Article Cite This: Environ. Sci. Technol. 2018, 52, 3156−3166
pubs.acs.org/est
Per- and Polyfluoroalkyl Substances (PFASs) in Indoor Air and Dust from Homes and Various Microenvironments in China: Implications for Human Exposure Yiming Yao,†,∥ Yangyang Zhao,†,∥ Hongwen Sun,*,† Shuai Chang,† Lingyan Zhu,† Alfredo C. Alder,†,‡ and Kurunthachalam Kannan§ †
MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China ‡ Eawag, Swiss Federal Institute of Environmental Science and Technology, 8600 Dübendorf, Switzerland § Wadsworth Center, New York State Department of Health, and Department of E nvironmental Health Sciences, School of Public Health, State University of New York at Albany, Albany, New York 12201, United States S Supporting Information *
ABSTRACT: A newly developed solid-phase extraction cartridge composed of mixed sorbents was optimized for collection of both neutral and ionizable perand polyfluoroalkyl substances (PFASs) in indoor air. Eighty-one indoor air samples and 29 indoor dust samples were collected from rooms of homes and hotels, textile shops, and cinemas in Tianjin, China. Fluorotelomer alcohols (FTOHs) were the predominant PFASs found in air (250−82 300 pg/m3) and hotel dust (24.8−678 ng/g). Polyfluoroalkyl phosphoric acid diesters were found at lower levels of nd−125 pg/m3 in air and 0.32−183 ng/g in dust. Perfluoroalkyl carboxylic acids (PFCAs) were dominant ionizable PFASs in air samples (121−20 600 pg/m3) with C4−C7 PFCAs contributing to 54% ± 17% of the profiles, suggesting an ongoing shift to short-chain PFASs. Long-chain PFCAs (C > 7) were strongly correlated and the intermediate metabolite of FTOHs, fluorotelomer unsaturated carboxylic acids, occurred in all the air samples at concentrations up to 413 pg/m3, suggesting the transformation of precursors such as FTOHs in indoor environment. Daily intake of ∑PFASs via air inhalation and dust ingestion was estimated at 1.04−14.1 ng/kg bw/d and 0.10−8.17 ng/kg bw/d, respectively, demonstrating that inhalation of air with fine suspended particles was a more important direct exposure pathway than dust ingestion for PFASs to adults. park.14 Dominating air emission of long-chain PFASs was found at a textile manufacturing although short-chain PFASs were claimed to be used.15 Moreover, the product profiles of shortchain substitutes may vary between countries. The emission profiles of PFASs in China may be unique and more complicated due to a co-occurrence of PFASs with different chain lengths in final consumer products. Therefore, exposure to PFASs in residential places is of primary interest. Besides, the occurrence of PFASs in public places where PFAS-containing products are stored, sold or used may also raise concerns for occupational exposure risk and is yet to be clarified in China. In addition to ingestion through diet and drinking water,16−18 indoor air inhalation and dust ingestion are major pathways of human exposure to PFASs.19 As for PFAAs, which are most concerned PFASs due to their persistence and toxicity, apart from direct uptake of from the environment,20 inhalation
1. INTRODUCTION Per- and polyfluoroalkyl substances (PFASs) are a family of synthetic compounds extensively applied in industrial processes and commercial products as protective coatings for fabrics and metals, and as additives in fire-fighting foams, due to their surface activity, and thermal and chemical stability.1,2 Longchain perfluoroalkanesulfonic acids (PFSAs, n ≥ 6) and perfluoroalkyl carboxylic acids (PFCAs, n ≥ 7) are persistent and bioaccumulative and have been ubiquitously detected in food,3,4 drinking water,5,6 and human specimens.7,8 PFASs exposure is associated with hepatotoxicity, reproductive toxicity, developmental toxicity, and immunotoxicity.9,10 The phase-out of C8 PFASs has been implemented in most developed countries,11,12 where shifting to shorter-chain PFASs and other alternatives has led to their increasing levels in environmental matrices and progressive human exposure risk.13 Meanwhile, the production and application of legacy long-chain perfluoroalkyl acids (PFAAs) and their precursor fluorotelomer alcohols (FTOHs) rehabilitated in mainland China.2 In China, perfluorooctanoic acid (PFOA) was found dominant in both indoor and outdoor dust around a fluorochemical industrial © 2018 American Chemical Society
