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Original Article Association between outdoor clothing use and serum perfluoroalkyl substances (PFAS): Korean National Environmental Health Survey cycle 4
Keon Woo Kimorcid, Jisoo Kang,*orcid, Seong-yong Choorcid, Seongyong Yoonorcid, Daehwan Kimorcid, Hyun Woo Parkorcid
Annals of Occupational and Environmental Medicine [Epub ahead of print]
DOI: https://doi.org/10.35371/aoem.2026.38.e4
Published online: January 8, 2026

Department of Occupational and Environmental Medicine, Soonchunhyang University Gumi Hospital, Gumi, Korea

*Corresponding author: Jisoo Kang Department of Occupational and Environmental Medicine, Soonchunhyang University Gumi Hospital, 179 1gongdan-ro, Gumi 39371, Korea E-mail: 135197@schmc.ac.kr
• Received: October 17, 2025   • Revised: December 19, 2025   • Accepted: December 22, 2025

© 2026 Korean Society of Occupational & Environmental Medicine

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  • Background
    Perfluoroalkyl substances (PFAS) are used in various products, and PFAS have been detected in outdoor clothing. PFAS can be absorbed into the human body via oral ingestion, inhalation, and dermal contact. In this study, we examined the association between the frequency of using outdoor clothing and serum PFAS concentrations in the Korean population using data from cycle 4 (2018–2020) of the Korean National Environmental Health Survey.
  • Methods
    Data from 2,993 adult participants were analyzed. The participants were classified into low-concentration and high-concentration groups based on the 75th percentile concentration of serum PFAS. The use of outdoor clothing was categorized into three groups: non-use, <4 times a week, and ≥4 times a week. The odds ratio (OR) for serum PFAS levels associated with use of outdoor clothing was determined through logistic regression analysis, adjusted for demographic characteristics, health-related factors, PFAS-treated items, dietary factors, and ventilation time.
  • Results
    ORs for high serum PFAS were higher in groups using outdoor clothing compared to the non-user group. In males, the adjusted ORs for the < 4 times a week and ≥ 4 times a week outdoor clothing usage group were as follows: perfluorooctanoic acid (PFOA), 1.26 (95% confidence interval [CI]: 1.10–1.44) and 1.70 (1.40–2.07); perfluorohexanesulfonic acid (PFHxS), 1.49 (1.16–1.92) and 1.70 (1.22–2.37); and perfluorononanoic acid (PFNA), 1.34 (1.19–1.51) and 1.68 (1.38–2.05), respectively. In females, the respective ORs were as follows: PFOA 1.32 (95% CI: 1.19–1.46) and 1.53 (1.01–2.32); PFHxS, 1.46 (1.08–1.96) and 2.63 (2.10–3.29); PFNA, 1.38 (1.22–1.55) and 1.45 (1.07–1.96).
  • Conclusions
    In adults, elevated serum PFAS levels were associated with increased frequency of using outdoor clothing.
  • Keywords: Outdoor clothing; PFAS; Korean National Environmental Health Survey
Perfluoroalkyl substances (PFAS) are compounds in which fluorine atoms replace hydrogen atoms in the hydrocarbon chain. They are highly stable substances owing to the strong covalent bond between carbon and fluorine.1 As PFAS are characterized by poor biodegradability and high persistence in living organisms, they can accumulate in the body over extended periods, potentially causing symptoms such as impairment of liver, kidney, and reproductive function.2,3 PFAS have a hydrophilic head and a hydrophobic tail, making them resistant to both water and oil.4 The surface tension of water and oil is reduced on surfaces coated with PFAS, imparting water-repellent and lipid-repellent effects.5 These properties make PFAS suitable for use in a wide range of products, including outdoor clothing, food packaging, cookware, and furniture.6
Outdoor clothing refers to garments designed for outdoor sports or leisure activities, including windbreakers, functional T-shirts, and hiking pants.7 Previous studies have detected PFAS in outdoor clothing.8,9 In South Korea, 70.9% of outdoor clothing buyers intend to use it for everyday wear.10,11 As outdoor clothing is used for extended periods, not only during outdoor activities but also in daily life, it may result in continuous exposure to PFAS.
PFAS are absorbed into the human body through various routes, including oral ingestion, inhalation, and skin contact.12,13 Previously, studies on human PFAS exposure have focused on dietary factors, with little research conducted on exposure from cloth wearing. To our knowledge, few studies have examined the association between the use of outdoor clothing and exposure to PFAS in South Korea. Therefore, this study aims to examine the association between the frequency of outdoor clothing use and serum PFAS in the Korean population using data from cycle 4 (2018–2020) of the Korean National Environmental Health Survey (KoNEHS).
Study participants and data sources
This study analyzed data of adults aged 19 years and older who participated in cycle 4 of KoNEHS conducted by the National Institute of Environmental Research from 2018 to 2020. The KoNEHS, a nationwide statutory survey in accordance with the Environmental Health Act, has been conducted every three years since 2009. A total of 2,993 participants were included in the analysis (1,298 men and 1,695 women), after excluding 1,246 individuals without serum values from the original sample of 4,239 adults (Fig. 1).
Serum PFAS concentration
The KoNEHS measured five types of PFAS: perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDeA). Blood samples were processed to remove serum proteins; then, the serum PFAS contents were separated and quantitatively analyzed using the Q-sight Triple Quad high-performance liquid chromatography/mass spectrometer (PerkinElmer, Waltham, MA, USA). The limits of detection for the substances were as follows: PFOA, 0.071 μg/L; PFOS, 0.056 μg/L, PFHxS, 0.071 μg/L; PFNA, 0.019 μg/L; and PFDeA, 0.017 μg/L. The participants were divided into low-concentration and high-concentration groups based on the 75th percentile concentration of serum PFAS.14
Outdoor clothing use
The KoNEHS survey categorized outdoor clothing use into seven categories: no use, once a month, two to three times a month, once a week, two to three times a week, four to six times a week, and every day. The participants were then divided into three groups: the participants who answered no use in the “no-use” group; those who used it once a month, two to three times a month, once a week, or two to three times a week were included in the “<4 times a week” group; and those who used it four to six times a week or daily were included in the “≥4 times a week” group.
Potential confounders
Age, body mass index (BMI), marital status, and smoking status were set as covariates for demographic characteristics and health-related characteristics, along with the use of PFAS-containing products, dietary factors, and ventilation time. The questionnaire for ventilation includes natural ventilation through windows and mechanical ventilation systems, such as air purifiers. Items containing PFAS included frying pans, pots, electric cookers, containers, coated agents or polish, as well as hiking boots. As dietary factors are a significant exposure pathway for PFAS, the frequency with which grilled fish, seaweed, and crustaceans are consumed, and the type of drinking water used, were considered.15-18 In the KoNEHS, dietary factors were assessed using a frequency scale with the following categories: rarely, once a month, two to three times a month, once a week, two to three times a week, four to six times a week, once a day, twice a day, and three times a day. Responses of rarely, once a month, and two to three times a month were grouped as <once a week consumption, and those of once a week or more as ≥once a week consumption.18 To account for potential exposure to PFAS in indoor environments, the average daily ventilation time in indoor spaces was also considered.19
Statistical analysis
Independent t-tests and χ²-tests were performed to analyze the differences in distribution of variables, including demographic characteristics, health-related characteristics, outdoor clothing use, PFAS-containing products, dietary factors, ventilation time, and serum PFAS. The odds ratio (OR) for serum PFAS associated with outdoor clothing use was calculated using logistic regression analysis after adjusting for demographic characteristics, health-related characteristics, PFAS-containing items used, dietary factors, and ventilation time. The statistical analysis was performed using IBM SPSS version 28 for Windows (IBM Corp., Armonk, NY, USA), and values with p-values <0.05 were considered statistically significant.
Ethics statement
This study received approval from the Institutional Review Board of Soonchunhyang University Gumi Hospital (IRB No.2025-09-02).
This study included 1,298 men (43%) and 1,695 women (57%). The average serum PFOA, PFOS, PFHxS, PFNA, and PFDeA concentrations were higher in men than in women. The average age of the participants was 47.4 years (men: 46.4 years, women: 48.5 years). Men were more likely to be overweight and smokers than women. Men were more likely to be in the ≥4 times a week outdoor clothing and hiking boots or sneakers usage group than women. Men had a higher proportion of using coated frying pans ≥4 times a week compared to women (Table 1).
