Supplementary data

Assessment of Indoor Volatile Organic Compounds in Head Start Child Care Facilities

Danh C. Vu1, Thi L. Ho2, Phuc H. Vo1, Mohamed Bayati3, Alexandra N. Davis4, Zehra Gulseven5, Gustavo Carlo5, Francisco Palermo5, Jane A. McElroy6, Susan C. Nagel7, Chung-Ho Lin1

1Center for Agroforestry, School of Natural Resources, University of Missouri, Columbia, MO, USA2Center of Core Facilities, Cuu Long Delta Rice Research Institute, Vietnam3Department of Civil and Environmental Engineering, University of Missouri, Columbia, MO, USA4Department of Individual, Family, and Community Education, University of New Mexico, NM, USA5Center for Children and Families Across Cultures, Department of Human Development and Family Science, University of Missouri, Columbia, MO, USA6Department of Family and Community Medicine, University of Missouri, Columbia, MO, USA7Department of Obstetrics, Gynecology and Women's Health, School of Medicine, University of Missouri, USA

Correspondence

Chung-Ho Lin

Email: linchu@missouri.edu

Table S1. Building and classroom characteristics

Table S2. List of VOCs monitored in this study

Table S3. Evaluation of non-cancer and cancer risks via the inhalation pathway

Table S4. Spearman rank correlation coefficients for aromatic hydrocarbons

Table S5. Spearman rank correlation coefficients for aldehydes and ketones

Table S6. Eigenvalues

Table S7. Factor loadings of variables after Varimax rotation

S8. Description on indoor sources of VOCs

Figure S1. Locations of the four studied Head Start facilities (School A, School B, School C, and

School D)

Figure S2. Comparison of VOC concentrations among the four Head Start facilities

Table S1. Building and classroom characteristics

Characteristics School A School B School C School D

Locations urban urban urban urbanBuilding age (years) 56 18 23 96Building type commercial

buildingcommercial building

commercial building

church building

Building material brick/concrete brick/concrete brick brickRenovation/repainting work (within the last 2 years)

yes* annual yes no

Area (sq. ft) 10,000Building ventilation(electric/gas)

electric electric electric unknown

Heating system gas electric electric unknownWater damage yes no yes yesPaint peeling no no no yesMold no no no noKitchen/eating room yes (basement) yes yes yesProximity to highway/traffic signal/gas station

four-block across the street

one-block four-block

Nearby dry-cleaners no across the street

no no

Proximity to grove/woods

onsite two-block 200 ft onsite

Classrooms 13 8 4 14Classroom area(sq. ft.)

1000

Number of children(per classroom)

20 8 - 12 15 20

Floor material tile teraflex carpet and tile tileUse of pesticides yes once a month yes noUse of air fresheners no no no noFrequency of cleaning daily daily daily dailyUse of scented/unscented candles

yes no no daily

Use of bleach/cleaner yes yes yes daily sanitation

Use of board/markers yes yes yes yesUse of electronic devices (TV, PC, camera)

yes yes yes yes

*: minor maintenance (repainting work) outside the building during the sampling time.

Table S2. List of VOCs monitored in this study

No. Compounds Chemical classification Retention time (min)

