Evaluation of Glove Performance after Decontamination

Abstract

Studies of healthcare providers doffing personal protective equipment, especially gloves, indicate that self-contamination does occur. Although generally this is not hazardous, working with particularly pathogenic organisms, such as Ebola virus and Clostridium difficile, can present a serious health risk. Decontaminating medical gloves before removal can reduce self-contamination and mitigate the spread of these types of pathogens. Also, in cases of extreme shortage, the Centers for Disease Control and Prevention (CDC) has specific recommendations for decontaminating gloves for extended use. Reuse of medical gloves is strongly discouraged by both the CDC and Food and Drug Administration. This work seeks to lay a foundation of testing to evaluate whether a decontamination method is compatible for a given glove type and material. Four potential methods of decontamination (commercial hand soap, alcohol-based hand sanitizer, commercial bleach, and quaternary ammonium solution) were tested on a variety of surgical and patient examination gloves. The method of barrier performance evaluation was ASTM D5151-19, Standard Test Method for Detection of Holes in Medical Gloves. Our results indicated that the performance of the gloves after treatment was highly dependent on the composition of the medical gloves. In general, the surgical gloves in this study performed better than the patient examination gloves, regardless of the material from which they were made. Specifically, vinyl examination gloves tended to have poorer performance. In this study, the number of gloves available to test were limited and therefore statistical significance is beyond the scope of this project.

Medical gloves are a common type of personal protective equipment (PPE) used to prevent the spread of disease-causing microorganisms.¹ The value of decontaminating gloves prior to doffing for the purposes of reducing transmission of pathogenic organisms is obvious in cases such as after working with Ebola virus or Clostridium difficile. The Centers for Disease Control and Prevention (CDC) has posted guidance on the decontamination of gloves prior to doffing after working with patients with Ebola virus disease.² A study by Wolfensberger et al.³ suggested that pathogens transfer more frequently after contact with moist body sites, longer duration of care, and care of patients with an invasive device. Tomas et al.⁴ performed a study attempting to reduce C. difficile hand contamination and found that a novel sporicidal formulation of ethanol rapidly reduced the spores on gloved hands without odor, respiratory irritation, or staining of clothing. In addition, CDC issued guidance on decontamination during extreme shortages; gloves can remain on but must be sanitized between patients within the cohort to prevent cross transmission of any other pathogens from patient to patient.⁵ This guidance provided specific decontamination methods for gloves.

However, the glove decontamination method should be evaluated prior to using a specific decontamination method. An important finding by Scheithauer et al.⁶ was that testing compatibility between the glove material and disinfectant is crucial. Various disinfectant/glove combinations produce relevant differences with regard to disinfection effectiveness. During the Ebola outbreak, removing gloves without decontaminating them first was found to put healthcare providers (HCPs) at risk of self-contamination.² Kpadeh-Rogers et al.⁷ evaluated the effects of alcohol-based hand rub and two Environmental Protection Agency (EPA)-registered hospital disinfectants (quaternary ammonium solution and commercially available bleach disinfecting wipes) on bacterial contamination of HCPs' hands. Further, Robinson et al.⁸ evaluated the effects of bleach sprays and bleach wipes. Finally, Gao et al.⁹ tested the effects of alcohol-based hand sanitizers (ABHSs) on medical gloves, then evaluated the tensile properties of those gloves. They found that alcohol-based solutions should be safe for most of the decontamination of gloves.

These studies highlight the need and practicality in decontaminating gloves, which perhaps can be viewed as worker safety or a practice of medicine.¹⁰ The Food and Drug Administration (FDA) regulates medical gloves as Class II devices, thereby requiring their premarket review. However, it does not regulate worker safety or the practice of medicine; this responsibility falls under the purview of the Occupational Safety and Health Administration (OSHA) or under the jurisdiction of the medical boards of each state.^11,12 After a medical glove is decontaminated, it is no longer considered a medical glove; to date, no medical glove has been approved or cleared for reuse.