The mean age was higher in the group with high concentrations of PFOA, PFOS, PFHxS, PFNA, and PFDeA. Among men, those in the ≥4 times a week group had the highest proportion of participants with high serum concentrations of PFOA, PFHxS, PFNA, and PFDeA. Among women, those in the ≥4 times a week group also showed the highest proportion of participants with high serum PFOA, PFOS, PFHxS, PFNA, and PFDeA. Among men, the non-user group of coated frying pans exhibited the lowest proportions of high serum concentrations of PFOA, PFOS, PFHxS, PFNA, and PFDeA than the user groups. Both men and women in groups using indoor and outdoor groundwater, simplified tap water, or tap water as their drinking water source showed a higher proportion of belonging to the high serum PFOA, PFOS, PFHxS, PFNA, and PFDeA groups compared to those using water purifiers or bottled water (Tables 2–5).
Both men and women in the <4 times a week and ≥4 times a week outdoor clothing usage groups showed higher ORs for high PFOA, PFOS, PFHxS, PFNA, and PFDeA compared with the no-use group. Among men, the adjusted OR for high PFOA was 1.26 (95% confidence interval [CI]: 1.10–1.44) in the < 4 times a week outdoor clothing usage group and 1.70 (95% CI: 1.40–2.07) in the ≥ 4 times a week group. The adjusted ORs were 1.66 (95% CI: 1.47–1.89) and 1.57 (95% CI: 1.05–2.34) for high PFOS; 1.49 (95% CI: 1.16–1.92) and 1.70 (95% CI: 1.22–2.37) for high PFHxS; 1.34 (95% CI: 1.19–1.51) and 1.68 (95% CI: 1.38–2.05) for high PFNA; and 1.62 (95% CI: 1.16–2.27) and 1.79 (95% CI: 1.59–2.02) for high PFDeA. Among women, the adjusted OR for high PFOA was 1.32 (95% CI: 1.19–1.46) in the <4 times a week outdoor clothing usage group and 1.53 (95% CI: 1.01–2.32) in the ≥4 times a week group. The adjusted ORs were 1.16 (95% CI: 1.08–1.25) and 1.84 (95% CI: 1.45–2.34) for high PFOS; 1.46 (95% CI: 1.08–1.96) and 2.63 (95% CI: 2.10–3.29) for high PFHxS; 1.38 (95% CI: 1.22–1.55) and 1.45 (95% CI: 1.07–1.96) for high PFNA; and 1.47 (95% CI: 1.23–1.77) and 1.44 (95% CI: 1.35–1.52) for high PFDeA (Table 6).
In this study, the adjusted OR for high serum PFAS levels was higher in the <4 times a week and ≥4 times a week outdoor clothing usage groups, compared to the no-use group. Particularly, when comparing <4 times a week and ≥4 times a week outdoor clothing usage groups, the ORs for PFOA, PFHxS, and PFNA were higher in the ≥4 times a week group, suggesting a dose-response relationship with increasing frequency of use. PFAS are referred to as “forever chemicals” because they have a long serum half-life in vivo of approximately 3.8–5.4 years and are bioaccumulative.20 PFAS remain in the body bound to albumin, potentially causing immunosuppression, impaired liver function, and reduced reproductive function.2,3,21 PFAS also act as endocrine disruptors and are associated with diabetes.22 PFOA and PFOS have been associated with chronic kidney disease and kidney cancer.23 PFNA are associated with birth weight deficits in newborns.24 PFHxS are known to cause non-alcoholic fatty liver disease.25 PFDeA is associated with hypertension.26
PFAS are widely used in outdoor clothing for their waterproof and oil-repellent properties, and are also utilized in the manufacture of such garments in South Korea.27 Previous studies have reported high concentrations of PFAS in outdoor clothing.8,9 A previous study conducted by Greenpeace identified PFAS in 36 out of 40 products from 11 global outdoor brands, including Korean products. A total PFAS concentration of up to 730 μg/m² was detected in 36 outdoor products. The detected substances included PFOA, PFOS, PFHxS, PFNA, and PFDeA, which were the focus of this study.9 PFAS used in outdoor clothing can detach from the fiber surface due to friction and ultraviolet exposure.28 These released PFAS can then be absorbed into the human body through skin exposure, inhalation, and ingestion.
A significant route of exposure to PFAS when using outdoor clothing is through skin contact. The skin structure consists of a lipophilic skin membrane and a water-rich, hydrophilic epidermis and dermis.29 PFAS exhibit greater lipophilicity with longer carbon-fluorine (CF) chains, and the PFOA, PFOS, PFHxS, PFNA, and PFDeA investigated in this study have long CF chains, resulting in strong lipophilicity.30 These chemicals accumulate in the skin membrane, which is rich in lipids. The skin membrane acts as a reservoir for PFAS, enabling continuous permeation.31 The permeated PFAS then gradually reaches the dermis through diffusion driven by the concentration gradient.31,32 Subsequently, they circulate throughout the body via the blood vessels, binding to albumin in the blood.
Increased sweat secretion hydrates the stratum corneum, loosening the packing of intercellular lipids and increasing skin permeability beyond normal levels. Furthermore, continuous friction between the skin and clothing causes microdamage to the stratum corneum, increasing skin permeability.32-34 Outdoor clothing frequently causes sweat secretion and friction because of the nature of activities in which it is used, causing a temporary increase in skin permeability and heightening the potential for PFAS exposure through the skin.
Experimental evidence supports dermal exposure to PFAS. In an in vitro study using 3D human skin equivalent models, most tested PFAS compounds showed measurable dermal absorption, and PFOA demonstrated substantial retention within skin tissue, reaching levels as high as 38%.35 These findings suggest that PFAS can remain in the skin after contact, supporting the potential for long-term exposure with repeated wearing of outdoor clothing. This finding is consistent with our results, which showed higher ORs with more frequent outdoor clothing use.
Although some types of outdoor clothing, such as outer-layer jackets, have limited direct contact with the skin, exposure to PFAS may still occur through inhalation and ingestion pathways, particularly in indoor environments.36,37 PFAS are classified into terminal PFAS, which do not break down in the body and accumulate as is, and precursor PFAS, which are metabolized and ultimately converted into terminal PFAS.38 The PFOA, PFOS, PFHxS, PFNA, and PFDeA investigated in this study are classified as terminal PFAS. Owing to their low vapor pressure, these PFAS exhibit low volatility, which reduces their potential for inhalation exposure.39 However, PFAS precursors are also commonly found in outdoor clothing. PFAS precursors are highly volatile and tend to vaporize, increasing their concentration in indoor air.40 Studies measuring the concentration of PFAS precursors in indoor air revealed low levels below 1 ng/m³ in typical indoor spaces like offices and kitchens. Meanwhile, outdoor clothing stores exhibited the highest levels, reaching up to 285.8 ng/m³.41 Therefore, inhalation of PFAS precursors released from outdoor clothing into indoor air may lead to their conversion within the body through oxidation processes into PFOA, PFOS, PFHxS, PFNA, PFDeA, and other compounds, potentially increasing serum PFAS.42
Outdoor clothing use may expose individuals to PFAS not only through skin contact but also via oral ingestion.13 If the bond with the fibers weakens, PFAS on clothing surfaces can transfer to hands or dust upon contact and be ingested.43 According to prior studies on outdoor jackets, dust ingestion can account for approximately 30%–40% of total PFOA exposure.44 These findings suggest that outdoor clothing can contribute to PFAS exposure through multiple pathways.
This study has some limitations. First, given its cross-sectional design, this study could not establish a causal relationship between outdoor clothing and serum PFAS. Second, as the survey was based on subjective reports, reporting and recall bias cannot be excluded. Third, although adjustments were made for drinking water intake and PFAS-related dietary factors, certain dietary items, such as pork offal and eggs, that have been reported to contain high levels of PFAS, were not included in this study. Finally, other important confounding variables not captured by the survey, such as single-use duration, contact area, occupational exposure, and additional unconsidered sources of PFAS exposure, may have influenced the findings.
To the best of our knowledge, South Korean studies on the association between outdoor clothing use and serum PFAS are insufficient. Therefore, despite the limitations of the study, its significance lies in its establishment of a correlation between outdoor clothing use and serum PFAS. This correlation is supported by data that is representative of the general population in South Korea, and it is further reinforced by extensive adjustments made for potential oral ingestion pathways. PFAS are substances that remain in the body for extended periods and exert various adverse effects on health. Therefore, exposure assessments for PFAS should also consider outdoor clothing use. The findings of this study can serve as a basis for future domestic PFAS safety management and the development of alternative materials.
This study examined the association between outdoor clothing use and serum PFAS in the general adult population of South Korea. Serum levels of PFAS (PFOA, PFOS, PFHxS, PFNA, and PFDeA) were elevated in adults who frequently used outdoor clothing.

