Characterizing Flame Retardant Applications and Potential Human

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Characterizing Flame Retardant Applications and Potential Human Exposure in Backpacking Tents Genna Gomes, Peyton Ward, Amelia Lorenzo, Kate Hoffman, and Heather M Stapleton Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.6b00923 • Publication Date (Web): 15 Apr 2016 Downloaded from http://pubs.acs.org on April 15, 2016

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Environmental Science & Technology

CAMPING TENT This Ar/cle meets CPAI-‐84 Flammability requirements

ACS Paragon Plus Environment


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Characterizing Flame Retardant Applications and Potential Human Exposure in Backpacking Tents

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Genna Gomes†, Peyton Ward†, Amelia Lorenzo, Kate Hoffman and Heather M. Stapleton* Nicholas School of the Environment, Duke University, Durham, NC 27708 †

co-first authors (Genna Gomes, Peyton Ward)

* Corresponding Author: Heather Stapleton, PhD Nicholas School of the Environment Duke University Box 90328 Levine Science Research Center, Room A220 Durham, NC 27708 Telephone: (919) 613-8717 Fax: (919) 684-8741 Email: [email protected]

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Abstract

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Flame retardant chemicals are applied to products to meet flammability standards; however,

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exposure to some additive FRs has been shown to be associated with adverse health effects.

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Previous research on FR exposure has primarily focused on chemicals applied to furniture and

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electronics; however, camping tents sold in the U.S., which often meet flammability standard

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CPAI-84, remain largely unstudied in regards to their chemical treatments. In this study, FRs

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from five brands of CPAI-84 compliant, two-person backpacking tents were measured and

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potential exposure was assessed. Dermal and inhalation exposure levels were assessed by

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collecting handwipes from 20 volunteers before and after tent setup, and by using active air

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samplers placed inside assembled tents, respectively. Organophosphate flame retardants

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(OPFRs) were the most commonly detected FR in the tent materials and included triphenyl

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phosphate (TPHP), tris (1,3 dichloro-2-propyl) phosphate (TDCIPP) and tris (2-chloroethyl)

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phosphate (TCEP). Levels of OPFRS measured on handwipes were significantly higher post tent

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setup compared to pre-set up, and in the case of TDCIPP, levels were 29 times higher post-set

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up. OPFRs were also detected at measurable concentrations in the air inside of treated tents.

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Significant, positive correlations were found between FR levels in treated textiles and measures

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of dermal and inhalation exposure. These results demonstrate that dermal exposure to FRs occurs

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from handling camping tents and that inhalation exposure will likely occur while inside a tent.

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INTRODUCTION

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The implementation of several consumer product flammability standards has been shown to be a

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primary driver of widespread flame retardant chemical (FR) use (1-3). Previous research studies

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have shown that chemical FRs migrate out of many products they are applied to and expose

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product users (1, 4-7). Concerns regarding the high use and exposure to FRs are heightened by

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evidence suggesting exposure to some classes of FRs is associated with adverse health effects,

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such as reproductive impairments and neurodevelopmental deficits (8-17).

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For example, a widely used class of FRs, polybrominated diphenyl ethers (PBDEs), were

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commonly applied to residential furniture, textiles and electronics until scientific studies

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demonstrated that PBDEs migrate from products, accumulate in human tissues, and are

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persistent, bioaccumulative, and potentially toxic to humans and animals (18-23). Movement

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away from PBDEs opened a large gap in the FR market. Consequently, new FRs with limited or

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unknown toxicities have emerged as replacements, including a variety of organophosphate flame

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retardants (OPFRs).

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According to the Outdoor Foundation’s 2014 Camper Report (24), approximately 40 million Americans

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went camping in 2013. The average camper surveyed for the report spent 14.9 days camping per year, and

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camping tents were the preferred type of shelter. Camping tents in the US are subject to compliance

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with the flammability standard CPAI-84, which was set forth by the Canvas Products

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Association International (CPAI) in 1976 (25). CPAI-84 specifies flammability requirements for

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all “camping tentage,” which includes “any portable temporary shelter or structure designed to

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protect people from the elements including [but not limited to] camping tents; play tents (indoor

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and outdoor); recreational vehicle awnings; dining flies and canopies; fabric screen houses; add3


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a-rooms; and ice fishing tents” (26). The standard specifically requires wall materials of camping

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tentage to resist ignition or significant burn damage when exposed to vertical flame for 12

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second, and flooring material must resist ignition or significant burn damage when exposed to a

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methenamine-timed smoldering tablet. Furthermore, the fabrics must also meet the

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aforementioned standards after an accelerated weathering process conducted by a carbon arc

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method, xenon arc lamp method or a UV fluorescent and condensation method (26).

