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32 GOLF COURSE MANAGEMENT 03.14 From Augusta National to Pebble Beach, turfgrass maintenance on golf courses gener - ally requires some pesticide applications. Past feld studies have indicated that, during the course of play, golfers in some locations may inhale levels of certain chemicals that exceed the reference doses associated with chronic dis - eases. (A chronic reference dose is the daily exposure over a 70-year lifespan that produces no harmful health effects — excluding cancer. The incremental cancer risk is measured sepa - rately.) However, those previous studies were limited to the northeastern United States, few chemicals were tested, and some of the chemicals tested are no longer used on golf course turf. The studies were limited in scope because of the expense involved in conducting the research on a large geographic scale with a large number of chemicals. A new study by engineers Hywel Wong, Ph.D., and Douglas Haith, Ph.D., uses math - ematical modeling to expand the reach of pre- vious work to include 37 chemicals and the entire continental United States. By develop - ing a fate and transport model, the researchers circumvented the diffculties involved in con - ducting a real-world study with numerous re- search sites and human experimental subjects. The model was tested against feld experiments at the University of Massachusetts Turfgrass Research Center that measured concentrations of eight pesticides. The authors found that testing of the mathematical model has proved that it is sound, and "it does not seem likely that a more accurate model would produce higher risk estimates." As of February 2012, all pesticides in the study (see the sidebar) were registered in the U.S for use on fairways, but only 25 were labeled for greens. Based on the relative size of different areas of the golf course, the model assumes that golfers spend 7 percent of a round on tees, 8 percent on greens and 85 percent on fairways. The model also assumes that golfers play one round of golf every day of the year, but are not otherwise exposed to these chemicals. Location is important because weather affects evapotranspiration, volatilization fuxes and concentrations. Nine locations were selected to correspond to climate and plant hardiness zones in the U.S. Mean an- nual temperature, mean annual growing sea- son precipitation, and months of the grow- ing season were collected for: Albany, N.Y.; Atlanta; Bismarck, N.D.; Columbus, Ohio; Fresno, Calif.; Houston; Madison, Wis.; Olympia, Wash.; and Roswell, N.M. Mean annual temperatures ranged from 41 F in Bis - marck to 68 F in Houston. Fresno had the least rainfall (5.3 inches), and Houston had the most (36.1 inches), but the two cities shared the lon - gest growing season (March-November). Wong and Haith conclude that "most (at least 60 percent) of the 37 pesticides" showed "negligible volatilization losses from golf course turfs," and losses from the rest "ranged from 0.2 percent to 10.4 percent of annual ap - plications." Differences in volatilization loss de- pended on the chemical used and the location (which affected weather and timing and fre - quency of applications). Using chronic reference doses and cancer potency factors, the authors could not fnd any "evidence of health risk to golfers from inhalation of these pesticides." The results of the study were published as "Volatilization of pesticides from golf courses in the United States: mass fuxes and inhala - tion health risks" by Hywel Wong and Doug- las A. Haith, in the December 2013 issue of the Journal of Environmental Quality 42:1615- 1622. Teresa Carson is GCM's senior science editor. Every breath you take Presented in Partnership with Barenbrug (turf) Teresa Carson firstname.lastname@example.org twitter: @GCM_Magazine Herbicides 2,4-D benefn carfentrazone-ethyl clopyralid dithiopyr furoxypyr isoxaben mecoprop-p oryzalin oxadiazon pendimethalin penoxsulam prodiamine rimsulfuron sulfentrazone sulfosulfuron triclopyr trifuralin Fungicides acibenzolar azoxystrobin chlorothalonil cyazofamid fudioxonil iprodione mancozeb myclobutanil propamocarb-HCl propiconazole thiophanate-methyl Insecticides acephate bifenthrin chlorantraniliprole halofenozide imidacloprid indoxacarb permethrin thiamethoxam Pesticides 032-033_March14_Turf.indd 32 2/18/14 3:26 PM