Chapter 211. Occupational Skin Diseases Due to Irritants and Allergens

Occupational dermatoses are any abnormal conditions of the skin caused or aggravated by substances or processes associated with the work environment. Occupational skin diseases (OSDs) are a major public health problem because they are common, are often chronic, and have significant economic impact on society and on workers.1 A thorough knowledge of potential irritants, allergens, and other causative factors in the workplace, as well as the workers’ compensation system, is essential for the dermatologist dealing with occupational dermatoses.

The US Department of Labor publishes annual incidence statistics on the safety and health of employees in private industry (http://www.bls.gov/). In 2008, of the 3.8 million nonfatal job related injuries and illnesses reported among the private industry establishments, 5.1% (193,800 cases) were work-related illnesses, of these, skin disorders were the second most common reported illness, accounting for almost 38,000 cases.2 Occupational contact dermatitis is the most commonly reported OSD, and in most countries, the reported incidence of occupational contact dermatitis varies from 5 to 19 cases per 10,000 full-time workers per year.3 Incidence rates also vary based on the specialty of the reporting physicians; rates are six to eight times higher in some studies when cases are reported by occupational physicians rather than by dermatologists.4

The number of OSD cases has declined,5 especially in the past 8 years, possibly due to better prevention, the ease with which workers’ compensation cases are accepted, and a change in reporting patterns of employees or employers.6 However, a large number of minor or transient cases still go unreported or untreated, so the exact incidence is not known. Occupational skin disease still accounts for a significant percentage of days away from work. In 2008, dermatitis led to 3,170 (8.4%) of the skin disease cases resulting in days away from work and 2,630 (83%) of these cases were caused by contact dermatitis.2

Distribution of nonfatal occupational injury and illness cases by category is demonstrated in Figure 211-1. Surface wounds and bruises and trauma-induced injuries are not considered among the skin disease and illnesses. Surface wounds and bruises accounted for 11,2870 (12.24%) of all traumatic injuries and disorders cases involving days away from work in 2008.7

(See Chapter 48.)

Irritant contact dermatitis (ICD) is a nonimmunologic inflammatory reaction of the skin to contact with a chemical, physical, or biologic agent. ICD is the most common OSD, accounting for up to 80% of cases, although some authors have found a relatively equal distribution of ICD and allergic contact dermatitis (ACD).3Chapter 48 discusses ICD in detail. Exogenous and endogenous factors influencing ICD are listed in Tables 48-1 and 48-2. In addition to the more common acute and chronic eczematous reactions, the clinical spectrum of ICD includes ulceration, folliculitis, acneiform eruptions, miliaria, pigmentary alterations, alopecia, contact urticaria, and granulomatous reactions (Table 211-1).8

Major Categories of Irritant Contact Dermatitis

The two major types of occupational ICD are acute ICD and cumulative ICD. These and the many other subtypes are discussed in Table 48-3, which summarizes their time onset and prognosis.

Acute Irritant Contact Dermatitis, Including Chemical Burns

Acute eczematous dermatitis after exposure to a potent irritant, often an acid or alkali, may overlap with chemical burns. Highly irritating chemicals may induce a reaction in anyone if the concentration and duration of action are sufficient. The intrinsic nature of the chemical is also important. Common irritants in the workplace are discussed in Common Occupational Irritants later in the chapter. In national statistics for work-related injuries, acute ICD reactions are often classified as chemical burns (Fig. 211-2).

Cumulative Irritant Contact Dermatitis

Cumulative ICD, the most common type of ICD, develops slowly after multiple subthreshold exposures to mild irritants (soap, water, detergents, industrial cleansers, solvents, etc.) under a variety of conditions.9 Some of the high-risk occupations for ICD are listed in Table 211-2. For a comprehensive list, see the sources presented in eTable 211-0.1. The other categories of ICD, as well as predisposing factors, including exogenous as well as endogenous factors, are discussed in Chapter 48. Atopic individuals have an increased susceptibility to skin irritation and account for a large percentage of workers’ compensation dermatitis claims.

