Environ. Sci. Technol. 2009, 43, 3054–3060
Semivolatile Organic Compounds in Residential Air along the Arizona-Mexico Border R O B E R T W . G A L E , * ,† WALTER L. CRANOR,† DAVID A. ALVAREZ,† JAMES N. HUCKINS,† JIMMIE D. PETTY,† AND GARY L. ROBERTSON‡ Columbia Environmental Research Center, United States Geological Survey, 4200 New Haven Road, Columbia, Missouri 65201, and Office of Research and Development, National Exposure Research Laboratory, Human Exposure and Atmospheric Sciences Division, United States Environmental Protection Agency, 944 East Harmon Avenue, Las Vegas, Nevada 89119
Received December 20, 2008. Revised manuscript received February 27, 2009. Accepted March 2, 2009.
Concerns about indoor air quality and the potential effects on people living in these environments are increasing as more reports about the toxicities and the potential indoor air exposure levels of household-use chemicals and chemicals from housing and furnishing manufacture in air are being assessed. Gas chromatography/mass spectrometry was used to confirm numerous airborne contaminants obtained from the analysis of semipermeable membrane devices deployed inside of 52 homes situated along the border between Arizona and Mexico. We also describe nontarget analytes in the organochlorine pesticide fractions of 12 of these homes; this fraction is also the most likelytocontainthebroadestscopeofbioconcentratablechemicals accumulated from the indoor air. Approximately 400 individual components were identified, ranging from pesticides to a wide array of hydrocarbons, fragrances such as the musk xylenes, flavors relating to spices, aldehydes, alcohols, esters and phthalate esters, and other miscellaneous types of chemicals. The results presented in this study demonstrate unequivocally that the mixture of airborne chemicals present indoors is far more complex than previously demonstrated.
Introduction Studies of potential health effects resulting from exposure to common household chemicals (CHCs) have been hampered by lack of information about the specific chemicals present, the anticipated levels, and the major sources of exposure. Also, because of the differing modes of action of the many CHCs present in indoor air, exposure to complex mixtures is a critical consideration. Compared with outdoor exposure concentrations, increased indoor exposure concentrations are likely for CHCs, because of decreased ventilation, slower chemical degradation rates in homes, and numerous ‘sinks’ or locations for accumulating large quantities of CHCs. Because people spend the majority of their lives inside, where they may be exposed to such concentrated environments of * Corresponding author phone: (573)441-2971; fax: (573)876-1896; e-mail:
[email protected]. † United States Geological Survey. ‡ United States Environmental Protection Agency. 3054 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 9, 2009
airborne chemicals, assessing the consequences of exposure to chemicals present in indoor air is of great concern (1-4). A subset of CHCs, household pesticides, warrants particular study. Often broad-spectrum products such as certain household pesticides may be used indiscriminately, increasing the potential for longer-term, higher-level exposure in indoor environments (5, 6). Legacy pesticides, such as aldrin and dieldrin were used in the United States from the 1950s to the 1970s. The U.S. Environmental Protection Agency (USEPA) banned the use of aldrin and dieldrin (except for termite control) in 1974, and banned aldrin and dieldrin for all uses in 1987 (7). Detection of dieldrin, the 6,7-epoxide of aldrin, indoors is an indicator of the prevalence and persistence of these pesticides in homes, and suggests that other legacy products may also continue to be exposure hazards (7). Two of the most widely used pesticides, chlorpyrifos and diazinon, were banned by the USEPA in 2001 and 2002, respectively. However, chlorpyrifos was used during the sampling period of this study (8) and was therefore considered an indicator of the prevalence of current-use pesticides in homes. The National Human Exposure Assessment Survey conducted a pilot study along the Arizona-Mexico border (NHEXAS-AZ), estimating multimedia pollutant exposures for the population of Arizona (8). As part of the pilot study (9), semipermeable membrane devices (SPMDs) were employed as passive samplers of airborne organic chemicals indoors to augment active sampling. Passive sampling offers the advantages of nonmechanized, unattended, integrated sampling of relatively large volumes of air over long sampling intervals (weeks to months or even years) for a wide range of semivolatile, low-polarity chemicals (10-19). In addition to pesticide-use scenarios, indoor environments provide the potential for long-term high-level exposure to great numbers of chemicals released from household products during typical use and from volatilization of chemicals incorporated into materials composing the structural and domestic features of buildings (1-4, 19-22). Indoor sources were found to predominate for many of consumer product chemicals that may potentially interfere with the action of endogenous hormones (3). A recent examination of equilibrium partitioning of these chemicals among indoor compartments has shown accumulation via direct air-tohuman transport to be potentially large, and that if the only removal mechanism is ventilation, some chemicals may persist indoors for hundreds to thousands of hours, or even for years (2). Most exposure assessment studies target chemicals that have either previously been determined to be a significant health risk or as posing significant exposure levels in particular settings. In the current study, long-term high-volume passive sampling provides a convenient bridge, linking more typical target chemical assessments and reconnaissance studies capable of identifying potential exposure risks from previously unrecognized chemicals. Presented herein are the results of the analysis of passive air samples from a subset of homes from the NHEXAS-AZ study for pesticides and other priority pollutants, and tentative identification of additional chemicals present in household air.
Experimental Section Details of the materials used, the analytical conditions, the procedures employed for identification of chemicals by mass spectrometry, and the quality control used in the present study are given in the Supporting Information. 10.1021/es803482u
Not subject to U.S. Copyright. Publ. 2009 Am. Chem. Soc.
