Appendix D: Gloves
The purpose of gloves is to prevent skin contact with potentially harmful chemicals. However, the 'art' of selecting the appropriate chemically-resistant glove is not well developed. In fact, wide variations in performance are typical between different brands, different lots, and even between different gloves of a single manufacturer bearing the same lot number. Selection charts published by manufacturers are a good place to start, but keep in mind these facts:
All gloves are short-term protection devices: virtually all gloves will be penetrated by most organic chemicals at varying rates.
The rate of permeation is proportional to the square of the glove thickness: thus 4 -5 mil ('surgical' or 'examination') gloves are very short term protection, and should be discarded after use and immediately after gross contamination.
5 mil Latex gloves are very susceptible to mechanical damage, and provide at best a few minutes, often only seconds of protection against non-polar solvents. Nitrile-Latex formulations are considerably better on both counts; resistance to abrasion and resistance to permeation and penetration by non-polar organics. However, they should still be regarded as short term protection. Basically, they should provide enough time to remove the glove on accidental contamination.
Thicker (10 mil) Nitrile gloves are suitable for most procedures involving chemical handling. Note however that they are readily penetrated by some agents such as acetone and other ketones.
Butyl Rubber gloves provide much greater protection, and should be worn for procedures involving highly toxic agents or continued contact (immersion).
Double-gloving (e.g.. with 4 mil Nitrile-Latex gloves as an inside layer) provides additional security. Double-gloving with a 4 mil Laminate (Silvershield or Safety 4H) is much more effective, and is advisable for the handling of certain special carcinogens and other highly toxic agents. This combination, with Butyl rubber outer gloves, has been tested and selected by the Coast Guard Hazardous Chemical Response Team as the most effective combination for use in handling mixed and unknown Hazardous Material Spills.
Before breakthrough, gloves often become permeated with the chemical to which they are exposed. Following the use of any non-disposable glove, decontamination must be carried out or the glove will become an active source of chronic chemical exposure. Washing gloves in aqueous solution of soaps or detergents, or any non-polar solvent, removes the plasticizing agents and very rapidly degrades and destroys the glove. Volatile contaminants may instead be removed by 'off-gassing' the glove in the fume hood. Gloves may be heated to not more than 140 F to expedite the process without damage.
Any gloves which show physical degradation, including pitting, cracking, swelling or discoloration should be immediately discarded.
On removal of gloves, always wash your hands. The use of barrier or other protective skin creams is highly recommended.
All gloves provide some protection, though often very little. No gloves provide total protection.
The best strategy when handling chemicals is:
Don't Get Any On You.
The best gloving strategy is:
Don't Get Any On Your Gloves - If You Do, Take Them Off And Wash Your Hands.
While this may seem impractical at first, most of the tasks performed in the laboratory involve brief and often avoidable contact with minimal amounts of chemicals. Under these circumstances, and when the chemicals involved are 'physiological reagents' in the sense that they are dilute aqueous solutions thin (5 mil) Latex disposables are usually adequate.
These gloves are fragile however, and perform very poorly against Organic Solvents.
They are also INADEQUATE protection for:
Most Aldehydes, including Formaldehyde
Amides, including Dimethyl Formamide
All Amines
Acid Anhydrides, including Acetic Anhydride
Organic Acetates
Acrylates, including Methyl Methacrylate
Carbon Disulfide
Ethers, including Tetrahydrofuran and Glycol Ethers such as Cellosolve
All Halogenated compounds
Heterocyclics, such as Pyridine, Propylene Oxide, and Dioxane
Ketones, including Acetone.