Low-Humidity Dermatitis

Workers, especially atopic individuals who are subjected to low relative humidity at work (Table 211-3),10 are also at risk for developing dermatitis, especially with the presence of other irritants. When relative humidity is below 35%–40%, the stratum corneum becomes drier and more brittle, and shows increasing permeability to marginal irritants. Symptoms such as pruritus and burning may be the only complaints and are more distressing than physical signs, which may involve exposed or covered areas. Differential diagnosis includes irritation from airborne substances, other dermatoses, and psychogenic causes.

Airborne Irritant Dermatitis

Airborne irritants are an important cause of contact dermatitis. The pattern is fairly characteristic, with subjective symptoms of stinging, burning, or smarting sensations. Objective findings range from barely visible diffuse lesions to more severe dermatitis of the eyelids, cheeks, nasal folds, and neck. Some airborne irritant particles cause symptoms only if occluded under clothing in the flexures and other intertriginous body areas.

The most frequent causes are irritating dusts and volatile chemicals, such as solvents, ammonia, formaldehyde, epoxy resins and their hardeners, cement dust, fibrous glass, and sawdust, especially from irritating woods.11 See Table 48-4 for a list of other airborne irritants.

Diagnosis of Irritant Contact Dermatitis

The diagnosis of ICD is based on a history of exposure to a known potential irritant, the clinical appearance, and the distribution of lesions.12 Subacute and chronic irritant dermatitis are almost always diagnoses of exclusion. Patch testing (see Chapter 13) helps to distinguish ACD from ICD or to diagnose a superimposed ACD or ICD. More detailed criteria for the clinical diagnosis of ICD are discussed in Chapter 48 and especially Box 48-1 and Table 48-7.

Common Occupational Irritants

Soaps and Detergents

Soaps and detergents are weak skin irritants; however, excessive use can cause cumulative insult dermatitis in susceptible individuals. The choice of cleanser varies with the job for which it is intended; for example, machinists and auto mechanics need a cleanser with a high detergent and abrasive action. The inappropriate use of products intended as industrial cleansers can also result in dermatitis.

Waterless Hand Cleaners

Waterless hand cleaners are formulated to remove tough oil and grease stains and are widely used at work sites where there is no convenient source of water. They should be applied sparingly because they may contain petroleum-derived solvents and may result in dermatitis if overused. Instant hand sanitizers, which often contain high concentrations of alcohol, can be drying to the skin.

Acids and Alkalis, Including Chemicals that Cause Burns

Chemical burns are an important cause of occupational injury.13 Copious irrigation is the primary method of treating all chemical burns; however, certain types of burns require specific antidotes and therapies (Table 211-4).14

Inorganic Acids

Inorganic acids are used in large quantities in industry; some of the occupations at risk for exposure are listed in Table 211-5. Acids are common causes of chemical burns and can cause erythema, blistering and necrosis, and discoloration of the skin. Mechanisms of action of common industrial irritants, including acids, are listed in Table 211-6.

Organic Acids

Organic acids, such as acetic, acrylic, formic, glycolic, benzoic, and salicylic acids, are less irritating than some other acids but can cause chronic irritant dermatitis after prolonged exposure. Formic acid has greater corrosive potential than other organic acids. Fatty acids, such as palmitic, oleic, and stearic acids tend to have low irritant potential.

Hydrofluoric Acid

Hydrofluoric acid (HF) is extremely irritating, even in low concentrations (15%–20%). Fluoride ions penetrate deep into the tissues and bind to calcium and magnesium ions, causing severe tissue damage including bone destruction, especially of the terminal digits of the hand.14 After exposure to lower concentrations of HF, the onset of symptoms may be delayed until release of fluoride ions occurs in deep tissues. Exposure to HF is a medical emergency requiring topical or subcutaneous administration of calcium gluconate after lavage to bind the fluoride ions (see Table 211-4).

Chromic Acid

Chromic acid is highly irritating, causing ulcerations of the skin (“chrome holes”) and perforation of the nasal septum. It can be absorbed and lead to renal failure.15

Alkalis

Alkalis saponify surface lipids and penetrate easily, leading to severe and extensive tissue destruction, including deep ulcerations that heal very slowly (see Table 211-5).