Monitored primary* and secondary ions

LOD, g/m3

LOQ, g/m3

1 Benzene Aromatic hydrocarbon 3.11 78, 77 0.003 0.010

2 Trichloroethylene Chlorinated hydrocarbon 3.45 130, 132 0.015 0.050

3 Methyl methacrylate Ester 3.56 69, 100 0.026 0.086

4 Bromodichloromethane Chlorinated hydrocarbon 3.63 83, 85 0.020 0.065

5 4-Methyl-2-pentanone Ketone 3.88 58, 57 0.031 0.101

6 1,4-Dioxane Ether 3.88 88, 58 0.035 0.116

7 trans-1,3-Dichloropropene Chlorinated hydrocarbon 3.97 75, 77 0.027 0.089

8 2-Hexanone Ketone 4.00 58, 57 0.030 0.098

9 Toluene Aromatic hydrocarbon 4.23 91, 92 0.001 0.003

10 cis-1,3-Dichloropropene Chlorinated hydrocarbon 4.27 75, 77 0.021 0.069

11 1,2-Dichloroethene Chlorinated hydrocarbon 4.40 61, 96 0.002 0.007

12 1,1,2-Trichloroethane Chlorinated hydrocarbon 4.40 97, 99 0.018 0.061

13 Octane Aliphatic hydrocarbon 4.64 57, 85 0.036 0.120

14 Hexanal Aldehyde 4.76 56, 57 0.011 0.035

15 Tetrachloroethylene Chlorinated hydrocarbon 4.78 166, 164 0.002 0.005

16 Dibromochloromethane Chlorinated hydrocarbon 4.85 127, 129 0.007 0.022

17 1,2-Dibromoethane Brominated hydrocarbon 4.94 107, 109 0.006 0.020

18 Butyl acetate Ester 4.95 56, 73 0.008 0.026

19 Chlorobenzene Chlorinated hydrocarbon 5.45 112, 77 0.002 0.006

20 Ethylbenzene Aromatic hydrocarbon 5.65 91, 106 0.001 0.004

21 m-Xylene Aromatic hydrocarbon 5.80 91, 1060.001 0.004

22 p-Xylene Aromatic hydrocarbon 5.80 91, 106

23 n-Butyl ether Ether 5.95 57, 87 0.003 0.008

24 Styrene Aromatic hydrocarbon 6.12 104, 103 0.001 0.004

25 o-Xylene Aromatic hydrocarbon 6.12 91, 106 0.002 0.006

26 Bromoform Brominated hydrocarbon 6.15 173, 171 0.001 0.004

27 n-Nonane Aliphatic hydrocarbon 6.17 57, 85 0.002 0.006

28 Heptanal Aldehyde 6.26 55, 70 0.008 0.026

29 2-Butoxyethanol Glycol ether 6.33 57, 87 0.059 0.196

30 Cumene Aromatic hydrocarbon 6.56 105, 120 0.001 0.004

31 2,2-Methoxyethoxy ethanol Glycol ether 6.75 59, 58 0.123 0.406

32 -Pinene Cyclic terpene 6.74 93, 92 0.011 0.037

33 n-Propylbenzene Aromatic hydrocarbon 6.98 91, 120 0.001 0.003

34 3-Ethyltoluene Aromatic hydrocarbon 7.08 105, 120 0.001 0.002

35 4-Ethyltoluene Aromatic hydrocarbon 7.12 105, 120 0.001 0.002

36 Benzaldehyde Aldehyde 7.14 77, 105 0.001 0.005

37 1,3,5-Trimethylbenzene Aromatic hydrocarbon 7.19 105, 120 0.001 0.003

38 2-Ethyltoluene Aromatic hydrocarbon 7.31 105, 120 0.001 0.003

39 α-Methylstyrene Aromatic hydrocarbon 7.35 118, 117 0.002 0.006

40 1,2,4-Trimethylbenzene Aromatic hydrocarbon 7.52 105, 120 0.001 0.003

41 Decane Aliphatic hydrocarbon 7.54 57, 71 0.002 0.006

42 2,2-Ethoxyethoxy ethanol Glycol ether 7.61 59, 72 0.035 0.116

43 Octanal Aldehyde 7.62 57, 84 0.007 0.023

44 1,3-Dichlorobenzene Chlorinated hydrocarbon 7.69 146, 148 0.001 0.003

45 3-Carene Cyclic terpene 7.73 93, 91 0.002 0.008

46 Benzyl chloride Chlorinated hydrocarbon 7.81 91, 126 0.001 0.002

47 1,4-Dichlorobenzene Chlorinated hydrocarbon 7.81 146, 148 0.002 0.008

48 1,2,3-Trimethylbenzene Aromatic hydrocarbon 7.86 105, 120 0.001 0.004

49 2-Ethylhexanol-1 Alcohol 7.94 57, 70 0.045 0.149

50 D-Limonene Cyclic terpene 7.96 68, 93 0.002 0.006

51 1,2-Dichlorobenzene Chlorinated hydrocarbon 8.04 146, 148 0.002 0.005

52 m-Diethylbenzene Aromatic hydrocarbon 8.17 119, 1050.003 0.009

53 o-Diethylbenzene Aromatic hydrocarbon 8.17 119, 105

54 p-Diethylbenzene Aromatic hydrocarbon 8.28 119, 105 0.002 0.008

55 n-Butylbenzene Aromatic hydrocarbon 8.28 91, 92 0.001 0.004

56 g-Terpinene Cyclic terpene 8.30 93, 91 0.002 0.005

57 Acetophenone Ketone 8.45 105, 77 0.003 0.010

