Prevent Occupational Skin Disorders
Protect Against Primary Irritants and Sensitizers

The National Institute for Occupational Safety and Health estimates that more than 13 million workers in the United States may be exposed to chemicals that can be absorbed through the skin. Dermal exposure to hazardous agents can result in a variety of occupational diseases and disorders, including occupational skin diseases and systemic toxicity.

Historically, efforts to control workplace exposures to hazardous agents have focused on inhalation rather than skin exposures. As a result, NIOSH says that assessment strategies and methods are well developed for evaluating inhalation exposures in the workplace, but are currently lacking for measuring and assessing skin exposures. Occupational skin diseases (OSD) are the second most common type of occupational disease and can occur in several different forms, including:
• Irritant contact dermatitis;
• Allergic contact dermatitis;
• Skin cancers;
• Skin infections;
• Skin injuries; and
• Other miscellaneous skin diseases.

Chemical agents are the main cause of occupational skin diseases and disorders and are divided into two types: primary irritants and sensitizers.

Primary or direct irritants act directly on the skin though chemical reactions.

Sensitizers may not cause immediate skin reactions, but repeated exposure can result in allergic reactions.

A worker’s skin may be exposed to hazardous chemicals through:
• Direct contact with contaminated surfaces;
• Deposition of aerosols;
• Immersion or splashes;
• Physical agents such as extreme temperatures (hot or cold) and radiation (UV/solar radiation);
• Mechanical trauma, including friction, pressure, abrasions, lacerations and contusions (scrapes, cuts and bruises);
• Biological agents, including parasites, microorganisms, plants and other animal materials.

Dermal absorption is the transport of a chemical from the outer surface of the skin both into the skin and into the body. Studies show that absorption of chemicals through the skin can occur without being noticed by the worker, and in some cases, may represent the most significant exposure pathway.

The rate of dermal absorption depends largely on the outer layer of the skin called the stratum corneum (SC). The SC serves an important barrier function by keeping molecules from passing into and out of the skin, thus protecting the lower layers of skin.

The extent of absorption is dependent on the following factors:

• Skin integrity (damaged vs. intact);

• Location of exposure (thickness and water content of stratum corneum; skin temperature);

• Physical and chemical properties of the hazardous substance;

• Concentration of a chemical on the skin surface;

• Duration of exposure;

• The surface area of skin exposed to a hazardous substance.

NIOSH recommends that employers follow a hierarchy of controls in order to prevent occupational skin disease in workers. Employers should take the following step to protect workers from OSD:
• Elimination: In most cases, preventing skin contact with chemicals or other skin damaging agents will prevent disease. Eliminating exposure to the compound or product that causes the skin condition is the most effective method of control.
• Substitution: If possible, employers should attempt to substitute the hazardous agent with a less hazardous compound.
• Engineering controls: If elimination or substitution is not possible, engineering controls such as local exhaust ventilation systems and isolation booths can prevent hazardous agents from contacting workers’ skin.
• Administrative controls: Employers should provide training programs that educate workers about hazards that they may be exposed to and ways to protect themselves from the hazards.
• Personal protective equipment: Personal protective equipment such as gloves, safety glasses or goggles, shop coats or coveralls, and boots should be provided by employers and worn by workers who need them.

Gloves and Hand Protection

Chemical protective clothing should not be considered as a replacement for engineering control methods. However, there are often few alternatives available, or an emergency requires their use. Since the clothing is the last line of defense for protecting the skin, care must be taken to ensure it provides the protection expected.

NIOSH says, a phrase commonly found on the Material Safety Data Sheet (MSDS), “Wear impervious (or impermeable) gloves,” has very limited value. It is technically inaccurate. No glove material will remain impervious to a specific chemical forever. No one glove material is resistant to all chemicals. Some chemicals will travel through or permeate the glove in a few seconds, while other chemicals may take days or weeks.

Information specifying the best type of chemical protective material is what should be on an MSDS (e.g., neoprene, butyl rubber).

Permeation rate is the rate at which the chemical will move through the material. It is measured in a laboratory and is expressed in units like milligrams per square meter per second (or some other [weight of chemical] per [unit area of material] per [unit of time]). The higher the permeation rate, the faster the chemical will move through the material.

Permeation is different from penetration. Penetration occurs when the chemical leaks through seams, pinholes and other imperfections in the material: permeation occurs when the chemical diffuses or travels through intact material.

Breakthrough time is the time it takes a chemical to permeate completely through the material. It is determined by applying the chemical on the glove exterior and measuring the time it takes to detect the chemical on the inside surface.

Degradation is a measurement of the physical deterioration of the material due to contact with a chemical. The material may get harder, stiffer, more brittle, softer, weaker or may swell. The worst example is that the material may actually dissolve in the chemical.

How to choose the right material for the job? Based on the above information, it’s apparent that you must carefully choose the appropriate material for each job. Before deciding about which kind of glove or other chemical protective clothing to use, you should gather and analyze information on a number of factors such as:
• Complete, accurate description of the task.
• Identification of all hazards that may require hand protection. This should include a list of the chemicals involved as well as physical hazards such as abrasion, tearing, puncture and temperature. The kind of hazards will also affect the decision to use other chemical protective clothing in addition to gloves.
• Flexibility and touch sensitivity needed for the task. This need may significantly limit the thickness of glove material that can be used. The requirement for textured or non-slip surfaces to improve grip must also be considered.
• Type of potential contact (e.g., occasional contact or splash protection or continuous immersion of hands). This will also help in choosing the appropriate length of the glove.
• Contact period. How long the worker could be in contact with the chemical (and which chemicals) may also influence the selection of type and thickness of the glove material and the choice of lined or unlined gloves.
• Potential effects of skin exposure. The immediate irritation or corrosion of the skin must be considered in addition to the potential health effects to the entire body from absorbing the chemical through the skin.
• Decontamination procedures. Consider whether the gloves should be disposed of or cleaned after use. If they are cleaned, consider the cleaning method, how often they can be cleaned, and any special procedures required for disposing of the “decontamination wash waste.”

Since personal protective equipment such as gloves are the last line of defense, considerable effort should be expended to ensure that adequate protection is actually being provided. FSM