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Hazardous Chemicals in Synthetic Turf Materials and Their Bioaccessibility in Digestive fluids

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Hazardous Chemicals in Synthetic Turf Materials and Their Bioaccessibility in Digestive fluids Journal of Exposure Science and Environmental Epidemiology (2008) 18, 600–607 r 2008 Nature Publishing Group All rights reserved 1559-0631/08/$30.00 www.nature.com/jes Hazardous chemicals in synthetic turf materials and their bioaccessibility in digestive fluids JUNFENG (JIM) ZHANGa, IN-KYU HANa,b,LINZHANGa AND WILLIAM CRAINc aSchool of Public Health, University of Medicine and Dentistry of New Jersey, 683 Hoes Lane West, Piscataway, New Jersey, USA bJohns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA cThe City College of New York, New York, New York, USA Many synthetic turf fields consist of not only artificial grass but also rubber granules that are used as infill. The public concerns about toxic chemicals possibly contained in either artificial (polyethylene) grass fibers or rubber granules have been escalating but are based on very limited information available to date. The aim of this research was to obtain data that will help assess potential health risks associated with chemical exposure. In this small- scale study, we collected seven samples of rubber granules and one sample of artificial grass fiber from synthetic turf fields at different ages of the fields. We analyzed these samples to determine the contents (maximum concentrations) of polycyclic aromatic hydrocarbons (PAHs) and several metals (Zn, Cr, As, Cd, and Pb). We also analyzed these samples to determine their bioaccessible fractions of PAHs and metals in synthetic digestive fluids including saliva, gastric fluid, and intestinal fluid through a laboratory simulation technique. Our findings include: (1) rubber granules often, especially when the synthetic turf fields were newer, contained PAHs at levels above health-based soil standards. The levels of PAHs generally appear to decline as the field ages. However, the decay trend may be complicated by adding new rubber granules to compensate for the loss of the material. (2) PAHs contained in rubber granules had zero or near-zero bioaccessibility in the synthetic digestive fluids. (3) The zinc contents were found to far exceed the soil limit. (4) Except one sample with a moderate lead content of 53 p.p.m., the other samples had relatively low concentrations of lead (3.12–5.76 p.p.m.), accordingto soil standards. However, 24.7–44.2% of the lead in the rubber granules was bioaccessible in the synthetic gastric fluid. (5) The artificial grass fiber sample showed a chromium content of 3.93 p.p.m., and 34.6% and 54.0% bioaccessibility of lead in the synthetic gastric and intestinal fluids, respectively. Journal of Exposure Science and Environmental Epidemiology (2008) 18, 600–607; doi:10.1038/jes.2008.55; published online 27 August 2008 Keywords: synthetic turf, PAHs, lead, heavy metals, bioaccessibility. Introduction individual legislators in Minnesota, New Jersey, and New York have called for moratoria on new synthetic turf Across the United States, Canada, and Europe, parks and installations until more research is conducted. A bill in athletic facilities are installing a ‘‘new generation’’ synthetic California calls for more research on the risks, and Connecti- turf. It is springier than the old AstroTurf and feels more like cut has allotted a modest amount of money for their study. natural grass. There are about 3500 full-sized synthetic turf In April 2008, concern intensified when the State of New fields in the United States, with 900–1000 new fields being Jersey Department of Health and Senior Services reported installed each year (McCarthy and Berkowitz, 2008). But high concentrations of lead in the plastic grass fibers in some despite the new turf’s popularity, local residents and of the old-variety AstroTurf fields (NJDHSS, 2008). Follow- government officials are increasingly concerned that it might up simulations in our laboratory indicated that the lead could contain toxic chemicals. Pilot studies reported in newsletters be absorbed by the human digestive tract (NBC, 2008). and on websites have raised the possibility that the tiny (0.5– These findings prompted the federal Centers for Disease 3 mm in size) rubber granules, which are made from discarded Control (CDC) to issue a June 18 health advisory (CDC, tires and contribute to the turf’s resiliency, might contain 2008). The CDC recommended precautions such as washing metals, polycyclic aromatic hydrocarbons (PAHs), or volatile hands after playing on synthetic turf fields, but the CDC organic compounds with toxic potential (see Brown, 2007; acknowledged the paucity of research information on the Claudio, 2008). These studies are very preliminary, but hazards. To assess the magnitude of the health risks of the ‘‘new generation’’ synthetic turf, public health officials need 1. Address all correspondence to: Dr. Junfeng (Jim) Zhang, UMDNJ- systematic information on the concentrations and variability SPH, 683 Hoes Lane West, Piscataway, NJ 08854, USA. ofanytoxicantsinit.Ourresearchstrivestobuildonthefew Tel.: 1 732 235 5405. Fax: 1 732 235 4004. þ þ studies (e.g., Plesser and Lund, 2004, in Norway), which E-mail: [email protected] Received 19 July 2008; accepted 4 August 2008; published online 27 have contributed such information with respect to PAHs and August 2008 selected metals. Hazardous chemicals and digestive fluids Zhang et al. More critically, data are needed not only on the content of All the samples were collected by hand on artificial turf fields toxicants but also on their bioavailabilityFwhether they can be and immediately placed into clean glass bottles and tightly absorbed into the body through exposure routes such as caped. The bottles were precleaned to be suitable for the ingestion, inhalation, and dermal contact. Our work explores the collection of water samples and urine samples in our other ingestion route, which we see as a particularly likely route for the studies. Sample information is summarized in Table 1. All the absorption of metals such as lead, chromium, and cadmium. eight samples were analyzed for their contents of PAHs. Previous studies on ingestion have been incomplete. In a Except samples 5, 6, and 7, all the other five samples were widely cited article, Birkholz et al. (2003) evaluated the analyzed for selected toxic metals. In addition, samples 3, 4, possibility that ingested tire rubber material from flat and 8 were analyzed for the bioaccessibility of PAHs and playground surfaces produces cancer. On the basis of the metals in digestive fluids including synthetic human saliva, results of in vitro genotoxicity assays, the investigators gastric fluid, and intestinal fluid. The methods for determin- concluded that the risk is negligible. However, the investiga- ing the contents and bioaccessible fractions of PAHs and tors did not specify the potentially harmful chemicals they metals are described below. tested. The U.S. Consumer Product Safety Commission All the samples were stored in a refrigerator until 24 h (CPSC, 2008) estimated the amount of lead picked up by before analysis. One day before the extraction procedure, hand contact with artificial grass fibers, which might be each sample was placed in a dessicator at room temperature. transferred to the mouth and ingested. However, the CPSC We were not able to analyze all the eight samples for metals didn’t directly study the lead concentrations that can be and for bioaccessibility tests due to equipment and budgetary absorbed in the digestive tract. In a report to the State of constraints. California, the Office of Environmental Health Hazard Assessment (OEHHA, 2007) summarized its study of Extraction for Determining PAHs Content simulated digestive tract absorption of heavy metals and We used a Soxhlet apparatus for the extraction of PAHs volatile organic compounds from tire shreds. OEHHA in the seven samples of rubber granules and the sample of concluded that the risks are minimal, but it only simulated artificial grass fiber. This method or similar methods absorption within the stomach environment. In this study, we have been used previously to determine PAHs contents in estimated the fractions of PAHs and metals that can be food and PAHs concentrations in air (Howard et al., 1986; dissolved into three synthetic digestive fluids: saliva, gastric Smith and Harrison, 1996; Han et al., 2007). In this fluid, and intestinal fluid. These fractions are referred as procedure, an aliquot of each sample (0.5–2.5 g, typically bioaccessible fractions (i.e., the fractions that are dissolved in 1.0 g) was placed in the Soxhlet apparatus filled with 150 ml the biofluids) not exactly bioavailable fractions (i.e., the of dichloromethane for B16 h at 601C. After the solution fractions that are absorbed by the body) (Yu et al., 2006), hadbeencooleddowntoroomtemperature,itwas although the use of the terminologies may be mixed in the concentrated to approximately 3–5 ml by a rotary evapora- literature. We examined the contents and bioaccessibility of tion apparatus at 401C. This concentrated solution was then bothPAHsandmetalsfromrubbergranulesaswellasfrom transferredintoa5mlconicalglasstubeandfurther plastic fibers. concentrated to B0.1 ml with pure nitrogen gas. The resulting solution was made to exactly 1 ml by adding Methods acetonitrile and then filtered through a 0.2 mm pore-size Sep- Pak C18 cartridge (Waters, Milford, MA, USA). This final We collected seven samples of rubber granules (artificial turf extract solution was then ready for analysis of PAHs using an infill) and one sample of artificial (polyethylene) grass fiber. HPLC system. Ta bl e 1 . Sample information. Sample Location of turf field
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