PESTICIDES: ARE GOLFERS SAFE?

40 ------------------------------------------------------------

60 ------------------------------------------------------------

80 ------------------------------------------------------------

5/265/19

water. First, the pesticides were stronglyadsorbed by and retained in the thatchlayer (Figure 1). For most of the OPpesticides studied, very little pesticideactually made it through the thatch andinto the soil. Secondly, the pesticideswere degraded by microorganisms thatessentially use the pesticides as a foodsource. Consequently, the concentrationof pesticide in the thatch/soil decreasedrapidly with time (Figure 2).

5/5 5/12Date (M/D)

4/28

AmountApplication Leached

Pesticide Date % of applied

Chlorpyrifos Jan. 27, 1992 0.15April 21, 1992 0.38

Fonophos Nov. 13, 1991 <0.01Jan. 27, 1992 0.02

Isazophos April 21, 1992 0.09Sept. 17,1992 0.02

Isofenphos April 21, 2001 0.02Sept. 17,1992 0.01

Ethoprop Sept. 17,1992 0.07

o4/21

20 ---------------------------------------7---------------~----

Figure 1Following application of three organophosphate

pesticides, most of the pesticide that was observed inthe thatch and soil was located in the thatch portion

120 Portion of total pesticide in thatch (%)

- Isazophos -- Chlorpyrifos - - - . Isofenphos

*Data extracted from Cisar and Snyder (7)

Table 1Pesticide leached following application at labeled rates to a USGA green,

expressed as a percent of the amount applied ':c

100

construction (2). The lysimeters wereused to collect percolate water from thegolf green for several months afterpesticide application. The pesticidesgenerally were applied as liquid sprays.With one exception, which will bediscussed later, less than 1% of theapplied pesticide was found in thepercolate water (Table 1).

There are two reasons why so littlepesticide was recovered in percolate

University of Florida studiessuggest that pesticides donot pose any significanthealth threat to golfers.by GEORGE H. SNYDER,JOHN L. CISAR, andCHRISTOPHER J. BORGERI'

~

ICLES about pesticide usageon golf courses and the dangers

to which golfers are exposedbecause of these pesticides oftenappear in the popular press. Thesearticles make good press with eye-catching headlines, but they oftenraise concern by citing potentialhazards without providing any scien-tifically based analyses. In order toprovide data that can be analyzedscientifically, the United States GolfAssociation has provided grantstotaling millions of dollars to univer-sity scientists to conduct research intothe fate of pesticides applied to golfturf and to assess the associated risksto golfers.

While no single university study hasprovided all the answers to this com-plex issue, each has made headway inanswering specific components of thepuzzle. For example, our work hasfocused on pesticide leaching, pesticideremoval in clippings, pesticide dislodge-ability from turf surfaces, and pesticidelosses by volatilization. Because dis-lodgeability and volatilization can re-sult in direct golfer exposure to pesti-cides, we have conducted assessmentsof the risks to golfers posed by suchpesticide losses. We concentrated ourstudies on the class of pesticides knownas organophosphates (OP) because oftheir widespread use, effectiveness asinsecticides and nematicides, and be-cause they are known to be toxic tohumans at certain levels of exposure.

Pesticide LeachingFollowing application at labeled

rates, we measured pesticide in thatch,soil, and in percolate. The field workwas conducted at the University ofFlorida/IFAS St. Lauderdale Researchand Education Center using a specialfacility that has stainless-steellysimetersinstalled in a research golf green ('Tif-dwarf' bermudagrass) patterned afterUSGA specifications for putting green

NOVEMBER/DECEMBER 2001 17

300

*Data from R. H. Snyder (9)

liquid and granular application, pesti-cide removal in clippings generallydeclined quite rapidly with time.

Dislodged PesticidesFrom our studies with OP pesticides,

it appears that most of the pesticidesdissipate rapidly, and there is little lossin clippings or percolate. These lossmechanisms should pose little hazardto golfers or to the environment. How-ever, there are two pesticide loss path-ways by which direct golfer exposurecan occur: dislodging from the turfsurface directly or indirectly to a golfer'sskin and inhalation of pesticides vola-tilized from the turf. We have investi-gated both of these loss pathways andhave estimated potential risks forseveral scenarios under which golfersmight be exposed to pesticides.

