Impact of clothing on dermal exposure to phthalates: observations and

Transcription

1 Supporting Information Impact of clothing on dermal exposure to phthalates: observations and insights from sampling both skin and clothing Mengyan Gong 1,2, Charles J. Weschler 1,2,3*, Yinping Zhang 1,2* 1 Department of Building Science, Tsinghua University, Beijing, China 2 Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Beijing, China 3 Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey, USA This supporting information (19 pages) includes 11 tables and 4 figures S1. Total dermal uptake of phthalates in summer and winter S2. Estimation of amount absorbed at equilibrium and time to equilibrium Table S1 Mean (SD) phthalate levels (μg) in blank samples Table S2 Phthalate levels on different body locations in summer (μg/m 2 ) (n=20) Table S3 Phthalate levels on different body locations in winter (μg/m 2 ) (n=11) Table S4 Spearman correlation coefficients between DEHP levels on different body locations in summer (n=20)/winter (n=11) Table S5 Spearman correlation coefficients between DnBP levels on different body locations in summer (n=20)/winter (n=11) Table S6 Spearman correlation coefficients between DiBP levels on different body locations in summer (n=20)/winter (n=11) Table S7 Phthalate levels in jeans (μg/g) Table S8 Spearman correlation coefficients between DEHP levels in jeans and on legs Table S9 Spearman correlation coefficients between DnBP levels in jeans and on legs S1

2 Table S10 Spearman correlation coefficients between DiBP levels in jeans and on legs Table S11 Estimated amount absorbed at equilibrium and time to reach equilibrium Figure S1 Comparison of dermally absorbed dose including and excluding body locations covered by cloth in both summer (n=20) and winter (n=11). Figure S2 Phthalate levels in jeans (μg/g). The symbols represent results for individual subjects (S1-S5). JC/JT represents phthalate levels in the calf/thigh area of the jeans. Figure S3 Phthalate levels in skinwipes (μg/m 2 ). 1 st -1 d represents sampling on the first day during the first experiment; 2 nd -1 d /3 d /5 d represents sampling on the first/third/fifth day during the second experiment; 3 rd -1 d /3 d /5 d /7 d /10 d represents sampling on the first/third/fifth/seventh/tenth day during the third experiment. Figure S4 Removal efficiency of phthalate from jeans through laundering. References S2

3 S1. Total dermal uptake of phthalates in summer and winter The daily dermal absorption (DA dermal, μg/kg/day) of phthalates for each adult was estimated using the following equation: å k p _ l C l,i SA i t exp i DA dermal = X BW (1) where k p_l is the skin permeability coefficient (m/h) from skin surface lipids to dermal capillaries for partially hydrated stratum corneum (0.076, 0.074, 0.04, and m/h for DiBP, DnBP, BBzP and DEHP, respectively 1 ). C l,i is the phthalate level in skin surface lipids at different exposed locations (μg/m 2 ). Based on human body characteristics and behaviour, exposed body locations were separated into head, trunk, arm, hand, leg and feet. In winter, measured median levels of phthalates on the forehead, back, forearms, calf and hand are used to determine C l,i on head, trunk, arm, leg and hand, respectively. In summer, measured median levels of phthalates on forehead, forearms and hand are used to determine C l,i on head, arm, and hand, while the levels on trunk and leg are calculated by multiplying the levels on the hand with the ratios of back/hand and calf/hand derived in winter (shown in Table 1). SA i is the skin surface area at different exposed locations (m 2 ), calculated using a Chinese adults surface area by body part as listed in Wang et al. 2 (0.12 m 2 for head, 0.57 m 2 for trunk, 0.30 m 2 for arm, 0.51 m 2 for legs, and m 2 for hand). t exp is the exposed time per day (h/day), assumed to be 24 h/day. X is the thickness of the skin surface lipids (μm), assumed to be 1.3μm for adults 3. BW is the body weight (kg), assumed to be 60 kg. S3

4 S2. Estimation of amount absorbed at equilibrium and time to equilibrium The amount absorbed at equilibrium can be estimated as follows: m equ K c _ g g (2) c C where, K c_g is the partition coefficient between the clothing and the gas phase, C g is the gas phase phthalate concentration (ng/m 3 ), and is the density of the jeans (g/cm 3 ), which was measured to be 0.61 g/cm 3. The lumped parameter method can be used to describe mass transfer within the clothing if the ratio of the diffusion resistance within the clothing to the air boundary layer around the clothing is less than 0.1 4, that is c h m L c D c K c _ g < 0.1 (3) where, hm is the convective transfer coefficient around the clothing (m/h), which is assumed to be 5 m/h; Lc is the thickness of the jeans (m), which was measured to be 5.8 x10-4 m, and D c is the diffusion coefficient through the clothing (m 2 /s). The results shown in Table S11 indicated that diffusion resistance in the clothing can be neglected 5. Hence, the governing equation describing the phthalate absorption to clothing can be expressed as: L c dc c dt = h m (C g - C c K c_ g ) (4) where, C c is the concentration in the jeans (μg/g), and t is the absorption time (h). The initial condition for equation (4) is: S4

