Contact dermatitis is a major problem for workers in many industries. Skin-related health issues are the third-highest reported cause of occupational impairment. Only musculoskeletal disorders such as back injuries and hearing damage outrank dermal allergies in frequency. Work-related contact dermatitis is most often seen in industries involving sanitary maintenance, health care or construction. Common to these jobs is required protective handwear, most often your garden-variety rubber glove.
When contact dermatitis occurs, the first instinct is to blame it on the gloves. However, more often than not, the reason for the allergic reaction is not attributable to one agent but is a combination of rubber and another source. As more information on the dangers of latex allergy is made available, rubber frequently becomes the primary suspect in cases of work-related dermatitis. In reality, chemicals such as detergents and cleansers, metals such as nickel or chromium, and irritant foodstuffs could be the culprits, as these agents can and do cause contact dermatitis. Moreover, they are affected by and react with the rubber in gloves, resulting in varying degrees of skin irritation. In most cases, gloves can prevent reactions. In certain situations, however, they can aggravate a condition.
One of the most notable causes of sudden contact dermatitis is a change in soap or detergents. Skin cleansers designed for and labeled as "heavy-duty cleansers" or "waterless hand cleaners" contain solvents and abrasives such as silica or wood particles, which can be extremely damaging. Liquid soaps contain preservatives such as formaldehyde releasers, isothiazolinones and parabens -- all well-known sensitizers. Formaldehyde is used in about 5 percent of the 8,000 products registered with the Cosmetic Product Registry of the Food and Drug Administration. Reactions can occur when these agents are not fully rinsed, leaving chemical residues on the skin. Wearing gloves after using these cleansers can trap residues, resulting in increased and intensified exposure.
Chromate sensitization, resulting from exposure to wet cement, has long been known to cause allergic contact dermatitis for construction workers. Wearing gloves when handling wet cement can help prevent the occurrence of this allergy.
Certain properties of an individual chemical compound make it more absorbable, more corrosive and more likely to cause an allergic response. Characteristics like pH or solubility in lipids and water determine whether a substance is absorbed into the skin. Some chemical agents can be metabolized and absorbed by the skin, injuring dermal cells. Irritant dermatitis results when the body absorbs chemicals. Initial exposure to an irritant manifests as a localized inflammation, but repeated exposure can lead to increasingly hypersensitive reactions and a condition known as allergic contact dermatitis.
Dermal Exposures
The dermal route of exposure to toxic chemicals is not as frequent as the oral and inhalation route of exposure. The skin has some degree of natural barrier protection, and chemicals are not as readily absorbed through intact skin as by other routes. Most toxicological exposure indices such as threshold limit values (TLVs) are based on inhalation exposure. Indeed, almost all of an inhaled chemical is absorbed directly into the bloodstream. Ingested chemicals are likely to undergo some kind of metabolism and may be excreted. Exposure to chemicals by the skin route, however, can lead to allergic reactions, local skin injury or even systemic toxicity that can impede job performance, disable or kill.
With new dangers evolving daily in the workplace, safety measures must be constantly scrutinized and re-evaluated. A laissez-faire attitude toward safety is intolerable and dangerous. Tragically, the most gifted and astute researchers have sometimes paid the ultimate price, even when using accepted precautions.
Dartmouth College researcher Dr. Karen Wetterhahn died from mercury poisoning six months after a drop of the rare chemical dimethyl mercury permeated through the latex gloves she was wearing. Because of Wetterhahn's death, the awareness of the very real hazards of highly toxic chemicals in the laboratory has reached a new level. Although most toxicology data is based on oral exposure or the inhalation route of exposure, many chemicals can be absorbed through intact skin and into the bloodstream.
These "skin-notation" chemicals can cause a severe toxic effect on a target organ or body system such as the central nervous system, immune system or reproductive system. Effects can be classified as acute toxicity (from a single exposure) or chronic toxicity (resulting from long-term exposure to low levels of the chemical). Glutaraldehyde and formaldehyde are two commonly used chemicals in health care that can cause an allergic reaction in sensitized individuals from long-term exposure to low levels of either chemical. This is one reason that natural-rubber latex gloves are not recommended for use with glutaraldehyde. The chemical permeates natural-rubber latex, resulting in exposure that leads to sensitization.
It is imperative that individuals are aware of the hazards associated with any chemical with which they might work. The skin's barrier protective ability can be compromised very easily by the slightest exposure to the wrong agents. Understanding how a substance can affect the skin and knowing how to avoid aggravating contact with that substance are essential tools for workplace safety.
