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American Journal of Infection Control 40 (2012) 250-7

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American Journal of Infection Control

journal homepage: www.aj ic journal .org

American Journal of Infection Control

Major article

Dermal and pulmonary absorption of propan-1-ol and propan-2-ol fromhand rubs

Harald Below PhD a,*, Ivo Partecke MDb, Nils-Olaf Huebner MD a, Nora Bieber MD a, Thomas Nicolai a,Alexander Usche a, Ojan Assadian MD, DTMHa, Elke Below PhD c, Günter Kampf MD a,d,Wolfram Parzefall PhD e, Claus-Dieter Heidecke MD, PhD b, Dariusz Zuba PhD f, Vincent Bessonneau g,Thomas Kohlmann PhDh, Axel Kramer MD, PhD a

a Institute of Hygiene and Environmental Medicine, Ernst Moritz Arndt University, Greifswald, GermanybDepartment of Surgery, Clinic of General, Visceral, Vascular and Thoracic Surgery, Ernst Moritz Arndt University, Greifswald, Germanyc Institute of Forensic Science, Ernst Moritz Arndt University, Greifswald, GermanydBODE Chemie GmbH, Scientific Affairs, Hamburg, Germanye Institute of Cancer Research, Medical University of Vienna, Vienna, Austriaf Institute of Forensic Research, Krakow, Polandg Environmental and Health Research Laboratory, French School of Public Health, Rennes, Franceh Institute for Community Medicine, Ernst Moritz Arndt University, Greifswald, Germany

Key Words:AlcoholBlood levelMetabolitesHand hygieneRisk assessmentToxicology

* Address correspondence to Harald Below, PhD, Inronmental Medicine, Ernst Moritz Arndt University, W17489 Greifswald, Germany.

E-mail address: below@uni-greifswald.de (H. BeloI.P. and N.-O.H. contributed equally to this articleThis study was supported by grants from Antisept

Chemie, Hamburg, Germany; B. Braun Medical, SeDeutschland, Düsseldorf, Germany; Lysoform Dr. Hansand Schülke & Mayr, Norderstedt, Germany.

Conflict of interest: G.K. is a paid employeeGermany. The other authors have no conflicts of inter

0196-6553/$36.00 - Copyright � 2012 by the Associadoi:10.1016/j.ajic.2011.03.009

Background: It has been shown that nontoxic concentrations of ethanol are absorbed after hand hygieneusing ethanol-based hand rubs. This study investigated whether absorption of propan-1-ol and propan-2-ol from commercially available hand rubs results in measurable concentrations after use.Methods: The pulmonary and dermal absorption of propanol during hand rubs was investigated. Rubscontained 70% (w/w) propan-1-ol, 63.14% (w/w) propan-2-ol, or 45% (w/w) propan-2-ol in combinationwith 30% (w/w) propan-1-ol.Results: Peak median blood levels were 9.15 mg/L for propan-1-ol and 5.3 mg/L for propan-2-ol afterhygienic hand rubs and 18.0 mg/L and 10.0 mg/L, respectively, after surgical hand rubs. Under actualsurgical conditions, the highest median blood levels were 4.08 mg/L for propan-1-ol and 2.56 mg/L forpropan-2-ol. The same procedure performed with prevention of pulmonary exposure through the use ofa gas-tight mask resulted in peak median blood levels of 1.16 mg/L of propan-1-ol and 1.74 mg/L ofpropan-2-ol.Conclusion: Only minimal amounts of propanols are absorbed through the use of hand rubs. Based onour experimental data, the risk of chronic systemic toxic effects caused by hand rubs is likely negligible.However, our study did not evaluate the consequences of long-term daily and frequent use of hygienichand rubs.

Copyright � 2012 by the Association for Professionals in Infection Control and Epidemiology, Inc.Published by Elsevier Inc. All rights reserved.

stitute of Hygiene and Envi-alther Rathenau Strasse 49a,

w)..ica, Pulheim, Germany; Bodempach, Switzerland; EcolabRosemann, Berlin, Germany;

of Bode Chemie, Hamburg,est to disclose.

tion for Professionals in Infection

Given that hands are the primary vehicle for transmission ofmicrobial pathogens causing infections, hand hygiene is essentialfor infection control in any health care setting,1-10 as well as in thecommunity.11-13 Most alcohol-based hand rubs contain ethanol,propan-1-ol or propan-2-ol, or a combination of these alcohols.1,2,10

In previous studies of hand rubs with ethanol-based formulations,under extreme test conditions usually not encountered in thehealth care setting, 0.5%-2.3% of the applied ethanol was absorbed,resulting in blood levels of<30mg/L (0.023%). Although absorptionwas found, in practice the use of ethanol-based hand rubs isconsidered safe.14,15

Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

H. Below et al. / American Journal of Infection Control 40 (2012) 250-7 251

Comparable blood levels were found for propan-2-ol; in a studyusing a commercial hand rub applied every 10 minutes over a4-hour period, subjects’ blood levels of propan-2-ol ranged from0.5to 1.8 mg/L.16 Leeper et al17 reported that after extensive epidermalapplication of 273 g of propan-2-ol, only 0.9% was absorbed within10 hours. In contrast, Brown et al18 found negligible blood levels ofpropan-2-ol in subjects who applied a hygienic hand rub 30 timesin a 1-hour period. Propanol-2-ol also was not detec\table in thebreath of these subjects. However, the Brown et al study useda method that is approximately 30-fold less sensitive than themethod used in the study of Turner et al16 and in the present study.

The dermal and inhalation absorption of propan-2-ol is sup-ported by case reports on intoxication.19-22 After preoperative skinantisepsis in pediatric surgery, serum levels of up to 12.2 mg/L(mean, 5.0 � 3.37 mg/L) were documented by Wittmann et al.23

Compared with propan-2-ol, the data on absorption of propan-1-ol is even scantier. On isolated human epidermis, the followingconstants of permeability have been determined: 800 cm/hour forethanol, 1,200 cm/hour for propan-1-ol, and 1,350 cm/hour forpropan-2-ol.24,25 Peschel et al26 demonstrated that after modifiedsurgical hand rubs with propanol-containing products with andwithout the ingestion of alcoholic beverages, propan-2-ol andpropan-1-ol levels could disturb the analysis of congeners.Measured propan-1-ol levels were generally 0.2-1.8 mg/L, withlevels pf 8.8 mg/L and 14 mg/L measured in 2 subjects.

The aim of the present experimental study was to determine theabsorbed amounts of propan-2-ol and propan-1-ol from the use ofcommercially available hand rubs. The primary goal is to assess thetoxicological risk from the absorption data. We tested 3 hand rubscontaining propan-1-ol alone, propan-2-ol alone, and both incombination under the same worst-case conditions as in ourprevious study examining ethanol absorption,14 as well as underclinical conditions with and without pulmonary exposure.