Published on Web 03/26/2009
Study Design and Home Selection. The samples were collected as part of a larger Arizona Border Study (NHEXASAZ) (8) that compared exposures of the border residents to the exposures of the remainder of Arizona to a large number of environmental contaminants. The Arizona border is comprised of three, environmentally distinct, populated areas. Study sites included Yuma, AZ, northwest of the AZ/ Mexico border; and Nogales and Naco, MEX, and Douglas, AZ situated on the southeastern AZ/Mexico border. The Douglas/Naco area is mountainous, with a history of mining and smelting. The Nogales area is primarily a border crossing, with significant industrial activity on the Mexican side of the border. The Yuma area is highly agricultural, with a long history of heavy pesticide use. Mexico only recently started to phase out the use of DDT; therefore, DDT from Mexico continues to be used in the border area (23). Sample Collection and Analysis. Passive integrative samples of indoor air were collected using standard SPMDs (10) (Supporting Information). Four SPMDs were deployed in different locations (kitchen, bath, living room, etc.) in each residence for 30 days and composited for analysis. SPMDs were deployed in 52 of the 83 homes selected for the NHEXASAZ pilot study. Samples were assigned nondescriptive codes for laboratory analysis and the identities of the specific indoor areas chosen for SPMD deployment were not known to the researchers. Sample extracts from 12 homes, a SPMD field blank, and a procedural blank, were selected for analyte confirmation and further examination by gas chromatography-mass spectrometry (GC/MS). These fractions represented fourSPMD composites, originally cleaned to remove surficial dust, processed by dialysis, high performance-size exclusion chromatography (HP-SEC), florisil and silica gel open-column fractionations (24) (Supporting Information). The organochlorine pesticide (silica-gel 2) fractions were selected for detailed analysis. A total of 2 µg of p-terphenyl-d14 was added to each extract (at 100 µL) prior to GC/MS analysis. The large amounts of residual nonvolatile material contained in these fractions when concentrated to ∼100 µL necessitated further cleanup by two additional HP-SEC steps to minimize gas chromatographic degradation. Analyses of laboratory and field blanks indicated that the majority of this material originated from SPMD manufacture. GC/MS analyses used automated searching and library routines developed to facilitate compilation of tentatively identified compounds. Gas chromatography with electroncapture detection (GC/ECD) was used for the primary quantification of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) following previously reported methods (24). Gas chromatography with photoionization detection (GC/PID) was used for the primary quantification of polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and total PID responsive compounds (24, 25). Total PAHs by GC/PID were represented by the sum of all PID response in the chromatographic PAH elution window and were reported as pyrene-equivalent amounts. Analytical conditions and quality control results are summarized in the Supporting Information.
Results and Discussion Polyaromatic Hydrocarbons, Polychlorinated Biphenyls, and Organochlorine Pesticides. Priority pollutant PAHs, PCBs, and OCPs were quantified by gas chromatography with either photoionization or electron-capture detection, and were confirmed by GC/MS. The levels of contaminants accumulated by passive sampling are expressed as total amounts, in µg for PAHs and in ng for OCPs and PCBs, per composite sample of four standard SPMDs deployed at the same location. The amounts of PAHs, PCBs, and OCPs found in composite samples are presented in Table 1. Priority
TABLE 1. Contaminants Quantified and Confirmed in SPMDs chemical PAHs (total as pyrene) naphthalene acenaphthylene acenaphthene Fluorine phenanthrene anthracene fluoranthene Pyrene benz[a]anthracene chrysene benzo[b]fluoranthene benzo[k]fluoranthene benzo[a]pyrene indeno[1,2,3-cd]pyrene dibenz[a,h]anthracene benzo[g,h,i]perylene
PCBs (total) HCB PCA R-BHC β-BHC δ-BHC Lindane (γ-BHC) Dacthal heptachlor heptachlor epoxide oxychlordane cis-chlordane trans-chlordane cis-nonachlor trans-nonachlor o,p′-DDT o,p′-DDE o,p′-DDD p,p′-DDT p,p′-DDE p,p′-DDD dieldrin endrin methoxychlor mirex endosulfan endosulfan-II endosulfan sulfate trifluralinc chlorpyrifosc cis-permethrinc trans-permethrinc diazinonc
average frequency amounta,b,c amount range detected (%) PAHs 260 15 1.7 0.6 7.4 3.8 1.2 1.9 2.5 1.0 0.5
27–1400 0.7–220 0.3–3.7 0.5–0.8 7.4– 7.4 0.8–15 0.5–3.4 1.0–8.5 0.8–35 0.5–2.6 0.5–0.5
1.1
1.1–1.1
OCPs 3.0 46 76 7.0 38 100 64 190 180 55 65 200 260 30 110 370 100 82 990 200 100 340 57 360 3.3 190 87 48 100 14,000 630 380 4,200
1.1–13 8.0–220 16–420 1.8–87 6.3–230 50–150 13–370 12–1100 2.0–3,800 20–170 30–110 11–1100 7.8–2000 8.6–130 4.1–730 12–7200 5.4–2000 13–350 88–9000 0.8–1800 7.7–920 89–1600 15–220 150–560 0.1–15 10–1600 3.7–490 19–100 23–280 49–72 000 92–1200 46–1100 330–27 000
100 33 15 13 2 96 45 45 75 9 2 nd 2 nd nd nd nd
56 98 100 93 38 9 76 38 98 29 9 91 98 49 96 73 64 24 40 96 29 42 45 7 71 85 89 5 67 100 25 42 100
a Amounts are µg per 4 standard SPMD composite for PAHs. b Amounts are ng per 4 standard SPMD composite for OCPs and PCBs. c n ) 52; except trifluralin, chlorpyrifos, diazinon, and cis/trans-permethrin n ) 12.
pollutant PAHs were detectable in most homes, though amounts generally were low (