Received: Revised: Accepted: Published: 3156
October 2, 2017 January 29, 2018 February 8, 2018 February 8, 2018 DOI: 10.1021/acs.est.7b04971 Environ. Sci. Technol. 2018, 52, 3156−3166
Article
Environmental Science & Technology
(SI)). The SPE cartridge (6 mL) consisted of two layers of absorbents: the upper layer of HC-C18 (250 mg) for trapping mainly neutral PFASs and the bottom layer of WAX (250 mg) for trapping ionizable PFASs. A diaphragm vacuum pump (Jinteng, GM-0.33A) was used for pumping air consecutively through the HC-C18 and WAX layers of absorbents. The validation of the sampling device including extraction efficiency, breakthrough, and microchamber spiking tests was given in the SI. Indoor air sampling was performed in Tianjin, China, in the summer (June−September) of 2015 in standard rooms of 13 hotels, living rooms of 19 homes, and microenvironments of 13 public places. Nine living rooms of the homes were resampled in the winter (December) for comparison of PFAS concentrations between the two seasons. The public places included five outdoor equipment shops (OS) that sell outdoor wear, three curtain shops (CurS), two carpet shops (CarS), and three cinemas, where the goods sold or decorations used were thought to be potential sources of PFASs. The details of indoor air sampling are given in Table S2. Prior to assembly, the SPE cartridges were sequentially conditioned with methanol and ethyl acetate and wrapped in aluminum foil sealed in polyethylene plastic (PP) bags. For sampling, two cartridges were connected to the pump in parallel to reduce the loading pressure and to increase sampling efficiency. Indoor air about 1 m above the floor was collected at an initial sampling rate of 4.5 L/min for 8−12 h to reach a volume of 2.16−3.24 m3. In some cases, sampling time was extended for convenience that gave a sampling volume up to 8.33 m3. At some public places, due to logical constraints, sampling time was less than 8 h but that volume was sufficient for the quantification of PFASs (SI Table S2). After sampling, the cartridges were detached on site, wrapped and sealed in aluminum foil and PP bags, transported to the laboratory, and kept at −20 °C before extraction. In summer, a total of 11 hotel and 18 home dust samples were collected within the period of air sampling. The dust samples from hotels were collected from dust bags in vacuum cleaners and those from homes were collected using a precleaned disposable bristle brush from multiple sites on surfaces of furniture and floor. The sampled areas were all kept from cleaning at least for 1 week. All dust samples were directly swept into PP tubes, sealed in PP bags, and kept at −20 °C until analysis. Neutral PFASs were analyzed using GC-MS, while ionizable PFASs were analyzed using HPLC-MS/MS. Details of chemical information, sample pretreatment, and instrumental analysis are provided in SI. 2.2. Calculation of Daily Intake. Direct and indirect exposure pathways to PFASs via indoor air inhalation and dust ingestion were estimated for toddlers (1−2 years) and adults (>20 years) using the following equations:36
of volatile precursors including FTOHs and perfluorooctane sulfonamidoethanols/sulfonamides (FOSE/FOSAs) and subsequent internal biotransformation also contributes to human exposure to PFAAs (called as indirect uptake). FTOHs and polyfluoroalkyl phosphoric acid diesters (diPAPs) of newly concern have been shown to be metabolized in human and rodents to produce PFCAs,21−24 whereas biotransformation of FOSE/FOSAs in vivo can yield perfluorooctanesulfonic acid (PFOS).25,26 Till now, the direct uptake of PFAAs in indoor dust has been well documented, however, a direct exposure to PFAAs via air inhalation has been less emphasized on. The ionizable PFASs (i.e., PFAAs) can be enriched in fine particles (