METHODS

Study design and setting

All 3 experiments had a controlled blinded design and wereapproved by the Ethics Committee of the Board of Physicians ofMecklenburg-Pomerania, University of Greifswald (BB 07/09). Inexperiment 1, under a worst-case model of excessive hygienic orsurgical hand rubs, hand rub application was performed in a 37 m3

room with 2 open windows and an open door, without controlledair exchange during applications. Between hand rub applications,participants were placed in a second room in which the use ofalcohol-based hand rubs was not permitted. Blood samples werecollected in another separate room.

Experiment 2 involved surgical hand rubs, including a hygienichand rub on entering the surgical theatre. Absorption was deter-mined during the routine surgical program, which included 3interventions of approximately 90 minutes each. Blood sampleswere collected in the doctors’ lounge in the surgical suite.

Experiment 3 was performed in the same manner as in exper-iment 2, but pulmonary exposurewas prevented through the use ofa gas-tight mask (X-plore 4390 with A2 filter; Draeger, Lübeck,Germany) during hand rub application and while the surgeon wasin the wash room.

Participants

Twelve participants (6 males, 6 females) participated in exper-iment 1, 10 surgeons (6 males, 4 females) participated in experi-ment 2, and 10 participants (6 males, 4 females) participated inexperiment 3. For all experiments, inclusion criteria were age at

least 18 years and the ability to perform a standardized applicationaccording to European Standard EN 1500:1997.27 Exclusion criteriawere defined as visible skin lesions on hands or arms, skin disease,alimentary intake of ethanol, and use of cosmetics in any formwithin 24 hours before the start of a test and on the day of the test.Furthermore, individuals with diabetes mellitus, pregnant orlactating women, and individuals who participated in a clinicalexperiment within 30 days before the start of the study also wereexcluded. To exclude potential oral alcohol consumption byparticipants, we also determined the ethanol levels of all partici-pants during the 3 experiments. Written consent was obtainedfrom all participants.

Hand rubs

Three commercially available hand rubs were tested: hand rubP1 (Skinman Sensitive, 70% w/w propan-1-ol; Ecolab, Düsseldorf,Germany), hand rub P2 (Manorapid ready for use, 63.14% w/wpropan-2-ol; Antiseptica, Pulheim, Germany), and hand rub P1P2(Sterillium Classic Pure, 45% w/w propan-2-ol in combination with30% w/w propan-1-ol and 0.2% w/w mecetronium etilsulfate; BodeChemie, Hamburg, Germany). All hand rubs were applied in bothhygienic and surgical hand rubs. The hand rubs did not contain anyfragrance or dye but a mixture of skin care components.

Hand rub application

In experiment 1, both hygienic hand rubs and surgical hand rubswere performed with P1P2 and P2, because at the time that thisexperiment was conducted, a hand rub containing only propan-1-ol was not commercially available. Hands were washed withnonmedicated neutral soap and dried thoroughly immediatelybefore the start of the experiment. For each hygienic hand rub, 4mLof hand rub was applied in the test room to both hands and rubbedin for 30 seconds according to the standard rub-in proceduredescribed in EN 1500:1997.27 After waiting for 1 minute outside thetest room, this procedure was repeated. A total of 20 hygienic handrubs were performed, resulting in a total exposure time of 10minutes over a 30-minute period.

The surgical hand rub experiments were started 7 days after thehygienic hand rub experiments. Here, 4 mL of hand rubwas appliedto the hands and rubbed on the hands and forearms. This procedurewas repeated 5 times, with the hands and forearms kept coveredwith the hand rub for the recommended application time of 3minutes.28 After a 5-minute wait outside the test room, theprocedure was repeated. A total of 10 surgical hand rubs wereperformed, resulting in a total exposure time of 30 minutes over an80-minute period. For hygienic and surgical hand rubs, each handrubwas tested individually on one of 2 consecutive test days. At theend of each test day, a skin care cream (Neutrogena; Johnson &Johnson, Düsseldorf, Germany) was applied to the treated skinareas.

For experiments 2 and 3, when entering the surgical theater,a hygienic hand rub was performed. This hygienic hand rub wasperformed for 30 seconds with the same hand rub as used for thesurgical hand rub. Then, 10 minutes later, a surgical hand rub withan application time of 1.5 minutes was performed before each of 3consecutive 90-minute surgical interventions. The exact volume ofthe product applied for both the hygienic hand rub and the 3surgical hand rubs was noted and used to calculate the absorptionrate. After the hand rub application and air-drying, surgical glovesand gowns were donned.

H. Below et al. / American Journal of Infection Control 40 (2012) 250-7252

Blood sampling

In all experiments, skin antisepsis was performed with analcohol-free skin antiseptic (7.5% povidone-iodine solution, Brau-nol; B Braun, Melsungen, Germany) before blood sampling witha peripheral intravascular catheter (Inside-W, 18 GA; BD, Sandy,UT). Baseline samples were obtained before the first hand rub. Inexperiment 1, samples were obtained at 2.5, 5, 10, 20, 30, 60, and 90minutes after the last hygienic hand rub or at 5, 10, 20, 30, 60, 90,and 120 minutes after the last surgical hand rub. In experiments 2and 3, blood samples were collected before the hygienic hand ruband 3 times at 90-minute intervals (after each surgical procedure),as well as at 60 and 90 minutes after the third surgical procedure.Blood samples were stored at 4�C before analysis and wereanalyzed within 12 hours.

Chemical analysis

Chemical analysis was performed using gas chromatography ina modification of the method described by Roemhild et al,14,29

which uses head-space injection (CombiPal-Autosampler; CTCAnalytics, Zwingen, Switzerland) with flame-ionization detection(5890 series II gas chromatograph; Hewlett Packard, Waldbronn,Germany). In brief, 1 mL of sample or 1 mL of standard and 0.5 g ofanhydrous Na2SO4 were filled in 1.5-mL head space vials andincubated for 45 minutes at 75�C. Then 2.5 mL was injected (timeinterval, 0.5 minute). A DB 624 column (60 m � 0.32 mm � 1.8 mm;J&W Scientific, Folsom, CA) was used for separation. The chro-moatographic conditions were an injector temperature of 150�C,a detector temperature of 250�C, a column temperature program of40�C for 8 minutes, followed by a ramp of 3�C/minute to 120�C (0minutes) and then 30�C/minute to 230�C (5 minutes). Nitrogen(5.0) served as the carrier gas at a rate of 1.45 mL/minute (21.9 cm/s).For each measurement, calibration was performed according to themethod of the external standard with 3 calibration points (Medi-drug BGS-S, levels 1-3; Medichem, Steinenbronn, Germany) andcustom-made standards in water. The latter were used for controlstandards and propionaldehyde, which is not included in thecommercially available standards. This calibration standard wasproduced based on the weight of the original contents of thesubstances followed by dilution to the calibration level. Themethod’s detection limits were 0.13 mg/L for propan-1-ol, 0.03 mg/Lfor propan-2-ol, 0.14 mg/L for ethanol, 0.01 mg/L for acetone, and0.02 mg/L for propionaldehyde.