Esmizadeh et al.¹³ suggested that reusing medical gloves would reduce medical waste; however, the chemicals and energy needed to properly decontaminate medical gloves likely would exceed the environmental cost of disposal, in addition to increasing the risk of transmission of pathogenic organisms. The work presented by Esmizadeh et al. indicated that gloves could be treated with alcohol, ultraviolet (UV) disinfection, and heat as means of decontamination for repeated use; however, the work neglected to investigate the impact of repeated doffing and donning when reaching their conclusion. Regardless, their work showed that alcohol, UV disinfection, and heat treatments may be good candidates for further study for both nitrile and vinyl gloves.

With consideration for previous reports and CDC recommendations, the current study was designed to provide a baseline in evaluating gloves' barrier performance following decontamination to reduce bioburden.¹¹,¹² In this work, “decontamination” refers to the OSHA definition for decontamination from 29 CFR 1910.1030, which states that “decontamination means the use of physical or chemical means to remove, inactivate, or destroy blood-borne pathogens on a surface or item to the point where they are no longer capable of transmitting infectious particles and the surface or item is rendered safe for handling, use, or disposal.”¹⁴ Further, decontamination was not verified in this work, and as such, all materials used should be considered to have potential for decontamination.

Table 2.

Results of ASTM D5151-19 for decontamination methods in multiple cycles. Results are for five gloves and expressed in percent of gloves that passed.

This work only serves as a starting point, with some general trends noted. A huge difference exists in quality among manufacturers, and different processing and manufacturing methods likely will affect the performance of a specific glove model with a specific decontamination method. If a healthcare facility is contemplating implementing glove decontamination prior to doffing with the intent of reducing transmission of pathogens or during an extreme shortage, the compatibility of the specific glove and decontaminating agent/method should be assessed, as well as the effectiveness of the decontaminating agent on the specific pathogen(s). As the purpose of this project was to identify possible glove material and decontamination methods that are or are not worth pursuing, running large numbers of gloves was beyond its scope.

In this study, four different methods (1, commercial hand soap; 2, ABHS; 3, commercial bleach; and 4, quaternary ammonium solution) were used to treat three surgical and four examination gloves prior to evaluation of barrier performance using ASTM D5151-19, Standard Test Method for Detection of Holes in Medical Gloves.¹⁵ The method used for decontamination solutions 1 and 2 mimicked an extreme shortage situation, and gloves tested remained on the hand throughout the procedure. For decontamination solutions 3 and 4, the gloves were removed and dried prior to testing.

CDC and FDA do not endorse the reuse of medical gloves. However, if extreme shortage of gloves occurs or if decontamination is needed after working with pathogenic organisms, baseline data of glove performance related to specific decontamination method would be useful.

Materials and Methods

Medical gloves were obtained from open sources and not identified beyond material and function (examination or surgical) This was not an exhaustive market survey; as such, it is FDA practice to anonymize specific manufacturers and products. No claims beyond “surgical glove” or “examination glove” were made, with the exception that all surgical gloves were labeled “sterile.” All materials used for decontamination were acquired from publicly available sources.

The materials were as follows: paraben-free hand soap that was not marketed as antibacterial; ABHS containing 70% ethanol; a commercial bleach (5.25–6.15% sodium hypochlorite) that was diluted with water to a concentration of 10% by volume prior to use; and quaternary ammonium disinfecting cleaner containing 0.105% dimethyl benzyl ammonium chloride and 0.105% dimethyl ethyl benzyl ammonium chloride, which was used undiluted. Mannequin hands (ASIN: B07P1T11SK; AORAEM) were purchased from Amazon.

Decontamination of the gloves was designed to emulate how HCPs would decontaminate their gloves prior to removing them. For the methods used that were designed for use on human hands (ABHS and hand soap), the investigator donned the gloves to perform the decontamination method. However, for the methods using disinfecting solution, the gloves were first fitted to a set of mannequin hands. The gloves were visually inspected for any tears or punctures prior to decontamination. If the gloves were faulty, then they were discarded and replaced. Five gloves were tested per treatment. Extra gloves were decontaminated for surplus in case of accident or loss and for possible subsequent chemical analysis.

