in unsealed glass tubes for cosmetic raw materials and in sealed glass tubes for cosmetic products, at high temperature (40±2)ºC and high relative humidity (75±5)% conditions over a period of 3 months. Possible changes wer e investigated at accelerated conditions after irradiation. Exper- imental studies carried out for this purpose are summarized in Table 4.

- ESR Behavior: Peaks obtained in the ESR studies in normal environmental conditions were also evaluated in the samples at the end of the stability studies to determine any radical formation.

RESULTS and DISCUSSION

Studies Carried Out Under Normal Conditions Physicochemical Properties

Physicochemical properties of soaps treated with

gamma radiation are widely described, but not for other cosmetics. Therefore, physicochemical tests were applied to cosmetic products considering the existing guidelines or other official sources. For those properties not officially mentioned, particle size measurements, organoleptic properties and ESR studies were considered as sufficient.

- Organoleptic Properties: Organoleptic properties of unirradiated and irradiated soaps are summarized in Table 5. It was determined that there was no change in the organoleptic properties of soap samples irradiated at the 3 different doses.

- pH: pH values of soaps were found to change after irradiation at all 3 doses. Changes in pH values of all soaps seem to be independent from irradiation dose levels (p>0.05). Results are given in Table 6.

Table 4. Physicochemical tests performed on cosmetic products and raw materials during the stability studies

COSMETIC PREPARATIONS Physicochemical Tests Solid and liquid soaps

-Organoleptic properties -Viscosity -pH -Foam height

Other preparations -Organoleptic properties -Particle size

COSMETIC RAW MATERIALS Physicochemical Tests -Organoleptic properties -Particle size

Table 5. Organoleptic properties of liquid and solid soaps before and after irradiation

Code

B C D M

Unirradiated Blue/light blue bar Orange, transparent bar

White, opaque liquid Yellow/light yellow bar

Dose (kGy) 5

+ + + +

7.5 + + + +

10 + + + + Organoleptic Properties

(+ : no change; - : change)

Table 6. pH values of unirradiated and irradiated soaps at two different temperatures

Code

B C D M

* value represents mean ± standard deviation, n=6.

Temperature (°C)

25

Unirradiated

9.31±0.01 9.15±0.02 6.11±0.04 9.39±0.02

5 9.45±0.04 9.29±0.02 6.05±0.08 9.45±0.02

7.5 9.64±0.03 9.48±0.04 5.87±0.04 9.71±0.03

10 9.69±0.03 9.54±0.04 5.95±0.04 9.65±0.02

Statistical Evaluation

p<0.05 p<0.05 p<0.05 p<0.05 Dose (kGy)

pH

40

Unirradiated

9.25±0.09 9.18±0.05 6.04±0.07 9.20±0.04

5 9.41±0.03 9.23±0.02 5.88±0.05 9.42±0.02

7.5 9.48±0.05 9.42±0.02 5.85±0.05 9.61±0.04

10 9.30±0.03 9.13±0.02 5.78±0.04 9.29±0.04

p<0.05 p<0.05 p<0.05 p<0.05 Dose (kGy)

pH Code

B C D M

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pH values of solid soaps B, C and M increased with the increase in radiation dose levels. However, pH value of liquid soap D decreased with the increase in irradiation dose. These differences in pH values may be attributed to the trace amount of radicals formed by irradiation. Results obtained in this study are in agreement with the literature, since it was reported that decrease in the pH value of an antibacterial agent after irradiation was found to be independent of the irradiation dose levels [8,9].

- Viscosity: Inconsistent results were obtained from viscosity measurements of solid soaps at 25°C due to the gel formation at room temperature (data not presented). Therefore, viscosity measurements of solid soaps were performed only at 40°C while viscosities of liquid soaps were measured at 25°C and 40°C.

Viscosities of unirradiated solid soaps (B, C, M) and those irradiated at the 3 different doses did not change significantly at 40°C (p<0.05). There were significant (p<0.05) differences in viscosities of unirradiated liquid soaps compared with samples irradiated at the 3 different doses at both temperatures. According to these results, it can be concluded that solid soaps are more stable against irradiation than liquid soaps.

Results are given in Figure 1 a-d. Jacobs et al. [10]

reported changes in viscosities of some materials after irradiation. For example, viscosity of tragacanth gum was decreased with increasing radiation dose [10]. In another study, application of radiation dose between 5 and 15 kGy on HPMC (hydroxypropyl methylcel- lulose) powder solution displayed pseudo-plastic behavior at the beginning followed by a Newtonian flow. Viscosity of HPMC solution was decreased with an increase in the irradiation dose (5-15 kGy) [11].