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Compliance with this standard, or the similar but less stringent flammability standard NFPA 701,

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is currently voluntary on a national level and mandatory in seven US states: California,

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Louisiana, Massachusetts, Michigan, Minnesota, New York, and New Jersey (27). Despite the

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limited range of states requiring compliance, most manufacturers of tents sold within the US

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comply for all tent products they sell to avoid complicating their supply chain with multiple

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versions of the same product. The types of chemical FR products and processes used to comply

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with CPAI-84 vary, are dependent on manufacturer, and are not known to be publicly available.

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Only one small study published in 2014 surveyed FR applications in eleven random camping

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tents of varying ages and sizes (2). Upon analysis of the eleven textiles, the FRs identified

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included the PBDE mixture DecaBDE, Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP),

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triphenyl phosphate (TPHP) and tetra-bromobisphenol-A (TBBPA). The same study also

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investigated potential exposure by collecting wipes of the tent textiles and hand wipes from

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participants setting up the tents. The data suggested that FRs were transferring from the textiles

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to users hands; however, that study was limited in that they did not investigate correlations

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between levels on handwipes with measured levels in the tent textiles themselves (2). Transfer of

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FRs to hands while handling tent materials may be concerning as previous research has shown

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that FRs measured in hand wipe samples are correlated to levels found in the body (6, 28). In 4



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addition, there were no detailed analyses conducted on the FR treatments among the various tent

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components (e.g. wall vs base, vs rainfly), nor any specific measurements of dermal or inhalation

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exposures estimated based on the concentration of the FR in the tent textile. The goals of the

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current study were: 1) to provide more detailed information on the FR applications and levels

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among the various components in five different brands of new CPAI-84 compliant back-packing

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tents; and 2) to estimate potential human exposure to the FRs through inhalation and dermal

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pathways.

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Materials and Methods

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Camping tents. Three replicate, new and unused, 2014 model two-person backpacking tents

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from five different brands were used in this study. These types of tents were selected for analysis

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in this study because they are typically more technical, innovative in design and materials, and

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standardized in size compared to other types of tents. Brands were assigned a letter, A, B, C, D

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and E, and replicate tents were assigned a number 1, 2 or 3. Four brands were actively involved

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in this research project and donated 12 of the 15 tents for analysis. The remaining three tents,

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representing one brand, were purchased from a national vendor retailing outdoor products.

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Textiles were sampled for chemical analysis using a box cutter and cardboard template to cut 2.5

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cm2 (1.0 in2) pieces from each of the main tent textile components. The cardboard template was

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cleaned between samples. Most tents were composed of four main textiles: base, wall, mesh, and

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rainfly, each of which was sampled for analysis (see Figure 1). Select tents had slightly

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different tent constructions. For example, some tents had walls made entirely of mesh, and there

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was no wall material to test. Therefore, adjustments were made to ensure all relevant textiles

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were included in the analysis. Between each sampling area and each tent sample, the box cutter

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was cleaned using hexane and methanol.

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Dermal Exposure. To assess dermal exposure to FRs from tent use, 20 research participants

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were recruited to set up one randomly assigned tent outdoors. Samples were collected over a

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three-hour period on a dry September day in 2014. Participants were males and females between

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the ages of 20-35 years old. All participants provided informed consent prior to sample

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collection, and the Institutional Review Board (IRB) at Duke University approved all protocols

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and procedures.

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Each participant completed a brief survey to collect data on potential background exposures to

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FRs based on lifestyle and time spent in various microenvironments (e.g. exposure from public

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transportation) and personal camping habits. Following the survey data collection, each

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participant randomly drew a letter A, B, C, D or E and a number 1, 2 or 3 to determine which tent

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sample they would handle.