Glove Thickness

Gloves were measured for actual thickness using a Mitutoyo Digital Dial Indicator (Kanagawa, Japan) in the location specified by ASTM D3577-19¹⁶ and ASTM D3578-19¹⁷ (Table 1).

Table 1.

Measured glove thickness in locations specified by ASTM D3577-19¹⁶ and ASTM D3578-19.¹⁷

Commercial Hand Soap

The investigator donned the gloves, proceeded to wash them with commercial hand soap (one solid pump; 1.9 g on average), and rinsed under tepid (20–25°C) running tap water—as one would wash their hands, including between the fingers—for a minimum of 30 seconds. (This was the investigator's normal wash time.) Excess water was wiped off using an absorbent towel. Gloves were decontaminated either once (1×), five times (5×), or 10 times (10×). For repeated decontamination cycles, the gloves remained on the hands of the investigator for the duration of the 5× and 10× treatments, with excess water wiped off between treatments (at least 1 min).

ABHS

As with commercial hand soap, the investigator donned gloves, applied one solid pump of ABHS (enough to completely “wet” the gloves; 2.1 g on average), and rubbed the ABHS on the gloves until the surface was completely coated. Excess ABHS was wiped off using an absorbent towel. As the ABHS could continue to react with the glove material, the gloves were analyzed on the same day as when decontamination occurred. Gloves were decontaminated multiple times in 1×, 3×, and 6× cycles, with five gloves per decontamination cycle. Between treatments, the excess ABHS was wiped off and the gloves remained on the investigator's hands for an additional minute to allow for complete evaporation before commencing the next treatment. During this time, the investigator never removed the gloves.

Commercial Bleach Decontamination

A stock solution of 10% commercially available bleach (by volume) was made daily. The gloves were placed on mannequin hands, dipped into the bleach solution for one minute, and rinsed copiously with tap water. The mannequin hand with glove then was stirred in a beaker of clean tap water for about 10 seconds. The gloves were removed from the mannequin hand, patted dry with an absorbent towel, and placed in a cabinet to dry overnight before further decontamination or analysis.

Of note, for extended use, the CDC recommends dipping gloved hands in solution for five seconds, then allowing the solution to stay on the gloves for one minute before rinsing.² The EPA recommends a five-minute exposure time if specifically dealing with Ebola, but only for hard nonporous surfaces.¹⁸ However, our purpose was to generically examine decontamination methods' compatibility with gloves. We chose to expose gloves to bleach for one minute, then followed the rinsing and storage procedure noted above. The gloves were decontaminated in batches of five gloves at a time. Once again, gloves were decontaminated either 1×, 5×, or 10× times.

Quaternary Ammonium Solution Decontamination

The gloves were placed on mannequin hands and dipped into the quaternary ammonium solution for five minutes, as this was the contact time indicated for viricidal kill in the manufacturer's instructions for use. Unlike with the commercial bleach solution, the quaternary ammonium solution was not diluted before use. The gloves then were rinsed with copious amounts of tap water and the mannequin hands stirred in a beaker of fresh room temperature water for about 15 seconds. The gloves then were removed from the mannequin hands, patted dry with an absorbent towel to remove moisture, and placed in a cabinet to dry overnight. The gloves were treated 1×, 5×, or 10× times with five gloves per exposure condition, then the rinsing and storage procedure noted above was followed.

ASTM D5151-19 Analysis

ASTM D5151-19 describes a test method for determination of holes in gloves.¹⁵ This method was used to evaluate all gloves. The full procedure can be accessed via ASTM and is only briefly outlined here, along with any notable deviations.

