Phthalate Esters on Hands of Office Workers ... - ACS Publications

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Phthalate esters on hands of office workers: Estimating influence of touching surfaces Wei Shi, Jing Guo, Yubin Zhou, Dongyang Deng, Zhihua Han, Hongxia Yu, Xiaowei Zhang, and John P. Giesy Environ. Sci. Technol. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.estlett.6b00458 • Publication Date (Web): 20 Dec 2016 Downloaded from http://pubs.acs.org on December 20, 2016

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Environmental Science & Technology Letters is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

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Environmental Science & Technology Letters

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Phthalate Esters on Hands of Office Workers: Estimating Influence

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of Touching Surfaces

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Wei Shi,† Jing Guo,† Yubin Zhou,† Dongyang Deng,† Zhihua Han,† Xiaowei Zhang,†,*

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Hongxia Yu,†,* and John P. Giesy,†,§,║,#

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Environment, Nanjing University, Nanjing 210023, People’s Republic of China

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§

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Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada

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State Key Laboratory of Pollution Control and Resource Reuse, School of the

Department of Veterinary Biomedical Sciences and Toxicology Centre, University of

Department of Zoology, and Center for Integrative Toxicology, Michigan State

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University, East Lansing, MI 48824, USA

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#

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City University of Hong Kong, Kowloon, Hong Kong SAR, China

Department of Biology & Chemistry and State Key Laboratory in Marine Pollution,

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ABSTRACT

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Phthalate esters are known to be transferred to hands by contact with surfaces,

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however, little is known about associations between masses on hand wipes and

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frequency or duration of touching surfaces, especially surfaces in office environments.

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Relationships between PAEs on hands and multiple surfaces in offices were

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investigated. Wipes of hands, computers, and mobile phones as well as dust on

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furniture were collected from 55 offices in China.

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between masses of di-2-ethylhexyl phthalate (DEHP), dibutyl phthalate (DnBP),

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benzyl butyl phthalate (BBP) and di-n-octyl phthalate (DnOP) on wipes of hands and

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wipes of keyboards of computers. When workers used keyboards with polymer

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covers (dust covers), masses of these lipophilic PAEs on hands were significantly

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correlated with masses on keyboards rather than dust on furniture.

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used keyboards without polymer covers, masses on hands were related to masses in

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dust on furniture.

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could increase the mass of exposure via hand to body of office workers, which could

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further result in as much as 10-fold greater hazard.

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less use of polymer products containing PAEs were recommended for office workers

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to reduce exposures.

Positive associations were found

For workers who

Use of polymer covers containing PAEs and less washing of hands

Thus, more hand washing and

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INTRODUCTION

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Phthalate esters (PAEs) are used as plasticizers to enhance flexibility in a variety

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of household and building materials, including cables, wires, silicone films, screen

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guards, vinyl flooring and polyvinylchloride (PVC) tubing 1.

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including di-2-ethylhexyl phthalate (DEHP), dibutyl phthalate (DnBP), dimethyl

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phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP) and

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di-n-octyl phthalate (DnOP) (Table S1)2, 3 are not chemically bound within products

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and can be slowly emitted into indoor environments. In a study that analyzed 89

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organic chemicals in 120 homes, phthalate esters were one of the most abundant

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indoor pollutants 4.

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Phthalate esters

Recently, indoor exposure of humans to PAEs on skin and especially on hands 5, 6

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has been shown to be non-negligible

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Phthalate esters that are transferred to

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hands by contact with surfaces and direct air-to-skin transport, can represent a

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significant proportion of total accumulation 6.

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skin, PAEs on hands can result in inadvertent ingestion, by biting of nails, sucking of

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digits or eating finger foods 7, 8.

Besides direct absorption through

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Since previous studies of PAEs have focused on residential exposures, little is

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known about exposure in offices, although studies have shown greater concentrations

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of PAEs in dust from offices than those from apartments 9. Phthalate esters which

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tended to be strongly adsorbed to indoor surfaces, such as protectors of computer

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screens, keyboards, furniture, floor and desks, are commonly touched by hands of

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office workers

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penetration through hands and further increase the health risk was unknown.

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.

Whether and how touching surfaces in offices can increase

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It was hypothesized that PAEs in office furniture might result in exposure of

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office workers through touching surfaces. The main objectives of the present study

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were to examine relationships between PAEs on hands of people and on probable

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touched surfaces in offices by determining amounts of PAEs on surfaces in offices,

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including computers, mobile phones and dust on furniture. Another objective was to

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better understand the role of behaviors of workers, including use of polymer covers

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and habits of hand washing to these relationships and also to the hazards of exposure 3

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via hand to body.

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MATERIALS AND METHODS

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Collection of samples.

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Samples were collected from April to June 2014.

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Participants for this study consisted of 55 adults who worked at least 20 h a week in

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an office and were healthy, nonsmokers in the cities of Huaian (n=12), Zhenjiang

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(n=31) and Nanjing (n=12) in East China.

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buildings, and only one person per office participated in the study. Questionnaires

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were also completed at the time samples were collected (see study design in SI).

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Within-individual variability was estimated by collecting samples in triplicate from

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four participants.