All chemicals can be toxic to someorganisms at some dose. The questionto be determined in our studies waswhether a golfer is likely to receive atoxic dose as a result of exposure topesticides applied to maintain golfturf. Toxicity may be immediate ormay occur only after many years ofexposure. The U.S. EnvironmentalProtection Agency (USEPA) providesvalues that can be used for assessingthe risk of exposure to various pesti-cides (10). Pesticides sprayed on turfsurfaces may contact golfers directlywhen a player touches the turf or in-directly when the golfer touches variousitems (club heads, golf balls, etc.) thathave come in contact with the turf. Inan extreme case, the golfer may haveoral contact with certain of these itemsand thereby ingest some pesticide.

A series of studies was conducted byUniversity of Florida graduate studentRaymond H. Snyder to evaluate therisks to golfers from pesticide dosesassociated with these exposures. Thesestudies measured the amount of pesti-cide that could be dislodged by variousmeans. For example, after applying apesticide at the labeled rate, moistcheesecloth was rubbed vigorously overthe turf surface. This procedure wasassumed to estimate, and probablygreatly overestimated, the maximumamount of pesticide that might be dis-lodged by touching the turfgrass. Golfgrips were placed on the turf and rolledaround, and a golf ball was puttedacross the surface twice. Following anapplication of pesticide to turf severalinches tall, a club head was swungthrough the grass to simulate chippingout of a rough. The amount of pesticideon the golf grips, golfball, and club face

5/265/19

- - - . Isofenphos

ment with this, when we applied fena-miphos a second time, only 1.1% of thatapplied was detected in percolate waterin the form of metabolites. Neverthe-less, this is considerably more than wasfound for other OP pesticides. For thisreason, we developed a sand-sized soilamendment (patent pending, Universityof Florida) that absorbs fenamiphosand its metabolites without reducingthe rate of water percolation (8).

Grass ClippingsOrganophosphate pesticide removal

in grass clippings for several weeks afterapplication also amounted to less than1% of that applied, in most of the trials,when the pesticides were applied assprays. In some cases, somewhat morewas recovered in clippings whengranules were used as the carrier, pre-sumably because some granules werepicked up by the mower (3). For both

5/5 5/12Date (MID)

Fenamiphos Isazofos Chlorpyrifos

- - - - - % of applied - - - - -2.89 1.40 1.120.10 0.08 0.060.00 0.02 0.01

4/28

, ---,, ,, ,, ,, ,, ,, ,, ','------~'-------~~~,-----------------------------------------, " ............'I: ",," ................

,,~-- - - - -. - - - - - - - ....----------------------------------

,,,,,

o4/21

Table 2Pesticide dislodged by vigorously wiping the turf surface with

damp cheesecloth at various intervals following pesticide application *Pesticide

100

Figure 2Three organophosphate pesticides rapidly disappearedfrom thatch and soil following application to a USGA

green due to microbial degradation

400 Total pesticide in thatch and soil (mg m-2)

- Isazophos -- Chlorpyrifos

15 minutes3 hours (irrigated)20 hours

TIme AfterApplication

The exception that we found to thegeneralization that OP pesticides arestrongly adsorbed in the thatch layer,and therefore undergo little leaching,was for the nematicide fenamiphos(Nemacur), and particularly for itsmetabolites (breakdown products),which also can be toxic. Following anapplication of fenamiphos, of the totalmetabolites in the 0-15 cm (0-6 inch)layer, we observed only 20% being inthe thatch (7). Nearly 18% of theapplied fenamiphos was observed asmetabolite in the leachate.

Ithas been established that followingfenamiphos applications, microbialpopulations that can readily degradethe pesticide rapidly increase in the soiland remain there for years (6). There-fore, when additional fenamiphosapplications are made, microbial break-down of the fenamiphos and of itsmetabolites can be very rapid. In agree-

18 USGA GREEN SECTION RECORD

The research field study showed that the pesticide dose received by a golfer very muchdepended on the time period and irrigation cycle after a pesticide application.

was measured to estimate the amountof pesticide that could be dislodged bythese methods and potentially betransferred to a golfer's skin.

