PARABENS IN COMMERCIAL COSMETICS 69 Sample pretreatment. An accurately weighed 1.00 g of cosmetic sample was transferred into a 10-ml glass centrifuge tube with plug. The sample was mixed with 10-ml methanol and subjected to ultrasound for 10 min. The solution was then centrifuged at 12,000 rpm for 5 min. The supernatant was fi ltered through 0.45 μm nylon membrane and then used for HPLC analysis. HPLC analysis. A Waters 2695-996 HPLC system (Milford, MA) equipped with a 600 gradient pump was used. A Waters Empower software workstation for instrument con- trol as well as data acquisition and processing was applied. An analytical column of Inertsil® ODS-3 C18 (250 × 4.6 mm, 5 μm) from Dikma (GL Science Inc. Tokyo, Japan) was used at room temperature. The mobile phase was a mixture of V(A):V(methanol):V(ac etonitrile) = 50:35:15 (where A was 0.05 mol/l sodium dihydrogen phosphate and 2 mmol/l cetyltrimethylammonium chloride, pH 3.5 adjusted with 85% orthophosphoric acid). The fl ow rate was 1.5 ml/min. A Waters 996 pho- todiode array detector was used, and the detection wavelength was set at 254 nm. The injection volume of the standard and sample solutions was 10 μl. They were injected by a Waters 717 plus autosampler. RESULTS AND DISCUSSION FREQUENCY OF USE OF PRESERVATIVES IN COSMETICS FOR CHILDREN In this study, four parabens (methylparaben, ethylparaben, propylparaben, and butylparaben) were detected in 70 leave-on and 35 rinse-off samples as shown in Table II. Methylparaben was the most commonly used paraben in both categories of children’s cosmetics. The detection rate of methylparaben was 93% in leave-on products and 46% in rinse-off prod- ucts. The detection rates of propylparaben were 69% and 43% for the leave-on and rinse- off products, respectively. Rinse-off samples contained no butylparaben. The frequencies of using mixed esters (more than two kinds of parabens) were higher than those of using only a single ester in cosmetics for children. The detection rates were 69% (72 of 105) and 17% (18 of 105) for the products using mixed esters and single ester, respectively. The detection rates of mixed esters were 89% (62 of 70) and 29% (10 of 35) Table II Frequency of Using Parabens in Cosmetics for Children Category Methylparaben Ethylparaben Propylparaben Butylparaben Number Detection rate (%) Number Detection rate (%) Number Detection rate (%) Number Detection rate (%) Leave-on products 65 93 30 43 48 69 11 16 Rinse-off products 16 46 1 3 15 43 ND ND Total 81 77 31 30 63 60 11 10 ND: Not detected.

JOURNAL OF COSMETIC SCIENCE 70 for leave-on samples and rinse-off samples, respectively. As shown in Table III, parabens were not detected in 2 of 70 leave-on samples and 13 of 35 rinse-off samples. Parabens were more often used in leave-on samples compared with the rinse-off samples as shown in Table III. CONTENTS OF PARABENS In general, the mean content of parabens was less than 0.10% in leave-on and rinse-off products. The maximum level of propylparaben detected in leave-on samples was 0.38%, which was close to the restriction level of 0.40% (8) as shown in Table IV. The levels of mixed esters in both categories of cosmetics were less than the restricted level of 0.8% (8). Among the 62 leave-on products with mixed esters, the levels in 2 samples were deter- mined to be 0.75% and 0.63%, which were approaching the limitation of 0.8%. The levels in 3 samples were between 0.40% and 0.60%, 8 samples fell in the range from 0.20% to 0.39%, 27 samples were between 0.10% and 0.19%, and 22 samples were below 0.09%. Among the 10 rinse-off products with mixed esters, the levels in 2 samples were determined to be 0.20% and 0.30%, and that in the other 8 samples were below 0.10%. The level of 18 samples with monoester were all less than 0.10% in both leave-on and rinse-off samples. In addition, we found that the levels of paraben preservatives in children’s cosmetics were at the same level as those in adults’ cosmetics (3,4). Parabens are capable of permeating through and accumulating in the skin (9). Considering that children’s body weight is less and their skin is more permeable than that of adults, the dosage of substances absorbed through skin is also higher than adults because of the high ratio between skin surface area (10). As a result, the exposure risk of parabens in cosmet- ics for children may be higher than those for adults. However, further supportive data are needed. Table III Frequencies of Using Mixed Esters and Monoester in Cosmetics for Children Preservatives Category Leave-on products Rinse-off products Methylparaben, ethylparaben, propylparaben, and butylparaben 3 ND Methylparaben, ethylparaben, and propylparaben 10 ND Methylparaben, ethylparaben, and butylparaben 1 ND Methylparaben, propylparaben, and butylparaben 7 ND Methylparaben and ethylparaben 15 ND Methylparaben and propylparaben 25 10 Ethylparaben and propylparaben 1 ND Methylparaben 4 6 Ethylparaben ND 1 Propylparaben 2 5 Not detected 2 13 ND: Not detected.