Glove Me Tender
LabConsumer tests nitrile laboratory gloves in response to increasing concerns about latex allergies
By Amy L.
Francis
Nitrile Glove Comparison Chart
| Photo: Larry Hand |
 AACR participants donned nitrile gloves for a LabConsumer survey. |
Precautions against exposure to HIV and hepatitis and crackdowns on lab safety have led to increased glove usage in recent years. Overwhelmingly, glove users have turned to latex, which provides low-cost barrier protection while allowing dexterity. However, with latex allergy sufferers seeking workers compensation in droves, hospitals and research administrators are looking for answers from researchers studying the problem.
Present just under the bark of Hevea brasiliensis (rubber trees), the milky sap known as latex helps protect the tree when the bark is punctured or scraped. Latex collects at the wound to prevent bacterial and fungal infections and promote healing. Latex has been harvested for its elastic properties since the 1870s, and southeast Asian countries such as Malaysia, Thailand, and Vietnam now collect and process the bulk of latex used in gloves and other rubber products. After tapping the rubber trees, latex collects in containers at the base of the tree, much like maple sap.
Glove Sick
Among more than 250 proteins found in latex, more than 30 are human allergens. Wearing latex gloves, particularly for long periods of time, causes contact dermatitis in some individuals. This reaction can be caused by chemical irritants added during latex processing (thiurams, carbamates) or an allergy to one or several latex proteins. Furthermore, allergens are easily absorbed by the cornstarch used to powder many types of gloves and inhaled when the application and removal of gloves aerosolizes the powder. According to Donald Beezhold, head of the laboratory of immunobiology at the Guthrie Research Institute in Sayre, Pa., "Glove powders tend to be about the size of a pollen particle and also contain foreign plant proteins, so it's a kind of particle that our immune systems are very good at recognizing." For those sensitized to latex proteins, the results range from itchy, watery eyes and a runny nose to respiratory difficulties, including asthma. More severe reactions, such as anaphylactic shock, can occur when allergic patients come into contact with latex products (surgeons' gloves or devices) during medical procedures. This danger has prompted some hospitals to become latex-free environments.
Sensitization to latex often occurs over time, and Sussman states that the development rate usually correlates with the cumulative dose of allergen encountered--the longer latex gloves are worn and powder inhaled, the more likely allergy development becomes. This is reflected in the statistics concerning the prevalence of latex allergies among the general population (1-6 percent) versus health care workers (8-12 percent), who are repeatedly exposed to latex gloves.1
Latex is all around us--balloons, Band-Aids, condoms, chewing gum, and even scratch-off lottery tickets--and once one is sensitized, avoiding latex products provides the only relief from symptoms. To make matters worse, foods such as bananas, kiwis, and avocados contain proteins similar to latex allergens, and some that become latex sensitive can expect to react to these foods.2
As a first step in alleviating the problem, Sussman recommends simply switching to powder-free latex gloves, thus eliminating the inhalant route of sensitization. He observes that this action relieves allergy symptoms in some sensitized people and projects that elimination of airborne latex should slow the rate of allergy development in high-risk environments.
Many latex-sensitized laboratory researchers, including Suich, turn to nonlatex alternatives for barrier protection. Vinyl (PVC) gloves are suitable for some tasks, but most researchers find that vinyl does not mold to the hand well enough for manipulation of lab tools. Many allergy sufferers use gloves made from nitrile, a synthetic polymer of butadiene, acrylonitrile, and carboxylic acid. The higher cost of nitrile gloves compared to latex is a factor that most labs cannot ignore, but increased demand has led to more suppliers, and prices are coming down. Nitrile gloves also feature better puncture and chemical resistance than latex gloves. In 1997, the poor chemical resistance of latex gloves was tragically illustrated by the death of Dartmouth College chemistry professor Karen E. Wetterhahn after a few drops of dimethylmercury penetrated her latex gloves in less than 15 seconds. (For a guide to the barrier protection from chemicals provided by different types of gloves consult the Centers for Disease Control and Prevention [CDC] Web site at www.cdc.gov/od/ohs/manual/pprotect. htm#hand protection.)
A Helping Hand
With more labs stocking nitrile gloves, LabConsumer decided to put seven major brands to the test. The gloves generously donated and tested were: Allegiance Healthcare's Multi-Flex(r) Nitrile T Ambi, Ansell Edmont's Touch N Tuff(tm), Best Manufacturing's N-DEX(r), HIGH FIVE's Nitrile Exam Gloves, Medline's Accutouch(tm) FT, Microflex's Supreno(tm), and Safeskin's Purple Nitrile(tm) gloves.