For all measurements, quality controls were performed usingcertified reference material (Medidrug BGS 2/05 S-Plus; Medi-chem). Parallel selected samples were analyzed in the chemicallaboratory of the Institute of Forensic Medicine, University ofGreifswald.

Data calculation and statistical analysis

Blood concentrations are expressed as median and 25% and 75%percentiles. Concentrations below the detection limit were set to 0.The amount of absorbed alcohol was calculated separately for eachparticipant based on the method of Wittmann et al.14,23 In brief, themedian amount absorbed is the product of the maximum bloodlevel, body weight, and a sex-dependent factor (0.6 for women; 0.7for men). The proportion of absorbed alcohol was calculated fromthe amount of alcohol initially applied and the percentage of thatamount absorbed. P values were calculated for differences in bloodconcentrations in each experiment using Wilcoxon’s rank-sum testand for differences between experiments 2 and 3 using the Mann-Whitney U test for unpaired samples. All analyses were done usingSPSS version 11.5.1 (SPSS, Munich, Germany).

RESULTS

Quality control

The results of the certified reference material analysis (n ¼ 9;propanols and acetone) and the comparison of the results ofparallel samples analyzed by the chemical laboratory at the Insti-tute of Forensic Medicine were within the limits of analyticaldeviation and fulfilled the requirements of an interlaboratory test.

Baseline blood concentrations

For each parameter, a total of 107 baseline values were deter-mined during the 3 experiments. For propan-1-ol, 91 of 107samples (85 %) were below the detection limit (median and 25thand 75th percentiles, <0.13 mg/L). For propan-2-ol 6, 7 of 107samples (62.6%) were below the detection limit (median and 25thpercentile, <0.03 mg/L; 75th percentile, 0.16 mg/L). For propio-naldehyde, 80 samples (74.8%) had concentrations below thedetection limit (median, 0.03 mg/L; 25th percentile, <0.02 mg/L;75th percentile, 0.07 mg/L). Acetone was detectable in all 107samples (median, 2.10 mg/L; 25th percentile, 1.57 mg/L; 75thpercentile, 3.08 mg/L). The ethanol baseline values were below thedetection limit in most cases (n ¼ 86; 80.4%), or at most 0.55 mg/L.

Blood levels and absorbed propanols and metabolites inexperiment 1

In the worst-case model, the calculated applied amounts forhygienic hand rubs were 44.25 g of propan-2-ol for P2, 30.64 g ofpropan-2-ol for P1P2, and 20.42 g of propan-1-ol for P1P2. Expo-sures for surgical hand rubs were 110.62 g of propan-2-ol for P2,76.6 g of propan-2-ol for P1P2, and 51.05 g of propan-1-ol for P1P2(Table 1).

In experiment 1, after the hygienic hand rubs, the highestmedian concentrations of propan-2-ol was 5.3 mg/L (0.0042%) withP2 and 4.9 mg/L (0.0038%) with P1P2, and the highest medianconcentrations of propan-1-ol was 9.15 mg/L (0.0088%) with P1P2.Propan-1-ol reached its highest median concentration at 30minutes after the last application (P1P2), and propan-2-ol reachedits highest median concentration at 60 min after the last applica-tion (P2 and P1P2) (Table 1). In the worst-case model, the medianblood concentrations after surgical hand rubs were higher: 5.8 mg/L (0.0046%) with P2 and 10.0 mg/L (0.0079%) with P1P2 for propan-2-ol (Table 3), and 18 mg/L (0.0173%) for propan1-ol with P1P2.Propan-1-ol reached its highest median concentration after 30minutes (P1P2), and propan-2-ol did so after 30 minutes with P1P2and after 60 minutes with P2 (Table 1).

The median amounts of absorbed propan-2-ol were 310 mg(0.7%) with P2 and 310 mg (1.0%) with P1P2; the median amount ofabsorbed propan-1-ol was 600 mg (2.9%) with P1P2 (hygienic handrub). For the surgical hand rubs, the median amount of absorbedpropan-2-ol was 472 mg (0.4%) with P2 and 569 mg (0.7%) withP1P2, and that of absorbed propan-1-ol was 918 mg (1.8%) withP1P2 (Table 1).

Acetone, the main metabolite of propan-2-ol, reached itsmaximum concentration at 60 minutes after the last application,6.2 mg/L for P2 and 4.5 mg/L for P1P2 (hygienic hand rub). After thesurgical hand rubs, the maximal median concentrations were 5.4mg/L for P2 and 4.95 mg/L for P1P2, at 60 minutes and 90 minutes,respectively, after the last application (Table 3).

Independent of the type of hand rub used, the concentration ofpropionaldehyde as a metabolite of propan-1-ol did not changesignificantly (Table 1).

Table 2Applied and median absorbed amounts and proportion of propanols after surgical hand rub with P1, P2 and P1P2 in experiment 2 (dermal and pulmonary absorption) andexperiment 3 (dermal absorption only)

Hand rub Substance Absorption Amount applied, g

Amount absorbed, mg (% of absorbed alcohol)

Median, mg 25th percentile, mg 75th percentile, mg

P1 Propan-1-ol Dermal and pulmonary 20.1 271 (1.3) 125 (0.6) 492 (2.4)Dermal only 20.1 109 (0.5) 55.2 (0.3) 174 (0.9)

P2 Propan-2-ol Dermal and pulmonary 18.25 92.7 (0.5) 72.4 (0.4) 156 (0.9)Dermal only 18.25 151 (0.8) 87.4 (0.5) 177 (1.0)

P1P2 Propan-1-ol Dermal and pulmonary 8.43 124 (1.5) 67.1 (0.8) 182 (2.2)Propan-2-ol 12.64 137 (1.1) 87.4 (0.7) 181 (1.4)Propan-1-ol Dermal only 8.43 97.6 (1.2) 45.3 (0.5) 124 (1.5)Propan-2-ol 12.64 129 (1.0) 64.1 (0.5) 159 (1.3)