The gloves were placed on the mandrel of the water leak test apparatus and secured with a tight-fitting O-ring (Figure 1). Up to five gloves could be fitted to the apparatus at a time. While fitted, they remained suspended with the opening of the glove facing upward and the fingers pointed down. Room temperature water (1 L) then was dumped into the glove all at once by the apparatus. The investigator then inspected each glove for sweating (where small beads of water pushed through the glove) and for punctures (where water rapidly leaked through the glove in a stream). If a glove leaked or sweated, it was denoted as a failure to meet the standard.

Figure 1.

ASTM D5151-19 glove tester fitted with five gloves for analysis.

As outlined in ASTM D3577-19¹⁶ and ASTM D3578-19,¹⁷ the sample size of gloves to determine the acceptable quality level (AQL) depends on lot size. However, we were unaware of the lot size, and the method of testing five gloves for each decontamination cycle falls well below any meaningful number of gloves in establishing an AQL of 1.5% for surgical glove or 2.5% for examination gloves.

Generally, all gloves leaked on the palm and fingers, with small beads forming at the failure site and slowly “weeping” except the nitrile examination gloves when treated with ABHS. This combination demonstrated significant tearing prior to removal from the investigator's hands (Figure 2). Of note, the doffing and donning of gloves (the bleach and quat samples), as compared with leaving gloves on the investigator's hands (washing with soap and water and ABHS), may have influenced the results. This was separated for a couple of reasons. First, failure of glove on an investigator's hands while using a more caustic solution (bleach or quat) was anticipated and deemed an unacceptable risk. This is why mannequin hands were used. Leaving gloves on the investigator's hands (washing with soap and water and ABHS) and anticipation of failure did not expose the investigator to unacceptable risk. Second, the situation in which gloves remained on the investigator's hands better mimicked the scenario of extended use during supply crisis, when gloves would remain on HCPs' hands.⁵

Figure 2.

Although the nitrile examination gloves maintained their integrity after three treatments with alcohol-based hand sanitizer (ABHS), significant tears in the gloves began to occur after six treatments with ABHS.

Results and Discussion

Because thickness is one of main differences in specifications between surgical and examination gloves, the actual thickness of the gloves used in this study was determined. All gloves met the basic requirements of 0.10 mm for surgical gloves and 0.08 mm for examination gloves (Table 1), as specified by ASTM D3577-19¹⁶ and ASTM D3578-19,¹⁷ respectively. Cuff measurements are required for surgical gloves¹⁶ but not examination gloves.¹⁷

The decontaminated gloves and control gloves were tested five at a time with the ASTM D5151-19¹⁵ glove tester, with the results shown in Table 2. The repeated decontamination cycles were performed to strenuously evaluate glove performance. However, without performing decontamination using microorganisms and subsequent biological testing, the effectiveness of the methods could not be quantified.

Commercial Hand Soap

Most of the gloves performed well after treatment with soap and water. During decontamination, the investigator wore the gloves to wash them, which increased strain on the gloves compared with later cases in which they were simply dipped in solutions for decontamination. The vinyl examination gloves performed well initially, but repeated treatment resulted in poor performance, with only 40% of gloves passing at five and 10 times (Table 2). The nitrile surgical gloves and neoprene examination gloves each failed once (after 3× and 5× decontamination cycles, respectively). A larger sample size would be needed to determine the statistical significance of the failure rate.

ABHS

All surgical gloves performed well even after repeated treatment with ABHS. Color changes were observed after ABHS treatments in latex, nitrile, and vinyl gloves (Figure 2). Once again, the vinyl examination gloves had the worst performance of the gloves tested, with 40% failing after just one treatment. Of note, the neoprene examination gloves also began to fail after one treatment and the nitrile examination gloves began to fail after repeated treatments (Figure 2).

Commercial Bleach

During treatment with commercial bleach, some gloves demonstrated a distinct change in color indicative of chemical reaction. The latex gloves yellowed slightly, while the nitrile gloves began to turn green. In Figure 3A and B, the extent of this color change after 10 decontamination cycles with commercial bleach is shown. The other gloves tested did not show a distinct change in color. The vinyl examination gloves had the worst performance in the glove tester after decontamination and can be seen “weeping” in Figure 2C. One of the surgical neoprene gloves tore when placed on the mannequin hand for the fifth treatment with bleach. This indicated a deterioration of the glove. In addition, one of the five nitrile examination gloves failed glove tester analysis.