CF

carbon-fluorine

CI

confidence interval

KoNEHS

Korean National Environmental Health Survey

OR

odds ratio

PFAS

perfluoroalkyl substances

PFDeA

perfluorodecanoic acid

PFHxS

perfluorohexanesulfonic acid

PFNA

perfluorononanoic acid

PFOA

perfluorooctanoic acid

PFOS

perfluorooctanesulfonic acid.

Funding

This research was supported by the Soonchunhyang University Research Fund.

Competing interests

The authors declare that they have no competing interests.

Author contributions

Conceptualization: Kim KW, Kang JS. Data curation: Kim KW, Kang JS. Formal analysis: Kim KW, Park HW. Methodology: Yoon SY. Validation: Kim KW, Park HW, Kim DH. Project administration: Cho SY. Funding acquisition: Kang JS. Writing - original draft: Kim KW, Kang JS. Writing - review & editing: Kim KW, Kang JS, Cho SY, Yoon SY, Kim DH, Park HW.

Acknowledgments

This study used the Korean National Environmental Health Survey Cycle 4 (2018~2020), made by the National Institute of Environmental Research (NIER-2020-01-01-016). We appreciate the National Institute of Environmental Research for making the raw data of the Korean National Environmental Health Survey available.

Supplementary Table 1.
Baseline characteristics of the participants.
aoem-2026-38-e4_Supplementary-Table-1.pdf
Supplementary Table 2.
Distribution of serum PFAS in men according to variables: PFOA and PFOS.
aoem-2026-38-e4_Supplementary-Table-2.pdf
Supplementary Table 3.
Distribution of serum PFAS in men according to variables: PFHxS, PFNA, and PFDeA.
aoem-2026-38-e4_Supplementary-Table-3.pdf
Supplementary Table 4.
Distribution of serum PFAS in women according to variables: PFOA and PFOS.
aoem-2026-38-e4_Supplementary-Table-4.pdf
Supplementary Table 5.
Distribution of serum PFAS in women according to variables: PFHxS, PFNA, and PFDeA.
aoem-2026-38-e4_Supplementary-Table-5.pdf
Fig. 1.
Participant selection flowchart. KoNEHS: Korean National Environmental Health Survey; PFAS: Perfluoroalkyl substance.
aoem-2026-38-e4f1.tif
Table 1.
Baseline characteristics of the participants
Category Total (n = 2,993)a Men (n = 1,298) Women (n = 1,695) p-value
PFAS
 PFOA 7.66 (7.33–8.00) 7.99 (7.53–8.45) 7.34 (7.13–7.55) <0.001b
 PFOS 18.87 (18.64–19.10) 20.26 (19.53–20.98) 17.48 (17.02–17.94) <0.001
 PFHxS 5.76 (5.39–6.12) 6.42 (6.11–6.74) 5.09 (4.68–5.50) <0.001
 PFNA 2.54 (2.52–2.57) 2.73 (2.71–2.75) 2.35 (2.32–2.39) <0.001
 PFDeA 1.08 (1.06–1.10) 1.15 (1.13–1.17) 1.01 (1.00–1.03) <0.001
Age (years) 47.4 ± 0.13 46.4 ± 0.18 48.5 ± 0.10 <0.001
BMI (kg/m2) 0.003c
 ≤25 1,577 (53.4) 595 (46.1) 982 (60.7)
 >25 1,416 (46.6) 703 (53.9) 713 (39.3)
Outdoor clothing use 0.001
 None 1,541 (52.3) 557 (43.7) 984 (60.8)
 <Four times a week 1,002 (32.4) 446 (33.9) 556 (30.9)
 ≥Four times a week 450 (15.3) 295 (22.4) 155 (8.3)
Coated frying pans use 0.002
 None 83 (2.5) 39 (2.6) 44 (2.3)
 <Four times a week 1,313 (40.1) 557 (36.9) 756 (43.2)
 ≥Four times a week 1,597 (57.4) 702 (60.5) 895 (54.4)
Crustacean consumption 0.076
 <Once a week 2,753 (91.8) 1,189 (91.6) 1,564 (92.1)
 ≥Once a week 240 (8.2) 109 (8.4) 131 (7.9)
Type of water drinking indoor 0.001
 Water purifier, bottled water, etc. 2,047 (71.4) 896 (73.5) 1,151 (69.4)
 Underground water, small-scale water-supply system, tap water 946 (28.6) 402 (26.5) 544 (30.6)
Type of water drinking outdoor <0.001
 Water purifier, bottled water, etc. 2,747 (93.3) 1,207 (95.1) 1,540 (91.4)
 Underground water, small-scale water-supply system, tap water 246 (6.7) 91 (4.9) 155 (8.6)
Average ventilation time per day (minutes) 0.043
 <30 354 (10.5) 174 (11.3) 180 (9.7)
 ≥30, <60 371 (11.1) 156 (10.6) 215 (11.4)
 ≥60, <600 1,112 (36.6) 488 (37.7) 624 (35.6)
 ≥600 1,156 (41.8) 480 (40.4) 676 (43.3)