Table 1Median maximum blood concentrations of propanols and their metabolites, applied and median absorbed amounts, and proportion of propanols after 20 hygienic or 10surgical hand rubs with formulation P2 or P1P2 from 12 participants in the worst-case model (experiment 1)

ExperimentHandrub Substance

Median maximum blood concentration

Amountapplied, g

Amount absorbed, mg (% of absorbed alcohol)

Time after exposure,minutes

Median (25th; 75th percentiles),mg/L P Median

25thpercentile

75thpercentile

1, HHR P2 Propan-2-ol 60 5.3 (3.2; 10.5) .001 44.25 310 (0.7) 225 (0.5) 416 (0.9)Acetone 60 6.2 (3.5; 11.9) .007

P1P2 Propan-1-ol 30 9.15 (4.87; 13.1) .001 20.42 600 (2.9) 410 (12.0) 1,043 (5.1)Propan-2-ol 60 4.9 (3.1; 6.6) <.001 30.64 310 (1.0) 229 (0.7) 479 (1.6)Acetone 60 4.5 (2.5; 5.6) <.001Propionaldehyde 10 0.15 (0.1; 0.3) .002

1, SHR P2 Propan-2-ol 60 5.8 (3.27; 7.47) .001 110.62 472 (0.4) 321 (0.3) 575 (0.5)Acetone 60 5.4 (4.17; 7.02) .002

P1P2 Propan-1-ol 30 18.0 (10.55; 25.1) <.001 51.05 918 (1.8) 703 (1.4) 1,220 (2.4)Propan-2-ol 30 10.0 (5,85; 12.9) <.001 76.6 569 (0.7) 364 (0.5) 746 (1.0)Acetone 90 4.95 (3.02; 6.1) <.001Propionaldehyde 60 0.2 (0.1; 0.2) .016

HHR, hygienic hand rub; SHR, surgical hand rub.

H. Below et al. / American Journal of Infection Control 40 (2012) 250-7 253

Blood levels and absorbed propanols and metabolites in experiments2 and 3

During the 1 hygienic hand rub and the 3 subsequent surgicalhand rubs, surgeons were exposed to a mean total of 33 mL of handrub, corresponding to a mean total propan-2-ol exposure of 18.25 gfor P2 and 12.64 g for P1P2 and a mean propan-1-ol exposure of20.1 g for P1 and 8.43 g for P1P2 (Table 2).

In experiment 2, the highest median blood level of propan-1-olwas 4.08 mg/L (0.0039%; P1), and that of propan-2-ol was 2.56 mg/L(0.0025%; P1P2) (Table 3). Excluding pulmonary adsorption inexperiment 3 resulted in lower median concentrations than wererecorded in experiment 2, with 1.16mg/L propan-1-ol (0.0011%; P1)and 1.74 mg/L propan-2-ol (0.0017%; P2) (Table 3).

In experiment 2, the highest median absorbed amounts ofpropan-1-ol and propan-2-ol were 271 mg (1.3%; P1) and 92.7 mg(0.5%; P2), respectively (Table 2). The combination of propanols(P1P2) influenced absorption; thus, we found 124 mg (1.5%)propan-1-ol and 137 mg (1.1%) propan-2-ol. In experiment 3, thehighest median absorbed amounts of propan-1-ol and propan-2-olwere 109 mg (0.5%) for P1, 151 mg (0.8%) for P2, and 97.6 mg (1.2%)and 129 mg (1.0%), respectively, for P1P2. The decline in theabsorbed amount of propan-1-ol (from 271 mg to 109 mg) issignificant (P¼ .023), whereas the increase in the absorbed amountof propan-2-ol (from 92.7 mg to 151 mg) is salient but not signifi-cant (Table 2).

The relative absorbed amount of propan-1-ol (1.2%-2.9%) wasapproximately 3 times higher than that of propan-2-ol (0.4%-1.1%).Absorption of propan-2-ol was approximately twice as high afterapplication of the mixture of the 2 propanols as after application ofpropan-2-ol alone (Tables 1 and 2).

The differences in acetone levels between experiment 2 andexperiment 3 are noteworthy. In experiment 2, there wasa significant increase in the blood concentration of acetone,with a maximum of 10.22 mg/L; in contrast, these were nosignificant changes in acetone blood levels in experiment 3(Table 3). In experiments 2 and 3, blood levels of propionalde-hyde did not increase significantly from baseline values (datanot shown).

DISCUSSION

The literature contains little information on absorption ofpropanols after application of hand rubs. In contrast to someauthors who found certain levels of absorption,16,26,30 othersdetected no propanol in the blood after application of handrubs16,18 or skin disinfection.15 Consequently, we opted toperform a 2-step experiment. The first step was a worst-casemodel to clarify whether any absorption occurred, and if so, towhat extent (experiment 1). In the second step, absorption wasdetermined under clinically relevant conditions (experiment 2),and also excluding the possibility of pulmonary absorption(experiment 3). For this purpose, we used a highly sensitiveanalytical method.14,29

The criteria for selecting the hand rubs used were commercialavailability, a pure formulation of propan-1-ol or propan-2-ol,and of the combination of the 2 propanols. Only one hand rubcontaining propan-1-ol was commercially available. To select thepure propan-2-ol and the combined product, we compiled a listof the 10 most-used hand rubs in Germany and chose 2 bylottery.

Table 3Experiments 2 and 3 (dermal and pulmonary absorption vs dermal absorption only), median blood concentrations (mg/L) of propanols and acetone before and after surgical hand rubs with P1, P2, and P1P2

Hand rub Substance Absorption Before first application

After application

First OP Second OP Third OP 60 minutes after last OP 90 minutes after last OP

P1 Propan-1-ol Dermal and pulmonary <0.13 (<0.13)* 2.77 (1.90-3.62) 4.08 (1.50-6.75) 3.25 (0.59-7.47) 0.95 (0.73-1.89) 0.54 (0.32-1.20)P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .007 P ¼ .017

Dermal only <0.13 (<0.13-0.00)* 0.86 (0.54-1.21) 0.85 (0.51-2.17) 1.16 (0.38-2.39) 0.64 (0.15-1.03) <0.13 (<0.13-0.24)P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .012 P ¼ .068

Propan-2-ol Dermal and pulmonary 0.21 (0.13-0.23) 0.60 (0.45-0.82) 0.90 (0.58-0.99) 0.55 (0.44-1.24) 0.46 (0.33-0.54) 0.36 (0.24-0.48)P ¼ .005 P ¼ .008 P ¼ .005 P ¼ .005 P ¼ .037

Dermal only <0.03 (<0.03-0.07) 0.06 (<0.03-0.07) 0.06 (<0.03-0.07) 0.07 (<0.03-0.14) 0.06 (<0.03-0.07) 0.06 (<0.03-0.11)P ¼ .686 P ¼ .752 P ¼ .183 P ¼ .344 P ¼ .482

