UCLA Department of Chemistry and Biochemistry Chemical Safety Office/ EH&S
Newsletter #6 November 1997
Which gloves offer the best protection when working with chemicals?
This is not a simple question, and it doesnt have a simple answer. Some gloves are protective against certain chemicals, while others are almost useless. The material that the glove is made from as well as the thickness of the glove determine its effectiveness. Various thickness have different protection factors. Some gloves can be used for total immersion in a solvent for a specific period of time, while others can only withstand intermittent contact with chemicals, such as splashes. Factors such as flexibility, cut and tear resistance and temperature range need to be considered when selecting gloves.
Anyone purchasing or planning to use gloves for protection should become familiar with the various protective materials which gloves are made and look at the glove selection charts for the suitability for the specific application. These charts can be obtained from the glove manufacturers, from laboratory supply catalogues, and from reference books, such as "Prudent Practices in the Laboratory", "Fundamentals of Industrial Hygiene" and other sources.
The common materials used in protective gloves are natural rubber, neoprene, nitrile, PVC and PVA. These are the large, thick type "rubber gloves", commonly used for handling hazardous chemicals. A chart showing solvent permeation rates through glove materials is shown here for various solvents and glove materials.
Disposable latex gloves should NEVER be used when handling toxic or hazardous materials.
They are simply not protective against these chemicals.
Latex gloves are totally destroyed by most solvents.
Disposable gloves are preferred by most students, researchers and staff because of the convenience of their use. Although they have numerous advantages such as providing good manual dexterity, they tear easily and are permeable to many solvents. Their use is not recommended for industrial settings.
If disposable gloves are used , they should be changed immediately after a splash or other contamination. Gloves should be changed frequently even if direct contact has not occurred.
As the recent case at Dartmouth College shows, use of disposable latex gloves, while handling toxic materials, can be fatal. Dr. Karen Wetterhahn, an international expert in heavy metal toxicology, was wearing latex gloves while dispensing dimethyl mercury. According to reports in C&E News and other sources, she spilled a few drops of dimethyl mercury on the disposable latex glove she was wearing while transferring the liquid in a fume hood, for an NMR standard. Three months after this single exposure, she experienced nausea and vomiting spaced weeks apart. Approximately five months after exposure, she noticed difficulty with balance, speech, loss of vision and hearing. Medical evaluation revealed a whole blood mercury concentration of 4000 ug/L which is 80 time the toxic threshold. Her symptoms progressed rapidly over three weeks to cognitive defects and coma. Ten months after exposure to dimethyl mercury, Dr. Wetterhahn died.
Permeation tests done by an independent testing laboratory found that dimethyl mercury penetrates disposable latex gloves in 15 seconds or less, and perhaps instantaneously.
The incident tragically illustrates the point that disposable latex gloves and/or disposable PVC or PVA DO NOT PROTECT against hazardous chemicals. Dr. Wetterhahn was following familiar procedures when she was working with dimethyl mercury, including using latex gloves.
For work with significant , direct contact with toxic or aggressive chemicals, a highly resistant glove should be worn.
Such a glove is a laminate (Silver Shield or 4H) worn under a pair of long, cuffed, unsupported neoprene, nitrile or similar heavy duty gloves.
Disposable latex gloves are not suitable!
Disposable nitrile gloves are available from the Research Storeroom, Room 3056 Young Hall. They are manufactured by Best Gloves and are useful for intermittent exposure. They are not designed for total chemical immersion; they provide protection from splash and intermittent contact only. They are manufactured in three thickness, 4 mil, 6 mil, and 8 mil. There is a comparison chart which provides information on permeation and degradation of these gloves. The chart is available in the Research Storeroom or in the Chemical Safety Office. They have a web site available at http://www.bestglove.com.
There are other disposable gloves which are available from laboratory supply catalogs. Remember to consult glove suitability and resistance charts or contact the manufacturer to determine if they are suitable for your application. YOU need to find out this information for your own protection.
|Bill Peck||Chemical Safety Officer||Young Hall 4204||(20)6-2661|