Wiping the turf surface with dampcheesecloth dislodged considerablymore pesticide than any of the othermethods. But even for this method, lessthan 3% of the applied pesticide couldbe dislodged only minutes after appli-cation. Several hours later, followingirrigation, no more than 0.10/0 wasdislodged even by this very aggressivemethod (Table 2).

Using the dislodgeability data, someof the golfer behaviors that could leadto contact with pesticides were investi-gated. They included a) placing a handon the turf surface following an appli-cation of pesticide, b) handling golfgrips that had been placed on the turfsurface, c) handling a golf ball that hadbeen putted twice across a pesticide-treated green, d) touching a club faceand back following chipping onto agreen, e) kissing or licking a golf ballthat had been putted on a treatedgreen. Since the studies did not involvehuman subjects, pesticide was dis-lodged from the turf and the golf equip-ment by means that no doubt were farmore thorough in dislodging pesticidethan by casual touch. Therefore, thestudies added an extra margin of safetyabove that margin incorporated intothe USEPA figure used to calculaterisks (generally 10- to 10,000-fold).

Because very little scientific infor-mation exists about the behaviors thatexpose golfers to pesticides, a theo-retical golfer was created to simulateboth high and worst -case estimates ofdermal and oral exposure. For purposesof the study, this theoretical golfer wasassumed to exhibit behavior thatexceeds what any real golfer wouldreasonably do. It was assumed that oneachJ:101e of golf the theoretical golferdid each of the five previously listedbehaviors that could lead to contactwith pesticide that had been applied toturfgrass. Since none of the pesticidesstudied have shown any carcinogeniceffects, risk was assessed using the haz-ard index approach to assess potentialnon-cancer effects. This approach com-pares the average daily intake (dermaland oral) of each pesticide to a pub-lished acceptable level of daily intakefor chronic or subchronic exposure(RID) (1). If the resulting hazard indexis less than or equal to 1.0, the chemi-cals are considered unlikely to repre-sent a risk to human health. If thehazard index is greater than one, a

potential risk to human health mayexist (4).

The field study showed that thepesticide dose received by the theo-retical golfer very much depended onthe time period after application, andon irrigation following pesticide appli-cation. Increasing either factor reducedthe golfer's estimated dose of pesticide.Thus, the golfer's risk also depended onthese two factors (Table 3). For be-haviors leading to hazard indexesgreater than 1.0, some level of riskmight exist. These behaviors rangefrom the absurd, such as playing 18

greens 30 minutes after pesticide appli-cation every day for a lifetime of 70years, thereby resulting in an unaccept-able risk from some pesticides, to morereasonable, although still unlikely,scenarios producing no measurablerisk (hazard index of less than 1.0).

The calculated indexes also are verydependent on the pesticide studied.Considering three contrasting pesti-cides, for example, the calculated risksare much higher for fenamiphos thanfor chlorpyrifos (Table 3). But even forfenamiphos, the chances of any of thebehaviors leading to hazard indexes

NOVEMBER/DECEMBER 2001 19

Table 3Hazard indexes calculated for various pesticides and behavioral scenarios 1

Hazard Index2

Behavior Fenamiphos Isazofos Chlorpyrifos

Golfer plays on 18 greens 30 minutes 152.00 55.12 0.31after pesticide application everydayfor a lifetime (70 years)Golfer plays on one green 30 minutes 17.05 6.80 0.04after pesticide application and on theremaining 17 greens after pesticideapplication and irrigation everydayfor a lifetimeGolfer plays on 18 greens after pesticide 9.08 3.95 0.02application and irrigation everydayfor a lifetimeGolfer plays on 18 greens the day after 0.84 1.30 .0.01 ' ~ I

application and irrigation everydayfor a lifetimeGolfer plays on 18 greens 30 minutes 21.65 7.86 0.04after pesticide application two times aweek for 35 yearsGolfer plays on one green 30 minutes 2.43 0.97 0.01after pesticide application and on theremaining 17 greens'after application andirrigation two times a week for 35 yearsGolfer plays on 18 greens after 1.29 0.56 0.003

.application and irrigation two timesa week for 35 yearsGolfer plays on 18 greens the day after. 0.12 0'.19 0.002application and irrigation two timesa week for 35 years

. 2Hazard risk less than 1.0 produces no measurable riskIData' from R. H. Snyder (9)

greater than 1.0 are minuscule, becausefenamiphos cannot be used legallymore than twice per year on anyonearea.

