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

Abstract

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.

Dermal uptake of nicotine from air and clothing: Experimental verification

“…Nicotine and metabolite concentrations measured in pooled samples for the participants wearing clean clothes were low (15 ng/mL). Clean clothes are expected to be protective for compounds such as nicotine that meaningfully sorb to clothing fibers, reducing the rate of transport to the skin . When the participants wore a set of exposed clothes, the concentrations were comparable or higher than for the bare‐skinned participants (peak nicotine: 29 ng/mL [P5], 55 ng/mL [P6]; peak cotinine: 46 ng/mL [P5], 43 ng/mL [P6]; peak 3OH‐cotinine: 48 ng/mL [P5], 148 ng/mL [P6]).…”

“…The type of clothes worn after exiting the exposure chamber may have had an effect as well. The substantial difference between the uptakes of the 2 participants wearing exposed clothes may have been additionally influenced by the cloth‐skin gap (ie, the clothes fitting more tightly on the participant with larger BSA [2.24 m 2 vs. 1.93 m 2 ]) . Other parameters, such as geometry and permeability of the fabric, laundering and exposure of the clothes to nicotine prior to wearing were identical for the 2 participants.…”

“…Both participants P3 and P4 had a lower normalized uptake in week 2 when they showered immediately after exposure in the chamber. After exiting the exposure chamber in week 1, the participants donned clothing, which is anticipated to reduce absorption due to transfer of nicotine from skin lipids to clothing . Showering in week 2 likely removed more effectively a fraction of the nicotine in skin surface lipids that had not yet penetrated into the epidermis and the dermis.…”

“…Clean clothes are expected to be protective for compounds such as nicotine that meaningfully sorb to clothing fibers, reducing the rate of transport to the skin. 23 When the participants wore a set of exposed clothes, the concentrations were comparable or higher than for the bare-skinned participants (peak nicotine: 29 a larger BSA covered with exposed clothes. The total uptakes of participants P5 and P6 with exposed clothes covering only part of the body (~50%) were similar or higher than uptakes of the bare-skinned (~90% exposed) participants, indicating a higher uptake rate when wearing exposed clothes.…”

“…The substantial difference between the uptakes of the 2 participants wearing exposed clothes may have been additionally influenced by the clothskin gap (ie, the clothes fitting more tightly on the participant with larger BSA [2.24 m 2 vs. 1.93 m 2 ]). 23,24 Other parameters, such as geometry and permeability of the fabric, laundering and exposure of the clothes to nicotine prior to wearing were identical for the 2 participants. Studies with more participants are warranted to better elucidate the effect of age and clothing on dermal uptake of nicotine.…”