5 C c = 0 (5) Solving equation (4) and (5), the concentration in jeans, C c, can be calculated as: - h m t K C c = K c _ g C g (1- e c _ g L c ) (6) When C c reaches 95% of the equilibrium concentration, the corresponding absorption time can be considered as the time to equilibrium and is calculated as follows: t equ = 3K c _ g L c h m (7) S5

6 Table S1 Mean (SD) phthalate levels (μg) in blank samples a Sampling description DMP DEP DiBP DnBP DEHP Skin wipe during summer 0.21(0.09) 0.04(0.02) 0.49(0.26) 0.42(0.15) 1.05(0.44) Skin wipe during winter 0.03(0.01) 0.01(0.01) 0.18(0.06) 0.13(0.05) 0.25(0.21) Skin wipe for jeans experiment 0.04(0.01) 0.01(0.01) 0.21(0.09) 0.16(0.05) 0.88(0.66) Jeans sampling 0.02(0.01) 0.004(0.001) 0.05(0.05) 0.04(0.07) 0.08(0.13) a BBzP levels were not detected in the blank samples. The laboratory instrument detection limit for BBzP was μg. S6

7 Table S2 Phthalate levels on different body locations in summer (μg/m 2 ) a (n=20) Phthalate forehead lforearm rforearm lbhand rbhand lpalm rpalm DiBP 50 th %tile nd b th %tile nd Mean Range nd-452 nd-98 nd-119 nd-408 nd-272 nd-947 nd-860 Detect% 25% 83% 80% 84% 65% 85% 74% DnBP 50 th %tile nd th %tile Mean Range nd nd Detect% 30% 100% 100% 100% 95% 100% 100% DEHP 50 th %tile th %tile Mean Range Detect% 100% 100% 100% 100% 100% 100% 100% a One left back-of-hand sample and two left arm samples were lost. One left palm and one right palm sample were excluded from statistical analysis since their recovery rates were less than 50%. b nd: non-detect. The results in this table have been reported in a previous paper 1. S7

8 Table S3 Phthalate levels on different body locations in winter (μg/m 2 ) (n=11) Phthalate forehead back a lforearm a rforearm a lcalf a rcalf a lbhand rbhand lpalm rpalm DiBP 50 th %tile nd b th %tile Mean Range nd nd-59 nd-54 nd Detect% 27% 100% 100% 91% 82% 82% 100% 100% 100% 100% DnBP 50 th %tile nd th %tile Mean Range nd-110 nd nd nd Detect% 36% 91% 100% 91% 100% 91% 100% 100% 100% 100% DEHP 50 th %tile th %tile Mean Range Detect% 100% 100% 100% 91% 100% 91% 100% 100% 100% 100% a Covered by clothing. b nd: non-detect. S8

9 Table S4 Spearman correlation coefficients between DEHP levels on different body locations in summer (n=20)/winter (n=11) DEHP forehead back lforearm rforearm lcalf rcalf lbhand rbhand lpalm rpalm forehead 1.00/1.00 -/0.78 ** 0.09/ /0.61 -/0.16 -/ /0.82 ** 0.40/0.82 ** 0.16/0.63 * 0.08/0.58 back -/1.00 -/0.83 ** -/0.82 ** -/0.43 -/0.50 -/0.67 * -/0.67 * -/0.39 -/0.48 lforearm 1.00/ ** /0.92 ** -/0.74 ** -/0.72 * 0.58 * / * / / /0.46 rforearm /0.71 * -/0.72 * 0.42/0.68 * 0.62 ** /0.68 * 0.41/ /0.50 lcalf -/1.00 -/0.96 ** -/0.34 -/0.34 -/0.17 -/0.20 rcalf -/1.00 -/0.38 -/0.38 -/0.27 -/0.29 lbhand 1.00/ ** /1.00 ** 0.58 ** /0.77 ** 0.42/0.76 ** rbhand 1.00/ * /0.77 ** 0.38/0.76 ** lpalm 1.00/ ** /0.94 ** rpalm 1.00/1.00 * p<0.05, ** p<0.01 S9

10 Table S5 Spearman correlation coefficients between DnBP levels on different body locations in summer (n=20)/winter (n=11) DnBP back lforearm rforearm lcalf rcalf lbhand rbhand lpalm rpalm back -/1.00 -/0.70 * -/0.80 ** -/0.58 -/0.60 -/0.93 ** -/0.90 ** -/0.72 * -/0.60 lforearm rforearm 1.00/ ** /0.93 ** -/0.75 ** -/0.69 * 0.68 ** / ** / * / / /1.00 -/0.62 -/0.68 * 0.55 * / * / * / /0.22 lcalf 1.00/1.00 -/0.78 ** -/0.44 -/0.68 * -/0.16 -/-0.13 rcalf -/1.00 -/0.54 -/0.65 * -/0.49 -/-0.06 lbhand rbhand lpalm rpalm 1.00/ ** /0.89 ** 0.81 ** /0.86 ** 0.64 ** /0.71 * 1.00/ ** /0.68 * 0.82 ** / / ** /0.73 * 1.00/1.00 * p<0.05, ** p<0.01 S10