Cement

Exposure to wet cement may cause severe alkaline and thermal burns due to the exothermic reaction of calcium oxide with water to form calcium hydroxide.16 Kneeling in wet cement for prolonged periods leads to deep burns of the knees (“cement knees”) and shins.17 Burns may also result from the trapping of wet cement in gloves and boots.

Other Chemicals and Agents

Phosphorus

Phosphorus can cause deep, destructive burns. It ignites spontaneously on exposure to air. The affected area should be kept moist until the chemical is completely removed. Severe metabolic derangements have been reported after phosphorus burns, and patients should be closely monitored for multiorgan failure.18

Ethylene Oxide

Ethylene oxide burns may result from contact with porous materials and devices that have been sterilized with ethylene oxide but not properly aerated.19 Ethylene oxide may cause delayed irritant reactions (see Table 48-5). Rarely, allergic contact dermatitis is reported to ethylene oxide.66

Phenol

Phenol is rapidly absorbed through intact skin and can cause local necrosis and nerve damage.

Solvents

The chief uses of solvents are in the manufacture of other chemicals and as carriers for chemical reactions, as pressure transmitters for hydraulic systems, and as coatings, industrial cleaners, printing inks, and pharmaceuticals. After water, the most common solvents are aliphatic and aromatic hydrocarbons, esters, ethers, ketones, amines, and nitrated and chlorinated hydrocarbons (eTable 211-6.1).20,21 Volatile solvents, in particular, act by dissolving the intercellular lipid of the epidermis, causing transient “whitening” of the skin and a feeling of dryness.

Fibrous Glass

Glass fibers, or man-made vitreous fibers, cause a highly pruritic contact dermatitis that may resemble scabies. Fibers larger than 3.5 m are generally responsible. Contact can be direct, indirect (through clothing), or through the air. Fibers may cause simple mechanical irritation by penetration into the skin, or secondary ACD from the associated finishing resins (e.g., epoxy).

Fabrics

Wool and rough synthetic clothing can cause irritant dermatitis, especially in atopic individuals. Fire-retardant fabrics, “NCR” paper (carbonless copy paper), and paper facemasks, such as are used in the semiconductor and other industries, can also induce irritation.

Plants

Florists, horticulturists, gardeners, nursery personnel, farm workers, grocery store workers, and outdoor workers are at risk for developing dermatoses caused by plants (see also Chapters 13 and 48). eTable 211-6.2 lists the various clinical types of plant dermatoses.

(See Chapter 13.)

ACD is reported less frequently than ICD in the work environment, possibly because most workers are not patch-tested, and thus the disorder is not diagnosed and reported. In a multicenter study conducted by the North American Contact Dermatitis Group that examined 839 cases identified as occupational dermatitis (29% of 2,889 patients referred for evaluation of contact dermatitis), 54% were primarily allergic dermatitis, 32% were irritant dermatitis, and 14% were conditions other than contact dermatitis that were aggravated by work.22 In this series, ACD was seen most commonly in nurses; the other occupational groups represented were assemblers, nurse's aides and orderlies, machinists, students, machine operators, auto mechanics, those performing compressing and compacting jobs, and cooks. Allergens strongly associated with occupational exposure were rubber (thiuram and carbamate accelerators), epoxy resin, and ethylenediamine. The recent increase in the use of computers has led to an increase in computer-related skin diseases; including ACD caused by plasticizers and possibly neoprene and rubber accelerators in the equipment.23

The principal occupational contact allergens are listed in Table 211-7. Additional more recently reported occupational allergens are discussed in eTable 211-7.1 and eTable 211-7.2 describes difficulties in the diagnosis of ACD.

The mechanism of ACD and its clinical manifestations are described in Chapter 13. It is important to remember that if a worker develops ACD 2 or 3 days after initial contact with an allergen, the induction of sensitivity must have occurred previously, perhaps during an earlier job.

(See Chapter 38)

Contact urticaria syndrome (CUS) comprises a heterogeneous group of inflammatory reactions that usually appear within minutes after cutaneous or mucosal contact with the eliciting agent and disappear within 24 hours, usually within a few hours. CUS has four stages: stage 1—localized urticaria, dermatitis, or itching, tingling, or burning; stage 2—generalized urticaria; stage 3—rhinoconjunctivitis, asthma, or gastrointestinal symptoms; and stage 4—anaphylaxis.