- Foam Height: Although foaming of soaps or deter- gents is independent from their cleansing properties, it is perceived as the sign of cleanliness due to psy- chological factors. Foam heights of soaps were found to change after irradiation. The results obtained showed that the changes in foam heights of all soaps were independent of radiation dose. Results are given in Table 7.

- Mean Particle Size and Distribution: Mean particle

sizes of cosmetic samples irradiated at the 3 different doses (5, 7.5, 10 kGy) were determined to change Table 7. Foam heights of solid and liquid soaps

before and after irradiation

Code

B C D M

* value represents mean ± standard deviation, n=6.

Temperature (°C)

25

Unirradiated

51.6±4.0 63.0±7.0 52.6±4.0 63.8±3.0

5 67.8±3.0 61.6±4.0 54.2±6.0 56.3±3.0

7.5 60.1±6.0 60.2±4.0 46.1±4.0 70.8±7.0

10 62.4±4.0 53.0±7.0 56.5±4.0 55.2±1.0

p<0.05 p<0.05 p<0.05 p<0.05 Dose (kGy)

Foam Height (%)

40

Unirradiated

65.3±3.0 60.7±5.0 55.5±2.0 77.5±2.0

5 58.9±4.0 64.2±2.0 44.1±2.0 81.3±1.0

7.5 61.5±4.0 51.3±3.0 47.5±2.0 65.1±1.0

10 72.2±2.0 54.2±4.0 44.0±3.0 47.5±2.0

p<0.05 p<0.05 p<0.05 p<0.05 Dose (kGy)

Foam Height (%) Code

B C D M

Figure 1 a-d. Flow curves of solid and liquid soaps before and after irradiation at 40C (n=6).

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when compared with the results of unirradiated samples (p<0.05). Results of particle sizes are shown in Figure 2 a-b.

Changes in mean particle sizes by irradiation were observed for cosmetic products and raw materials.

Particle sizes may be different because of the changes in forces regulating the particles in a powder [12].

However, it is not clear whether these changes are dependent or independent of radiation since samples did not show homogeneous particle size distribution.

- ESR Studies: ESR studies were performed only on cosmetic raw materials. ESR spectra of unirradiated and irradiated samples were measured under the same conditions. No by-product peaks were detected in unirradiated and irradiated talc and bentonite samples. No peaks were observed for gelatin, corn and wheat starch before irradiation. ESR spectra of irradiated samples are given in Figures 3, 4 and 5.

Peak-to-peak intensities were determined from ESR spectra and dose-response curves were plotted (Fig.

6 a-c). Formation of similar radicals was found on evaluating the ESR spectra of corn and wheat starch after irradiation. This is expected because the type and structure of the two starches are similar.

A simulation study based on possible radical species formation was also performed and hydroxyalkyl and aldehydalkyl radicals were detected. These results are in agreement with the literature since hydroxyalkyl and aldehydalkyl radicals were determined after irradiation of wheat, lentil and broad bean, which contain a high amount of starch [13,14]. Suggested radicals resulting from simulation studies are shown in Figure 7 (for A and B) and spectroscopic parameters are given in Table 8.

Evaluating the chemical structure of gelatin, formation of R-CHO• (radical C) and •H (radical D) may occur due to the degradation of CHOH by irradiation.

Simulation studies were also carried out for gelatin, and possible radicals and their spectroscopic parameters are summarized in Table 9. Based on simulation

Figure 2 a-b. Mean particle size and size distribution of cosmetic products and cosmetic raw materials before and after irradiation (n=6).

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Figure 3. Experimental and theoretical ESR spectra of wheat starch.

Figure 4. Experimental and theoretical ESR spectra of corn starch.

Figure 5. Experimental and theoretical ESR spectra of gelatin.

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studies, the suggested radicals are shown in Table 9 and Figure 5.

Microbiological Properties

-Bioburden: Cosmetic products and ingredients may sometimes have high bioburden. The product should be free, as much as possible, from microbial contamination, i.e. from bioburden. Generally, the lower the bioburden, the greater is the margin of safety [15]. As seen in Table 10, microbiological growth was observed in samples D, F, H, J, L, N, O, P, R, S, T, U, V and Y, while no microbial growth was observed in samples B, C, G, I, K and M. These results may be attributed to the general belief that solid soaps (B, C and M) are not appropriate media for microbial growth and production of B, C, G, I, K and M were under acceptable GMP conditions.

