Howe reviews history of latex allergy issue

ERJ staff report (RPN)

Akron, Ohio – William Howe got an inkling in 1991 that a major storm was coming in the rubber latex industry, comments Mike McNulty for Rubber & Plastics News. His sources proved to be accurate.

It arrived in small waves and grew into a major, long-term downpour that ultimately caused many rubber glove manufacturers to change the way they do business, others to close up shop and eventually led to the growth of synthetic rubber dipped disposable medical products.

Howe, vice president for moulding and coating services at Kent, Ohio-based DipTech Systems Inc., reviewed the crisis that hit the industry in the early 1990s and current trends for materials used for thin film dip moulded elastomeric devices while attending the International Latex Conference in Fairlawn, Ohio, July 23-24. He presented a paper at the conference, “The Fall and Resurgence of Natural Rubber Dip Moulded Goods and the Medical Marketplace.”

“The dip moulding industry grew exponentially starting in 1986 after the medical community recognized the HIV virus as a major threat to mankind,” he said. The need for disposable hand protection grew overnight, and producers of gloves began to tool up for additional production.

Rapid growth, sharp fall

In 1987, according to Howe, about 1 billion latex gloves were imported into the U.S., and by 1988, 8 billion were imported. While not as big an increase, the latex condom industry also experienced solid growth at that time.

“By 1990, responding to company directives to reduce manufacturing costs, major U.S. and European manufacturers began focusing their factory growth expansion by implementing new plants in Southeast Asia and other latex producing countries,” he said, leading to the creation of new glove and condom factories in Malaysia, Thailand, Indonesia Sri Lanka and India.

Unfortunately, he said, inexperienced companies were created in an attempt to capitalize on a fast-growing market. That led to the neglect of quality control by the new manufacturers, and in particular it created a major problem because of insufficient on-line water leaching, Howe said.

Allergic reaction to Hevea natural rubber “became a hot topic in the medical marketplace for dip moulded products, particularly for disposable latex gloves, condoms and other disposable medical components,” he said.

Latex allergy cases—including some involving anaphylactic shock, at times causing death—became big news in the 1990s. For example, 16 deaths were recorded from the use of a latex barium enema tip, resulting in a recall of the device in 1991 ordered by the U.S. Food and Drug Administration “and an increase in awareness of the risk of a life-threatening Type I allergy associated with natural latex devices,” the executive said. The NR used on the device was replaced with silicone after the recall.

Howe also related how it was discovered that the donning powder applied to disposable gloves enhanced latex hypersensitivity, as proteins often became airborne when powder was released while donning the gloves.

At that time, he said, it was estimated that from 2 to 10 percent of the U.S. population had some type of allergy related to latex goods exposure.

Steady rebound

Howe said the quick response by companies in the dip moulding industry to the growing problem was threefold:

• Polymer coatings were developed as a donning agent to replace corn starch powders.

• Many manufacturers worked to remove extractable proteins from natural rubber latex products via on-line protein removal stations in the dipping process. Glove makers learned proteins could be further removed through water post-leaching stations after the final curing.

• Research and development efforts began to find rubber latex alternatives, such as polyvinyl chloride, polyurethane, nitrile, chloroprene, styrene butadiene and, later, polyisoprene. They were developed and formulated aggressively for use in dip moulding applications. All are powder free.

Of those, “the key industry breakthrough discovered by those still manufacturing natural rubber latex gloves was the use of post-oven water leaching before the gloves were removed from the mould,” he said. The method had been used to make latex condoms.

Over time, other technologies were found to help reduce proteins in Hevea latex, including using a chemical additive at the latex plantation processing level, Howe said. “Surfactant systems were also designed as leach tank additives to accelerate the rate of protein removal from latex films as part of the on-line water leaching process.

All of that is paying off now because many of the alternative materials “are used strategically and selectively,” he said.

Crisis benefits

“Latex allergy has certainly caused significant health problems and increased health costs in general since identified in the early 1990s as a serious problem in the medical marketplace,” according to Howe. “However, an argument can be made that the many benefits have in turn resulted from the presence of the serious crisis that occurred with natural rubber latex dipped goods.”

He cited three:

• Numerous materials have been developed for use as thin-film elastomeric alternatives, including nitrile latex disposable gloves.

• The FDA came out with multiple standards to heighten awareness to the allergy problem, mandating that product producers implement good manufacturing practices and keep a close watch on quality measures. In March, it drafted another document to deal with the labeling of medical products that do not contain natural rubber latex.

• Many sub-par manufacturing plants were shut down or consolidated when purchased by larger firms. That has improved industry credibility and the quality of the products.

Citing International Rubber Study Group figures, Howe said the global production and consumption of NR and SR for all industries has risen every year but one, 2009, from 2006 through 2012. NR accounts for about 43 percent of the world's production and SR the remaining 57 percent.

Howe said in the last 20 years nitrile has supplanted NR as the dominant material in medical examination and industrial gloves.

NR continues to hold sway in surgical gloves, although polyisoprene and polychloroprene have gained market share the executive said.

NR continues to be the material of choice for condoms, as well as catheters and speciality dipped items used in the medical industry.

However, breathing bags have gravitated over the years to synthetic materials from natural rubber latex, according to Howe.