There are three varieties of contact urticaria (CU): (1) nonimmunologic CU, (2) immunologic CU, and (3) CU of uncertain mechanism (see also Chapter 38).

Nonimmunologic Contact Urticaria

In nonimmunologic CU, exposed individuals develop reactions without previous sensitization. Depending on the nature of the substance, its concentration, the area of skin exposed, and the mode of exposure, the reaction usually remains localized; and systemic symptoms of wheezing, rhinorrhea, and syncope do not occur. Causative urticants include benzoic acid, sorbic acid, cinnamic acid, cinnamic aldehyde, and nicotinic acid esters.24,25

Affected occupational groups and the causative agents to which they may be exposed include the following: gardeners—nettles, various plants, caterpillar hairs, moths, and other insects; cooks—fish, mustard, cayenne pepper, and thyme; and medical and related personnel—alcohol, balsam of Peru, benzocaine, methyl salicylate, tar extracts, tincture of benzoin, witch hazel, and dimethyl sulfoxide.

Immunologic Contact Urticaria

(See Chapter 38.)

Immunologic CU, an immunoglobulin E-mediated immediate allergic reaction, occurs in persons previously sensitized to a specific agent. Atopic individuals, especially those with atopic dermatitis, are more susceptible. The prototype is natural rubber latex (NRL) allergy, which results from a reaction to one or more proteins present in NRL.26 The highest prevalence of NRL allergy is in individuals with spina bifida. Also affected are health care workers; kitchen workers; cleaners; others who wear NRL gloves; and workers involved in the manufacture of rubber bands, surgical gloves, and latex dolls.

The next most common cause of immunologic CU is food items such as raw potato and meat. Other causes are antibiotics and other medications, preservatives, disinfectants, fragrances, epoxy resin hardeners, several woods, birch pollen, and formaldehyde in clothing.

Contact Urticaria of Uncertain Mechanism

CU of uncertain mechanism includes reactions to ammonium persulfate, which is used as a booster in bleaching hair. The dermatitis, which occurs mostly in clients, has a sudden onset and is characterized by erythema, edema, severe itching, urticaria, and occasionally syncope, with wheezing and dyspnea. Hairdressers should be made aware of the seriousness of this problem. Both nonimmunologic and immunologic mechanisms have been demonstrated to be present in the immediate reactions to ammonium persulfate.

Diagnosis of Contact Urticaria

Other than for NRL allergy, there are few statistical data on CU. Data from Finland indicate that farmers (from exposure to cow dander) account for the most cases but that the highest incidence is found among bakers.25 Recent data from Australia included 143 cases of occupational CU diagnosed over 12 years, which represented 8.3% of 1,720 cases of occupational skin diseases. Natural rubber latex allergy in health care workers accounted for the majority of cases, followed by foodstuffs in food handlers and ammonium persulfate utilized in hair dressers. The most frequently affected sites of CU were the hands, all of which were occupational, followed by the arms and face.69 Diagnosis of immunologic CU typically involves skin testing with the suspected substance and serologic assays for specific immunoglobulin E. When a chemical hapten is the suspected cause, it must be conjugated with a protein, usually human serum albumin, a nonstandard procedure.71

CU occurs from direct contact with skin (most cases) or mucosa (e.g., latex and chlorhexidine; the latter may be associated with systemic toxicity), or from contact with airborne allergen (e.g., cinchona, mulberry, xylene). Exposure may be accidental or caused by equipment failure (e.g., xylene). Standard ingredients (e.g., Tinofix) or trace contaminants or impurities (e.g., an anhydride present in sorbitan sesquioleate) may be responsible. CU may be associated with other urticaria such as delayed pressure urticaria. Occasionally, only erythema, burning, and itching occur, but at least some people should develop urticaria at the application site for the agent to be regarded as causing CU. Combined CU and delayed allergic eczematous reactions may occur.27