- Decontamination Dose: Microbial amounts in sam- ples after irradiation are given in Table 11. According to the results determining the decontamination dose, decontamination dose of all samples except corn and wheat starches was determined to be below or around

Figure 6 a-c. Dose-response curves of a: wheat starch, b: corn starch, c: gelatin (n=6).

Table 8. ESR spectroscopic parameters resulting from simulation studies for corn and wheat starches

Parameter Γ(Gauss)I A(Gauss) (Hβ1) A(Gauss) (OH) A(Gauss) (Hβ2)

G Γ(Gauss)I A(Gauss) (H)

G

Corn starch 92.145 3.2358 13.305 5.0368 5.0374 2.0029 53.954 3.7440 35.786 2.0029

Wheat starch 171.050

3.4812 13.308 4.8782 4.8618 2.0029 92.773 3.9558 36.858 2.0028 Radicals

A

B

I: Intensity Γ : Half-width. g: Spectroscopic splitting factor. A: Hyper-fine splitting constant.

Figure 7. Suggested radicals of corn and wheat starches A:

hydroxyalkyl B: aldehydalkyl.

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Table 9. ESR spectroscopic parameters and radicals for gelatin

RADICALS

C R-CHO•

D

•H

I: Intensity. Γ: Half-width. g: Spectroscopic splitting factor, A: Hyper-fine splitting constant.

PARAMETERS I Γ(Gauss) A(Gauss) (proton at CHO)

A(Gauss) (proton at CH2) A(Gauss) (proton at CH2)

g I Γ(Gauss) A(Gauss)

g

GELATIN 127.660

3.6672 13.872 4.9174 4.327 2.0028 46.941 5.8685 38.840 2.0031

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5 kGy. Decontamination dose of corn and wheat starches was determined to be about 7 kGy. Starches provide more appropriate conditions for microbial growth due to their hygroscopic structure. Therefore, decontamination dose of starches was found to be higher than of the other samples.

Survival rates of microorganisms versus dose levels were plotted on a logarithmic scale and the results are given in Figure 8.

Biological Properties

- Irritation Properties: Results obtained in irritation

tests were evaluated according to Score Table (Table 3) and are given in Table 12. It was found that irritation properties of all samples did not change after irradiation (p>0.05).

Table 10.Bioburden of samples (normal microflora of cosmetic samples)

Code

A B C D E F G H I J K

Amount of Microorganism (cfu.mL-1)

50 0 0 10 40 10 0 60

0 20

0

Code

L M N O P R S T U V Y

Amount of Microorganism (cfu.mL-1)

50 0 120

10 50 30

>3000 1800

40

>3000 170

Table 11.Amount of microorganisms in samples before and after irradiation

Code

A B C D E F G H I J L M N O P R S T U V Y

Unirradiated

106 106 106 106 106 106 106 106 106 106 106 106 106 106 106 106 106 106 106 106 106

2 kGy 250

- - - 290 240 820 - 620 170 170 - - - - - - - - 310 240

5 kGy 80

0 0 80 190 10 140 730 160 80 30 0 30 300 300 380 200 870 610 130 40

7.5 kGy 0 0 0 20

0 0 0 30

0 0 0 0 20 10 40 10 10 120 250 0 0

10 kGy 0 0 0 0 0 0 0 20

0 0 0 0 0 0 0 0 0 20 30 0 0 Microbial Amount (cfu.mL-1)

* All samples were contaminated by Bacillus pumilus spores (106 cfu/ml).

A:

D:

E:

F:

G:

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H:

I:

J:

L:

N:

O:

P:

R:

S:

T:

U:

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Stability Studies

Organoleptic properties of samples irradiated at the 3 different doses were not changed, as with the samples stored under normal conditions. There were differences in pH, viscosity, foam height, and mean particle size values independent of irradiation doses (p<0.05). This result was also the same as with the samples stored under normal conditions.

With regard to ESR behavior, no external peaks were detected for gelatin, corn and wheat starches on the 90th day.

CONCLUSIONS

The use of gamma radiation for decontamination is advantageous for finished cosmetic products as well as raw materials. Sterilization is not an obligation for cosmetic products. However, they have to be protected from any contamination or deterioration. This is particularly important for the cosmetic products used for the eyes and mouth or for babies.

