Cleanup of Gloves Contaminated with Granular Terbufos and Tefluthrin

C. Guo,1 J. Stone,2 H. M. Stahr,3 M. Shelley4

1 Ansell Healthcare Products Inc., 1875 Harsh Avenue SE, Massillon, Ohio 44648-0550, USA2 Textiles and Clothing Extension, Iowa State University, 1055 LeBaron Hall, Ames, Iowa 50011-1120, USA3 College of Veterinary Medicine, Diagnostic Laboratory, 2630 Veterinary Medicine, Iowa State University, Ames, Iowa 50011, USA4 Department of Statistics, 210 Snedecor, Iowa State University, Ames, Iowa 50011, USA

Received: 11 April 2001 /Accepted: 13 October 2001

Abstract. Chemical-resistant gloves are used for protectionfrom pesticides in farming operations. Cleanup of gloves afterpesticide contamination was the focus of this research. Nitrile,neoprene, and barrier laminate glove specimens were exposedto 300 mg terbufos or tefluthrin granules for 3 or 30 min in petridishes in a laboratory. Specimens were cleaned by flush withrunning water or LaunderOmeter washing with detergent. Fol-lowing the cleanup treatments, specimens were dried andplaced in test tubes with solvents to extract pesticide residue.Levels of contamination remaining were determined by gaschromatography. The residue remaining varied with exposuretime, material type, cleanup method, and pesticide. Flush wasmore effective with the shorter exposure time. Tefluthrin wasmore effectively removed than terbufos. Barrier laminate wasconfirmed as a single-use material. Cleanup procedures re-duced contamination in nitrile and neoprene, but findings showthat these materials retained residue after cleanup.

Protective gloves for pesticide handling are recommended bygovernment agencies and people teaching pesticide safety(U.S. EPA 1993; Stone 1996). Use of gloves is considered animportant part of reducing pesticide exposure. However, littleresearch has been conducted on the effectiveness of commonlyaccepted cleaning procedures for gloves that are not considereddisposable after one wearing. A considerable body of researchconcerning laundering of textile fabrics exists (Easley et al.1983; Laughlin et al. 1985; North Central Agricultural Exper-iment Stations 1988), but few previous studies have consideredglove cleanup.

Stone et al. (1997) compared two methods for laboratorycontamination and cleanup of nitrile, neoprene, and barrierlaminate glove materials contaminated by terbufos (Counter15-G). In that study, half the glove specimens were washed inwarm water with detergent and stirred in a beaker 3 min in aneffort to clean them. Contamination levels of specimens weredetermined using gas chromatography, and those not washed

were compared with those that were washed. With the glove-finger exposure method, no significant difference was foundbetween before- and after-washing contamination levels for thebarrier laminate, but the level of contamination in neoprene andnitrile was significantly reduced. With a 30-min exposure togranular terbufos by petri-dish exposure method, contamina-tion levels after washing were not significantly less than beforewashing for any of the materials.

Guo et al. (1997) reported additional research concerningcleanup of gloves exposed to granular terbufos (Counter 15-G)for 30 min. The petri-dish method of contamination mentionedin the previous study was used for contamination of nitrilegloves (Stansolv A-15 from Mapa Pioneer). Three methods ofcleanup were investigated: (1) a flush process in which con-taminated specimens were held under a separation funnel for30 s as 150 ml of distilled water was released and flushed overthem; (2) a beaker wash with detergent with stirring for 3 min;and (3) a combination treatment using first the flush treatmentfollowed by the beaker washing. In this study, there was nosignificant difference among cleanup methods based on extrac-tion of the chemical from the glove material. Further analysisof the water used in cleanup processes revealed that there alsowas no significant difference in contamination levels of thewaste water.

In a recent study, the effects of exposure time, material type,and the granular pesticides terbufos and tefluthrin on contam-ination of neoprene, nitrile, and barrier laminate gloves (Guo etal. 2001) were reported. In that study, a linear relationship wasfound between exposure time and contamination level in allthree materials for both terbufos and tefluthrin. In general, thelonger exposure time the higher contamination level. The long-est exposure time tested was 24 h. No pesticide was detected onalpha cellulose pads held under the glove materials during thatperiod. Nitrile had significantly less contamination than neo-prene or barrier laminate for both terbufos and tefluthrin.Tefluthrin contamination was significantly less than terbufoscontamination, and the statistical analysis showed interactionbetween material and pesticide type, demonstrating that glovematerials are not equally protective for all pesticides.

