ANTIPOLLUTION COSMETIC EFFECTIVITY AGAINST AIR POLLUTANT ABSORPTION 43 to 3.36 for naphthalene (21)], the main physicochemical parameter affecting dermal fl ux is HCP, and as Henry’s constant increases, molecular fl ux increases too (R2 = 0.92) (see Table 3) (13,22). R egarding permeability values obtained for the different HAPs, it should be noticed that the higher the Henry solubility constant, the higher is the permeability at equilibrium of the analytes in water. Thus, once again, the HCC value is the main physicochemical pa- rameter affecting permeability at equilibrium. As it can be seen in Figure 1, halogenated compounds reached permeabilities at equilibrium from 1.6 to 7.4 μg cm-2 signifi cantly higher than those obtained from BTEX compounds (0.67–1.2 μg cm-2). Moreover, it should be noticed that naphthalene and nitrobenzene provided permeability values of 7.8 and 78 μg cm-2, respectively, which can be attributed to their high HCC values of 57 and 1,140, respectively. EFFECT OF C OSMETICS COMPOSITION ON ANTIPOLLUTION EFFECTIVENESS As it has b een mentioned in the scientifi c literature (4), surfactants and barrier-forming polymeric materials have demonstrated an important antipollution effect versus organic compounds. Antipollution cosmetic B has a total composition of consistency factors, mainly polyacrylates, glyceryl stearates, and hydrophobic waxy polymers, of 3.2% w/w versus only 1% w/w of the antipollution cosmetic A. This difference of consistency factors provides signifi cant differences in viscosity (see Table 2) but also signifi cant differences in antipollution effectiveness against organic compounds (see Table 4). In this sense, it should be commented that the percentage of dimethicone (polydimethylsiloxane) used as emollient in the formula is also higher (6.0% w/w) in the antipollution cosmetic B than in A (3.0% w/w). Polydimethylsiloxane has been previously used as a synthetic skin simulant in dermal absorption experiments (11), which demonstrated that increasing the width of the polydimethylsiloxane membrane decreases fl ux and increases lag time. Thus, Table V Lag Time (τ) Experimentally Calculated for the Studied HAPs in Control and Cosmetic-Treated Strat-M Membranes HAPs τ (min ± s) Control Cosmetic A Cosmetic B t-testa 1,2-dichloroethane 10 10 50 ± 5 14.237 Benzene 10 10 37 ± 3 21.362 Bromodichloromethane 10 10 54 ± 6 14.347 Toluene 10 10 39 ± 3 19.106 1,2-dibromoethane 10 10 41 ± 4 3.431 Chlorobenzene 10 10 33 ± 8 6.713 Ethylbenzene 10 10 53 ± 5 20.428 m+p-xylene 10 10 50 ± 7 11.521 Bromoform 10 10 50 ± 6 3.789 o-xylene 10 10 55 ± 6 17.249 Nitrobenzene 10 10 64 ± 29 3.757 Naphthalene 10 10 74 ± 7 10.379 a Student t critical values equal to 2.230 (n = 10) .

JOURNAL OF COSMETIC SCIENCE 44 it would be expected that the presence of higher amounts of polydimethylsiloxane in the cosmetic formula increases its antipollution effect. The percent age of talc in antipollution cosmetic B is also higher than that in A. It has been previously demonstrated that organic compounds such as benzene and toluene are adsorbed on talc (23), which would increase the antipollution effect of cosmetic products. Moreover, t he addition of high–molecular weight polysaccharides, such as xanthan gum, an antipollution active principle with demonstrated effects against the adsorp- tion of organic compounds (4), to antipollution product B would provide an increase in antipollution effectiveness. In summary, the combination of all the aforementioned compounds provides a demonstrated antipollution effect to cosmetic product B, which is superior to that of cosmetic product A and clearly superior to the application of any cosmetic product. CONCLUSIONS In this stu dy, an analytical methodology has been developed and validated for the evalu- ation of dermal absorption of different HAPs, using in vitro vertical Franz diffusion cells and simulant human skin membranes, to assess the effectivity of antipollution cosmetic products. In this sense, an exposition chamber, with a fi xed and constant concentration of HAPs, has been designed to simulate contaminated atmospheres. The effi cacy of antipol- lution cosmetic products has been evaluated using a multi-pollutant approach, represent- ing a situation with more stringent conditions. The behavio r of HAPs, using Strat-M® as simulant of human skin, followed Fick’s fi rst law, allowing the calculation of diffusion parameters. Antipollution effectiveness is dem- onstrated by statistical evaluation of the diffusion parameters obtained for controls and cosmetics samples. So, the more cosmetics reduce fl ux values and increase lag times, the more will be their antipollution effectiveness. Thus, although cosmetics A and B present a considerable antipollution effect, it has been demonstrated that product B has higher antipollution effectiveness than product A. ACKNOWLEDGME NTS The authors acknowledge the fi nancial support obtained from RNB for the project “De- sarrollo de nuevos cosméticos antipolución, urbancream“ under the CDTI funding proj- ect program (CPI-19-027). The autho rs declare that they have no known competing fi nancial interests or personal relationships that could have appeared to infl uence the work reported in this paper. This article does not contain any studies with human par- ticipants or animals performed by any of the authors. REFERENCES (1) R. Beelen, O. Raaschou-Nielsen, M. Stafoggia, Z. Jovanovic Andersen, G. Weinmayr, B. Hoffmann, K. Wolf, E. Samoli, P. Fischer, M. Nieuwenhuijsen, P. Vineis, W.W. Xun, K. Katsouyanni, K. Dimakopoulou, A. Oudin, B. Forsberg, L. Modig, A.S. Havulinna, T. Lanki, A. Turunen, B. Oftedal, W. Nystad, P. Nafstad, U. De Faire, N.L. Pedersen, C.G. Östenson, L. Fratiglioni, J. Penell, M. Korek, G. Pershagen, K. Thorup Eriksen, K. Overvad, T. Ellermann, M. Eeftens, P.H. Peeters, K. Meliefste,