Values are presented as mean (95% confidence interval), number (%) for categorical variables or as mean ± standard error for continuous variables.

PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid; BMI: body mass index.

aUnweighted count;

bp-value by t-test;

cp-value by χ2 test.

Table 2.
Distribution of serum PFAS in men according to variables: PFOA and PFOS
Variable PFOA PFOS
Low (n = 974)a High (n = 324) p-value Low (n = 974) High (n = 324) p-value
Age (years) 43.5 ± 0.29 57.3 ± 0.22 <0.001b 43.1 ± 0.21 60.3 ± 0.99 <0.001
BMI (kg/m2) 0.081c 0.763
 ≤25 460 (79.3) 135 (20.7) 454 (81.1) 141 (18.9)
 >25 514 (78.3) 189 (21.7) 520 (81.1) 183 (18.9)
Outdoor clothing use 0.004 0.011
 None 442 (83.1) 115 (16.9) 430 (84.6) 127 (15.4)
 <Four times a week 319 (76.0) 127 (24.0) 328 (77.3) 118 (22.7)
 ≥Four times a week 213 (74.4) 82 (25.6) 216 (80.1) 79 (19.9)
Coated frying pans use 0.086 0.004
 None 27 (82.6) 12 (17.4) 30 (88.2) 9 (11.8)
 <Four times a week 429 (78.2) 128 (21.8) 406 (78.6) 151 (21.4)
 ≥Four times a week 518 (79.0) 184 (21.0) 538 (82.3) 164 (17.7)
Crustacean consumption 0.001 0.001
 <Once a week 902 (80.2) 287 (19.8) 895 (82.1) 294 (17.9)
 ≥Once a week 72 (63.2) 37 (36.8) 79 (69.7) 30 (30.3)
Type of water drinking indoor 0.009 0.006
 Water purifier, bottled water, etc. 688 (82.2) 202 (17.8) 687 (84.8) 203 (15.2)
 Underground water, small-scale water-supply system, tap water 286 (69.3) 122 (30.7) 287 (71.1) 121 (28.9)
Type of water drinking outdoor 0.013 0.001
 Water purifier, bottled water, etc. 901 (79.4) 290 (20.6) 908 (82.1) 283 (17.9)
 Underground water, small-scale water-supply system, tap water 73 (68.0) 34 (32.0) 66 (63.7) 41 (36.3)
Average ventilation time per day (minutes) 0.005 0.003
 <30 122 (74.7) 52 (25.3) 123 (76.0) 51 (24.0)
 ≥30, <60 116 (81.9) 40 (18.1) 116 (84.9) 40 (15.1)
 ≥60, <600 373 (76.7) 115 (23.3) 359 (76.9) 129 (23.1)
 ≥600 363 (81.0) 117 (19.0) 376 (85.4) 104 (14.6)

Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; BMI: body mass index.

aUnweighted count;

bp-value by t-test;

cp-value by χ2 test.

Table 3.
Distribution of serum PFAS in men according to variables: PFHxS, PFNA, and PFDeA
Variable PFHxS PFNA PFDeA
Low (n = 974)a High (n = 324) p-value Low (n = 974) High (n = 324) p-value Low (n = 974) High (n = 324) p-value
Age (years) 44.1 ± 0.35 53.8 ± 0.06 0.002b 43.0 ± 0.28 60.2 ± 0.04 <0.001 43.1 ± 0.28 60.3 ± 0.20 <0.001
BMI (kg/m2) 0.017c 0.082 0.062
 ≤25 454 (75.1) 141 (24.9) 456 (81.3) 139 (18.7) 458 (81.4) 137 (18.6)
 >25 520 (76.9) 183 (23.1) 518 (79.7) 185 (20.3) 516 (80.4) 187 (19.6)
Outdoor clothing use 0.006 0.011 <0.001
 None 429 (81.1) 128 (18.9) 433 (84.0) 124 (16.0) 442 (85.3) 115 (14.7)
 <Four times a week 326 (72.5) 120 (27.5) 335 (78.4) 111 (21.6) 326 (77.6) 120 (22.4)
 ≥Four times a week 219 (71.6) 76 (28.4) 206 (76.4) 89 (23.6) 206 (77.1) 89 (22.9)
Coated frying pans use 0.155 0.005 <0.001
 None 29 (88.5) 10 (11.5) 26 (82.4) 13 (17.6) 31 (89.4) 8 (10.6)
 <Four times a week 422 (75.7) 135 (24.3) 405 (77.7) 152 (22.3) 403 (77.0) 154 (23.0)
 ≥Four times a week 523 (75.7) 179 (24.3) 543 (82.0) 159 (18.0) 540 (82.9) 162 (17.1)
Crustacean consumption 0.011 0.001 <0.001
 <Once a week 900 (77.7) 289 (22.3) 894 (82.0) 295 (18.0) 897 (82.6) 292 (17.4)
 ≥Once a week 74 (58.5) 35 (41.5) 80 (63.4) 29 (36.6) 77 (62.1) 32 (37.9)
Type of water drinking indoor 0.009 0.003 0.004
 Water purifier, bottled water, etc. 677 (78.1) 213 (21.9) 695 (84.4) 195 (15.6) 697 (85.0) 193 (15.0)
 Underground water, small-scale water-supply system, tap water 297 (70.6) 111 (29.4) 279 (69.5) 129 (30.5) 277 (69.7) 131 (30.3)
Type of water drinking outdoor 0.001 0.002 0.003
 Water purifier, bottled water, etc. 894 (76.6) 297 (23.4) 908 (81.4) 283 (18.6) 908 (81.9) 283 (18.1)
 Underground water, small-scale water-supply system, tap water 80 (66.1) 27 (33.9) 66 (62.9) 41 (37.1) 66 (62.9) 41 (37.1)
Average ventilation time per day (minutes) 0.006 0.008 0.052
 <30 125 (71.1) 49 (28.9) 119 (73.8) 55 (26.2) 125 (77.2) 49 (22.8)
 ≥30, <60 117 (83.8) 39 (16.2) 119 (85.0) 37 (15.0) 116 (83.2) 40 (16.8)
 ≥60, <600 362 (71.6) 126 (28.4) 369 (78.6) 119 (21.4) 361 (78.3) 127 (21.7)
 ≥600 370 (79.6) 110 (20.4) 367 (82.8) 113 (17.2) 372 (83.6) 108 (16.4)

Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

PFAS: perfluoroalkyl substances; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid; BMI: body mass index.

aUnweighted count;

bp-value by t-test;

cp-value by χ2 test.