Chemical-protective clothing provides excellent protection and must be worn any time the potential for exposure to a hazardous substance exists. Most manufacturers of chemical protective clothing provide data on the chemical resistance properties of their products. Such data are derived from standardized testing designed by the American Society for Testing and Materials (ASTM) in the United States. The most common ASTM method for reporting chemical resistance data for gloves and chemical-resistant garments is the ASTM F-739 test method for total immersion in the test chemical. The test method simulates the worst kind of exposure to a chemical -- eight hours of total and continuous immersion in the substance.
Chemical resistance data is the best means for gauging how long a worker can safely wear a garment before significant chemical exposure occurs. Using the proper gloves can significantly reduce or eliminate potential long-term effects from exposure to hazardous chemicals in the workplace.
However, it simply isn't enough to wear gloves. A worker must wear the right glove for the right application. Wearing the wrong glove only increases the chance of suffering from a debilitating allergic reaction. In cases such as these, the glove can make an already bad situation worse. For example, latex gloves are commonly worn when handling glutaraldehyde. Latex rubber, however, allows a low level of the chemical to permeate the gloves and be absorbed by the skin. Although not immediately detectable, the wearer is exposed to low levels of glutaraldehyde. This exposure can lead to allergic sensitization. In this case, the gloves facilitated and enhanced the allergic reaction. Severe occupational skin injuries often result from the unlikely combination of chemical or biological hazards and rubber gloves used as protection.
Latex Allergy
It is estimated that almost 1 million U.S. health care workers are allergic to latex rubber. Latex-related allergy is one of the most common causes of disability among health care professionals. Allergic reactions to latex rubber can occur in varying degrees of severity, from a mildly irritating rash to completely debilitating anaphylactic shock. To guard against occupationally induced illnesses like latex allergy, never get too comfortable with safety precautions.
Most allergic reactions occur with unsupported gloves. Most of these reactions are reported in a health care environment where gloves are worn and changed frequently and hands are washed whenever those gloves are changed. There are at least three causes of contact and allergic contact dermatitis (Type IV Delayed Contact Urticaria). Natural rubber proteins, glove powder or rubber accelerators can cause irritant or allergic contact dermatitis.
A small percentage of the general population is allergic to the rubber accelerators used to process rubber gloves. These accelerators are used in natural rubber and synthetic rubber (nitrile) gloves and commonly include carbamates, thiurams and mercaptobenzothiazole (MBT). These ingredients are present in almost every elastomeric or unsupported glove made. Thiuram accelerators are responsible for about 60 percent of cases of contact dermatitis from accelerators. Carbamates are responsible for about 30 percent, and thiazoles, like MBT, account for 1 percent to 5 percent of cases. To determine which ingredient is causing the contact dermatitis, consider the following process of elimination:
- If previously identified as allergic to natural rubber proteins, change to a synthetic alternative glove (nitrile or vinyl).
- If still allergic after changing to a nitrile glove, an individual could be experiencing irritant contact dermatitis from the cornstarch powder. If so, a powder-free nitrile should be used.
- If allergic reaction is still present, even after changing to a nitrile glove, allergies may stem from the rubber accelerator used during processing.
These accelerators are known to cause allergic reactions in some individuals. An individual can be allergic to one or to all rubber accelerators. If no accelerator can be tolerated, try a vinyl disposable glove or a glove that is free of accelerators. Another viable alternative is to wear a disposable food handler's polyethylene glove under a nitrile glove.
Contact dermatitis may have many causes, including soaps, water, metals, foodstuffs, chemicals and rubber. Because contact dermatitis can be a lifelong condition, it is very important to identify the cause of the condition and make any necessary lifestyle changes to prevent exposure and illness. These changes may involve:
- Altering work habits;
- Avoiding certain soaps, creams or detergents;
- Eliminating exposure to metals by wearing gloves when working with wet cement, avoiding cheap jewelry and avoiding nickel and coins;
- Using a glove that offers more protection from chemicals such as corrosives, irritants or sensitizers;
- Changing to a nonlatex glove to avoid latex proteins; and
- Changing gloves to avoid certain accelerators.
Because there are many causes of contact dermatitis, identifying the irritant agent and avoiding subsequent exposure seems very complicated and troublesome. Given that healthy hands are a vital part of a productive and satisfying career and lifestyle, it's an effort well worth making.
Donald F. Groce is a product development manager for Best Manufacturing, a privately held glove maker based in Menlo, Ga. An analytical chemist, Don worked for the Centers for Disease Control prior to joining Best on clinical studies that included the Agent Orange Report. He is a noted speaker and expert on a variety of occupational and workplace hazards, including latex allergies and chemical exposure-related illnesses.