The purpose of this research was to investigate the effective-ness of cleanup methods for glove materials contaminated byCorrespondence to: J. Stone; email: jfstone@iastate.edu

Arch. Environ. Contam. Toxicol. 42, 383–388 (2002)DOI: 10.1007/s00244-001-0015-4

A R C H I V E S O F

EnvironmentalContaminationa n d Toxicology© 2002 Springer-Verlag New York Inc.

terbufos (Counter 20CR) and tefluthrin (Force) for exposuretimes of 3 and 30 min.

Materials and Methods

A 2 � 3 � 2 � 3 factorial design was used. The two pesticides wereterbufos and tefluthrin. The three gloves were barrier laminate, neo-prene, and nitrile. The two exposure times were 3 and 30 min. Thethree wash methods were controls (contaminated, not washed), flush,and Launder-Ometer.

An explanation of the glove materials, pesticides, and glove speci-men contamination used in this study was previously reported (Guo etal. 2000). After two cleanup methods were used, contamination levelson specimens with 3- and 30-min exposure were compared with thoseon control specimens. The cleanup methods were a flush treatment anda LaunderOmeter washing.

For the flush method, a 200-ml separatory funnel was filled with 150ml of E-Pure� ultra-pure water. An edge of the contaminated specimenwas held by a tweezers underneath the open end of the separatoryfunnel filled with the water at ambient room temperature (about 21°C)directly from the water purification system. The 150 ml of water wasreleased from the separatory funnel, and the contaminated face ofspecimens was flushed about 30 s. After the flushed specimens weredried under a hood, they were placed individually in 25 ml of solventin separate test tubes for 24-h extraction time.

In the LaunderOmeter method an ATLAS LP2 was used to wash thecontaminated 4 � 4 cm glove specimens. Each specimen was placedin a standard metal canister and laundered for 9 min at 60°C with 150ml E-Pure ultra-pure water, 0.2 ml Liquid Tide� detergent, and 20steel balls. After laundering, the 4 � 4 cm laundered glove specimenseach were rinsed for 3 min and again for 2 min at 49°C with 150 mlE-Pure ultra-pure water and 20 steel balls. After rinsing, the specimenswere taken out of metal canisters and dried under a hood. Whenspecimens were dry, they were put individually into test tubes with 25ml of solvent for 24-h extraction time. Ethyl acetate was used toextract terbufos, and iso-octane was used for tefluthrin.

After the 24-h extraction period, the glove specimens were removedfrom their respective test tubes. The test tubes containing unknownquantities of pesticide and 25 ml of extraction solvent were kept in arefrigerator at 4°C until time for the gas chromatography analysis.

Two gas chromatographs were used for this study. A Varian 3400gas chromatograph with a thermionic N.P. selective detector was usedfor the terbufos analysis. A Packard 427 gas chromatograph with anelectron capture detector was used for the tefluthrin analysis. Theparameters of gas chromatography were previously presented (Guo etal. 2000).

Three specimens were used for each treatment, with two GC injec-tions per specimen, so there were six total observations for eachtreatment. The value of each observation was converted into theamount of pesticide residues per cm square specimen. The mean of sixvalues were used as the pesticide residue amount (ng/cm2) in eachtreatment.

Results

The effects of exposure time, material type, and cleanupmethod were interrelated so that each variable affected theresidue remaining after cleanup for terbufos and tefluthrin asshown in Tables 1 and 2.

Exposure Time

A significant difference (p � 0.01) in terbufos and tefluthrinresidue was found in comparing 3-min and 30-min exposuretime based on the results of factorial analysis of variance asshown in Table 3 and Table 4. For all materials, contaminationlevels with terbufos were lower with 3-min exposure andcleanup was more effective. For example, with terbufos, after3-min exposure and flush cleanup the contamination level fornitrile was 27.19 ng/cm2, but after 30-min exposure and flushcleanup the contamination level was 421.77 ng/cm2 or about 16times more. With tefluthrin, after 3-min exposure and flushcleanup, the contamination level for nitrile was 4.05 ng/cm2,but after 30-min exposure and flush cleanup, the contaminationlevel was about twice as much, or 7.90 ng/cm2.

Material Type

The three glove materials differed significantly (p � 0.01) interbufos and tefluthrin contamination levels before and aftercleanup with either method. The rank order of the three glovematerials in terbufos and tefluthrin residue after cleanup wasconsistent with that of the three glove materials in contamina-tion levels in controls before cleanup. With both pesticidesafter either flush or LaunderOmeter wash (hereafter referred toas LOM), nitrile showed lower ng/cm2 contamination thanneoprene or barrier laminate. The lowest terbufos residue,27.19 ng/cm2 for 3-min exposure time, was in the nitrile afterthe flush treatment, and the highest terbufos residue, 1,890.90ng/cm2 for 30-min exposure time, was in the neoprene afterflush. The lowest tefluthrin residue, 0.15 ng/cm2 for 30-minexposure time, was in the nitrile after the LOM treatment andthe highest tefluthrin residue, 488.28 ng/cm2 after 30-min ex-posure time, was in the barrier laminate after flush.