Table 4.
Distribution of serum PFAS in women according to variables: PFOA and PFOS
Variable PFOA PFOS
Low (n = 1,272)a High (n = 423) p-value Low (n = 1,272) High (n = 423) p-value
Age (years) 44.9 ± 0.15 61.5 ± 0.07 <0.001b 44.8 ± 0.03 62.7 ± 0.06 <0.001
BMI (kg/m2) <0.001c 0.004
 ≤25 775 (83.0) 207 (17.0) 779 (82.8) 203 (17.2)
 >25 497 (70.5) 216 (29.5) 493 (73.9) 220 (26.1)
Outdoor clothing use 0.002 <0.001
 None 769 (81.1) 215 (18.9) 759 (81.5) 225 (18.5)
 <Four times a week 400 (75.0) 156 (25.0) 412 (79.0) 144 (21.0)
 ≥Four times a week 103 (67.5) 52 (32.5) 101 (64.5) 54 (35.5)
Coated frying pans use 0.007 0.04
 None 31 (78.2) 13 (21.8) 28 (77.6) 16 (22.4)
 <Four times a week 540 (72.2) 216 (27.8) 535 (75.8) 221 (24.2)
 ≥Four times a week 701 (82.8) 194 (17.2) 709 (82.1) 186 (17.9)
Crustacean consumption 0.792 0.213
 <Once a week 1,182 (78.1) 382 (21.9) 1,178 (79.5) 386 (20.5)
 ≥Once a week 90 (78.2) 41 (21.8) 94 (77.5) 37 (22.5)
Type of water drinking indoor 0.004 0.006
 Water purifier, bottled water, etc. 893 (80.5) 253 (19.5) 905 (82.9) 241 (17.1)
 Underground water, small-scale water-supply system, tap water 379 (72.8) 170 (27.2) 367 (71.2) 182 (28.8)
Type of water drinking outdoor 0.002 0.002
 Water purifier, bottled water, etc. 1,159 (79.9) 352 (20.1) 1,159 (81.7) 352 (18.3)
 Underground water, small-scale water-supply system, tap water 113 (62.0) 71 (38.0) 113 (58.3) 71 (41.7)
Average ventilation time per day (minutes) 0.015 0.062
 <30 128 (67.1) 52 (32.9) 135 (79.0) 45 (21.0)
 ≥30, <60 153 (75.6) 62 (24.4) 154 (76.0) 61 (24.0)
 ≥60, <600 467 (76.6) 157 (23.4) 465 (77.8) 159 (22.2)
 ≥600 524 (82.4) 152 (17.6) 518 (81.5) 158 (18.5)

Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; BMI: body mass index.

aUnweighted count;

bp-value by t-test;

cp-value by χ2 test.

Table 5.
Distribution of serum PFAS in women according to variables: PFHxS, PFNA, and PFDeA
Variable PFHxS PFNA PFDeA
Low (n = 1,272)a High (n = 423) p-value Low (n = 1,272) High (n = 423) p-value Low (n = 1,272) High (n = 423) p-value
Age (years) 45.6 ± 0.25 58.4 ± 0.27 <0.001b 44.8 ± 0.06 63.3 ± 0.09 <0.001 45.3 ± 0.15 61.1 ± 0.07 <0.001
BMI (kg/m2) 0.024c <0.001 0.004
 ≤25 749 (79.3) 233 (20.7) 782 (84.9) 200 (15.1) 770 (82.3) 212 (17.7)
 >25 523 (73.8) 190 (26.2) 490 (72.3) 223 (27.7) 502 (74.8) 211 (25.2)
Outdoor clothing use 0.002 0.002 0.014
 None 771 (80.6) 213 (19.4) 759 (81.3) 225 (18.7) 765 (82.0) 219 (18.0)
 <Four times a week 399 (74.9) 157 (25.1) 407 (78.9) 149 (21.1) 401 (76.2) 155 (23.8)
 ≥Four times a week 102 (60.6) 53 (39.4) 106 (74.0) 49 (26.0) 106 (72.2) 49 (27.8)
Coated frying pans use 0.08 0.009 0.008
 None 32 (82.4) 12 (17.6) 30 (78.8) 14 (21.2) 30 (78.4) 14 (21.6)
 <Four times a week 552 (76.2) 204 (23.8) 532 (75.1) 224 (24.9) 535 (75.3) 221 (24.7)
 ≥Four times a week 688 (77.7) 207 (22.3) 710 (83.9) 185 (16.1) 707 (82.7) 188 (17.3)
Crustacean consumption 0.517 0.09 0.024
 <Once a week 1,179 (77.3) 385 (22.7) 1,177 (79.7) 387 (20.3) 1,179 (79.6) 385 (20.4)
 ≥Once a week 93 (75.5) 38 (24.5) 95 (82.5) 36 (17.5) 93 (76.6) 38 (23.4)
Type of water drinking indoor 0.003 0.006 0.016
 Water purifier, bottled water, etc. 885 (80.5) 261 (19.5) 904 (83.5) 242 (16.5) 909 (82.9) 237 (17.1)
 Underground water, small-scale water-supply system, tap water 387 (69.6) 162 (30.4) 368 (72.0) 181 (28.0) 363 (71.5) 186 (28.5)
Type of water drinking outdoor <0.001 <0.001 <0.001
 Water purifier, bottled water, etc. 1,147 (79.2) 364 (20.8) 1,167 (83.2) 344 (16.8) 1,157 (81.7) 354 (18.3)
 Underground water, small-scale water-supply system, tap water 125 (59.7) 59 (40.3) 105 (51.8) 79 (48.2) 115 (59.2) 69 (40.8)
Average ventilation time per day (minutes) 0.127 0.214 0.213
 <30 134 (77.0) 46 (23.0) 135 (76.4) 45 (23.6) 135 (73.6) 45 (26.4)
 ≥30, <60 158 (76.2) 57 (23.8) 155 (78.4) 60 (21.6) 161 (79.2) 54 (20.8)
 ≥60, <600 463 (73.2) 161 (26.8) 462 (78.9) 162 (21.1) 455 (79.0) 169 (21.0)
 ≥600 517 (80.7) 159 (19.3) 520 (82.1) 156 (17.9) 521 (81.0) 155 (19.0)

Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

PFAS: perfluoroalkyl substances; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid; BMI: body mass index.

aUnweighted count;

bp-value by t-test;

cp-value by χ2 test.