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Hand wipes were collected using previously described methods (6). In brief, two sets of hand

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wipe samples were collected from each study participant, one before tent set-up and one after

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tent set-up. Hand wipe samples were collected using pre-cleaned cotton twill wipes

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manufactured by MG Chemicals (Burlington, Ontario) soaked in approximately 3 mL of

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isopropyl alcohol. Each hand wipe sample was collected by wiping one prepared cotton wipe

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over the front and back of each hand from wrist to fingertips, including between fingers. Prior to

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handling their tent sample, a preliminary hand wipe was collected to both assess background

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levels of FRs present on participants’ hands, and to remove FRs that were present on their hands

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before they contacted the tent material. After the participants’ hands had dried, they were asked 6



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to set up the assigned tent, simulating normal product use. Tent set up took each participant

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between five to ten minutes. After tent set up, a second hand wipe was collected from each

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participant to assess transfer of FRs to the hands while handling camping equipment.

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Immediately after collecting wipe samples, the exposed gauze wipes were wrapped in aluminum

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foil, placed in a plastic storage bag, and stored at -20°C until analysis. The same researcher

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collected all hand wipe samples to minimize bias and variability during collection. Field blanks

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(n=5) were kept in the testing area during sample collection.

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Investigation of inhalation exposure potential. Inhalation exposure was assessed using active

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air samplers placed inside each assembled tent. Air samples were collected using polyurethane

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foam (PUF) plugs containing a glass fiber filter housed in glass sleeves using methods described

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in Allen et al. 2007 (29). Tubes, PUFs, and glass sleeves were purchased from SKC Inc. (Eighty

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Four, PA). Air was actively pulled through the sampling tubes at a rate of 2.0 L/min using Airlite

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sample pumps (SKC Inc.). The airflow on each pump was measured prior to and at the end of air

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sampling to ensure the flow rate did not change significantly during sample collection.

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Active air sampling was conducted inside fully assembled tents, including the rain fly attached as

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an outside cover. Air samples were collected in three tents (replicates of the same brand) all on

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the same day. All tents were sampled over a five-day period. The average temperature over the

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course of the sampling period was 20.9±1.9 °C, average humidity was 72.4±2.3%, and average

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wind speed was 3.4±2.6 mph (Wunderground.com). Active air samplers were hung

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approximately 30 cm above the base in the center of the tent to simulate the breathing zone

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during sleep. Air samplers/pumps were run in empty tents for 20.3 to 24.3 hours. While the air

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sampling was active, which has the potential to impact measured concentrations emitted from the 7


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tent material, the air sampling rate (2 L/min) was very low, and is less than the average

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inhalation rate of an adult (~9 L/min; EPA Exposure Factors Handbook), and should therefore

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reflect realistic inhalation exposures. After each collection period, the glass sampling tubes were

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wrapped in aluminum foil, placed in plastic bags and frozen at -20°C until analysis. Field blanks

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(n=3), used for quality assurance and quality control, were briefly attached to pumps, then

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wrapped in foil and stored with the samples.

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Sample Extractions and Analysis.

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Tent textile samples were first screened for FRs using a previously reported method (3). If a FR

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was identified during the screening step, a second aliquot of each sample was extracted and

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analyzed using a previously published method for quantification (2). The tent textiles were

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screened for thirteen additive FRs that included 1,2,5,6,9,10- hexabromocyclododecane (HBCD),

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1,2-bis(pentabromophenyl) ethane (DBDPE), 2,2-bis(chloromethyl)trimethylene bis[bis(2-

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chloroethyl) phosphate] (V6), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB), bis(2-

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ethylhexyl)-tetrabromophthalate (TBPH), decabromodiphenyl ether (DecaBDE),

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cctabromodiphenyl ether (OctaBDE), pentabromodiphenyl ether (PentaBDE), 3,5,3’,5’-

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tetrabromobisphenol A (TBBPA), tris(1,3-dichloro-2-propyl)phosphate (TDCIPP), triphenyl

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phosphate (TPHP), tris(2-chloroethyl) phosphate (TCEP), and tris(2-chloropropyl) phosphate

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(TCIPP). The CAS numbers for these compounds can be found in Table S1 of the supplementary

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information.