Aspects of Evaluation

Making medical determinations in cases of putative occupational skin disorders and in workers’ compensation cases confronts the physician with several challenging tasks: (1) weighing patient assertions and demands concerning the work relatedness of the disease, job changes, and job modifications; (2) serving as gate keeper with regard to time off from and date of return to work; (3) dealing with lack of adequate workplace information—job description, list of chemicals used at the workplace, and exposures, including material safety data sheets; (4) balancing clinical judgment against technology (e.g., determining whether hand eczema in a machinist is work related when patch test results are negative); (5) establishing causation in the legal sense, which usually requires only probability of work association (within reasonable certainty or more than 50% medical certainty), rather than absolute certainty, such as fulfilling Koch's postulates.28,29

The medicolegal essentials in evaluating OSD in the workplace consist of the following:

1. Making an accurate diagnosis, including taking a detailed medical and occupational history, performing a complete skin examination, and ordering diagnostic tests as indicated (Table 211-8).

2. Determining causation. Mathias30 has proposed that a Yes answer to four of the following seven questions is adequate to establish occupational causation and aggravation in contact dermatitis cases:

   1. Is the clinical appearance compatible with contact dermatitis?

   2. Are there workplace exposures to potential irritants or allergens?

   3. Is the anatomic distribution of the eruption compatible with job exposure?

   4. Is the temporal relationship between exposure and onset consistent with contact dermatitis?

   5. Have causal nonoccupational exposures been excluded or made highly unlikely?

   6. Does the dermatitis improve away from work exposure to the suspected irritant or allergen?

   7. Do patch or provocation tests identify a probable cause?

      The Mathias criteria were found to be valid and useful in a study of occupational contact dermatitis and the concepts are applicable to other occupational dermatoses.70

3. Providing recommendations for treatment, prevention, disability status (if any), job placement, rehabilitation, and use of other resources (industrial hygiene consultation and consultations with other medical specialists, such as allergists, pulmonologists, or occupational medicine physicians).

Diagnostic Testing

Patch Testing

Because of the importance of ACD in the etiology of OSD, patch testing (see Chapter 13) should be performed in almost all cases of contact dermatitis, even in patients who are thought to have only ICD. Testing should be performed using commercially prepared allergens. Further testing with substances in the worker's environment, including topical medications, protective equipment such as gloves, sensitizing ingredients in cleansers or other products, and occasionally the products themselves (e.g., cutting oils), is sometimes indicated. eTable 211-8.1 lists additional patch testing series that may be useful in making a diagnosis. Slodownik et al recently showed that in 1,532 patients who were patch tested for occupational dermatoses, 101 patients (6.6%) reacted to their own products, which in 20 (1.3%) of these patients was the only clue for detecting the responsible allergen.42 Testing with irritants such as most solvents, soaps, cement, and the like should not be done, and patch testing with other environmental chemicals should be performed only by knowledgeable individuals to avoid false-positive irritant reactions. Standard texts can be consulted for patch test concentrations. See eTable 211-0.1.

Tests for Immediate Hypersensitivity

If type I immediate hypersensitivity is suspected, testing of agents in nonirritating concentrations can be carried, out (Fig. 211-3). Radioallergosorbent tests and skin prick testing, including to the patients own food samples, are recommended as part of the routine assessment of patients in high risk occupations for OCU, particularly if the hands are affected and there is a history of atopy and exposure to urticants.69

Initial treatment for OSDs depends on the cause and is essentially the same as that for diseases of nonoccupational origin. However, it is important that patients be told the specific cause(s) of their disease and methods to avoid recurrences, and be given information on the appropriate use of skin cleansers, topical treatments, and protective clothing as well as on other preventive measures. Most occupational skin disorders are preventable, and their avoidance requires environmental, personal, and medical methods.31

Environmental Methods and Workplace Visits

Environmental methods are the preferred control measures, but they are sometimes also the most expensive measures to implement. Environmental methods involve industrial hygiene and environmental engineering interventions such as the following:

1. Hazard identification: workplace visits are an important but often overlooked part of the evaluation of workers with OSD. Hazard identification and assessment of means of exposure can be evaluated by direct observation and may be required for problem solving, especially when more than one worker is affected.

