Chemical accelerators in glove production – and what accelerator-free really means
Accelerators give a glove its strength and elasticity, and cause roughly 80 % of glove-related contact allergy. Which families are used, and why a glove labelled "accelerator-free" may not be.
Accelerators are the chemicals that make a glove a glove. Without them, vulcanisation is too slow and too incomplete to produce the tensile strength, elasticity and barrier performance that a medical glove needs. They are also the leading cause of glove-related contact allergy, responsible for roughly 80 % of allergic contact dermatitis cases associated with single-use gloves [1].
That is the trade-off, and it is genuine. This article covers which accelerators are used, what they do, the health consequences, and – the part that matters most commercially – why a glove labelled "accelerator-free" may not be.
The three families
Accelerators used in glove manufacture fall into three groups. A manufacturer typically uses between one and six in a single formulation.
Thiurams carry the highest allergy burden – around 80 % of Type IV allergies linked to rubber products [2]. At Eastwest Medico we refrain from thiuram accelerators entirely.
Dithiocarbamates have a second problem beyond sensitisation: they are also used as fungicides, and handling salad produce with rubber gloves can deposit reportable levels of dithiocarbamate residue on the food. The risk is highest with gloves that have already been worn. The recommendation from that work is blunt – rubber gloves should not be used for handling produce at any stage of harvesting, grading or distribution [3]. Worth knowing if you are specifying gloves for food handling as well as clinical use.
Mercaptobenzothiazoles are largely historical now, but the mechanism is instructive. MBT is a non-volatile vulcanisation accelerator and an intermediate in producing other accelerators [4]. On exposure to occupational oxidants – hypochlorous acid, iodine, hydrogen peroxide, all common in clinical settings – MBT oxidises to MBTS within the glove matrix, and subsequent reactions with proteins are thought to contribute to its allergenicity [5]. In a 2005 survey ZMBT was found in 9 of 19 gloves tested, at 0.15 to 1.5 µmol/g of glove material [4]. Two decades on, most manufacturers have moved away from this family.
Why accelerators are used at all
The point is easily lost in the allergy discussion: accelerators are not an optional additive that a manufacturer includes to cut corners. They speed the crosslinking reactions between rubber molecules, which is what turns raw latex or nitrile compound into a film with useful properties. Removing them costs:
Accelerator-free production is slower, harder to control, and yields less. That is why accelerator-free gloves cost more, and why the price gap is not going to close.
The health picture
Type IV delayed hypersensitivity is cell-mediated and appears 6 to 48 hours after exposure [1]. It is not noticeable on first exposure and develops over repeated contact, which is why it disproportionately affects people who wear gloves all day rather than occasionally.
Symptoms present as contact dermatitis: redness, swelling, small blisters, itching. Chronic cases progress to dry, thickened, peeling skin and open lesions [1] – and open lesions on the hands of a healthcare worker are an infection-control problem, not just a comfort one.
Medical gloves are among the most frequent causes of occupational allergic contact dermatitis, particularly among healthcare workers. In a study of 23 patients with allergic contact dermatitis from rubber accelerators, every patient had positive patch test reactions to one or more of carbamates, thiurams, 2-mercaptobenzothiazole and 1,3-diphenylguanidine [6]. The range matters: switching from one accelerated glove to another accelerated glove often changes nothing.
Note also that nitrile was itself introduced as the allergy-safe alternative to natural rubber latex. It solved the Type I latex protein problem and inherited the Type IV accelerator one [7]. Latex allergy is in decline; accelerator sensitisation is not.
The claim to be sceptical about
This is the section to read if you buy gloves.
Gloves marketed as "accelerator-free" have been found to still contain accelerators [8]. The mechanism is a definitional sleight of hand: some manufacturers base the claim on test reports showing accelerators are non-detectable by water and acetone extraction. Non-detectable residue is not the same as never used. Gloves passing that test can and do still provoke reactions in people with established Type IV allergy.
So the specification test is straightforward:
Accept a glove as accelerator-free only if the manufacturer provides a declaration that no accelerators were used in the compounding – not an extraction test report showing none were detected.
That single sentence in a tender document filters out most of the market. Our own biodegradable nitrile glove is accelerator-free by formulation, and the declaration says so.
A related caution: for someone with a diagnosed sensitivity to a specific accelerator, "accelerator-free" from an unverified source is not a safe substitution. Change glove type, verify the declaration, and where sensitisation is established, cotton or nylon inner gloves reduce exposure further [1].
What accelerator-free gloves are actually like to wear
Beyond the allergy case, there are two practical differences reported consistently by users:
Where they earn their price is any setting with all-day glove use: healthcare, dental, laboratory, food processing, pharmaceutical production, electronics assembly. For occasional use, standard nitrile is usually the rational choice.
What to require in a tender
Key takeaways
Frequently asked questions
Which accelerators are used in single-use gloves? Principally thiurams, dithiocarbamates and benzothiazoles, in combinations of one to six compounds depending on the formulation.
Are all nitrile gloves accelerator-free? No. Standard nitrile gloves are accelerated and may retain residual thiurams or carbamates. Nitrile solves the latex protein allergy problem, not the accelerator one.
What causes glove allergies? Two distinct mechanisms. Type I is an immediate reaction to natural rubber latex proteins. Type IV is a delayed reaction to residual processing chemicals, chiefly accelerators, and occurs with synthetic gloves as readily as with latex.
Is "accelerator-free" the same as "hypoallergenic"? No. Hypoallergenic has no agreed definition in this context and should not be accepted in a specification. Accelerator-free, when backed by a compounding declaration, is verifiable.
How do I know if a glove is really accelerator-free? Ask for a declaration from the manufacturer that no accelerators were used in compounding. Reject extraction test reports offered in place of one – they demonstrate non-detectability, not absence.
References
[1] – Allergic contact dermatitis (Type IV) and its implications for single-use gloves, Shield Scientific [2] – Allergies, Sempermed knowledge area, archived August 2025. The page has since moved to HARPS Global and no longer states the figure. [3] – Dithiocarbamate contamination of salad produce and the use of rubber gloves [4] – SCCP opinion on mercaptobenzothiazole, European Commission [5] – Oxidative transformation of MBT to MBTS, Chemical Research in Toxicology [6] – Allergic contact dermatitis from rubber accelerators in gloves, JAMA Dermatology [7] – Contact allergy to rubber accelerators, PubMed 25711250 [8] – Accelerator-free gloves, Shield Scientific technical newsletter
Seventeen years sourcing and supplying medical gloves and PPE to governments, UN agencies, NGOs and healthcare systems. Writes on glove standards, quality management and responsible sourcing for institutional buyers, working from the source standards rather than secondary summaries.
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