Table 6.
Adjusted ORs and 95% CIs of use of outdoor clothing with high concentrations of serum PFAS
Category Unadjusted Adjusteda
None <4 times a week ≥4 times a week None <4 times a week ≥4 times a week
Men
 PFOA 1 1.55 (1.38–1.75) 1.70 (1.65–1.75) 1 1.26 (1.10–1.44) 1.70 (1.40–2.07)
 PFOS 1 1.61 (1.26–2.05) 1.36 (1.23–1.51) 1 1.66 (1.47–1.89) 1.57 (1.05–2.34)
 PFHxS 1 1.63 (1.32–2.01) 1.70 (1.60–1.82) 1 1.49 (1.16–1.92) 1.70 (1.22–2.37)
 PFNA 1 1.45 (1.30–1.62) 1.62 (1.38–1.90) 1 1.34 (1.19–1.51) 1.68 (1.38–2.05)
 PFDeA 1 1.68 (1.49–1.90) 1.72 (1.52–1.95) 1 1.62 (1.16–2.27) 1.79 (1.59–2.02)
Women
 PFOA 1 1.55 (1.38–1.75) 1.70 (1.65–1.75) 1 1.32 (1.19–1.46) 1.53 (1.01–2.32)
 PFOS 1 1.61 (1.26–2.05) 1.36 (1.23–1.51) 1 1.16 (1.08–1.25) 1.84 (1.45–2.34)
 PFHxS 1 1.63 (1.32–2.01) 1.70 (1.60–1.82) 1 1.46 (1.08–1.96) 2.63 (2.10–3.29)
 PFNA 1 1.45 (1.30–1.62) 1.62 (1.38–1.90) 1 1.38 (1.22–1.55) 1.45 (1.07–1.96)
 PFDeA 1 1.68 (1.49–1.90) 1.72 (1.52–1.95) 1 1.47 (1.23–1.77) 1.44 (1.35–1.52)

OR: odds ratio; CI: confidence interval; PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid.

aAdjusted for age, body mass index, marital status, smoking, hiking boots and sneakers use, coated frying pans use, coated pot use, electric cookers use, coated containers use, coated agent or polish use, grilled fish, crustacean, seaweed consumption, type of water drinking indoor, type of water drinking outdoor, average ventilation time per day.

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        Association between outdoor clothing use and serum perfluoroalkyl substances (PFAS): Korean National Environmental Health Survey cycle 4
        Korean Journal of Occupational and Environmental Medicine. 2026;e4  Published online January 8, 2026
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      Association between outdoor clothing use and serum perfluoroalkyl substances (PFAS): Korean National Environmental Health Survey cycle 4
      Image
      Fig. 1. Participant selection flowchart. KoNEHS: Korean National Environmental Health Survey; PFAS: Perfluoroalkyl substance.

      Fig. 1.

