Latex: a sensitive issue

The number of people who have an adverse allergic reaction to latex is growing on a daily basis. And while there are synthetic options available, the bad news is that the favourable properties of natural rubber latex have yet to be replicated.

A huge range of workplaces incorporate latex-containing products into their premises. General manager at Fabri-Cell, Ron Williams told Safety Solutions that from an industrial perspective, a wide range of safety gloves and other products contain latex.

"In general industry, you have a diversity of users such as the food processing industry, pharmaceuticals manufacturing and the automotive industry," he says.

"The medical institutions such as hospitals, health and aged care, general practitioners and dental surgeries are all major consumers of disposable latex products.

"These products are also consumed in considerable quantities in service industries like cleaning and janitorial, retail food preparation and service."

Latex products have been used for a long time, but it is relatively recently - the last 15 years or so - that such spikes in the reporting of adverse reactions to latex in the workplace have been seen.

Guidelines increase latex use

Sydney's St Vincent's hospital attributes this increase to the release of guidelines for Universal Precautions by the Center of Disease Control and Prevention in Atlanta in 1987. These guidelines were issued in response to the AIDS epidemic and saw an increase in latex glove use of 8:1 in just one year.

"These guidelines instructed healthcare workers to wear gloves for almost the entire working day to prevent infection."

Many cases of latex sensitivity are gradual, with users only starting to develop allergic responses after repeated use.

This sharp increase of latex at work, at home and out and about has seen allergic responses in millions of individuals the world over. In fact, more than 15 billion pairs of latex gloves are purchased and used each year.

Most people imagine latex allergy to be a relatively non-threatening but annoying response. While this is true for some users who persist in wearing latex-containing products, for others the condition can be fatal. The Australian Society of Clinical Immunology and Allergy (ACSIA) reports a range of symptoms in response to latex allergy, ranging from mild irritation to death.

The most common response to the frequent use of latex gloves is irritant dermatitis. ASCIA describes this condition as: "A non-allergic skin rash, characterised by erythema, dryness, scaling, vesiculation and cracking. Such changes are caused by sweating or irritation of the glove with its powder residue."

At the other end of the scale, people highly sensitive to natural rubber latex could go into anaphylactic shock.

Fortunately, there have been major developments in the production of latex-containing products - especially gloves - to enable people with more minor allergic reactions to continue to use these products.

The majority of people who react to products containing latex are reacting to one of the 240 proteins found in the milky sap. A much smaller number are reacting to the chemicals that are added to the latex during manufacturing to bring out its unique qualities, such as elasticity.

These reactions occur through the latex coming into direct contact with skin or via the air. Depending on their occupation, workers' allergies can result in a few days of sick leave or decrease their capacity to earn an income.

Manufacturing low-allergen products

Ansell has described a number of manufacturing processes that can be implemented to reduce the number of proteins found in the latex.

"Manufacturers have adopted three basic approaches to reduce the natural latex rubber protein allergen content of gloves:

1. Developing leaching/washing processes either online or in the post processing of the gloves.
2. Utilisation of chlorination processes.
3. The development and utilisation of 'de-proteinised' natural latex rubber."

The company explains that in the early days of latex allergy, powdered gloves manufactured by standard methods contained some of the highest levels of natural latex rubber allergens.

"The ex-machine washing, post-processing for powdered gloves usually entailed washing the gloves in hot water with detergent, and then a final rinsing with hot water.

"The cycle times varied from one hour to one and a half hours. After the washing process the gloves were dried and powdered using a dry powdering process. Natural latex rubber formulations had to be specifically developed to withstand this type of aggressive processing.

"This was also true for powder-free gloves except that usually there was the additional step of chlorination - a process by which the rubber surface is exposed to chlorine. The chlorine reacts with the double bonds of the polyisoprene and dramatically changes the surface properties."

The added benefit of the chlorination process is that the gloves need to be neutralised and washed after their exposure to chlorine, which further assists in the reduction of the allergen content.

Despite the advances in the production of latex-containing products, there are concerns that the dramatic increase in the use of such products has meant that not all manufacturers are using the more time-intensive methods to create products with lower levels of allergens.

And there are currently no adequate standards that manufacturers must adhere to as far as latex and allergen content is concerned. "We do have standards for gloves, but these standards are mostly to do with size, fit, chemical permeation, cut resistance etc. Most of these standards have been derived from following the core principals and guidelines from those applied in Europe," says Fabri-Cell's Williams.

A guide to glove terminology

According to Food and Drug Administration (FDA) labelling regulations in the US, low-protein latex gloves must have 50 mcg or less of latex protein per gram of rubber glove.

The term 'hypoallergenic' pertaining to gloves does not mean the product actually contains a low protein count. In fact, they could actually contain more protein than regular latex gloves. The term hypoallergenic refers to the low level of chemical additives found in those products.

Low-powder latex gloves create fewer air-borne latex particles which can be inhaled. However, a recent report by St Vincent's Hospital warns that latex sensitisation can progress, even in gloves with low levels of powder.

Powder-free or powderless latex gloves can still contain up to 2 mg of powder per glove to meet FDA regulations. Manufacturers should be able to specify what the amount of residual powder is in their specific product.

There are a number of steps a workplace can take to minimise the risk of latex sensitivity. ASCIA recommends the following three steps as preventative strategies:

1. The introduction of powder-free products will immediately minimise sensitisation via the inhaled route.
2. Move to purchasing only low allergen-containing products to minimise the risk of sensitisation through compulsory glove wear. This strategy requires the cooperation of industry and the insistence on declaration of allergen content on glove products.
3. The identification of high-risk individuals.

A person who has already developed a high sensitivity to latex, however, has no choice but to cease wearing latex-containing products completely.

If latex-containing products must be used and vinyl alternatives are not suitable, the sensitive employee will need to be retrained and transferred to an area in which they do not come in contact with such products.