2. Substitution of less irritating and allergenic chemicals [e.g., rubber gloves without thiurams and carbamates, an alternative resin (phenolic or polyester) for epoxy resins, an alternative metalworking fluid without a sensitizing additive].

3. Isolation and enclosure of the process.

4. Local exhaust ventilation.

5. Chemical dispensers.

6. Good housekeeping.

Personal Methods

Barrier Creams

Barrier creams have been called invisible gloves, but they are an inadequate substitute for protective clothing and are often used when gloves, sleeves, and facemasks cannot be conveniently or safely used. Several types are available: ordinary emollient creams, water-repellant creams, oil- and solvent-resistant creams, and products for use against poison ivy and poison oak. The most effective barrier creams are sunscreens and sunblocks, which ideally should be worn by all outdoor workers. Problems associated with the use of barrier creams are a false sense of security, improper selection and use, allergy to an ingredient (often a preservative or fragrance), potential for increased absorption of occupational chemicals, and inadequate or infrequent application.

Skin Cleansers

Skin cleansers are discussed in Section “Common Occupational Irritants.”

Protective Clothing

Protective clothing ranges from gloves, aprons, hoods, boots, and work shoes to full-body clothing. Fabrics that resist heat, cold, acids, alkalis, solvents, and ultraviolet radiation are available. Certain types are resistant to mildew and fire. Personal protective equipment is addressed by the Occupational Safety and Health Administration in specific standards for general industry, shipyards, marine terminals, and long-shoring, including the US Government Code of Federal Regulations (29 CFR Part 1910).32 Manufacturers of personal protective equipment provide catalogs with guidelines for the selection of clothing for various exposures. Forsberg provides a handy reference guide.33 eTable 211-8.2 lists major glove materials and present general guidance regarding their suitability for use in handling certain chemicals.

Medical Methods

Physicians often overlook certain medical aspects of prevention. Basic principles consist of the following:

1. Initial and subsequent employment physical examinations should include appraisals of the skin and evaluation of fitness for work.

2. Workers with skin disease may require accommodation in the workplace.

3. Potentially sensitizing topical preparations (neomycin, bacitracin, benzocaine, etc.) should be avoided when treating OSD.

4. Well-motivated workers should undergo medical and vocational rehabilitation; this is covered by many workers’ compensation plans.

Fitness for Work and Workplace Accommodation

The Americans with Disabilities Act of 1990 brought to the fore issues of job placement and accommodation. Most individuals with chronic skin conditions can perform normal work activities, but in some instances accommodation in the workplace is required.34

Although the prognosis of chronic OSD is guarded, there has been improvement, with clearance reported in 70%–84% of cases.35 Minimizing workplace exposure and maximizing patient knowledge regarding potential irritants and allergens is one of the most important factors in improving prognosis.35,36 Certain conditions, such as chromium sensitivity, have a poor prognosis and are notoriously long lasting. Atopic dermatitis, especially in occupations in which there is frequent or prolonged contact with water, soaps, and detergents, is also associated with a poor prognosis.

Of the several causes of persistence of OSD, the most important is an incomplete or incorrect diagnosis. Other factors include failure to eliminate the cause(s), improper job placement, improper therapy, the presence of secondary diagnoses (e.g., allergy to topical medications or multiple contact allergies), exposure to cross-reacting substances at home or in vocational activities, and improper cleansing of the skin. Some workers develop an ongoing dermatitis termed persistent postoccupational dermatitis for which there is no obvious present cause, precipitated by prior occupational dermatitis. This has significant implications for prognosis and workers’ compensation.37,38

Evaluation of patients with OSD is discussed in more detail in other sources.28,29,72 However, dermatologists should be aware of the Guides to the Evaluation of Permanent Impairment, published by the American Medical Association.73 The Guides chapter on skin disease has been used for more than 30 years to evaluate patients with permanently impairing skin disorders (diseases that have reached maximum medical improvement—often after 6–12 months’ duration) of both occupational and nonoccupational origin. The Guides are used by a number of state workers’ compensation authorities and provide examples of five classes of impairment ranging from 0% to 95%.

