Predicting dermal absorption of gas-phase chemicals: transient model development, evaluation, and application

Gong, Maoqiong; Zhang, Yinping; Weschler, Charles J.

doi:10.1111/ina.12079

Cited by 72 publications

(94 citation statements)

References 65 publications

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“…The model is based on one‐dimensional transport through multiple layers including skin layers, air, and clothing. To be consistent with the transient models of Gong et al . and Morrison et al .…”

Section: Methodssupporting

confidence: 54%

Dermal uptake of phthalates from clothing: Comparison of model to human participant results

2016

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In this research, we extend a model of transdermal uptake of phthalates to include a layer of clothing. When compared with experimental results, this model better estimates dermal uptake of diethylphthalate (DEP) and di-n-butylphthalate (DnBP) than a previous model. The model Accepted ArticleThis article is protected by copyright. All rights reserved.predictions are consistent with the observation that previously exposed clothing can increase dermal uptake over that observed in bare-skin participants for the same exposure air concentrations. The model predicts that dermal uptake from clothing of DnBP is a substantial fraction of total uptake from all sources of exposure. For compounds that have high dermal permeability coefficients, dermal uptake is increased for i) thinner clothing, ii) a narrower gap between clothing and skin and iii) longer time intervals between laundering and wearing.Enhanced dermal uptake is most pronounced for compounds with clothing-air partition coefficients between 10 4 and 10 7 . In the absence of direct measurements of cotton cloth-air partition coefficients, dermal exposure may be predicted using equilibrium data for compounds in equilibrium with cellulose and water, in combination with computational methods of predicting partition coefficients. PRACTICAL IMPLICATIONSThis model improves predictions of dermal uptake from clothing for two phthalates. Successful extension of this model to other compounds will improve population exposure estimates.

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Section: Methodssupporting

confidence: 54%

Dermal uptake of phthalates from clothing: Comparison of model to human participant results

2016

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“…However, as noted above, the actual absorbed nicotine is likely higher than 570 µg, suggesting that dermal uptakes could even exceed inhalation uptake. Moreover, three hours of exposure is not sufficient to reach steady-state uptake for SVOCs such as nicotine (as was illustrated for phthalates in Gong et al (2014)). A substantially longer exposure period would be required to reach steady-state absorption, at which point dermal uptake would be much larger.…”

Section: Inhalation Compared To Dermal Uptakementioning

confidence: 99%

Measurements of dermal uptake of nicotine directly from air and clothing

et al. 2016

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In this preliminary study, we have investigated whether dermal uptake of nicotine directly from air or indirectly from clothing can be a meaningful exposure pathway. Two participants wearing only shorts and a third participant wearing clean cotton clothes were exposed to environmental tobacco smoke (ETS), generated by mechanically “smoking” cigarettes, for three hours in a chamber while breathing clean air from head-enveloping hoods. The average nicotine concentration (420 μg/m3) was comparable to the highest levels reported for smoking sections of pubs. Urine samples were collected immediately before exposure and 60 hour post-exposure for bare-skinned participants. For the clothed participant, post-exposure urine samples were collected for 24 hour. This participant then entered the chamber for another three-hour exposure wearing a hood and clothes, including a shirt that had been exposed for five days to elevated nicotine levels. The urine samples were analyzed for nicotine and two metabolites—cotinine and 3OH-cotinine. Peak urinary cotinine and 3OH-cotinine concentrations for the bare-skinned participants were comparable to levels measured among non-smokers in hospitality environments before smoking bans. The amount of dermally absorbed nicotine for each bare-skinned participant was conservatively estimated at 570 μg, but may have been larger. For the participant wearing clean clothes, uptake was ~20 μg, and while wearing a shirt previously exposed to nicotine, uptake was ~80 μg. This study demonstrates meaningful dermal uptake of nicotine directly from air or from nicotine-exposed clothes. The findings are especially relevant for children in homes with smoking or vaping

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“…Recognizing that steady‐state uptake is not realistic when exposure conditions are changing or there is insufficient time to achieve steady state, Gong et al. () developed a dynamic model of transdermal uptake. This model accounted for transfer from air to skin and assumed Fickian diffusion through two skin layers (stratum corneum and viable epidermis).…”

Section: Introductionmentioning

confidence: 99%

Dermal uptake directly from air under transient conditions: advances in modeling and comparisons with experimental results for human subjects

2016

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To better understand the dermal exposure pathway, we enhance an existing mechanistic model of transdermal uptake by including skin surface lipids (SSL) and consider the impact of clothing. Addition of SSL increases the overall resistance to uptake of SVOCs from air but also allows for rapid transfer of SVOCs to sinks like clothing or clean air. We test the model by simulating di-ethyl phthalate (DEP) and di-n-butyl phthalate (DnBP) exposures of six bare-skinned (Weschler et al. 2015, Environ. Health Perspect., 123, 928) and one clothed participant (Morrison et al. 2016, J. Expo. Sci. Environ. Epidemiol., 26, 113). The model predicts total uptake values that are consistent with the measured values. For bare-skinned participants, the model predicts a normalized mass uptake of DEP of 3.1 (μg/m )/(μg/m ), whereas the experimental results range from 1.0 to 4.3 (μg/m )/(μg/m ); uptake of DnBP is somewhat overpredicted: 4.6 (μg/m )/(μg/m ) vs. the experimental range of 0.5-3.2 (μg/m )/(μg/m ). For the clothed participant, the model predicts higher than observed uptake for both species. Uncertainty in model inputs, including convective mass transfer coefficients, partition coefficients, and diffusion coefficients, could account for overpredictions. Simulations that include transfer of skin oil to clothing improve model predictions. A dynamic model that includes SSL is more sensitive to changes that impact external mass transfer such as putting on and removing clothes and bathing.

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Predicting dermal absorption of gas-phase chemicals: transient model development, evaluation, and application

Cited by 72 publications

References 65 publications

Dermal uptake of phthalates from clothing: Comparison of model to human participant results

Dermal uptake of phthalates from clothing: Comparison of model to human participant results

Measurements of dermal uptake of nicotine directly from air and clothing

Dermal uptake directly from air under transient conditions: advances in modeling and comparisons with experimental results for human subjects

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