Furthermore, there are behaviors agolfer can easily avoid to further re-duce the risk posed by pesticides. Forexample, it is known that a muchhigher proportion of pesticide is ab-sorbed into the body following oralversus dermal exposure (2.5% of thepesticide that reaches a golfer's skin isassumed to be adsorbed into thebody, but 100% of the pesticide ingestedby oral exposure is assumed to beadsorbed). Therefore, simply avoidingthe "kissing or licking the golf ball"behavior is a good way to reducewhatever dose of pesticide might bereceived.

Pesticide VolatilizationA portion of the pesticide applied to

golf turf is volatilized into the atmo-sphere. Inhalation of volatilized pesti-cides represents another way that pesti-cide can enter the body. We and others

20 USGA GREEN SECTION RECORD

(5) have observed that more pesticidemay be lost from turf by volatilizationthan by leaching or dislodging. Forexample, we have observed losses byvolatilization, measured only duringdaylight hours, ranging from 2.5% to13.6% of that applied (Table 4), whichare greater losses than we observeddue to leaching, dislodging, or clippingremoval for some of the same pesti-cides.

Table 4Pesticide volatilized over athree-day period, excluding

nighttime periods, expressed asa percent of the amount applied

Study Year

Pesticide 1999 2000Ethoprop 11.3% 13.6°/0Fonofos 7.2%Chlorpyrifos 6.0°/0Isophenfos 2.5°/0 2.8°/0

Risks associated with inhalation ofvolatilized pesticides also can be calcu-1ated when USEPA chronic referencedose (RID) data are available. Theaverage daily inhaled dose of pesticidefor a 70 kg adult (154 pounds) playinga 4-hour round of golf can be estimatedas (5):

D = (C~'R*4h)/70 kg (Equation 1)

where D = daily inhaled dose of pesti-cide (micrograms kg-l), C = measuredair concentration of pesticide (micro-grams m-3), and R =adult breathing rateduring moderate activity (2.5 m3 h-l).

For chlorpyrifos, the USEPA chronicreference dose (RID) is 3.0 microgramskg-ldol.Using Equation 1 and assumingthat all inhaled pesticide is absorbed bythe body, it can be calculated that theconcentration (C) of chlorpyrifos in airthat provides a daily inhaled dose (D)equal to the RID is 21 micrograms kg-lm-3• This value was not exceeded ineither of the two studies we have con-ducted (Table 5), indicating that golferexposure to volatile losses of chlor-pyrifos poses little health hazard.

However, it should be noted thatthe RID for chlorpyrifos is rather highcompared to certain other organophos-phate pesticides, so the lack of a healthhazard for chlorpyrifos should not betaken as a generalized lack of healthhazard for other pesticides. For example,fenamiphos has a RID of only 0.25micrograms kg-l dol.Based on Equation1, C is only 1.75. However, this valuewas exceeded for only a short time inone of two studies conducted on fena-miphos volatilization (Table 5). Ofcourse, the calculations assume expo-sure to the corresponding concentra-tion of pesticide for an entire round ofgolf every day for a lifetime, which willnot occur based on the data from ourstudy (Table 5) and the regulatory re-quirement that fenamiphos be used nomore than twice per year.

ConclusionsNo single study can answer all the

questions that have been raised aboutthe fate of pesticides applied to golfturf and the risks they pose to golfers.We can only hope that our work pro-vides a piece of the scientific informa-tion needed to make a comprehensiveassessment of pesticide risks to golfers.However, working with a selection ofOP pesticides, we generally have ob-served relatively small losses by clip-ping removal or by leaching becauseof the strong adsorbing ability of thethatch layer of the turf. Furthermore,

under most reasonable golfing sce-narios, for the pesticides we studied, wefind little reason to anticipate thatgolfers are incurring any serious riskdue to dislodged or volatilized pesti-cides used for maintaining turfgrass ongolf courses.