Nitriles, including Acetonitrile
Organosilanes
They WILL withstand:
Most Alcohols, but NOT Ethanol
Phenols
Inorganic Acids and Bases at reasonable dilutions, but NOT Chromic Acid
Many Organic Acids, but NOT Picric Acid
Dimethyl Sulfoxide
Biological Agents
Because of these limitations, we advise the use of 4-8 mil Nitrile disposables in place of Latex for routine laboratory use. These have much improved mechanical strength and greater chemical resistance, with only a small loss of dexterity and tactile sensitivity. Best Mfg. Co. are the only such gloves currently available; in 4 mil, 6 mil with a long cuff (highly recommended) and 8 mil. No specific data has yet been published on permeation and penetration, however, in general;
Nitrile formulations are:
Resistant to abrasion
Very much more resistant to Organic Solvents
They are INADEQUATE protection for:
Carbon Disulfide
Ketones including Acetone, MEK or MIK
Nitriles, including Acetonitrile
Nitro-Compounds: Dinitrotoluene, Nitrobenzene, Nitrosamines
Some Aldehydes, including Acetaldehyde and Acrolein
Amides - Limited Protection against Dimethyl Formamide
Isocyanates
Methacryalates
Halogenated Organics
Propylene Oxide
Ethylene Oxide
Dioxane (Limited Protection)
Pyridine
They Will withstand:
Alcohols
Inorganic Acids and Bases including Chromic Acid, and Most Organic Acids
Organosilanes
Organic Nitrates and Nitrites
Some Aldehydes, including Formaldehyde and Glutaraldehyde
Many, but not all Amines
Most Organic Acetates; Amyl and Ethyl Acetate only briefly
Ethers and Glycol Ethers including Cellosolve, but not Tetrahydrofuran
Hydrazine
Most Aliphatic and Cyclic Hydrocarbons
Many Organic Solvents: Limited protection against Xylene and Toluene
Phenols
Picric Acid
Thin Polyvinyl Chloride (PVC) gloves are also available: Their performance is very similar to Latex, but tactile sensitivity is much reduced. They also develop 'pinhole' penetrations after brief use, and are in general not recommended.
Tasks Requiring Greater Protection
Some tasks may require more extensive chemical contact, and greater protection. This can be accomplished by the use of thicker gloves and specific selection of other polymer formulations. However, testing procedures are poorly standardized at present, and published recommendations should not be taken as guarantees of performance. If at all possible
Redesign The Task To Minimize Chemical Contact
For many of these tasks, such as washing glassware or pouring strong acids or other caustics, 10 mil Nitrile gloves should be sufficient. For tasks involving more extensive contact with any of the chemicals not recommended for Nitrile gloves, EH&S will provide assistance in determining the best choice. Some generalities:
BUTYL Rubber gloves are much superior to Nitrile in many aspects, at about 5 times the cost. In particular
They WILL withstand:
Aldehydes, including Acetaldehyde
Amides, including Dimethyl Formamide
Amines
Organic Acetates, including Amyl and Ethyl Acetate
Aldehydes, including Acetaldehyde
Acrylics, including Methyl Methacrylate
Ketones, including Acetone, MEK and MIK
Nitriles, including Acetonitrile and Acrylonitrile
Pyridine
Nitro Compounds including Dinitrobenzene and Nitrosoamines
Propylene Oxide
Ethylene Oxide
Dioxane
Most Isocyanates
They perform LESS WELL than Nitrile gloves with many Aliphatic and Alicyclic Hydrocarbons and are UNSUITABLE for Xylene, Toluene, Hexane and Pentane.
They perform LESS WELL than Nitrile gloves with many Ethers:
They WILL NOT WITHSTAND Tetrahydrofuran or Carbon Disulfide
They offer LIMITED PROTECTION to many Halogenated Organics, undergoing destructive DEGRADATION in the process.
VITON, a fluoroelastomer, is available in 10 mil thickness and greater, and provides both reasonable dexterity and will withstand most halogenated organics. It is by far the most protective conformal glove on the market for this purpose. However, their cost is again about 5 times that of butyl gloves, and they undergo destructive DEGRADATION in Ketones, such as Acetone, in many Aldehydes, including Acetaldehyde, Amides, including Dimethyl Formamide, and most Amines.
Note that while NEOPRENE gloves are recommended in some publications for Chlorinated Solvents, they are in fact rapidly destroyed by Halogenated Organics. In general, their performance is somewhat less than Nitrile.
Poly Vinyl Alcohol (PVA) is very effective in withstanding halogenated organics. It is also resistant to permeation by Tetrahydrofuran. However, it lacks tensile strength and is only available as surface coating on other materials, and is uniquely WATER SOLUBLE
Unsurpassed protection is afforded by certain thin (3-4 mil) Laminates, such as SILVERSHIELD, and SAFETY 4H. They are also reasonably priced at about $2.00-$4.00/pair. However, they are not elastic or conformal, and provide a very uncertain grip. For very difficult cases, where some loss of tactile sensitivity can be tolerated, they can provide an ideal solution when worn underneath a thin conformal glove.