58 Heptanoic acid Carboxylic acid 8.48 60, 73 0.104 0.343

59 1,2-Dibromo-3-chloropropane Chlorinated hydrocarbon 8.72 157, 155 0.002 0.005

60 Undecane Aliphatic hydrocarbon 8.74 57, 71 0.001 0.002

61 Nonanal Aldehyde 8.82 57, 56 0.002 0.008

62 Decamethylcyclopentasiloxane Organosilicon 9.03 73, 267 0.001 0.002

63 Dodecane Aldehyde 9.82 57, 71 0.002 0.006

64 Naphthalene Aromatic hydrocarbon 9.82 128 0.002 0.005

65 Decanal Aldehyde 9.91 57, 55 0.003 0.009

66 Hexachlorobutadiene Chlorinated hydrocarbon 10.02 225, 190 0.001 0.002

67 Benzothiazole Heterocylic hydrocarbon 10.26 135, 108 0.007 0.022

68 Tridecane Aliphatic hydrocarbon 10.81 57, 71 0.001 0.004

69 Tetradecane Aliphatic hydrocarbon 11.74 57, 71 0.001 0.003

70 Pentadecane Aliphatic hydrocarbon 12.61 57, 71 0.001 0.003

71 Hexadecane Aliphatic hydrocarbon 13.43 57, 71 0.001 0.005

72 2-Ethylhexyl salicylate Ester 15.06 120, 138 0.001 0.003

73 Homosalate Ester 15.68 138, 109 0.001 0.003

Table S3. Evaluation of non-cancer and cancer risks via the inhalation pathway

The Exposure Concentration (EC) (g/m3) for non-cancer and cancer risks was calculated using

the following equation:

EC=CA× ET× EF×EDAT

in which, CA is the VOC concentration in indoor air (g/m3), ET is exposure time (hours/day),

EF is exposure frequency (days/year), ED is exposure duration (years), and AT is averaging time

(period over which the exposure is averaged, hours).

For the evaluation of non-cancer risk, Hazard Quotient (HQ) for the inhalation pathway was

calculated as follows:

HQ= ECToxicity Value×1000

in which HQ is dimensionless, and Toxicity Value (mg/m3) for chronic exposure is the inhalation

Reference Concentration (RfC) that is available in the EPA's online IRIS system (EPA, 2009).

An HQ higher than 1 represents a possible adverse non-cancer effect, and an HQ less than or

equal to 1 indicates that adverse non-cancer effects are not likely to occur.

The cancer risk for children exposed via the inhalation pathway was estimated using the linear low-dose represented by the following relationship:

Cancer risk=IUR×EC

in which IUR is Inhalation Unit Risk (probability of cancer for a 70-year exposure to 1 μg/m3)

(μg/m3)-1. IUR values were obtained from the IRIS system. A value higher than 1 × 10-6 indicates

a possible carcinogenic effect, and a value less than or equal to 1 × 10-6 represents no

carcinogenic effects are expected as a result of exposure. It is suggested that exposures to

carcinogenic VOCs in early-life may result in higher lifetime cancer risks than comparable

exposure durations later in life. Therefore, 10-fold and 3-fold adjustments were made for

exposures with respect to two age groups: < 2 years of age, and 2 to 6 years of age, respectively

(EPA, 2009).

Table S3A. Exposure parameter values

Parameters Unit School A School B School C School DET Exposure time hrs/day 8 8 8 8EF Exposure frequency days/year 232 235 235 239

EDExposure duration(Age 3 – 5) years 3 3 3 3

AT (non-cancer) Average time days 26280 26280 26280 26280AT (cancer) 25550 25550 25550 25550

Table S3B. Toxicity values

Compounds RfC, mg/m3IUR 10-6, (g/m3)-

1 References

1,2,3-Trimethylbenzene 0.06 EPA

1,2,4-Trimethylbenzene 0.06 EPA

1,3,5-Trimethylbenzene 0.06 EPA

Benzene 0.03 29 EPA, OEHHA

Cumene 0.4 EPA

Ethylbenzene 1 2.5 EPA, OEHHA

Xylenes 0.1 EPA

Naphthalene 0.003 34 EPA, OEHHA

Styrene 1 EPA

Toluene 5 EPA

2-Butoxyethanol 1.6 EPA

1,4-Dichlorobenzene 0.8 11 EPA, OEHHATetrachloroethylene (PERC) 0.04 6.1 EPA, OEHHA

