21-Oct-2002

You've got to hand it to Motorola...

Abstract

Bob W. Baker of Motorola documents the incidence of latex allergy caused by the long-term use of latex gloves

The medical fraternity is abuzz with discussions about allergies caused by using NRL (natural rubber latex) gloves. It is reported that at least 15% à of healthcare workers are allergic and react to chemicals or the proteins in the latex glove. The problem has become serious enough for OSHA à to consider recommending that employees do not wear NRL gloves except in situations where there is exposure to blood and other potentially infectious materials. If implemented, this recommendation will also affect electronic workers who use gloves in various environments, particularly cleanrooms. It will also necessitate a switch from NRL gloves to synthetic alternatives like nitrile, polyurethane, neoprene and PVC gloves. In the electronics industry, powder-free NRL gloves are the most widely used type of glove – powder-free to control contamination of products. NRL gloves offer unparalleled characteristics compared to synthetic gloves.

These characteristics are: 1. Synthetic gloves shed more particles compared to NRL. 2. Comfort. NRL gloves are elastic and soft, and therefore stretch to fit better 3. Tactility. NRL gloves are thin and therefore allow users better feel and tactility 4. Green product. NRL gloves are made from natural rubber, which degrades naturally into non-toxic waste 5. Cost. NRL gloves are reasonable in cost 6. Quality. NRL gloves have been proven to maintain barrier integrity better than synthetic gloves.

Do the benefits outweigh the risks? Is the risk the same for healthcare workers and electronic workers? A review of Motorola's experience based on user surveys over the last five years indicates that the allergic incidence rate is insignificant. This article looks at the difference in the sensitisation numbers between healthcare workers and Motorola's experience with its own employees.

Literature review What is latex allergy? There are three types of adverse reactions2 associated with latex products. They include Type I immunoglobulin E (IgE)–mediated hypersensitivity (allergic contact dermatitis), Type IV chemically induced hypersensitivity (irritant contact dermatitis) and contact dermatitis. Type 1 hypersensitivity is the most severe type of reaction. Symptoms can range from mild to severe and life threatening. Patients may, but rarely do, suffer from IgE mediated anaphylactic [3, 4] reactions and in severe cases may die from it. Proteins present in NRL ä are the primary cause of this type of allergy. Type IV hypersensitivity is less severe. Symptoms [6-8] include dry, cracked and split skin, rhino-conjunctivitis, eczema, asthma, blistering, itching and blisters, caused by chemicals used in glove manufacture. Most allergic healthcare workers are Type IV who may develop Type I hypersensitivity. Contact dermatitis is localised skin reactions, which is the least severe adverse reaction to latex. They are caused by the chemicals rather than by the latex proteins.

Causes Studies conducted by various scientists such as in [2, 5, 9] have proved that latex allergies are caused by chemicals used in glove manufacturing, cornstarch used as a donning agent [10-12] for gloves and proteins present in NR [5, 12, 13]. Until recently, most gloves used in the medical environment were powdered. Studies have also shown that the quality of gloves in the market differs greatly i.e. protein level, powdering residues, cleanliness (chemical residue) of gloves ë. Poorly manufactured powdered gloves have high chemical residues, high powder and/or protein content. Proper manufacturing techniques are capable of leaching the gloves so that chemical residue and NRL proteins are reduced to a minimum. A good manufacturing line is also able to reduce the amount of powder applied to facilitate donning. Modified cornstarch is used in glove manufacturing, which has been proven to adsorb NRL proteins onto its surface during the manufacturing process ñ. When gloves are donned or doffed, the proteinised cornstarch is released into the atmosphere and can remain suspended for as long as five hours. When inhaled, these aerosolised cornstarch particles will expose the mucous membranes to the NRL proteins. Over time, Type 1 hypersensitivity develops ä. Chemical residues cause Type IV reactions and breakages in the skin barrier cause proteins from the glove and cornstarch to gain entry to the body.

Motorola allergy incidence survey The survey was carried out at three Motorola facilities in Phoenix, Arizona. These facilities had been using NRL gloves supplied from a single source since November 1994. The objective was to determine if the gloves had caused any allergic reactions with any of the workers. Two surveys were carried out in November 1997 and June 1999, respectively (Table 1).

The Motorola results The main reason for the results in the survey, which defy the healthcare industry experience, is that the gloves used were low protein, low chemical powder-free gloves as opposed to powdered gloves in healthcare. The powder-free gloves were manufactured using a chlorination process. A regular powdered glove is put through a chlorination process and then a proprietary washing process to remove manufacturing debris and chemical residues. This also removes powder, chemicals and proteins from the NRL glove. Based on conclusions drawn by medical researchers, it supports our view that the powder-free glove used, which is very low in protein and 'clean' (very low chemical traces), has maintained the health of our workers. The push by Motorola to obtain a better glove with tighter specs on particle counts and chemical traces resulted in a glove that is 'hypoallergenic'. This is shown by test results carried out in 1999 by the Research Triangle Institute (RTI). Among the 12 gloves tested by RTI for Motorola, the gloves supplied by the current supplier came up as the top two gloves in terms of cleanliness, that is low in particle counts.

Longitudinal study by Mayo Clinic í The manufacturer used the same process to make a medical glove called Set-Rite. This glove was the subject of a year-long longitudinal study between March 1999 and March 2000. The allergenicity of the product was measured over a year, determining the consistency of the manufacturing process and the ageing effect on allergenicity. Every month, newly manufactured gloves were tested. From each lot 10 gloves were randomly chosen and tested for latex allergenic content. Buffer extracts were made from these samples and the allergen quantified. The test method is a competitive immunoassay using human IgE and labeled antihuman IgE detection (RAST inhibition Test). Gloves were retested after a month (Table 2). The conclusion was that the process used to manufacture gloves supplied to Motorola was a process that produced consistently hypoallergenic gloves. The study also showed that allergen levels reduce after aging by an average of 65%. It also found that this phenomenon is a once-occurring event and allergen content stabilises after a month.

RRIM study The RRIM (Rubber Research Institute of Malaysia), along with Dr. K. Turjanmaa of the Department of Dermatology, Tampere University in Finland, conducted a study in 1996. A group of latex hypersensitive subjects were skin-tested with latex gloves of varying extractable protein (EP) content and their allergic responses were measured. A follow-up study was also conducted by Dr. T. Palosuo of the Department of Immunobiology, Institute of National Public Health in Helsinki. The results of the studies indicated that at EP content of 400mgm/gm using the RRIM Modified Lowry Test, 60% of sensitised subjects show no response and when EP contents reduce to 100mgm/gm almost 100% of sensitised subjects show no response. The EP content of the glove supplied to Motorola using the RRIM Modified Lowry Test was always less than 20mgm/gm, explaining why there were a negligible number of allergic individuals in the survey undertaken.

Synthetic gloves The two popular alternatives to NRL gloves are polyvinyl chloride (PVC) and nitrile gloves. NRL gloves are superior in terms of comfort, tactility, barrier, costs and the environment î. PVC gloves particulate badly, affecting the clean environment and yields in the cleanroom. PVC gloves have the least recorded cases of allergies but have chemical components that are carcinogenic î. Nitrile gloves are known to be more rigid than NRL and have less comfort and tactile sensitivity. They are also more expensive.

Conclusion We believe that the NRL glove offers superior benefits. From our experience over the past five years, a good quality programme implemented with the manufacturer can ensure good yields, worker safety, comfort and lower costs with NRL gloves, as well as being more environmentally friendly.

For further information contact Latex Dippers Sdn Bhd at tel +603 6201 3773 or email: mohan@cld.po.my

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