Cleanup Method

No significant difference was found between the flush andLOM cleanup methods for nitrile and barrier laminate with3-min exposure time. Both the flush and LOM cleanup meth-ods reduced terbufos contamination in these materials as com-pared with controls. After the flush treatment, terbufos residueswere 66% lower for nitrile and 30% lower for barrier laminate.Flush significantly reduced terbufos residue in neoprene spec-imens (62%), but LOM did not provide a significant effect withneoprene. After the 30-min exposure time, flush made nosignificant difference, but LOM reduced terbufos residues 67%in nitrile and 36% in barrier laminate. Neither flush nor LOMsignificantly reduced terbufos residue in the neoprene after30-min exposure.

With tefluthrin, both flush and LOM significantly reducedcontamination for each type of glove material with the 3-minexposure time. After 30-min exposure, flush was effective inreducing residue in nitrile but made no significant difference inresidue in neoprene and barrier laminate.

After 30-min exposure, the LOM treatment significantlyreduced the contamination in all materials. With LOM, con-tamination was reduced 99% in nitrile, 87% in neoprene, and

384 C. Guo et al.

59% in barrier laminate. No significant difference in cleanupmethods was found for nitrile.

The Scheffe test confirmed that residue after cleanup variedwith exposure time, material type, and cleanup method. It alsoshowed that considering all data, the LOM was more effectivethan the flush to reduce residue.

Interaction Effects

Table 3 shows that factorial analysis of variance of terbufosdata identified significant interactions among variables: glovematerial and exposure time and cleanup method and exposuretime. After a 3-min exposure with the flush method, the per-centage reduction in contamination for neoprene was almostthe same for nitrile, but after a 30-min exposure and LOM,neoprene retained more terbufos contamination than nitrile andbarrier laminate.

Table 4 shows the results of the factorial analysis ofvariance indicating that exposure time, material type, andcleanup method significantly affected the amount of tefluth-rin residue in specimens. This analysis identified three sig-nificant interactions among variables: glove material andcleanup method, glove material and exposure time, andcleanup method and exposure time. With nitrile material,either flush or LOM reduced tefluthrin effectively, but withneoprene and barrier laminate, LOM was much better thanflush, especially with the 30-min exposure times. With the3-min exposure time, flush reduced tefluthrin residues sig-nificantly for each type of glove material. However, after the30-min exposure time, tefluthrin residues were not signifi-cantly reduced by flush for neoprene or barrier laminate.

Pesticide Effect

The whole set of data from GC analysis, including bothterbufos and tefluthrin (n � 216), was examined usingfactorial analysis of variance. The results of this analysis aresummarized in Table 5. The amount of residue found inglove materials after laundering differed significantly (p �0.001) by pesticide type, glove material type, cleanupmethod, and exposure time. Interaction effects between vari-ables were significant (p � 0.001) for pesticide and glovematerial, pesticide and exposure time, and glove materialand exposure time. The interaction effect between cleanupmethod and exposure time also was significant at the p �0.05 level. No significant difference was found for interac-tion effects between pesticide and cleanup method or be-tween glove material and cleanup method. After laundering,the terbufos residue found in glove materials was muchhigher than the tefluthrin residue under the same treatmentconditions.

Table 2. Scheffe test confirms significant mean differences attribut-able to predictor variables

MainEffect Level

Terbufos Tefluthrin

StatisticalGrouping

Mean*(ng/cm2)

StatisticalGrouping

Mean*(ng/cm2)

Glove Nitrile a 188.42 a 22.24BL** b 630.49 b 309.17Neoprene c 1,084.06 c 70.20

Time 3-min a 184.16 a 68.4130-min b 1,084.49 b 199.33

Cleanup Control a 719.25 a 210.13Flush ab 641.15 b 133.15LOM b 542.57 c 58.33

* Means with different letters are significantly different at p � 0.05.** BL � barrier laminate.