Acetone Dermal and pulmonary 1.85 (1.69-3.60) 4.21 (3.29-5.44) 6.34 (4.60-8.88) 9.15 (5.64-12.78) 8.21 (4.12-16.96) 6.98 (4.70-13.51)P ¼ .074 P ¼ .007 P ¼ .008 P ¼ .005 P ¼ .005

Dermal only 2.32 (1.87-3.09) 2.03 (1.54-2.54) 1.99 (1.58-2.54) 2.21 (1.71-2.73) 2.13 (1.78-2.79) 1.98 (1.48-2.25)P ¼ .333 P ¼ .333 P ¼ .646 P ¼ .575 P ¼ .333

P2 Propan-1-ol Dermal and pulmonary <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13)Dermal only <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13) <0.13 (<0.13)

Propan-2-ol Dermal and pulmonary 0.13 (0.06-0.24) 0.92 (0.68-1.43) 1.50 (0.87-1.86) 1.70 (1.16-2.22) 1.00 (0.74-1.58) 0.85 (0.50-1.10)P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005

Dermal only 0.06 (<0.03-0.07) 0.85 (0.36-1.25) 1.54 (0.87-2.66) 0.95 (0.57-1.69) 1.74 (1.38-2.73) 1.35 (0.54-2.36)P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005

Acetone Dermal and pulmonary 2.15 (1.49-2.51) 4.08 (3.36-5.91) 6.72 (5.07-7.93) 9.02 (6.74-10.42) 8.25 (6.38-9.59) 7.93 (5.22-10.07)P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005

Dermal only 2.90 (2.38-3.63) 2.40 (1.96-2.93) 3.62 (2.26-4.62) 4.16 (2.91-5.54) 4.10 (2.58-5.29) 4.43 (2.68-5.40)P ¼ .017 P ¼ .386 P ¼ .053 P ¼ .059 P ¼ .114

P1P2 Propan-1-ol Dermal and pulmonary <0.13 (<0.13-0.15) 2.14 (1.18-3.00) 1.21 (0.72-3.28) 0.51 (0.3-2.07) 0.3 (0.17-0.87) 0.43 (0.25-0.87)P ¼ .005 P ¼ .007 P ¼ .059 P ¼ .441 P ¼ .515

Dermal only <0.13 (<0.13) 0.53 (0.27-0.94) 0.50 (0.18-2.20) 0.68 (0.29-1.66) 0.18 (<0.13-0.56) 0.08 (<0.13-0.27)P ¼ .008 P ¼ .012 P ¼ .012 P¼0.028 P ¼ .042

Propan-2-ol Dermal and pulmonary 0.22 (0.04-0.399) 2.56 (1.29-3.02) 1.96 (1.26-3.09) 1.39 (0.91-2.29) 0.82 (0.68-1.66) 1.36 (0.96-1.63)P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .008 P ¼ .005

Dermal only <0.03 (<0.03-0.06) 0.64 (0.49-1.22) 0.89 (0.63-1.90) 1.24 (0.50-2.20) 0.70 (0.43-1.20) 0.61 (0.39-1.19)P ¼ .007 P ¼ .005 P ¼ .013 P ¼ .007 P ¼ .012

Acetone Dermal and pulmonary 2.51 (1.70-3.59) 6.42 (3.80-7.82) 8.54 (5.94-12.09) 8.14 (6.56-11.69) 8.81 (7.03-10.50) 10.22 (6.80-11.93)P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005 P ¼ .005

Dermal only 2.40 (1.75-2.68) 2.34 (1.79-2.68) 3.06 (2.18-3.66) 4.17 (3.18-5.59) 4.45 (3.01-6.43) 3.96 (3.33-4.12)P ¼ .959 P ¼ .333 P ¼ .028 P ¼ .022 P ¼ .017

*The values are median alcohol concentration (25th and 75th percentiles) from 10 participants (total exposure to 33 mL; total contact time, 5 minutes).

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Baseline values

The ethanol baseline values indicate that the participantsabstained from ethanol before and during our experiments. Theproportion of propan-1-ol values below the limit of detection is inline with reports in the literature and suggests a physiological,endogenous low-level blood concentration. Small amounts ofpropan-1-ol in the blood could not be explained by intake ofalcoholic beverages.31 A strong indication that propan-1-ol may beformed under physiological conditions is the finding that afterparticipants drank propan-1-ol-free alcoholic beverages, theirpropan-1-ol levels rose to detectable levels (up to 0.2 mg/L).26,31

Because ADH preferentially metabolizes ethanol, the metabolismof propan-1-ol is competitively inhibited by ethanol, which mayresult in an increase of measurable concentrations of propan-1-ol.Themain reason that propan-1-ol is not recognized as physiologicalis likely its detection limit, which is 5-fold higher than that ofpropan-2-ol (0.13 mg/L vs 0.03 mg/L).

Endogenous propan-2-ol blood levels reported in the literaturevary greatly, ranging from 0.01 to 10 mg/L.23,31,32 Our results are inthe lower range of this range (<0.03-0.25 mg/L; <0.000024%-0.0002%). A possible reason for the presence of physiologicalpropan-2-ol could be the reduction of acetone in certain metabolicsituations, such as hunger and illness.32,33

Zuba et al34 reported that acetone, acetaldehyde, methanol,propan-2-ol, and propan-1-ol are commonly found in the blood ofalcoholic patients. The origin of these substances is related mainlyto their presence in alcoholic beverages as impurities (congeners),which lead to steady-state concentrations after prolongedconsumption and ultimately to metabolic changes in the body. Thepeak concentration of propan-2-ol was 75.6 mg/L, and that ofpropan-1-ol was 13.5 mg/L.34

Relationship between applied and absorbed amounts

We found a clear, direct correlation between the amountsapplied and the amounts absorbed (Tables 1 and 2). In all 3experiments, systemic uptake was seen, with the greatest absorp-tion occurring in the worst-case model. In experiment 1, theincrease in concentrations of propanols and their metabolites wassignificant at all time points studied. In experiments 2 and 3,dermal absorption also was significant at most time points, but wasmarkedly lower than that seen in experiment 1 (Tables 1-3).

The proportion of median absorbed propanols ranged from 0.4%to 2.9% (mean, 1.1%). The use of P1P2 was apparently associatedwith a slightly increased relative absorption rate.