Figure 3.

A, B, and C were treated with commercial bleach 10 times. A shows the change in the color of the latex examination gloves after treatment (right), and B shows the change in the color of the nitrile examination gloves after treatment (right). C demonstrates “weeping” of the vinyl examination gloves after treatment with bleach. D, E, and F were treated with alcohol-based hand sanitizer 10 times. D shows the change in the color of the latex examination gloves after treatment (right), and E shows the change in the color of the nitrile examination gloves after treatment (right). F shows the change in the color of the vinyl examination gloves after treatment (right).

Quaternary Ammonium Solution

The most profound change that occurred in this study was with nitrile surgical gloves (Figure 2F). These gloves became “tacky” and the fingers stuck together after quaternary ammonium solution treatment. This change in texture did not occur in the other treatment methods and is likely due to a chemical reaction with the quaternary ammonium solution. Of note, this change was not observed in the nitrile examination gloves, which could be a result of differences in glove thickness or manufacturing processes potentially involving additives or coatings. Despite this, the gloves all passed, even after pulling the fingers apart to put them on the mannequin hands or ASTM D5151-19 tester. Again, the vinyl examination gloves had poor performance, with some failing after both the initial treatment and repeated treatments. All surgical gloves performed well in the ASTM D5151-19¹⁵ water leak test, as did the latex examination gloves. The neoprene and nitrile gloves had some failures, but again, it is unclear whether they would be statistically significant.

Limitations

This study limitations included the small number of samples and, therefore, lack of analysis regarding statistical significance; consideration of any effect of the repeated donning/doffing of the gloves for bleach and quaternary ammonium treatments; and lack of measurements of other physical properties (e.g., tensile strength, elongation). However, this study provided data to eliminate or show promise of decontamination methods for specific glove materials with a relatively simple test, before proceeding to more elaborate and time-consuming methods.

Conclusion

During the 2014 Ebola outbreak, decontamination of gloves prior to their removal was recommended by CDC as an extra precaution to prevent the spread of this deadly disease.² With the extreme supply chain issue for PPE during the SARS-CoV-2 pandemic, CDC issue recommendations for decontaminating gloves for extended use—only in instances of extreme shortage—among the same cohort of patients.⁵ The purpose of this study was to examine which glove/decontamination systems were or were not worth pursuing in the event of an emergency in which gloves were not readily available or if extra decontamination measures were necessary. The experimental conditions used in this study were derived from CDC recommendations^2,5 and the open literature as a possible first step in outlining methods to determine the compatibility of different gloves with four different decontamination methods.

The intent of this study was to evaluate whether a decontamination method is compatible with a given glove type and material. Based on the test data presented, it appears that glove barrier performance is related to glove material, treatment, and number of treatments. Among the four decontamination methods evaluated, treatment with ABHS appeared to have the greatest impact on the glove's barrier property. Vinyl medical gloves were shown to be poor candidates for decontamination, as they had a high number of failures across all decontamination methods used. In contrast, surgical and examination latex gloves consistently had the best performance in the water leak test for all treatments (100%; Table 2). In general, the surgical gloves performed better than the examination gloves, with very few failures detected. This may be due to the higher thickness specification for latex surgical gloves (0.1 mm; ASTM D3577-19¹⁶) compared with that for latex examination gloves (0.08 mm; ASTM D3578-19¹⁷) (Table 1).

Although this work investigated the detection of holes in gloves, other studies would need to be conducted for proof of viability of decontamination methods paired with each glove type, including microbiological studies, tensile strength, and elongation. Also, if a specific microorganism of concern is targeted, appropriate selection of decontamination method and contact time needs to be established.

Disclaimer

The findings and conclusions in this article have not been formally disseminated by the FDA and should not be construed to represent any agency determination or policy. The mention of commercial products, their sources, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health & Human Services.