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Hand wipe and air samples were only analyzed for organophosphate flame retardants (TCEP,

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TCIPP, TDCIPP and TPHP), as they were the dominant FRs detected in the textiles. Our

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extraction method was previously reported (28). Prior to extraction, all hand wipes were spiked 8



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with isotopically labeled internal standards that included deuterated Tris(1,3-dichloro-2-propyl)

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phophate-(d15TDCIPP), 13C- labeled triphenyl phosphate (13C-TPHP), and 13C-labeled

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decaBDE (13C-BDE 209) from Wellington Labs (Guelph, Ontario Canada). Field blanks used in

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the dermal exposure experiment (n=5) and laboratory blanks (n=9) were analyzed along with the

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samples.

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Air filters and PUFs were extracted together and analyzed using a previously reported method

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(29). Prior to extraction, all air filters were spiked with the internal standards that included

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dTDCIPP, 13C TPHP and F-BDE-69. Field blanks used in the air exposure experiment (n=3)

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and laboratory blanks (n=8) were analyzed along with the samples.

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Prior to mass spectrometry analysis, all extracts were spiked with a second standard to measure

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the recovery of the internal standards. For quantification of dTDCIPP and 13C TPHP, samples

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were spiked with dTCEP and dTPHP, respectively. For quantification of F-BDE-69, samples

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were spiked with an isotopically-labeled chlorinated diphenyl ether (13C-CDE-141) from

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Wellington Labs (Guelph, Ontario Canada). Samples were analyzed for specific FRs using

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either gas chromatography mass spectrometry operated in either electron impact mode (GC/EI-

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MS: OPFRs) or electron capture negative ionization mode (GC/ECNI-MS; brominated FRs) or

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by using liquid chromatography tandem mass spectrometry (LC/MS-MS) for more polar

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compounds (e.g. V6).

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Inhalation Exposure Estimation. Inhalation exposure to OPFRs was estimated using the

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average adult inhalation rates and body weights reported in the EPA Exposure Factors Handbook

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for adults and children ages 6-11. According to the EPA Exposure Factors Handbook (2011) the 9


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average inhalation rate for an adult age 16-60 is 15.9 m3/day and 12 m3/day for a child age 6-11.

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Average body weights used in the calculation were 31.8 kg for a child age 6-11, and 80 kg for an

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adult. Average inhalation exposures were calculated using the average air concentration of the

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OPFR measured within each tent, multiplied by the inhalation rate (by age class) and adjusted for

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body weight. For this estimation it was assumed that each person would spend 8 hours within

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the tent (i.e. sleeping).

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QA/QC

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Strict quality control and quality assurance (QA/QC) measures were used throughout the analysis

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including the use of laboratory and field blanks. For each batch, samples were blank-corrected

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by subtracting the average value of the field blanks. Method detection limits (MDLs) were set

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equal to three times the standard deviation of the field blanks.

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TCEP, TDCIPP, TCIPP and TPHP were detected in the hand wipe and air sampler field blanks,

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and were very similar to the lab blank values. MDLs for these analytes in the hand wipe samples

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were 18.1, 4.7, 9.0 and 5.6 ng, respectively. MDLs for these compounds in the air were 18.0, 8.3,

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20.4, 3.15 ng/m3 respectively. Average recovery of dTDCIPP and 13C TPHP were 93 ± 11%

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and 99 ± 10 %, respectively.

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Statistical Analysis. Statistical analyses were performed using the R software package

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Mavericks build (Vienna, Austria). Descriptive statistics were calculated and indicated that the

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levels of FRs in active air samples, hand wipes and textiles were not normally distributed and

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were closer to a log normal distribution. Therefore analyses were conducted using either non-

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parametric methods or using log transformed data. Associations between FR levels in tents and 10



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potential exposure were conducted using Spearman’s rank order correlation. To evaluate the

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impacts of tent set up on the mass of FRs on participants hands, linear mixed effects regression

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models were used, which easily accommodate data that are correlated, i.e., multiple

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measurements in participants (30, 31). To aid in the interpretation of results, beta coefficients

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were exponentiated (10β) for each time point, producing the multiplicative change in FR levels.

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For statistical analyses, if a value was

Characterizing Flame Retardant Applications and Potential Human

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