Table 1. Terbufos and tefluthrin residue (ng/cm2) in glove materials before and after cleanup

Terbufos Tefluthrin

Nitrile NeopreneBarrierLaminate Nitrile Neoprene

BarrierLaminate

3-min exposureControl* 79.79a 314.17a 348.23a 57.31a 89.98a 242.45a

(16.89) (37.69) (36.22) (17.84) (26.51) (24.11)Flush 27.19b 120.73b 244.90b 4.05b 19.75b 142.19b

(6.69) (57.72) (64.83) (1.09) (4.77) (18.91)LOM 30.10b 313.54a 178.75b 0.18b 6.46b 53.33c

(24.91) (70.29) (13.31) (0.05) (3.72) (10.05)30-min exposure

Control* 431.25a 2,000.20a 1,141.88a 63.82a 149.39a 657.81a

(162.63) (233.29) (123.11) (12.19) (99.16) (64.67)Flush 421.77a 1,890.90a 1,141.35a 7.90b 136.73a 488.28ab

(104.68) (672.00) (148.5) (1.08) (136.00) (36.41)LOM 140.42b 1,864.80a 727.81b 0.15b 18.91b 270.97b

(87.63) (265.44) (31.11) (0.03) (18.67) (5.94)

Means followed by a different letter within the same glove material and time treatments are significantly different at p � 0.05. The number inparentheses is the respective standard deviation.* Before laundering.

Gloves Contaminated with Terbufos and Tefluthrin 385

Discussion

Exposure Time

The length of exposure time, 3 or 30 min, affected whetherterbufos or tefluthrin residues could be removed effectivelyfrom glove specimens. In the case of the 3-min exposure withthe flush method, the pesticide had less time to diffuse into thematerial. It seemed the dry surface contamination was easilyrinsed off with the water of the flush method. However, withthe 30-min exposure, the pesticide had enough time to pene-trate into the glove material so that it was not as easily rinsedor washed away. This finding is consistent with those ofprevious research studies on cleanup of glove materials ex-posed to granular terbufos (Guo et al. 1997; Stone et al. 1997).Stone et al. (1997) found that with a 3 min exposure to granularterbufos by the glove-finger method, contamination of neo-prene and nitrile glove materials was reduced significantly bystirring the specimen in a beaker of warm water with detergent.This wash process did not significantly reduce contaminationafter 30-min of petri dish exposure. In another study, Guo et al.(1997) also found that after 230-min exposure neither stirringin a beaker, flush, nor their combination could reduce terbufosresidues effectively in nitrile specimens.

Glove Material

Neoprene had larger terbufos residues after cleanup than didnitrile and barrier laminates. The reason may be that although

the same amount of granular terbufos was applied to each ofthree glove materials, the neoprene material absorbed more ata faster rate because of its weaker chemical polarity comparedwith the other two glove materials.

Among the three glove materials, barrier laminate showedthe worst tefluthrin cleanup performance. The reason may bethat the barrier laminate materials have a strong chemicalpolarity, which makes them absorb more tefluthrin than theother two materials due to the attraction between barrier lam-inate materials and tefluthrin. Furthermore, hydrogen bondscan be formed between the O-H of the barrier laminate materialand the nitrogen, oxygen, or fluorine of the tefluthrin. Thisbond is not as strong as a regular covalent bond, but it is stillan important attraction. This obstructs the removal of tefluthrinresidues from barrier laminate materials by laundering. Inpractical terms, this poor cleanup performance underscores thefact that these materials are marketed as “disposable” or “sin-gle-use.”

Cleanup Method

Both flush and LOM methods significantly reduced terbufosand tefluthrin residues in glove specimens. There were manysimilarities between tefluthrin and terbufos in the effects ofcleanup methods on reduction of pesticide residues. However,there were some differences.

The LOM significantly reduced terbufos residues in nitrileand barrier laminate glove specimens no matter whether theexposure time was 3 min or 30 min. Compared with the flush,

Table 3. Factorial analysis of variance shows that exposure time, glove material, cleanup method, and interactions significantly affectterbufos residue

SourceDegrees ofFreedom

Sum ofSquares

MeanSquare F Value Pr � F

Glove 2 14,439,949 7,219,975 191.67 0.0001Method 2 564,424 282,212 7.49 0.0010Time 1 21,886,316 21,886,316 581.02 0.0001Measure 1 27,812 27,812 0.74 0.3925Glove * method 4 352,236 88,059 2.34 0.0613Glove * time 2 8,935,951 4,467,975 118.61 0.0001Method * time 2 387,186 193,593 5.14 0.0077Error 89 3,352,514 37,669Total 107 49,964,294

Table 4. Factorial analysis of variance shows that exposure time, glove material, cleanup method, and interactions significantly affecttefluthrin residue