References1. Borgert, C. J., S. M. Roberts, R. D.Harbison, J. L. Cisar, and G. H. Snyder.1994. Assessing chemical hazards on golfcourses. USGA Green Section Record.33(2):11-14.2. Cisar, J. c., and G. H. Snyder. 1993.Mobility and persistence of pesticides in aUSGA-type green. I. Putting green facilityfor monitoring pesticides. Int. Turfgrass Soc.Res. J. 7:971-977.

3. Cisar, J. L., and G. H. Snyder. 1996.Mobility and persistence of pesticidesapplied to a USGA green. III. Organophos-phate recovery in clippings, thatch, soil, andpercolate. Crop Sci. 36:1433-1438.4. Davis, B. K, and A. K Klien. 1996.Medium-specific and multimedium riskassessment. In: A. M. Fan and L. W Chang(eds.). Toxicology and Risk Assessment.Marcel Dekker, Inc., New York.5. Murphy, K c., R. J. Cooper, and J. M.Clark. 1996. Volatile and dislodgeable resi-dues following trichlorfon and isazofosapplication to turfgrass and implications forhuman exposure. Crop Sci. 36:1446-1454.

6. Ou, L. T. 1991. Interactions of micro-organisms and soil during fenamiphosdegradation. Soil Sci. Soc. Amer. J. 55 :716-722.

7. Snyder, G. H., and J. L. Cisar. 1993.Mobility and persistence of pesticides ina USGA-type green II. Fenamiphos andfonophos. Int. Turfgrass Soc. Res. J. 7:978-983.

8. Snyder, G. H., C. L. Elliott, and J. L. Cisar.2001. A cross-linked phenolic polyether(CPP) for reducing fenamiphos leaching ingolf greens. Int. Turfgrass Res. J. (Part 1).9:40-44.

9. Snyder, G. H. 1998. Dislodgeable residuesof pesticides applied to turfgrass and impli-cations for golfer exposure. M.S. Degreethesis, University of Florida, Soil and WaterScience Department, Gainesville, Florida.

10. USEPA. 1989. Risk Assessment Guid-ance for Superfund. Vol. 1. Human HealthEvaluation Manual, Part A. EPA/540/1-89/002.

Chlorpyrlfos FenamiphosStudy 1 Study 2 Study 1 Study 2- - - - - - _ (g m.3) _

4.24 6.39 0.39 3.151.02 6.48 0.00 0.041.22 5.27 0.09 0.020.32 3.52 0.00 0.020.19 3.18 0.00 0.020.08 0.51 0.01 0.01

Table 5Concentration of chlorpyrlfos and fenamiphos

in air following application to bermudagrass turf

Sample limeFollowing ApplicationStudy 1 Study 2

- - - (hours) - - -0-2 0-12-4 1-24-6 2-36 - 18 3 - 418- 24 4 - 524 - 27 5 - 19

DR. GEORGE H. SNYDER, DistinguishedProfessor of Soil and Water Science, Uni-versity of Florida Everglades Research andEducation Center, Belle Glade, Florida.

DR. JOHN L. CISAR, Professor of Environ-mental Horticulture, University of Florida,Ft. Lauderdale Research and EducationCenter, Ft. Lauderdale, Florida.

DR. CHRISTOPHERJ. BORGERT,AppliedPhannacology and Toxicology, Inc., Alachua,Florida, and Department of PhysiologicalSciences, College of Veterinary Medicine,University of Florida, Gainesville, Florida.

(Left) The University of Florida has conducted research to measure direct golfer exposure to pesticides used on the golf course.For purposes of this research, their theoretical golfer was exposed to situations created to simulate a worst case of exposure.(Right) A pesticide-adsorbing resin in the air sampler was used to measure the pesticide concentration in the air following itsapplication to the turf.

NOVEMBER/DECEMBER 2001 21