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including dust on desks, chairs, bookcases and personal accessible furniture by use of

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a standardized protocol that used a mini vacuum cleaner.

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Offices were located in ten different

Samples of dust were collected from each participant’s office,

To avoid contamination of hands from sources other than the offices, participants

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were asked to wash their hands before entering the office.

Samples of PAEs on

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hands were collected by use of wipes applied at close of business.

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sterile gauze pad pre-cleaned with dichloromethane and acetone was immersed in 3.0

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mL of isopropyl alcohol (Tedia Co. Ltd, Fairfield, OH, USA) and then used to wipe

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the palm and back of the hand from wrist to fingertips, including sides.

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computer keyboards and mobile phones were collected from participants in their

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office after collection of wipe samples of hands and at least 1 day after the last time

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the computer, phone or furniture was cleaned.

A 7.6×7.6 cm

Wipes of

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To confirm sources of PAEs, wipes of keyboards were further collected from

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twelve computers in six offices. In each office, there were two keyboards, one with a

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polymer cover and one without a polymer cover. Polymer keyboard covers are

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removable polymer plastic sheets that are placed on keyboards and left in place while

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typing. Keyboards and polymer covers were cleaned with isopropyl alcohol in the

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morning and they were kept in offices without disruption for 5 days. More

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information for collection of samples is given in supporting information (SI).

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Preparation of samples and quantification of PAEs. extracted by use of accelerated solvent extraction (ASE). 4

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PAEs in samples were

PAEs were quantified by

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use of a Thermo TSQ Quantum Discovery triple-quadrupole mass spectrometer (San

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Jose, CA, USA) in multiple-reaction monitoring (MRM) mode.

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information for instrumental analysis, procedural blanks and other QA/QC procedures

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is listed in SI, Table S1 and Table S2.

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More detailed

The concept of relative cumulative hazard

Assessment of cumulative hazard.

quotient (HQ), developed previously, was employed to incorporate cumulative

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exposure into the assessment 11.

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hands was divided by tolerable daily intake values for each PAE (TDIi value) and the

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HQ for individual PAEs (HQ-PAEi) were summed to obtain total hazard quotients

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(HQs) including BBP, DBP, DEP and DEHP.

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n

n

i =1

i =1

HQs = ∑ HQ-PAE i = ∑

The daily intake (DI) of PAEs through exposure on

DI i (µg/kg bw/day) TDI i (µg/kg bw/day)

(1)

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Where: DIi is daily intake (exposure through hand) of individual PAEs, and n is the

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number of PAEs considered. DIi is the sum of exposure through hand-to-mouth

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contact (µg/kg bm/day) and absorption through the dermis of the hand (µg/kg bm/day)

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(More detail is shown in SI and Table S3).

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Data analysis. We used Spearman correlations (SPSS statistics software package,

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V. 17.0) to determine associations between continuous variables while minimizing the

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influence of outliers. To minimize effects of skewed data and outliers, we created

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categorical variables from surfaces and hand wipe data: Two-level variables (lesser,

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and greater) were created using the median as a cut-point (detail is in SI).

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RESULTS AND DISCUSSION Phthalate esters on wipes of hands.

Phthalate esters were detected in all

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wipes of surfaces of hands (Table S4).

As expected, DEHP was the predominant

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compound, followed by DnBP and DnOP.

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with the pattern observed in serum of people from China for DEHP, DnBP and DnOP,

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although no study has previously reported masses of DnOP on wipes of hands

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Few studies have examined phthalates in wipes of hands (Table S5). Generally,

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DEHP and DnBP are among the most widely detectable PAEs on wipes of hands in

This pattern for skin wipes is consistent

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Korea, Beijing in China and also East China detected in the present study 14, 15. DEP

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was not detected on wipes of hands of Koreans, while a frequency of detection of less

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than 20% was observed in the study of people in Beijing, which is approximately the

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same as the frequency of 52% observed in the present study.

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its greater vapor pressure, which results in a greater partition coefficient 16.

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Phthalate esters from surfaces in offices.

This might be due to

PAEs were detectable on surfaces

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of furniture, keyboards and phones, which based on the results of questionnaires, were

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the most touched surfaces (Table S4).

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detection frequency for all types of surface samples.

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predominant compound, with geometric means (GM) of 148 µg/g, 83.6 µg and 10.2 µg

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for dust, keyboards and phones, respectively.

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were 3- to 8-fold greater than those on phones, which might be due to the large area of

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keyboards and limited variation indicated similar sources for PAEs on keyboard and

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phone.

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wipe samples had similar variability (Figure S1), and masses not concentrations on

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wipes of hands, surfaces of computer keyboards and phones were used in the

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following studies. Concentrations and masses of PAEs in repeated samplings of dust

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and wipes over a three month period are mostly consistent (See repeated

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measurements in SI and Figure S2).

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DnBP, BBP, DEHP and DnOP had a greater DEHP was the most

For all PAEs, masses on keyboards

Distributions of masses and normalized concentrations of PAEs measured on

Associations of PAEs on hand wipes with indoor surfaces.

Total masses of

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PAEs on wipes of hands were positively correlated with masses on wipes of surfaces

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of computer keyboards, with a Spearman correlation coefficient (R) of 0.59 (p