SourceDegrees ofFreedom

Sum ofSquares

MeanSquare F Value Pr � F

Glove 2 1,700,885 850,442 415.86 0.0001Method 2 414,776 207,388 101.41 0.0001Time 1 462,758 462,758 226.29 0.0001Measure 1 338 338 0.17 0.6852Glove * method 4 179,986 44,997 22 0.0001Glove * time 2 531,631 265,816 129.98 0.0001Method * time 2 39,809 19,905 9.73 0.0002Error 89 182,006 2,045Total 107 3,549,289

386 C. Guo et al.

the LOM process provided more energy from mechanical ag-itation and two additional rinse cycles. However, in the LOMprocess, redeposition can occur with the pesticide on the out-side of the specimen floating in the water to contaminate theoriginally uncontaminated side. The LOM did not completelyremove terbufos from nitrile and barrier laminate glove spec-imens.

For tefluthrin, with the 3-min exposure time, either flush orLOM removed most of the contamination from nitrile andneoprene specimens; tefluthrin residues in nitrile specimensafter LOM wash were less than 1 ng/cm2. With a 30-minexposure time, the flush removed 88% of tefluthrin from thenitrile specimens; this suggests that most tefluthrin remained onthe surface of the nitrile material after the 30-min exposure.With the 30-min exposure time, the flush did not removetefluthrin effectively from neoprene materials, but the LOMwash significantly reduced the tefluthrin residues.

Pesticide Effect

Tefluthrin residues in glove materials were much lower thanterbufos after the flush or LOM wash. In other words, tefluthrinresidues could be removed from glove specimens more effec-tively by laundering treatments. Several researchers reportedthat the water solubility of pesticides might play a more im-portant role than chemical class in the effectiveness of pesticideremoval after laundering (Easley et al. 1983; Laughlin et al.1985). In this study, the water solubility of terbufos is 15 ppmand the water solubility of tefluthrin is 4 ppm. Therefore, thewater solubility of these pesticides was not a reason for thedifference between them in laundering effectiveness. Tefluthrinis a synthetic pyrethroid, whereas terbufos is an organophos-phate; they have different chemical structures. These findingsprovide evidence to support those of Keaschall et al. (1986)and the North Central Agricultural Experiment Stations (1988),who found that pesticide class, such as organochlorines, or-ganophosphates, and carbamates, was one of the factors affect-ing laundering effectiveness in reducing pesticide contamina-tion.

The results of this study suggest that chemical composition

of the pesticide affects laundering effectiveness, but the limitednumber of pesticides, materials, and cleanup methods studiedprevents making broad claims or strong conclusions. Furtherwork needs to be done to confirm these findings. Considerationof other classes of pesticide would help sort out the importanceof pesticide composition in relation to laundering effectiveness.

Considered from the practical standpoint, the results showthat barrier laminate, which is marketed as a single-use prod-uct, should indeed not be reused. The other materials wereshown to be protective, given the amount of pesticide applied,for up to 24 h in previous work (Guo et al. 2001), but since thatwould imply reuse over a period of days, the likelihood of theirbeing maintained free of inside contamination during repeateddonning and doffing might be questioned. The results ofcleanup methods used in this study show that contamination ofneoprene and nitrile gloves was not fully removed; if the gloveswere reused they would start out contaminated for their seconduse period.

Acknowledgments. This work was supported by the USDA NC-170Regional Research Project, the College of Veterinary Medicine, andUniversity Extension at Iowa State University. No criticism nor en-dorsement is implied for products mentioned or not mentioned. Journalpaper no. J-19137 of the Iowa Agriculture and Home EconomicsExperiment Station, Ames, Iowa. Project no. 2599.

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Table 5. Factorial analysis of variance shows that pesticide, exposure time, glove material, cleanup method, and interactions significantlyaffect pesticide residue

SourceDegrees ofFreedom

Sum of Squares(106)

Mean Square(106) F Value Pr � F

Pesticide 1 13,524,499 13,524,499 305.96 0.0001Glove 2 8,807,389 4,403,694 99.62 0.0001Method 2 972,089 486,044 11.00 0.0001Time 1 14,356,998 14,356,998 324.80 0.0001Measure 1 17,143 17,143 0.39 0.5342Pesticide * glove 2 7,333,445 3,666,723 82.95 0.0001Pesticide * method 2 7,112 3,556 0.08 0.9227Pesticide * time 1 7,992,075 7,992,075 180.80 0.0001Glove * method 4 378,104 94,526 2.14 0.0775Glove * time 2 4,698,107 2,349,053 53.14 0.0001Method * time 2 331,521 165,760 3.75 0.0252Error 195 8,619,601 44,203Total 215 67,038,082

Gloves Contaminated with Terbufos and Tefluthrin 387

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