11 Table S6 Spearman correlation coefficients between DiBP levels on different body locations in summer (n=20)/winter (n=11) DiBP back lforearm rforearm lcalf rcalf lbhand rbhand lpalm rpalm back -/1.00 -/0.59 -/0.43 -/0.36 -/0.50 -/ /0.03 -/ /0.04 lforearm 1.00/ ** /0.92 ** -/0.67 * -/0.77 * 0.45/ * / / /-0.12 rforearm 1.00/1.00 -/0.57 -/ * / * / / /-0.30 lcalf -/1.00 -/0.86 ** -/ /0.12 -/ /-0.38 rcalf -/1.00 -/0.03 -/ / /-0.37 lbhand 1.00/ * /0.84 ** 0.61 ** /0.64 * 0.48 * /0.38 rbhand 1.00/ / ** /0.19 lpalm ** /0.44 rpalm 1.00/1.00 * p<0.05, ** p<0.01 S11

12 Table S7 Phthalate levels in jeans (μg/g) Experiment Subject DEHP DnBP DiBP DEP DMP Calf Thigh Calf Thigh Calf Thigh Calf Thigh Calf Thigh S First S a a S S S S Second S S S S S Third S S S a The negative value means that the measured phthalate amount in jeans after wearing was smaller than the amount before wearing. S12

13 Table S8 Spearman correlation coefficients between DEHP levels in jeans and on legs DEHP jeans thigh jeans calf skin thigh skin calf jeans thigh ** jeans calf * 0.43 skin thigh ** skin calf 1.00 * p<0.05, ** p<0.01 Table S9 Spearman correlation coefficients between DnBP levels in jeans and on legs DnBP jeans thigh jeans calf skin thigh skin calf jeans thigh ** jeans calf skin thigh ** skin calf 1.00 * p<0.05, ** p<0.01 Table S10 Spearman correlation coefficients between DiBP levels in jeans and on legs DiBP jeans thigh jeans calf skin thigh skin calf jeans thigh * jeans calf ** 0.69 ** skin thigh skin calf 1.00 * p<0.05, ** p<0.01 S13

14 Table S11 Estimated amount absorbed at equilibrium and time to reach equilibrium (see section S2) Phthalate D c K c_g 10-6 h m L c t equ C g m equ (m 2 /s) a (-) D c K c _ g (day) (ng/m 3 ) d (μg/g) DiBP b DnBP c DEHP b a Values from Table S3 in Cao et al. 5. b Adjusted values from measured values at 25 o C from Table 2 of Cao et al. 5 by multiply the ratio between density of T-shirt (0.27 g/cm 3 ) used in Cao et al. 5 and density of jeans (0.61 g/cm 3 ) used in present study. c Value from Table 1 of Morrison et al. 6 ; d: Values from Table 1 of Wang et al. 7 S14

15 Figure S1 Comparison of dermally absorbed dose including and excluding body locations covered by cloth in both summer (n=20) and winter (n=11). S15

16 Figure S2 Phthalate levels in jeans (μg/g). The symbols represent results for individual subjects (S1-S5). JC/JT represents phthalate levels in the calf/thigh area of the jeans. S16

17 S17

18 Figure S3 Phthalate levels in skinwipes (μg/m 2 ). 1 st -1 d represents sampling on the first day during the first experiment; 2 nd -1 d /3 d /5 d represents sampling on the first/third/fifth day during the second experiment; 3 rd -1 d /3 d /5 d /7 d /10 d represents sampling on the first/third/fifth/seventh/tenth day during the third experiment. Figure S4 Removal efficiency of phthalate from jeans through laundering. S18

19 References 1. Gong, M.; Zhang, Y.; Weschler, C. J. Measurement of phthalates in skin wipes: Estimating exposure from dermal absorption. Environ. Sci. Technol. 2014, 48 (13), Wang, Z.; Liu, S.; Chen, X. Estimation of skin surface area for Chinese in risk assessment. J. Saf. Enviro. 2008, 8(4), In Chinese. 3. Nazzaro-Porro, M.; Passi, S.; Boniforti, L.; Belsito, F. Effects of aging on fatty acids in skin surface lipids. J. Invest. Dermatol. 1979, 73 (1), Xu, Y.; Zhang, Y. An improved mass transfer based model for analyzing VOC emissions from building materials. Atmos. Environ. 2003, 37 (18), Cao, J. P.; Weschler, C. J.; Luo, J. J.; Zhang, Y. P. Cm-history method, a novel approach to simultaneously measure source and sink parameters important for estimating indoor exposures to SVOCs. Environ. Sci. Technol. 2016, 50(2), Morrison, G.; Li, H.; Mishra, S.; Buechlein, M. Airborne phthalate partitioning to cotton clothing. Atmos. Environ. 2015, 115, Wang, X.; Tao, W.; Xu, Y.; Feng, J.; Wang, F. Indoor Phthalate Concentration and Exposure in Residential and Office Buildings in Xi an, China. Atmos. Environ. 2014, 87, S19