Comparison of thin latex and nitrile diagnostic-protective gloves in the context of protection level against Covid-19 and other hazards.

Lek. Sławomir Gondek

Introduction

Since the beginning of 2019, in connection with the Covid-19 pandemic, there has been a significant increase in the demand for medical and protective gloves, both in Poland and globally. In fact, the increased demand exceeded production capacities, leading to real problems with glove availability in many countries.

In Europe, the USA, and Poland, the primary and most widely used material for producing diagnostic-protective gloves for healthcare workers is nitrile-butadiene rubber (nitrile). This synthetic material has replaced and almost completely displaced the previously commonly used natural latex from everyday use.

In situations of shortage or complete unavailability of nitrile gloves, the question arises whether latex gloves offer a sufficient level of protection to be used in place of nitrile gloves.

Legal and Normative Requirements

n the legal system of the European Union, ensuring proper quality and safety levels is based on CE marking. To be allowed on the market within the community, glove manufacturers must demonstrate compliance of their products with the essential requirements of relevant Directives and European Regulations, which guarantee an appropriate level of safety. For medical devices, these are Directive 93/42/EEC and its current replacement, Regulation MDR (EU REG. 2017/745), and for personal protective equipment, it is Regulation 2016/425. The simplest and most effective way to demonstrate compliance with the essential requirements is to conduct tests and show compliance with European and international standards. For medical devices, this is primarily standard EN 455, and for personal protective equipment, the standards are EN 420 and EN ISO 374 and their derivatives.

It should be emphasized that current normative requirements do not distinguish between glove materials and are the same for both nitrile and natural latex. This means that both nitrile and latex gloves must meet the exact same essential requirements to offer an analogous, minimal level of safety.

Resistance to Viral Penetration

Material taken from finished gloves can be tested according to ASTM F 1671 for viral penetration. The test uses the bacteriophage Phi X 174, which serves as a surrogate for the etiological agent of viral hepatitis.

Both latex and nitrile gloves pass the aforementioned test positively. As long as the glove material is not damaged, both latex and nitrile offer proper barrier protection and full coverage. Currently, medical gloves that also serve as personal protective equipment undergo an additional test according to EN 374-5. In this test, both materials also demonstrate an identical level of protection.

Glove Integrity

Both nitrile and latex gloves guarantee safety if their material is undamaged and intact. Glove integrity is tested according to EN 455-1, and the Acceptable Quality Level (AQL) is determined. For medical gloves, this index can reach a maximum value of 1.5, while for personal protective equipment, the maximum is 4.0. Again, there is no distinction in the requirements for latex and nitrile, therefore the integrity of both types of gloves is identical.

Mechanical Resistance and Susceptibility to Damage

The EN 455-2 standard specifies the minimum requirements for physical parameters, such as minimum tensile strength, sizes, and lengths. According to the requirements of the current version of the standard, gloves must maintain these minimum parameters throughout their shelf life. The standard's requirements are identical for both latex and nitrile gloves, with the only exception being gloves made from polyvinyl chloride (PVC), for which lower minimum parameters are specified. The minimum parameter values are set at a level that ensures the gloves can be easily donned in the appropriate size for the user.

Another aspect is susceptibility to damage. According to literature reports, nitrile gloves, with a similar wall thickness, offer higher puncture resistance. However, it should be noted that the current average thickness of powder-free latex gloves on the fingers, which is 0.11-0.12 mm, is about 30% greater than the average thickness of the most popular thin nitrile gloves. Therefore, the level of protection offered in this aspect is likely to be similar.

Chemical Resistance

Nitrile rubber generally has better protective parameters against the penetration of many chemical substances compared to natural latex. However, for example, the resistance to the permeation of organic solvents and many alcohols is at a similar level.

When in contact with alcohols, the glove material degrades, which manifests as a decrease in tear resistance and an increase in susceptibility to damage. In this area, the natural material—latex rubber—has certain advantages. According to research, the decrease in tear strength after disinfecting latex gloves is significantly smaller than that of nitrile gloves.

User Characteristics

Natural latex is significantly more flexible compared to nitrile. The stretchability of latex gloves reaches 800-900%, whereas nitrile gloves typically stretch to about 450-500%. In practice, this means easier donning, significantly better fit to the shape of the hand, and better tolerance for size. In cases of shortages, a person with a hand size L, for example, will be able to wear M size latex gloves and perform their tasks with only a slight decrease in comfort, whereas it is often impossible to wear nitrile gloves that are one size too small.

Natural latex also features better grip and is less slippery. The material itself is also softer than nitrile, providing the sensation of a thin, almost non-existent coating on the hand that does not limit tactile sensation.

Glove Allergies

Most of the nitrile gloves currently used, as well as all latex gloves, undergo vulcanization with sulfur during production. This process requires the use of chemical catalysts—known as vulcanization accelerators. These substances can cause delayed type IV allergic reactions.

Latex gloves also contain latex proteins, which can cause immediate allergic reactions, not only contact but also systemic. The risk of allergic reactions can be significantly reduced by removing the powder and thoroughly rinsing the gloves during the production process.

 

Summary

Cecha

Lateks naturalny

Nitryl

Resistance to Viral Penetration

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Odporność mechaniczna

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Odporność na penetrację substancji chemicznych

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Podatność na uszkodzenia

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Degradacja po dezynfekcji

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Elastyczność i komfort

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Chwytność i czucie

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Ryzyko alergii

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Analyzing the physical characteristics, as well as the level of safety and comfort, latex gloves provide a safe alternative to nitrile gloves, offering an appropriate level of protection. The balance of advantages and disadvantages of both materials is equal for individuals not allergic to latex. Therefore, gloves made from natural latex can be successfully used in contact with patients, including those with an increased risk of infection or infected with the SARS-CoV-19 virus.