Trichloroethylene (TCE) 0.002 2 EPA, OEHHA

References

EPA. 2009. Risk Assessment Guidance for Superfund (RAGS): Part F. 2009.

https://www.epa.gov/sites/production/files/2015-09/documents/partf_200901_final.pdf

Integrated Risk Information System (IRIS) Assessments. 2018.

https://cfpub.epa.gov/ncea/iris/search/index.cfm. Assessed July 4th 2018

The Office of Environmental Health Hazard Assessment (OEHHA). Toxicity criteria on

chemicals evaluated by OEHHA. 2018. https://oehha.ca.gov/chemicals. Assessed July 4th 2018

Table S4. Spearman rank correlation coefficients for aromatic hydrocarbons

Variables 123T 124T 135T MeS BenzCumen

e DETB ETB ETT MPX NAP PRB OXY STY TOL123T 1 0.96 0.93 0.27 -0.15 0.23 0.94 0.43 0.86 0.83 0.41 0.61 0.81 0.14 0.42124T   1 0.92 0.16 -0.22 0.19 0.89 0.38 0.90 0.80 0.38 0.58 0.77 0.09 0.32135T     1 0.23 -0.07 0.32 0.85 0.46 0.87 0.78 0.43 0.68 0.74 0.26 0.37MES       1 -0.04 0.21 0.22 0.16 0.06 0.29 0.29 0.21 0.29 0.27 0.42

BENZ         1 0.23 -0.02 0.09 -0.27 -0.24 0.19 0.11 -0.25 0.22 -0.03CUME           1 0.36 0.92 0.36 0.30 0.28 0.84 0.33 0.95 0.27DETB             1 0.56 0.84 0.80 0.45 0.68 0.81 0.24 0.41ETB               1 0.53 0.53 0.39 0.87 0.56 0.84 0.34ETT                 1 0.75 0.41 0.71 0.72 0.29 0.31MPX                   1 0.35 0.59 0.98 0.23 0.61NAP                     1 0.50 0.37 0.35 0.22PRB                       1 0.57 0.79 0.30OXY                         1 0.25 0.60STY                           1 0.24TOL                             1

Abbreviations: 123T = 1,2,3-trimethylbenzene; 124T = 1,2,4-trimethylbenzene; 135T = 1,3,5-trimethylbenzene; MeS = -methylstyrene; Benz = benzene; DETB = diethylbenzenes; EtB = ethylbenzene; EtT = ethyltoluenes; MPX = m/p-xylenes; NAP = naphthalene; PrB = propylbenzene; OXY = o-xylene; STY = styrene; TOL = toluene.

Values in bold are different from 0 with a significance level p < 0.005

Table S5. Spearman rank correlation coefficients for aldehydes and ketones

Variables Acetophenone Benzaldehyde Decanal Heptanal Nonanal OctanalAcetophenone 1 -0.02 -0.36 0.07 -0.09 -0.38Benzaldehyde 1 0.28 -0.18 0.11 0.16Decanal 1 0.38 0.67 0.73Heptanal 1 0.42 0.46Nonanal 1 0.60Octanal 1

Values in bold are different from 0 with a significance level p < 0.05

Table S6. Eigenvalues

  F1 F2 F3 F4 F5 F6 F7 F8 F9Eigenvalue 8.103 6.097 3.565 3.496 2.971 2.228 1.537 1.276 1.188