The current scientific approach to risk reduction in occupational health is based on risk assessment, which is separated into four basic elements: (1) hazard identification, (2) dermal exposure assessment, (3) dose-response assessment, and (4) risk characterization.39,40

Hazard Identification

Hazard identification involves determining whether exposure to an agent can cause disease or injury using material safety data sheets. Material safety data sheets provide information only about substances considered hazardous; those present in concentrations of less than 1% are not required to be listed, and the physician may need to call for additional information.

Dermal Exposure Assessment

Dermal exposure assessment determines the nature and size of populations exposed to a chemical agent via the skin, as well as the magnitude and duration of the exposure. Considerations regarding exposure include the method of exposure: spills, contaminated tools or rags, aerosols or sprays, or permeation of protective clothing. Thus, work activity (e.g., task duration and frequency, amount of chemical used), work substance (molecular weight, particle size, solubility, volatility, etc.), and worker (e.g., surface area exposed, personal hygiene, presence of dermatitis) are three major factors.

Dose-Response Assessment

Dose-response assessment describes the quantitative relationship between the dose at the target and the toxicologic effect. Persons with atopic dermatitis have increased transepidermal water loss and enhanced reactivity to irritants.

Risk Characterization

Risk characterization involves the integration of the data to determine safe exposure by comparing exposure levels with levels at which no adverse effects are observed, while allowing for a safe margin of error. With the exception of nickel and chrome exposure, few skin exposures have been characterized in this way, and it may be difficult to do so. Also, attention must be given to percutaneous absorption as well as to dermal exposure.

Medico-Legal Reports

Physicians may be asked to report on patients with putative occupational skin diseases. These may range from brief diagnosis and treatment medical reports to more complex impairment and disability evolutions for workers compensation authorities, or attorneys. Evaluation guidelines may be provided by the authority or attorney requesting the report; if not physicians should consult their own state's workers compensation guidelines, if any, or the federal government in case of federal employees. Dermatologists are usually asked to evaluate “outlying” claims such as persistent and recurrent hand eczema persisting despite job change or modification, contested claims for work-related causation or percentage of disability, and transient skin complaints with few objective findings. Workers compensation claims become more difficult to resolve the longer the patient remains out of work. References by Clark and Zirwas and by Taylor provide further information and guidance for impairment and disability evaluation for dermatologic conditions.28,29,72,73

Formal return to work guidelines is primarily utilized for musculoskeletal complaints rather than skin disorders. Workers with severe enough dermatitis to miss work often are eligible for temporary total disability which is typically short term, less than 6 months. For disorders lasting longer than 6 months, the AMA Guides to the Evaluation of Permanent Impairment may be utilized, but states differ on which edition of the Guides is accepted. Unduly restrictive limitations upon return to work, such as avoiding all contact with chemicals, may jeopardize a worker's job. Before writing such recommendations they should be discussed with the patient/employee and employer. Change of jobs does not always result in clearing of a worker's dermatitis and some union–management contracts may restrict worker placement. Some skin diseases become chronic and do not clear with treatment and allergen and irritant avoidance. Possible reasons are listed in Section “Prognosis and Persistence.” eTable 211-8.3 discusses fitness to work with skin disease and lists selected conditions that may disqualify an individual for work. eTable 211-8.4 lists some work-aggravated skin disorders that may require accommodation by an employer.

A physician's report should list and summarize all diagnoses. A summary statement regarding causation is then made; for example, within a reasonable degree of medical certainty (51% or greater) the disease is (or is not) related to work. A physician is not required to have such an opinion and in some cases may not be able to make a determination of probable cause. Impairment is then discussed including a description of specific clinical findings related to impairment; if permanent refer to the specific section of the AMA Guides.73 Specific recommendations for medical and pharmaceutical therapy should be included along with a brief explanation of the treatment. Recommendations for prevention including work restrictions are made next, including suggestions for environmental modification (exhaust ventilation, splash guards, etc.) and personal protective equipment. The effect of future exposures to chemical, physical and biological agents should be addressed, along with any need for rehabilitation. Some states and insurance carriers may provide rehabilitation services.