Handle with Care

A Primer on Protective Gloves

Probably the single most common item of personal protection in the laboratory is the glove. Yet it is also the item most likely to receive the least amount of thought or consideration and may be the most misunderstood. In the laboratory, when we need to protect our hands, we often reach for whatever is closest, put it on and think we are good to go. We are protected from … anything, everything. Whoever put that box of gloves on the shelf must have known the hazards faced in the lab and selected the proper type, right? Why else would they be there? Not so fast. Do you recall the highly publicized fatality of the New Hampshire researcher in 1997? She was working with dimethyl mercury. While transferring the material in a hood, a few small drops spilled onto the back of her latex-gloved left hand. She cleaned up the spill, removed and disposed of her gloves, and didn’t give any more thought to the incident until she was hospitalized five months later. Almost 300 days post-exposure and after three months of aggressive treatment, she died from mercury poisoning. 1,2 Latex offers no protection from this organic substance, and glove permeation occurred in about 15 seconds.

Assess the job and the risks

Granted, this tragic accident is an extreme example, but thousands of accidents occur every year due to improper hand protection. Given the myriad glove types and materials, it is imperative that both employees and supervisors know which gloves are suitable for the task at hand (no pun intended). This brings us to the first step in a good hand protection program—conduct a detailed and thorough glove audit and job hazard analysis. We have written articles on this previously, but it boils down to simply identifying the hazard and the employees at risk, then selecting the right control measures, which include personal protective equipment, for the job. When performing the audit and hazard analysis, keep in mind questions like:

• Can the procedure or process be changed to prevent or eliminate the hazard?
• Can a less hazardous material or substance be substituted?
• Will personal protective equipment solve the problem?
• Is the risk acceptable?

Identify the hazard(s)

Hazards in a research laboratory span a wide array. Physical hazards such as cuts or punctures from broken glassware or burns from hot equipment or containers demand a much different protective glove than chemical hazards such as dermatitis, corrosive burns or absorption. Fortunately, innovations in materials and technology have produced a huge selection of protective gloves for nearly every purpose. Advanced polymers and fibers provide superior protection from abrasion, punctures and lacerations compared to the old standbys, cotton and leather. These new materials provide even more protection when various coatings are applied.

When we enter the realm of the typical research laboratory, though, the characteristic we most need in gloves is resistance to chemicals. Chemicals take all forms—liquids, dusts or powders, gases and vapors—and selecting the right glove will require a little homework. Luckily for us, there are excellent manufacturers’ Web sites available to help. (A few of these resources are given below.) But before we leap into cyberspace, we should know the terminology or lingo so we can decipher the mountain of information out there. Here are the most important ones:

• Contamination: Occurs when the inside of the glove is contaminated, either prior to or during donning (putting the glove on). Manufacturers cannot prevent this. Only careful and conscientious employees can. Make sure everyone is trained and follows good, safe housekeeping procedures.
• Penetration: Happens when a substance passes through a seam or damage in the glove, e.g., a pinhole or tear. Employees must be very attentive. Double-glove when handling extremely hazardous materials. Change to fresh gloves at the first sign of a problem or if there is any doubt about integrity.
• Degradation: Happens when the chemical breaks down or damages the glove material. Manufacturers usually provide an over-time rating. Selecting the best or most appropriate glove material, i.e., the highest rating for the longest time, is key to preventing exposures from degradation.
• Permeation: Occurs when the substance passes through the intact glove material at the molecular level. This is commonly referred to as “breakthrough” and is usually rated in terms of minutes. The larger the breakthrough number, the longer the glove material can be in contact with the chemical before contamination takes place.

Choose the best glove for the job

As we mentioned above, the Internet resources provided below will help you select the best glove that will provide the most protection. For chemical mixtures or multiple hazards, pick the glove with the highest resistance to the most toxic substance or consider a doubleglove protocol. If in doubt, do not hesitate to call the manufacturer’s representative for technical assistance. To get you started, here is a brief summary of the major glove materials.

Nitrile—Nitrile is a synthetic polymer made from acrylonitrile, butadiene and any one of many carboxylic acids. It is a very good substitute for natural rubber, vinyl or neoprene. Nitrile provides excellent protection from many corrosives, solvents, oils and grease. Nitrile is generally more resistant to cuts, snags, punctures and abrasions than neoprene or PVC gloves of the same thickness. Nitrile gloves do not contain latex, a source of many allergic reactions. Dexterity is considered very good.

PVC—Polyvinylchloride gloves are typically resistant to petroleum hydrocarbons, oils, acids and caustics. They also may provide protection from alcohols and glycol ethers, but not ketones, aldehydes or aromatics. They provide very good abrasion resistance, but dexterity is poor to fair depending on the specific product.

Butyl—Butyl rubber is a copolymer of isobutylene (usually 98%) and isoprene. It was first developed for tire inner tubes, as this material generally has the highest permeation resistance to gases and water vapors. Butyl rubber provides good chemical resistance to alcohols, aldehydes, amines, bases and glycol ethers. Butyl rubber does not do well against halogenated compounds, aliphatic or aromatic hydrocarbons. Flex and dexterity can be very good with the right product.

Viton®—This is a DuPont trademark for a fluoroelastomeric material. It was developed specifically for handling chlorinated and aromatic solvents. Viton gloves are also reported to provide excellent resistance to PCBs. Abrasion resistance is very good, as are flexibility and dexterity.

Silver Shield®—This is a trade name for a flexible laminate made of polyethylene/ethylene-vinyl alcohol. This material offers resistance to permeation and breakthrough for the widest range of hazardous and toxic chemicals. Silver Shield material is excellent against aromatics, chlorines, esters and ketones. Abrasion resistance is very good. Dexterity and flexibility are fair to good depending on the product.

Wrap-up

Choosing the right protective glove for the job is critical for safe handling of hazardous and toxic chemicals. The descriptions above should be used for general guidance. We must stress that you should match the individual glove by manufacturer and style to the required task and exposure particulars. No single glove will protect against all harmful substances. Nor will one glove suit all applications. No matter which glove is used, all gloves can potentially leak or become punctured or torn. No glove can offer 100% protection as permeation and degradation take their toll during use. To ensure the highest level of protection, train employees to know the hazards of the substances they handle and the estimated breakthrough times for the gloves selected. Always handle toxic and hazardous chemicals with utmost care.

References

1. Dimethylmercury Hazard Information Bulletin, OSHA. March 1998. www.osha.gov/dts/hib/hib_data/hib19980309.html
2. Delayed Cerebellar Disease and Death after Accidental Exposure to Dimethylmercury, David W. Nierenberg et al. New England Journal of Medicine. June 1998. http://content.nejm. org/cgi/content/full/338/23/1672?ijkey=576bbde99ab04c294 5a8286ebe7b275c6c057a72&keytype2=tf_ipsecsha