Most safety professionals are well aware of the issue of allergic reactions to latex that has surfaced over the past two decades. The problem has been studied and well documented, and we know a lot more now than we did ten years ago about the cause of latex protein allergy.

As awareness of this problematic issue has grown, so, too, has the use of non-latex alternatives in the manufacture of gloves. Synthetic polymers such as vinyl and nitrile have emerged as the most common alternative materials for new gloves because they do not contain any natural rubber latex and, therefore, can be used by workers with latex allergy. Vinyl gloves are inexpensive but lack the feeling of latex gloves, and studies have shown repeatedly that their protection against chemicals, abrasion and other physical hazards is limited.

What’s in a name?

Nitrile gloves are widely regarded as the optimal alternative to latex gloves. Nitrile is the commonly used name for acrylonitrile-butadiene rubber, a synthetic elastomeric polymer first developed in 1930. Nitrile is made from three constituents: acrylonitrile, butadiene and carboxylic acid. These three ingredients can be varied slightly to give custom benefits useful in different properties. Acrylonitrile is an industrial chemical that imparts chemical resistance to fats and oils. Butadiene is a gas that contributes softness and flexibility. The carboxylic acid portion of the polymer is also responsible for reacting with zinc oxide during vulcanization or curing and gives the physical properties such as abrasion resistance and tensile strength.

Nitrile gloves have excellent protection qualities when compared to latex gloves and are superior to latex when handling petroleum-based products. Recent studies have shown that nitrile gloves have an even lower failure rate than natural rubber latex gloves in side-by-side comparisons of simulated use. However, although nitrile has become a favorable alternative to latex, until recently even nitrile gloves caused allergic reactions in a small number of workers.

Type IV reactions: accelerators

Allergic reactions to synthetic gloves became apparent as non-latex glove use became more prevalent. In some cases, reactions continued even after latex use was discontinued. It was discovered that chemical additives, called accelerators, which are necessary in the manufacture of synthetic gloves, could cause some types of allergic reactions.

Most elastomeric gloves contain accelerators. Accelerators are used in natural rubber latex, nitrile and neoprene gloves to promote cross linking and polymer formation to make gloves stronger and more resilient. These accelerators generally include three classes of compounds: thiurams, carbonates and thiazoles. The type of allergic reaction to accelerators is called a Type IV reaction, and is characterized by severe contact dermatitis that may resemble a poison oak reaction. This is a localized reaction that only occurs where the glove has touched the skin and may appear much later, after the glove has been removed.

Until recently, all elastomeric gloves were made using accelerators. However, at least one major glove manufacturer has developed a patented formulation for making a nitrile glove that is accelerator-free (1). With no latex proteins and no accelerators, this glove is free of the causative agents for both Type I and Type IV allergic reactions. The glove has received an FDA 510K registration as a Class 2 medical device and, according to the manufacturer, is the only disposable rubber glove that can be labeled “non-allergenic.” In short, it provides users effective barrier protection without causing allergic reactions.

More advantages

Beyond its non-allergenic properties, nitrile has other advantages over natural rubber latex. Nitrile is more resistant to punctures, although this by no means implies that nitrile is puncture-proof. No disposable glove is puncture-proof. But nitrile gloves will tear away completely if punctured, versus latex, which is more prone to developing pinprick holes that may not be visible to the naked eye and can result in unintentional exposure to hazards.

Heavyweight nitrile gloves are commonly used in the chemical industry and in laboratories because of their solvent-resistant properties and their resistance to organic chemicals such as aliphatic hydrocarbon solvents. In comparison, natural rubber has poor resistance to organic chemicals. Nitrile is widely used in the petrochemical industry and in agricultural pesticide applications. Because they resist oils and fats, nitrile gloves are used extensively in chicken and meat processing as well.

Nitrile gloves are close to natural rubber latex in feel, fit, durability and dexterity. Continued research and development has produced lower modulus nitrile gloves and the ability to produce gloves in varying mil thicknesses, suitable for a wider range of applications. The shelf-life of nitrile is longer than natural rubber latex because of natural rubber’s tendency to break down with exposure to the elements and ozone.

When it comes to worker acceptance, durability and long-term protection from latex allergies, nitrile is a popular choice of workers today. Continued innovations on the part of manufacturers will only broaden the potential applications for nitrile and offer greater protection to workers across a variety of industries.

FOOTNOTE

(1) N-DEX® Free from Best Manufacturing, an extension of Best’s N-DEX® line