Conventional cosmetic products contain carbohy- drates, sugars, fatty acids, alcohols, starches, proteins, amino acids, glycosides, steroids, peptides, vitamins and some herbal ingredients in their formulations.

Figure 8. Survival-dose rates of all cosmetic samples (coded as A-Y).

V:

Y:

Table 12. Results of irritation test

Code A

B C

D E

F G

H I

J K

L M

N O

P R

S T

U V

Y

Evaluation Erythema

Dryness Edema Erythema

Dryness Edema

0 kGy 0.33±0.58

0 0.5±0.5-

0 - 1.33±0.58

0 0.5±0- 0.5±0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 0.17±0.29-

0 - 0.33±0.58

0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 -

5 kGy 0.67±1.15

0 0.17±0.29-

0 - 0.17±0.29

0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 0.17±0.29-

0 - 0.33±0.58

0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 -

7.5 kGy 0 0 - 0 0 - 0.17±0.29

0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 0.17±0.29-

0 - 0.33±0.58

0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 -

10 kGy 0 0 0.17±0.29-

0 - 0.17±0.29

0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 - 0 0 -

p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 p>0.05 Clinical Score

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Additionally, modern cosmetic products contain sev- eral sensitive raw materials such as minerals, hor- mones and enzymes. All these raw materials are potential nutrition media for the growth of microorganisms. Therefore, contamination can easily occur as [16]:

a) Raw material contamination and b) Product contamination.

For raw material contamination, ingredients within the formulation and packaging materials are the main contamination sources. Industrial water is a major challenge in this sense. Starches in particular are hygroscopic raw materials and as potential media for the microorganisms, can easily create problems in storage. The indications of contamination may be gas formation and changes in color, odor, viscosity, particle size, and pH. These organoleptic properties should be followed although this is sometimes time- consuming.

Product contamination is the result of production processes originating from equipment, environment or staff. Insufficient cleaning and disinfection of equipment and contaminated environment or person- nel are the factors leading to product contamination.

Gamma irradiation of raw materials decreases the contamination risk of finished products and thus the cost. Therefore, physicochemical properties of raw materials are the predictions of GMP conditions of a production process.

In this study, no significant change was determined in organoleptic properties of raw materials S, T, U, V and Y. Mean particle sizes of T, U and V were affected by gamma irradiation. T and U are the starches and due to their hygroscopic character, the particles get agglomerated and the sizes increased. V, bentonite, is also another hygroscopic ingredient and showed similar behavior. Some radicals causing radiolysis (originating from hygroscopic property) were determined by ESR studies; however, no significant changes were found in the raw materials.

According to the physicochemical tests, no change was observed in the organoleptic properties of soap, make-up products, baby powders and raw materials after irradiation. However, pH, viscosity and foam height of soaps irradiated at the 3 different doses were changed when compared with the unirradiated samples. Similarly, mean particle sizes of irradiated make-up products, baby powders and raw materials were changed.

When the bioburden of all cosmetic raw materials and finished products was investigated, product N and raw materials S and V were found to have very high microbiological loads when compared to the official limitations (Turkish Ministry of Health Guide- line Limitations, EC Directive-DOC XI/40517/76).

The other products and raw materials were found in conformity with the limits.

No difference was observed between the irritation scores produced by unirradiated and irradiated samples. Decontamination dose required to decrease the bioburden of all samples was found to be about 5 kGy while it was around 7 kGy for the starches.

Starches provide more convenient media for microbial growth than the other cosmetic raw materials and products due to their hygroscopic character. Therefore, decontamination dose for starches was found to be higher than for the other samples. Potential for change in the product increases with an increase in irradiation dose. It was concluded that 5kGy was the optimal gamma irradiation dose for decontamination purposes for all products and raw materials, except for wheat and maize starches.

Cosmetic products and raw materials tested in this study, except talc and bentonite, and produced locally or imported seem to be prepared according to the GMP guidelines.

As a result, it can be concluded that sterilization/decontamination using gamma radiation is an alternative method for decontamination of cosmetic products and raw materials. Gamma radiation can also be used much more extensively in the cosmetic field, especially in the field of bulk raw materials.

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Furthermore, gamma irradiation is a clean and non- residual technology that is environmentally friendly and safe for both employee and the community.

ACKNOWLEDGEMENTS

We wish to express our gratitude to ‹.E. Ulagay for supplying some of the chemical materials. This study was supported by H.U. Research Foundation (Project No: 01.01.301.006).

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