Risk assessment of absorbed amounts

Propan-1-olDuring clinical exposure, both propanols were absorbed in

measurable concentrations. The median absorbed amount ofpropan-1-ol was 271mg (Table 2). The highest median propan-1-olconcentration was 4.08 mg/L (experiment 2; Table 3). Blood levelsafter rubs with P1 reached about half the values attained afterdrinking alcoholic beverages containing propan-1-ol.34

In contrast to propan-2-ol, propan-1-ol is not fully accepted asa physiological compound. However, certain foods and beveragescontain detectable amounts of propan-1-ol, for example, 6-73 mg/Lin beer, 3-8 mg/L in malt beer, 12-68 mg/L in wine, 5-217 mg/L infruit wine, and 94-5,773 mg/L in fruit brandy.35 The amountabsorbed depends on the kind of beverage consumed. Althoughpropan-1-ol is not usually detected in vodka and other distilledspirits, subjects have measurable concentrations after drinkingthese beverages.31 Typical serum propan-1-ol concentrations after

bolus intake (over 1-1.5 hours) with resulting blood ethanol levelsof approximately 1.0%-1.3% were up to 0.05 mg/L for vodka, 0.30mg/L for beer, 0.20 for wines, 0.40 for brandy, and 2.5 mg/L for fruitbrandy.36 Because we found higher blood levels of propan-1-olafter hand rubs compared with levels reported after drinkingalcoholic beverages, the risk of toxicity must be carefully consid-ered. However, although data on the high dose range for propan-1-ol toxicity have been reported,37 such data are lacking on the lowdose range (see below), which is of interest here. Our data fromexperiments 2 and 3 show no significant increase in concentrationsof propionaldehyde, the main metabolite of propan-1-ol; in no casedid the blood propionaldehyde level exceed 0.1 mg/L. Thus, weconclude that propan-1-ol toxicity due to the metabolite propio-naldehyde is highly unlikely.

As a consequence of the European Union assessment, it isnecessary to limit propan-1-ol; in scenarios with short-term andrepeated exposures,38 exposure should be reduced. In the case ofhand rubs, this can be achieved only by decreasing inhalationexposure, that is, by increasing room ventilation.

Propan-2-olThe median absorbed amount of propan-2-ol during clinical

exposure was 137 mg (experiment 2; Table 2) at a concentration of2.56 mg/L (Table 3). In contrast to propan-1-ol, an acceptable dailyintake of 2.4 mg/kg (144 mg/60 kg) has been determined forpropan-2-ol.39 However, the risk of hand rubs should not be eval-uated based on an acceptable daily intake, which expresses thelimit for life-long intake via food and includes a safety factor of atleast 100. Hand rubs are applied mainly by health care profes-sionals, and the possible health risk depends on the actual expo-sure. Under our exaggerated experimental conditions, it is possiblethat the acceptable daily intake of propan-2-ol could be reached.This indicates that the safety factor of 100 may be somewhatuncertain, but does not imply a significant toxic risk.

When used in combination with ethanol drinking, propan-2-oland propan-1-ol have similar elimination rate constants (0.14 �0.07 g kg�1h�1 vs 0.14� 0.12 g kg�1h�1). Their elimination rate is inthe same range as that of ethanol in social drinkers (0.15 g/kg/h).They both have a high biological half-life, 5.1 � 4.3 hours forpropan-1-ol and 4.8 � 2.4 hours for propan-2-ol.34

Previous case reports on acute intoxication suggest that propan-2-ol blood levels<50mg/L are harmless. Only levels>500mg/L areassociatedwithmild intoxication. Patientswith a blood level�1,500mg/L are deeply comatose.19-22,40 In 2 reported cases of oral intoxi-cationwith propan-2-ol, blood levels reached 3,150 mg/L and 4,200mg/L,whichwouldbe lethalwithout intensivemedical care.41 Thesedata aredifficult to comparewith low-level chronic exposure suchasoccurs from the use of hand rubs, and it is not possible to reliablydetermine a threshold for toxic effects after chronic exposure.

The German MAK (threshold limit value) Commission has seta propan-2-ol inhalation exposure limit of 200 ppm (500mg/m3) inthe workplace; in the United States, theOccupational Safety andHealth Administrationhas set this limit at 400 ppm.42 Applicationof 10 mL of hand rub (8 g) could achieve this value temporarily ina 20-m3 room without ventilation. Thus, potential health risks bypulmonary absorption should be minimized by appropriateventilation.

Metabolic aspects

For propan-1-ol, we found a low but statistically significantincrease in the main metabolite, propionaldehyde, only in theworst-case model. Surprisingly, we found increased propan-2-ollevels after application of P1, which contains only propan-1-ol(experiment 2; Table 3). In experiment 2, participants had the

H. Below et al. / American Journal of Infection Control 40 (2012) 250-7256

greatest increase in acetone levels of any experiments. The partic-ipants did not eat during the experiment, and abstinence increasedtheir acetone blood levels. In experiment 3, during which theparticipants were permitted to eat between the surgical proce-dures, acetone levels increased only moderately, and, accordingly,no propan-2-ol was detected (Table 3).

Propan-2-ol is oxidized to acetone, which is subsequentlydegraded to acetate and formiate.43 Acetone is a physiologicalmetabolite generated during ketogenesis from fatty acid break-down44; as such, acetone was detectable at baseline levels (0.8-5.9mg/L) on all experimental days. The great variations observedcorrespond with levels reported in the literature ranging from 0.01mg/L to 10 mg/L.23,31,45 Elevated urinary acetone is a possiblemarker of exposure to propan-2-ol. Conversely, propan-2-ol may beproduced from acetone by reductive metabolism in the presence ofsufficient nicotinamide adenine dinucleotide and nicotinamideadenine dinucleotide phosphate.46 Thus, elevated levels of acetonemay lead to an increase in propan-2-ol blood concentration.31,43

This metabolic pathway may explain the appearance of propan-2-ol in our participants after application of P1 alone. Some authorshave suggested that both propan-2-ol and acetone should beconsidered when evaluating physical stress.47 The “endogenous”level of propan-2-ol depends mainly on diet and disease states. Thepropan-2-ol level is elevated in alcoholics, but this may bea consequence of the “special” diet (ie, starvation, low-calorie food),not alcohol per se, during prolonged consumption of alcoholicbeverages, resulting in metabolic disturbances. In addition, thelarge excess of nicotinamide adenine dinucleotide phosphate favorsreduction processes.

Dermal absorption without inhalation exposure

During routine hand rub application, it is practically impossibleto avoid inhalation exposure. Until now, the proportion of inhala-tion absorption was generally unknown. By preventing pulmonaryabsorption, the absorbed amount of propan-1-ol was significantlylower than the combined dermal and pulmonary absorption (109mg vs 271 mg; P ¼ .023) (Table 2). After eliminating one value froma participant with inexplicably high absorption, the differenceremained (P ¼ .041).