Variability (%)21.90

1 16.479 9.635 9.449 8.029 6.022 4.155 3.449 3.211

Cumulative %21.90

1 38.380 48.015 57.464 65.492 71.515 75.670 79.119 82.330

Table S7. Factor loadings of variables after Varimax rotation

F1 F2 F3 F4 F5 F6 F7 F8 F9

1,2,3-Trimethylbenzene 0.9781,2,4-Trimethylbenzene 0.9781,3,5-Trimethylbenzene 0.952Benzene 0.790Cumene 0.938Diethylbenzenes 0.942Ethylbenzene 0.918Ethyltoluenes 0.841m/p-Xylenes 0.670Naphthalene 0.744o-Xylene 0.705Styrene 0.935Toluene 0.819Decane 0.872Docecane 0.919Hexadecane 0.728Nonane 0.862OctaneTetradecaneTridecane 0.842Undecane 0.590Pinene 0.898Limonene 0.7022-Butoxyethanol2-Ethylhexanol-1 0.80222EE 0.82522MEE 0.916Benzaldehyde 0.779Decanal 0.724Nonanal 0.505Octanal 0.8292-Ethylhexylsalicylate 0.809Butyl acetate 0.763Homosalate 0.7351,4-Dichlorobenzene 0.511PERC 0.830Trichloroethylene 0.518

% of data variance 17.3 8.9 11.0 8.6 10.9 6.0 7.6 4.5 7.4Cumulative (%) 17.3 26.2 37.2 45.8 56.7 62.7 70.4 74.9 82.3

Abbreviations: 22EE = 2-(2-Ethoxyethoxy)ethanol, 22MEE = 2-(2-Methoxyethoxy)ethanol

S8. Description on indoor sources of VOCs

- Factor 1 consisting of aromatic hydrocarbons (trimethylbenzenes, diethylbenzenes,

ethyltoluenes, and xylenes) likely represents vehicle-associated emissions and solvents emissions

(inks, paints, coatings).

- Factor 2 contains PERC (tetrarchloroethylene), TCE (trichloroethylene), nonane, and

decane which are indicative of emissions from dry-cleaning process.

- Factor 3 accounts for high loadings of cumene, ethylbenzene, styrene, and 2-

ethylhexanol-1, reflecting emissions from decorative materials, computers, and printers. Factor 4

is contributed mainly by 2-ethylhexylsalicylate, homosalate, toluene, and undecane. While the

former two compounds indicate use of sunscreen, toluene and undecane are likely linked to oil-

based paints and adhesives.

- Factor 5 is characterized mainly by 22EE, 22MEE, benzaldehyde, naphthalene, and

hexadecane which point out the presence of consumer cleaning products such as floor cleaners,

floor sealants, floor polish, paints, and paint removers. High factor loadings of -pinene, D-

limonene, and butyl acetate in Factor 6 reflect uses of fragrance products as well as scented

cleaning products.

- Factor 7 includes octanal, nonanal, and decanal which can be released from building

materials such as cabinetry materials (plywood subfloor and paneling), carpet, and paints.

Emissions of these aldehydes are also associated with uses of perfumes and odorants. Besides,

the VOCs in these two factors were reportedly related to air fresheners (Chin et al., 2014; Mishra

et al., 2015; Hoang et al., 2016). However, no use of air fresheners was documented at the

investigated Head Start facilities during the sampling period of time, therefore it is likely that

their emissions were not attributed to air fresheners.

- Benzene which was present in Factor 8 is indicative of vehicle-associated emissions.

- Factor 9 (dodecane, tridecane, and 1,4-dichlorobenzene) could reflect oils, lubricants,

degreasers, and paint removers. 1,4-dichlorobenzene is also used in mothballs.

References

EPA. 2009. Risk Assessment Guidance for Superfund (RAGS): Part F.

https://www.epa.gov/sites/production/files/2015-09/documents/partf_200901_final.pdf.

Chin, J.Y., Godwin, C., Parker, E., Robins, T., Lewis, T., Harbin, P. and Batterman, S., 2014.

Levels and sources of volatile organic compounds in homes of children with asthma. Indoor Air

24(4), 403-415.

Mishra, N., Bartsch, J., Ayoko, G.A., Salthammer, T. and Morawska, L., 2015. Volatile organic

compounds: characteristics, distribution and sources in urban schools. Atmos. Environ. 106, 485-

491.

Hoang, T., Castorina, R., Gaspar, F., Maddalena, R., Jenkins, P.L., Zhang, Q., McKone, T.E.,

Benfenati, E., Shi, A.Y. and Bradman, A., 2016. VOC exposures in California early childhood

education environments. Indoor Air 27(3), 609-621.

Figure S1. Locations of the four studied Head Start facilities (School A, School B, School C, and

School D)

Figure S2. Comparison of VOC concentrations among the four Head Start facilities