OSU's Cornish displays need for glove durability standards

FAIRLAWN, Ohio—When Katrina Cornish got into the rubber industry, about 2 billion gloves per year came into the U.S. Following the AIDS epidemic, this number jumped to 30 billion. And before the COVID-19 pandemic, the U.S. had about 300 billion gloves per year.

During the pandemic, however, this doubled to 600 billion, but it has since settled down to about 450 billion, Cornish said.

With this many gloves coming into the country, and as more domestic glove manufacturers come online, she said, it's wise to be interested in the quality of items preventing the spread of infectious diseases.

After all, gloves "are the first line of defense against illness causing bacteria and viruses," said Cornish, research director at the Ohio State University.

"We're very interested in the safety of gloves and are gloves as they are supposed to be. Do they have the performances they're supposed to have?"

Different gloves throughout the medical industry have different uses and requirements, Cornish said, pointing out that surgeons, for example, have hours of extended wear with little opportunity to change gloves.

"They want one that's not only comfortable with good tactile sensation, but you want one that's going to last," she said.

Morticians, oncologists and first responders, on the other hand, need thicker gloves with equal durability due to exposure to harsh chemicals, bodily fluids and drugs.

In her presentation, "Durability Variation amongst Medical Gloves Made from Different Elastomers," at the Healthcare Elastomers Conference, organized by Rubber News, Cornish noted that there are no ASTM standards for medical gloves once they are removed from their packaging.

"(Gloves are) supposed to have certain physical properties when they're made. Then you put them in the box … and that's all you know," she said. "You have no idea what you've got on your hand, whether they're going to stay intact."

In some cases, she said, gloves may not even meet the standards already in place. And an unreliable glove means higher rates of disease transfer and infections.

"The bottom line is flimsy gloves cost lives," Cornish said.

And there seems to be plenty of flimsy gloves on the market, according to Cornish's own durability testing done at the Ohio State University.

Over the years with undergraduate students, Cornish developed the Capstone Glove Assessment Device, dubbed the C-GAD, a prototype to test the durability of gloves. This then became the "New" Glove Assessment Device, or N-GAD, upon her start-up company, EnergyEne Inc., receiving a Phase II grant from the U.S. Department of Agriculture's Small Business Innovation Research program.

With the grant, Cornish and her team were able to build out the automated device, which can detect breaks in gloves within a second, eliminating the need for manual inspection, according to Cornish's MDPI article, "Invention of a Medical Glove Durability Assessment Device."

On the N-GAD, fine weight sandpaper on a drum goes up and down on the fingertips of the glove, which is attached to a vacuum.

"As soon as the glove material fails, the vacuum fails and the machine instantly detects that and turns down," Cornish said.

To test the durability of several gloves, including a guayule latex glove she and her team developed, Cornish used the N-GAD, along with electronic calipers to determine glove thickness at the fingertips and cuffs and the ASTM D412 test method using an Instron tensiometer for mechanical properties.

Cornish said she tested stress relaxation at 100-, 300-, and 500-percent elongation using a die D, and determined tear strength based on ASTM D624 methods.

Cornish's research showed that when it came to the gloves' durability, guayule latex gloves consistently outperformed PVC, nitrile, hevea latex, polyisoprene and polychloroprene gloves, among others.

Looking at tear strength, particularly, while PVC gloves were the thickest, they were also the weakest and stiffest. Nitrile gloves were some of the strongest but did not have as much elongation as hevea or guayule latex gloves. And hevea latex gloves, she said, had higher elongation, but were not as strong as their nitrile counterparts.

Guayule, on the other hand, was found to be as strong as nitrile with the highest elongation, making it the softest and stretchiest of the four materials.

When looking at stress relaxation, her research showed that nitrile gloves were stiffer when first worn but softened with use. Hevea latex gloves did not change much with use and were softer than nitrile, which could mean less hand fatigue. Guayule gloves, however, "fit like a second skin" compared to hevea, Cornish said.

"You pretty much forget you're wearing it," she said of the guayule glove.

She also added that while nitrile gloves are strong, they tear easily once they perforate. "It's good until there's a break, and then the glove will very quickly just disintegrate," she said.

Of 10 different brands of medical exam and surgical gloves tested, three failed to meet ASTM standards as required by the FDA. These included two nitrile exam gloves and one PVC.

Several that did meet the standards, however, only received a "poor" or "fair" quality rating, according to Cornish's tests. Only four brands, including EnergyEne's own guayule latex surgical glove, achieved "good" and "excellent" ratings.

Katrina Cornish, along with undergraduate students, over several years developed the "New" Glove Assessment Device, dubbed the N-GAD, which is designed to test the durability of gloves.

Cornish noted the gloves were obtained at random.

"These are just ones we obtained. We're not picky about whose gloves these are," she said, later adding "… But of this group we had two nitrile and one PVC that did not meet the requirements that, when in effect, claimed that they did on the boxes in which those were received."

According to Cornish, ASTM has a working group looking at standards particularly for synthetic rubber gloves, and discussions are in the works with the FDA about these standards and the rate of inspection on gloves that aren't meeting them.

"A glove should be what a glove claims to be and provide the level of protection that you expect," Cornish said.

She noted that rates of inspection are so low that some manufacturers find it to be a better business practice to lie about the quality of their gloves and risk paying fines.

"They prefer to risk paying the fine because the chances of getting caught with a substandard glove were so low that it's a better business proposition for them to make an inferior glove and claim it's a good one—because they're not going to get caught," she said. "They can make it cheaper."

Simply increasing inspection rates could potentially save the lives of health care workers and patients, she said.

Cornish also noted a shift back to natural materials for gloves could prove beneficial, not just in quality, but because of their sustainability.

"And then if we shifted back to the natural latexes, which in general are higher performing materials than synthetics, this would help us reduce the carbon footprint of the medical glove industry," she said. "And most importantly, it would help biologically and geographically diversify the critical natural rubber supply."

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