This tendency was not seen with propan-2-ol. Application ofP1P2 resulted in no significant change in the absorption of eitherpropan-2-ol or propan-ol-1. Here and with application of P2 alone,the differences were not significant. Our results support thesuspicion that propan-2-ol is dermally absorbed to a greater extentthan propan-1-ol, which might be attributed to the higher dermalpermeability coefficient of propan-2-ol (1,350 cm/hour vs 1,200cm/hour).24,25 Unlike propan-2-ol, a large proportion of propan-1-ol is absorbed through the lungs, although propan-2-ol has slightlyhigher volatility (8 10�6 atm.m3/mol at 25�C vs 7.4 10�6 atm.m3/mol at 25�C). Propan-1-ol from P1P2 is apparently absorbed pref-erably via dermal contact. This observationmay be explained by thelower volatility of P1P2 due to the mixture of 45% propan-2-ol and30% propan-1-ol, compared with P1 which is 70% propan-1-ol. Inaddition, the high proportion of propan-2-ol could increase thedermal absorption of propan-1-ol. We found no uniform tendencyof absorption in experiments 2 and 3, possibly due to differences inskin integrity (eg, microlesions). The small sample size (n ¼ 10)makes it difficult to draw conclusions regarding the predominantexposure pathway. In addition, individual genetic variability inmetabolic enzymes might play a role in determining the internaldose of alcohols, although investigating this was beyond the scopeof this study.

Compared with propanolols, ethanol has lower dermal absorp-tion24,25 and less toxicity, and it is more easily metabolized by ADH.

Thus, ethanol-based preparations may be preferable in wards witha high frequency of hygienic hand rub use. Yet the differing dermalabsorption and metabolization of alcohols is certainly not the onlyrelevant factor in product selection in wards with a high frequencyof hand rub use. The spectrum of antimicrobial activity, efficacy,dermal tolerance, and possible impact on compliance in handhygiene also should be taken into account. Irrespective of the typeof alcohol in a hand rub, it seems advisable to increase air exchangein the room to prevent unnecessary pulmonary absorption.

This study has several limitations. The number of participantswas relatively low. Dermal absorption is influenced by the integrityof the skin (undetectable microlesions) and may vary among theparticipants and also on different days, implying that small differ-ences between pulmonary and dermal absorption are difficult torecognize. The chosen exposure was a 1-day application, whichrepresents a common frequency of hand rubs in a surgical theater.We did not evaluate the consequences of daily chronic and frequenthygienic hand rubs. We also did not assess the risks to health careworkers who are metabolically deficient in aldehyde dehydroge-nase, a condition that could present an increased risk of toxicity.

In conclusion, in the present study, propanols were absorbed atsuch low levels that no acute toxic symptoms could be observedand were not expected to arise in our participants. The studyrevealed that on average, only 0.4%-2.9% of the administeredamounts of propanols were absorbed; these substances weremetabolized quickly, and their concentrations rapidly decreased tophysiological levels. They were rapidly eliminated after the end ofexposure and did not accumulate, as also demonstrated by thenonaccumulation of propionaldehyde or acetone in experiments 2and 3. Because long-term exposure to propanols through theapplication of hand rubs has yet to be investigated, and given thelack of toxicologic data, further studies are needed. In cases ofalcohol dehydrogenase and/or aldehyde dehydrogenase malfunc-tion, a different risk assessment should be conducted.

References

1. Boyce JM, Pittet D. Guideline for hand hygiene in health-care settings:recommendations of the Healthcare Infection Control Practices AdvisoryCommittee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. InfectControl Hosp Epidemiol 2002;23(12 Suppl):S3-40.

2. Kampf G, Kramer A. Epidemiologic background of hand hygiene and evaluationof the most important agents for scrubs and rubs. Clin Microbiol Rev 2004;17:863-93.

3. Rotter M. Handwashing and hand disinfection. In: Mayhall CG, editor. Hospitalepidemiology and infection control. Philadelphia: Lippincott Williams & Wil-kins; 2002. p. 1727-46.

4. Hilburn J, Hammond BS, Fendler EJ, Groziak PA. Use of alcohol hand sanitizer asan infection control strategy in an acute care facility. Am J Infect Control 2003;31:109-16.

5. Larson E. A causal link between handwashing and risk of infection?Examination of the evidence. Infect Control 1988;9:28-36.

6. Larson E. Skin hygiene and infection prevention: more of the same or differentapproaches? Clin Infect Dis 1999;29:1287-94.

7. Pittet D, Hugonnet S, Harbarth S, Mourouga P, Sauvan V, Touveneau S, et al.Effectiveness of a hospital-wide programme to improve compliance with handhygiene. Lancet 2000;356:1307-12.

8. Sandora TJ, Taveras EM, Shih MC, Resnick EA, Lee GM, Ross-Degnan D, et al.Randomized, controlled trial of a multifaceted intervention including alcohol-based hand sanitizer and hand-hygiene education to reduce illness trans-mission in the home. Pediatrics 2005;116:587-94.

9. World Health Organization. WHO guidelines on hand hygiene in health care.Geneva [Switzerland]: World Health Organization; 2009. p. 270.

10. Widmer AF, Rotter M, Voss A, Nthumba P, Allegranzi B, Boyce J, et al. Surgicalhand preparation: state of the art. J Hosp Infect 2010;74:112-22.

11. Hammond B, Ali Y, Fendler E, Dolan M, Donovan S. Effect of hand sanitizer useon elementary school absenteeism. Am J Infect Control 2000;28:340-6.

12. Van Camp RO, Ortega HJ. Hand sanitizer and rates of acute illness in militaryaviation personnel. Aviat Space Environ Med 2007;78:140-2.

13. White C, Kolble R, Carlson R, Lipson N. The impact of a health campaign onhand hygiene and upper respiratory illness among college students living inresidence halls. J Am Coll Health 2005;53:175-81.

H. Below et al. / American Journal of Infection Control 40 (2012) 250-7 257

14. Kramer A, Below H, Bieber N, Kampf G, Toma CD, Hübner NO, et al. Quantity ofethanol absorption after excessive hand disinfection using three commerciallyavailable hand rubs is minimal and below toxic levels for humans. BMC InfectDis 2007;7:117-29.

15. Kirschner MH, Lang RA, Breuer B, Breuer M, Gronover CS, Zwingers T, et al.Transdermal resorption of an ethanol- and 2-propanol-containing skin disin-fectant. Langenbecks Arch Surg 2009;394:151-7.

16. Turner P, Saeed B, Kelsey MC. Dermal absorption of isopropyl alcohol froma commercial hand rub: implications for its use in hand decontamination.J Hosp Infect 2004;56:287-90.