All gloves tested were disposable, powder-free, nitrile gloves, approximately 9.5 in. long and 4 mil. (0.1 mm) thick. With the help of 286 researchers attending the American Association for Cancer Research annual meeting in San Francisco (April 1-5, 2000), each glove brand was put through a series of blind tests to compare fit, comfort, and maneuverability. Testers did not know which brands they were testing or even which companies were represented.
The testers were people who are actively involved in laboratory research and who currently use gloves on a regular basis. In fact, 89 percent report using gloves every time they do an experiment to protect against chemicals (79 percent), biological fluids (75 percent), radioactivity (65 percent), and laboratory animals (24 percent). The majority of testers (61 percent) currently use powder-free latex gloves, 25 percent use powdered latex, 11 percent use nitrile, and 3 percent use vinyl. Most seem to be particular about their gloves, as 62 percent have tried two or more kinds in the past year.
Concordant with published reports, 8 percent of the AACR glove testers reported being allergic to latex and another 10 percent suspect an allergy. Most (69 percent) were aware that latex allergies can develop over time, but 60 percent had never tried nitrile gloves prior to the survey. Interestingly, two-thirds of those with actual or suspected latex allergies continue to use latex gloves. Those who don't currently use nitrile gloves gave several reasons: 43 percent reported that they didn't know enough about them, 20 percent thought they were too expensive, 19 percent indicated that their preferred vendor didn't carry them, and 9 percent didn't think they were necessary for their application.
Each tester completed several tasks wearing samples of each of the seven brands in turn: First, testers found the glove size with the best fit and rated both the fit and the ease with which the gloves could be put on. After making a fist and releasing a few times, they rated the ease of movement allowed for each glove. The last phase required gloved participants to pick up a Gilson Pipetman(r), pipet water into a 0.5 ml microcentrifuge tube, and cap the tube. Finally, testers gave an overall evaluation of each glove brand on a 1-20 scale. Bear in mind that these tests evaluate initial impressions and do not approximate typical usage conditions, in which gloves are worn for longer periods of time.
Testers indicated that they liked the fit of Safeskin's Purple Nitrile and Allegiance's Multi-Flex Nitrile T Ambi. These brands were also found to be the easiest to put on, least restrictive of finger movement, and along with HIGH FIVE's Nitrile Exam Gloves, most comfortable during pipetting tasks. Although many reported that Best's N-DEX gloves were hard to put on and had a distinctive odor, testers found them to be less restrictive than most other brands. Overall scores were close, but testers liked Safeskin's Purple Nitrile best, followed by Allegiance's Multi-Flex Nitrile T Ambi, Medline's Accutouch FT, HIGH FIVE's Nitrile Exam Gloves, Best's N-DEX, Ansell Edmont's Touch N Tuff, and Microflex's Supreno.
Surprisingly, after testing all brands of gloves, 40 percent stated that they actually prefer nitrile to latex. The remaining survey participants were split between preferring latex and finding them about the same. Other types of nonlatex gloves are also available, such as Microflex's NeoPro(tm) chloroprene glove.
LabConsumer surveyed prices for the tested brands at eight distributors and found many to be priced competitively with latex gloves. For example, VWR Scientific sells a box of Ansell Edmont's Touch N Tuff gloves (100/box) for $9.91, Midwest Scientific offers Microflex's Supreno for $11.50/box, Lab Safety Supply sells Best's N-DEX for $11.15/box, and online shoppers at Scientific Supply Source can find Safeskin's Purple Nitrile gloves for $12.50/box. Note that these are list prices and do not include institutional discounts given by many distributors, so actual prices may be lower.
In summary, cancer researchers participating in our glove survey found nitrile gloves to be a suitable replacement for latex. Current latex glove users concerned about developing allergies should give nitrile a try. And with a little shopping around, most brands of nitrile gloves can be purchased at prices not far from those of high-quality latex gloves. If you'd like to take matters into your own hands, most manufacturers are happy to send out glove samples for real-world tests. S
Amy L. Francis can be contacted at afrancis@the-scientist.com.
References
1. "NIOSH Alert: Preventing allergic reactions to natural rubber latex in the workplace," DHHS (NIOSH) Publication No. 97-135, August 1997.
2. D. Beezhold et al., "Latex allergy can induce clinical reactions to specific foods," Clinical and Experimental Allergy, 26:416-22, 1996.
Editor's note: The pipettors used during tests were generously lent by Rainin Instrument Co. of Woburn, Mass., and the pipet tips and microcentrifuge tubes kindly provided by AxyGen Scientific Inc. of Union City, Calif. The Scientist does not have an affiliation or advertising relationship with any of the glove companies mentioned. The testing was conducted solely as a service to readers of The Scientist.