      Association between outdoor clothing use and serum perfluoroalkyl substances (PFAS): Korean National Environmental Health Survey cycle 4
      Category Total (n = 2,993)a Men (n = 1,298) Women (n = 1,695) p-value
      PFAS
       PFOA 7.66 (7.33–8.00) 7.99 (7.53–8.45) 7.34 (7.13–7.55) <0.001b
       PFOS 18.87 (18.64–19.10) 20.26 (19.53–20.98) 17.48 (17.02–17.94) <0.001
       PFHxS 5.76 (5.39–6.12) 6.42 (6.11–6.74) 5.09 (4.68–5.50) <0.001
       PFNA 2.54 (2.52–2.57) 2.73 (2.71–2.75) 2.35 (2.32–2.39) <0.001
       PFDeA 1.08 (1.06–1.10) 1.15 (1.13–1.17) 1.01 (1.00–1.03) <0.001
      Age (years) 47.4 ± 0.13 46.4 ± 0.18 48.5 ± 0.10 <0.001
      BMI (kg/m2) 0.003c
       ≤25 1,577 (53.4) 595 (46.1) 982 (60.7)
       >25 1,416 (46.6) 703 (53.9) 713 (39.3)
      Outdoor clothing use 0.001
       None 1,541 (52.3) 557 (43.7) 984 (60.8)
       <Four times a week 1,002 (32.4) 446 (33.9) 556 (30.9)
       ≥Four times a week 450 (15.3) 295 (22.4) 155 (8.3)
      Coated frying pans use 0.002
       None 83 (2.5) 39 (2.6) 44 (2.3)
       <Four times a week 1,313 (40.1) 557 (36.9) 756 (43.2)
       ≥Four times a week 1,597 (57.4) 702 (60.5) 895 (54.4)
      Crustacean consumption 0.076
       <Once a week 2,753 (91.8) 1,189 (91.6) 1,564 (92.1)
       ≥Once a week 240 (8.2) 109 (8.4) 131 (7.9)
      Type of water drinking indoor 0.001
       Water purifier, bottled water, etc. 2,047 (71.4) 896 (73.5) 1,151 (69.4)
       Underground water, small-scale water-supply system, tap water 946 (28.6) 402 (26.5) 544 (30.6)
      Type of water drinking outdoor <0.001
       Water purifier, bottled water, etc. 2,747 (93.3) 1,207 (95.1) 1,540 (91.4)
       Underground water, small-scale water-supply system, tap water 246 (6.7) 91 (4.9) 155 (8.6)
      Average ventilation time per day (minutes) 0.043
       <30 354 (10.5) 174 (11.3) 180 (9.7)
       ≥30, <60 371 (11.1) 156 (10.6) 215 (11.4)
       ≥60, <600 1,112 (36.6) 488 (37.7) 624 (35.6)
       ≥600 1,156 (41.8) 480 (40.4) 676 (43.3)
      Variable PFOA PFOS
      Low (n = 974)a High (n = 324) p-value Low (n = 974) High (n = 324) p-value
      Age (years) 43.5 ± 0.29 57.3 ± 0.22 <0.001b 43.1 ± 0.21 60.3 ± 0.99 <0.001
      BMI (kg/m2) 0.081c 0.763
       ≤25 460 (79.3) 135 (20.7) 454 (81.1) 141 (18.9)
       >25 514 (78.3) 189 (21.7) 520 (81.1) 183 (18.9)
      Outdoor clothing use 0.004 0.011
       None 442 (83.1) 115 (16.9) 430 (84.6) 127 (15.4)
       <Four times a week 319 (76.0) 127 (24.0) 328 (77.3) 118 (22.7)
       ≥Four times a week 213 (74.4) 82 (25.6) 216 (80.1) 79 (19.9)
      Coated frying pans use 0.086 0.004
       None 27 (82.6) 12 (17.4) 30 (88.2) 9 (11.8)
       <Four times a week 429 (78.2) 128 (21.8) 406 (78.6) 151 (21.4)
       ≥Four times a week 518 (79.0) 184 (21.0) 538 (82.3) 164 (17.7)
      Crustacean consumption 0.001 0.001
       <Once a week 902 (80.2) 287 (19.8) 895 (82.1) 294 (17.9)
       ≥Once a week 72 (63.2) 37 (36.8) 79 (69.7) 30 (30.3)
      Type of water drinking indoor 0.009 0.006
       Water purifier, bottled water, etc. 688 (82.2) 202 (17.8) 687 (84.8) 203 (15.2)
       Underground water, small-scale water-supply system, tap water 286 (69.3) 122 (30.7) 287 (71.1) 121 (28.9)
      Type of water drinking outdoor 0.013 0.001
       Water purifier, bottled water, etc. 901 (79.4) 290 (20.6) 908 (82.1) 283 (17.9)
       Underground water, small-scale water-supply system, tap water 73 (68.0) 34 (32.0) 66 (63.7) 41 (36.3)
      Average ventilation time per day (minutes) 0.005 0.003
       <30 122 (74.7) 52 (25.3) 123 (76.0) 51 (24.0)
       ≥30, <60 116 (81.9) 40 (18.1) 116 (84.9) 40 (15.1)
       ≥60, <600 373 (76.7) 115 (23.3) 359 (76.9) 129 (23.1)
       ≥600 363 (81.0) 117 (19.0) 376 (85.4) 104 (14.6)
      Variable PFHxS PFNA PFDeA
      Low (n = 974)a High (n = 324) p-value Low (n = 974) High (n = 324) p-value Low (n = 974) High (n = 324) p-value
      Age (years) 44.1 ± 0.35 53.8 ± 0.06 0.002b 43.0 ± 0.28 60.2 ± 0.04 <0.001 43.1 ± 0.28 60.3 ± 0.20 <0.001
      BMI (kg/m2) 0.017c 0.082 0.062
       ≤25 454 (75.1) 141 (24.9) 456 (81.3) 139 (18.7) 458 (81.4) 137 (18.6)
       >25 520 (76.9) 183 (23.1) 518 (79.7) 185 (20.3) 516 (80.4) 187 (19.6)
      Outdoor clothing use 0.006 0.011 <0.001
       None 429 (81.1) 128 (18.9) 433 (84.0) 124 (16.0) 442 (85.3) 115 (14.7)
       <Four times a week 326 (72.5) 120 (27.5) 335 (78.4) 111 (21.6) 326 (77.6) 120 (22.4)
       ≥Four times a week 219 (71.6) 76 (28.4) 206 (76.4) 89 (23.6) 206 (77.1) 89 (22.9)
      Coated frying pans use 0.155 0.005 <0.001
       None 29 (88.5) 10 (11.5) 26 (82.4) 13 (17.6) 31 (89.4) 8 (10.6)
       <Four times a week 422 (75.7) 135 (24.3) 405 (77.7) 152 (22.3) 403 (77.0) 154 (23.0)
       ≥Four times a week 523 (75.7) 179 (24.3) 543 (82.0) 159 (18.0) 540 (82.9) 162 (17.1)
      Crustacean consumption 0.011 0.001 <0.001
       <Once a week 900 (77.7) 289 (22.3) 894 (82.0) 295 (18.0) 897 (82.6) 292 (17.4)
       ≥Once a week 74 (58.5) 35 (41.5) 80 (63.4) 29 (36.6) 77 (62.1) 32 (37.9)
      Type of water drinking indoor 0.009 0.003 0.004
       Water purifier, bottled water, etc. 677 (78.1) 213 (21.9) 695 (84.4) 195 (15.6) 697 (85.0) 193 (15.0)
       Underground water, small-scale water-supply system, tap water 297 (70.6) 111 (29.4) 279 (69.5) 129 (30.5) 277 (69.7) 131 (30.3)
      Type of water drinking outdoor 0.001 0.002 0.003
       Water purifier, bottled water, etc. 894 (76.6) 297 (23.4) 908 (81.4) 283 (18.6) 908 (81.9) 283 (18.1)
       Underground water, small-scale water-supply system, tap water 80 (66.1) 27 (33.9) 66 (62.9) 41 (37.1) 66 (62.9) 41 (37.1)
      Average ventilation time per day (minutes) 0.006 0.008 0.052
       <30 125 (71.1) 49 (28.9) 119 (73.8) 55 (26.2) 125 (77.2) 49 (22.8)
       ≥30, <60 117 (83.8) 39 (16.2) 119 (85.0) 37 (15.0) 116 (83.2) 40 (16.8)
       ≥60, <600 362 (71.6) 126 (28.4) 369 (78.6) 119 (21.4) 361 (78.3) 127 (21.7)
       ≥600 370 (79.6) 110 (20.4) 367 (82.8) 113 (17.2) 372 (83.6) 108 (16.4)
      Variable PFOA PFOS
      Low (n = 1,272)a High (n = 423) p-value Low (n = 1,272) High (n = 423) p-value
      Age (years) 44.9 ± 0.15 61.5 ± 0.07 <0.001b 44.8 ± 0.03 62.7 ± 0.06 <0.001
      BMI (kg/m2) <0.001c 0.004
       ≤25 775 (83.0) 207 (17.0) 779 (82.8) 203 (17.2)
       >25 497 (70.5) 216 (29.5) 493 (73.9) 220 (26.1)
      Outdoor clothing use 0.002 <0.001
       None 769 (81.1) 215 (18.9) 759 (81.5) 225 (18.5)
       <Four times a week 400 (75.0) 156 (25.0) 412 (79.0) 144 (21.0)
       ≥Four times a week 103 (67.5) 52 (32.5) 101 (64.5) 54 (35.5)
      Coated frying pans use 0.007 0.04
       None 31 (78.2) 13 (21.8) 28 (77.6) 16 (22.4)
       <Four times a week 540 (72.2) 216 (27.8) 535 (75.8) 221 (24.2)
       ≥Four times a week 701 (82.8) 194 (17.2) 709 (82.1) 186 (17.9)
      Crustacean consumption 0.792 0.213
       <Once a week 1,182 (78.1) 382 (21.9) 1,178 (79.5) 386 (20.5)
       ≥Once a week 90 (78.2) 41 (21.8) 94 (77.5) 37 (22.5)
      Type of water drinking indoor 0.004 0.006
       Water purifier, bottled water, etc. 893 (80.5) 253 (19.5) 905 (82.9) 241 (17.1)
       Underground water, small-scale water-supply system, tap water 379 (72.8) 170 (27.2) 367 (71.2) 182 (28.8)
      Type of water drinking outdoor 0.002 0.002
       Water purifier, bottled water, etc. 1,159 (79.9) 352 (20.1) 1,159 (81.7) 352 (18.3)
       Underground water, small-scale water-supply system, tap water 113 (62.0) 71 (38.0) 113 (58.3) 71 (41.7)
      Average ventilation time per day (minutes) 0.015 0.062
       <30 128 (67.1) 52 (32.9) 135 (79.0) 45 (21.0)
       ≥30, <60 153 (75.6) 62 (24.4) 154 (76.0) 61 (24.0)
       ≥60, <600 467 (76.6) 157 (23.4) 465 (77.8) 159 (22.2)
       ≥600 524 (82.4) 152 (17.6) 518 (81.5) 158 (18.5)
      Variable PFHxS PFNA PFDeA
      Low (n = 1,272)a High (n = 423) p-value Low (n = 1,272) High (n = 423) p-value Low (n = 1,272) High (n = 423) p-value
      Age (years) 45.6 ± 0.25 58.4 ± 0.27 <0.001b 44.8 ± 0.06 63.3 ± 0.09 <0.001 45.3 ± 0.15 61.1 ± 0.07 <0.001
      BMI (kg/m2) 0.024c <0.001 0.004
       ≤25 749 (79.3) 233 (20.7) 782 (84.9) 200 (15.1) 770 (82.3) 212 (17.7)
       >25 523 (73.8) 190 (26.2) 490 (72.3) 223 (27.7) 502 (74.8) 211 (25.2)
      Outdoor clothing use 0.002 0.002 0.014
       None 771 (80.6) 213 (19.4) 759 (81.3) 225 (18.7) 765 (82.0) 219 (18.0)
       <Four times a week 399 (74.9) 157 (25.1) 407 (78.9) 149 (21.1) 401 (76.2) 155 (23.8)
       ≥Four times a week 102 (60.6) 53 (39.4) 106 (74.0) 49 (26.0) 106 (72.2) 49 (27.8)
      Coated frying pans use 0.08 0.009 0.008
       None 32 (82.4) 12 (17.6) 30 (78.8) 14 (21.2) 30 (78.4) 14 (21.6)
       <Four times a week 552 (76.2) 204 (23.8) 532 (75.1) 224 (24.9) 535 (75.3) 221 (24.7)
       ≥Four times a week 688 (77.7) 207 (22.3) 710 (83.9) 185 (16.1) 707 (82.7) 188 (17.3)
      Crustacean consumption 0.517 0.09 0.024
       <Once a week 1,179 (77.3) 385 (22.7) 1,177 (79.7) 387 (20.3) 1,179 (79.6) 385 (20.4)
       ≥Once a week 93 (75.5) 38 (24.5) 95 (82.5) 36 (17.5) 93 (76.6) 38 (23.4)
      Type of water drinking indoor 0.003 0.006 0.016
       Water purifier, bottled water, etc. 885 (80.5) 261 (19.5) 904 (83.5) 242 (16.5) 909 (82.9) 237 (17.1)
       Underground water, small-scale water-supply system, tap water 387 (69.6) 162 (30.4) 368 (72.0) 181 (28.0) 363 (71.5) 186 (28.5)
      Type of water drinking outdoor <0.001 <0.001 <0.001
       Water purifier, bottled water, etc. 1,147 (79.2) 364 (20.8) 1,167 (83.2) 344 (16.8) 1,157 (81.7) 354 (18.3)
       Underground water, small-scale water-supply system, tap water 125 (59.7) 59 (40.3) 105 (51.8) 79 (48.2) 115 (59.2) 69 (40.8)
      Average ventilation time per day (minutes) 0.127 0.214 0.213
       <30 134 (77.0) 46 (23.0) 135 (76.4) 45 (23.6) 135 (73.6) 45 (26.4)
       ≥30, <60 158 (76.2) 57 (23.8) 155 (78.4) 60 (21.6) 161 (79.2) 54 (20.8)
       ≥60, <600 463 (73.2) 161 (26.8) 462 (78.9) 162 (21.1) 455 (79.0) 169 (21.0)
       ≥600 517 (80.7) 159 (19.3) 520 (82.1) 156 (17.9) 521 (81.0) 155 (19.0)
      Category Unadjusted Adjusteda
      None <4 times a week ≥4 times a week None <4 times a week ≥4 times a week
      Men
       PFOA 1 1.55 (1.38–1.75) 1.70 (1.65–1.75) 1 1.26 (1.10–1.44) 1.70 (1.40–2.07)
       PFOS 1 1.61 (1.26–2.05) 1.36 (1.23–1.51) 1 1.66 (1.47–1.89) 1.57 (1.05–2.34)
       PFHxS 1 1.63 (1.32–2.01) 1.70 (1.60–1.82) 1 1.49 (1.16–1.92) 1.70 (1.22–2.37)
       PFNA 1 1.45 (1.30–1.62) 1.62 (1.38–1.90) 1 1.34 (1.19–1.51) 1.68 (1.38–2.05)
       PFDeA 1 1.68 (1.49–1.90) 1.72 (1.52–1.95) 1 1.62 (1.16–2.27) 1.79 (1.59–2.02)
      Women
       PFOA 1 1.55 (1.38–1.75) 1.70 (1.65–1.75) 1 1.32 (1.19–1.46) 1.53 (1.01–2.32)
       PFOS 1 1.61 (1.26–2.05) 1.36 (1.23–1.51) 1 1.16 (1.08–1.25) 1.84 (1.45–2.34)
       PFHxS 1 1.63 (1.32–2.01) 1.70 (1.60–1.82) 1 1.46 (1.08–1.96) 2.63 (2.10–3.29)
       PFNA 1 1.45 (1.30–1.62) 1.62 (1.38–1.90) 1 1.38 (1.22–1.55) 1.45 (1.07–1.96)
       PFDeA 1 1.68 (1.49–1.90) 1.72 (1.52–1.95) 1 1.47 (1.23–1.77) 1.44 (1.35–1.52)
      Table 1. Baseline characteristics of the participants