17. Leeper SC, Almatari AL, Ingram JD, Ferslew KE. Topical absorption of isopropylalcohol-induced cardiac and neurologic deficits in an adult female with intactskin. Vet Hum Toxicol 2000;42:15-7.

18. Brown TL, Gamon S, Tester P, Martin R, Hosking K, Bowkett GC, et al. Canalcohol-based hand-rub solutions cause you to lose your driver’s license?Comparative cutaneous absorption of various alcohols. Antimicrobial AgentsChemother 2007;51:1107-8.

19. McFadden SW, Haddow JE. Coma produced by topical application of iso-propanol. Pediatrics 1969;43:622-3.

20. Dyer S, Mycyk MB, Ahrens WR, Zell-Kanter M. Hemorrhagic gastritis fromtopical isopropanol exposure. Ann Pharmacother 2002;36:1733-5.

21. Garrison RF. Acute poisoning from use of isopropyl alcohol in tepid sponging.JAMA 1953;152:317-8.

22. Senz EH, Goldfarb DL. Coma in a child following use of isopropyl alcohol insponging. J Pediatr 1958;53:322-3.

23. Wittmann S, Gilg T, Dietz H-G, Grantzow R, Peschel O, Meyer L. Isopropanoland acetone serum levels after presurgical disinfection with isopropanol-containing antiseptics. Blutalkohol 1992;29:326-35.

24. Scheuplein RJ, Irvin H, Blank D. Mechanisms of percutaneous absorption, IV:penetration of nonelectrolytes (alcohols) from aqueous solutions and frompure liquids. J Invest Dermatol 1973;60:286-396.

25. Boatman RJ, Perry LG, Fiorica LA, English JC, Kapp RW, Bevan C, et al. Dermalabsorption and pharmacokinetics of isopropanol in the male and female F-344rat. Drug Metab Dispos 1998;26:197-202.

26. Peschel O, Bauer MF, Gilg T, Meyer L. Change in congener analysis caused bypercutaneous absorption of propanol-containing antiseptics. Blutalkohol 1992;29:172-84.

27. German Institute for Standardization European Union. DIN EN 1500. Chemicaldisinfectants and antisepticsdhygienic handrubdtest method and require-ments (phase 2/step 2). Brüssel: CEN, European Comittee for Standardization;1997. p. 1-20.

28. German Institute for Standardization European Union. DIN EN 12791. Chemicaldisinfectants and antisepticsdsurgical handrubdtest method and require-ments (phase 2/step 2). Brüssel: CEN, European Comittee for Standardization;2005. p. 1-31.

29. Roemhild W, Krause D, Bartels H, Wittig H. Congener analysis by means of“headspace” GC/MS. Blutalkohol 1998;35:10-8.

30. Turner C, Spanel P, Smith D. A longitudinal study of ammonia, acetone andpropanol in the exhaled breath of 30 subjects using selected ion flow tube massspectrometry, SIFT-MS. Physiol Meas 2006;27:321-37.

31. Iffland R, Balling P, Oehmichen M, Lieder F, Norpoth T. Methanol, isopropanol,n-propanol-endogenous formation affected by alcohol? Blutalkohol 1989;26:87-97.

32. Tiess D. Endogenes isopropanol (propan-2-ol). Endogenous isopropanol(propan-2-ol). Current state of knowledge, forensic and toxicological relevance(short message). Kriminalistik 1986;63(64):160-2 (in German).

33. Davis PL, Dal Cortivo LA, Maturo J. Endogenous isopropanol: forensic andbiochemical implications. J Anal Toxicol 1984;8:209-12.

34. Zuba D, Piekoszewski W, Pach J, Winnik L, Parczewski A. Concentration ofethanol and other volatile compounds in the blood of acutely poisoned alco-holics. Alcohol 2002;26:17-22.

35. Bonte W. Congeners of alcoholic beverages. In: Weinig E, Berg S, editors.Working methods of medical and scientific criminology, vol. 17. Lübeck[Germany]: Verlag Max Schmidt-Römhild; 1987. p. p. 352 (in German).

36. Gilg T. Methanol and congeners as markers of alcohol use and abuse. In:Wurst FM, editor. New and upcoming markers of alcohol consumption.Darmstadt [Germany]: Steinkopf; 2001.

37. True BL, Dreisbach RH. Alcohols and glycols. In: Dreisbach’s handbook ofpoisoning: prevention, diagnosis and treatment. Norwalk [CT]: Appleton andLange; 2001. p. 199-215.

38. European Commission. Propan-1-ol, part II: human health. European Unionrisk assessment report. 2008;82:104-226. Available from: http://ec.europa.eu/health/ph_risk/committees/04_scher/docs/scher_o_105.pdf. Accessed June 27,2011.

39. European Flavour and Fragrance Association. Opinion of the Scientific Panel onFood Additives, Flavourings, Processing Aids and Materials in Contact withFood on a request from the Commission related to Propan-2-ol as a carriersolvent for flavourings, Question Number EFSA-Q-2003-136. EFSA J 2005;202:1-10.

40. Kapp RW, Bevan C, Gardiner TH, Banton MI, Tyler TR, Wright GA. Isopropanol:summary of TSCA test rule studies and relevance to hazard identification. RegulToxicol Pharm 1996;23:183-92.

41. Petkovits T, Bohn G, Brinkmann B. Medical and toxicological aspects of prop-anol-2-intoxication. Z Rechtsmed 1989;102:69-75 (in German).

42. Occupational Safety and Health Administration. Occupational safety and healthadministration guideline for isopropyl alcohol, 2008. Available from: http://www.osha.gov/SLTC/healthguidelines/isopropylalcohol/recognition.html#workplacemonitoring. Accessed May 6, 2011.

43. Kalapos MP. On the mammalian acetone metabolism: from chemistry toclinical implications. Biochim Biophys Acta Gen Subj 2003;1621:122-39.

44. Buddecke E. Biotransformationsreaktionen. In: Buddecke E, editor. Outline ofbiochemistry for students of medicine, dentistry and natural science. 9th ed.Berlin: Gruyter; 1994. p. 454-8 (in German).

45. Felby S, Nielsen E. Congener production in blood samples during preparationand storage. Blutalkohol 1995;32:50-8.

46. Ellenhorn MJ, Schonwald S, Ordog G, Wasserberger J. Ellenhorn’s medicaltoxicology, diagnosis and treatment of human poisoning. Philadelphia: Wil-liams & Wilkins; 1997.

47. Brinkmann B, Kohler H, Banaschak S, Berg A, Eikelmann B, West A, et al. ROCanalysis of alcoholismmarkers: 100% specificity. Int J LegalMed2000;113:293-9.