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

Dr. 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	+++	+++
Odporność mechan­icz­na	+++	+++
Odporność na pen­e­trację sub­stancji chemicznych	++	+++
Podat­ność na uszkodzenia	++	++
Degradac­ja po dezyn­fekcji	++	+
Elasty­czność i kom­fort	+++	++
Chwyt­ność i czu­cie	+++	++
Ryzyko alergii	+	+++

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.