      Values are presented as mean (95% confidence interval), number (%) for categorical variables or as mean ± standard error for continuous variables.

      PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid; BMI: body mass index.

      Unweighted count;

      p-value by t-test;

      p-value by χ2 test.

      Table 2. Distribution of serum PFAS in men according to variables: PFOA and PFOS

      Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

      PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; BMI: body mass index.

      Unweighted count;

      p-value by t-test;

      p-value by χ2 test.

      Table 3. Distribution of serum PFAS in men according to variables: PFHxS, PFNA, and PFDeA

      Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

      PFAS: perfluoroalkyl substances; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid; BMI: body mass index.

      Unweighted count;

      p-value by t-test;

      p-value by χ2 test.

      Table 4. Distribution of serum PFAS in women according to variables: PFOA and PFOS

      Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

      PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; BMI: body mass index.

      Unweighted count;

      p-value by t-test;

      p-value by χ2 test.

      Table 5. Distribution of serum PFAS in women according to variables: PFHxS, PFNA, and PFDeA

      Values are presented as mean ± standard error for continuous variables or number (%) for categorical variables.

      PFAS: perfluoroalkyl substances; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid; BMI: body mass index.

      Unweighted count;

      p-value by t-test;

      p-value by χ2 test.

      Table 6. Adjusted ORs and 95% CIs of use of outdoor clothing with high concentrations of serum PFAS

      OR: odds ratio; CI: confidence interval; PFAS: perfluoroalkyl substances; PFOA: perfluorooctanoic acid; PFOS: perfluorooctanesulfonic acid; PFHxS: perfluorohexanesulfonic acid; PFNA: perfluorononanoic acid; PFDeA: perfluorodecanoic acid.

      Adjusted for age, body mass index, marital status, smoking, hiking boots and sneakers use, coated frying pans use, coated pot use, electric cookers use, coated containers use, coated agent or polish use, grilled fish, crustacean, seaweed consumption, type of water drinking indoor, type of water drinking outdoor, average ventilation time per day.

      Table 1.

      Table 2.

      Table 3.

      Table 4.

      Table 5.

      Table 6.

      Ann Occup Environ Med : Annals of Occupational and Environmental Medicine
      © Korean Society of Occupational & Environmental Medicine.
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