Contact Dermatitis in the United States: Epidemiology, Economic Impact, and Workplace Prevention




Contact dermatitis in the United States poses a significant public health concern. This article provides a definition of contact dermatitis and its associated risk factors. The authors discuss the epidemiology of occupational contact dermatitis including its incidence and prevalence, and describe how estimates are calculated in the United States. The burden of disease on the individual, and its economic impact and cost to society, are also elucidated. A review of preventive measures to help reduce contact dermatitis in the workplace and an additional section on patch testing concludes the article.


Contact dermatitis is defined as either an acute or chronic inflammatory reaction in response to substances that come into contact with the skin. The former is characterized by pruritus, erythema, and vesiculation while the latter involves pruritus, xerosis, lichenification, hyperkeratosis, and fissuring.


Irritant contact dermatitis (ICD) is caused by an external agent acting merely as a chemical or physical irritant, thus eliciting a nonallergic inflammatory host response. The potential to cause irritation and intensity of the reaction depends on certain features of the agent including its concentration, pH, vehicle, and length of exposure. ICD only occurs above a threshold level, which varies from person to person depending on the penetrability and thickness of the stratum corneum. Very strong irritants elicit an acute reaction after first exposure, which occurs within minutes or is delayed up to 8 to 24 hours ; however, the majority of ICD cases are attributable to chronic cumulative exposures to milder irritants (water, soap, detergents), environmental factors (low-humidity air, heat, cold) or even repetitive trauma (rubbing, friction, pressure, abrasions). Repetitive exposures create a chronic disturbance of the barrier function allowing even low concentrations of offending agents to penetrate the skin, and subsequently induce a chronic inflammatory response. Irritation is the most common cause of contact dermatitis, and the skin findings vary greatly depending on severity of exposure. Box 1 lists the most common substances responsible for ICD.



Box 1





  • Cleansers




    • Water/wet work, soaps, detergents, waterless hand cleaners, degreasing agents, bleaches, isopropyl alcohol, benzoyl peroxide




  • Acids and Bases




    • Hydrofluoric acid, cement, chromic acid, phosphorus, ethylene oxide, phenol, fluorohydrogenic acid, nonanoic acid, metal salts, inorganic and organic acids




  • Industrial Solvents




    • Benzene, toluene, xylene, ethyl benzene, cumene, gasoline, kerosene, Stoddard solvent, hexane, carbon tetrachloride, trichloroethane, tetrachloroethane, trichloroethylene, methylene chloride, ethylene dichloride, methyl alcohol, ethyl alcohol, isopropyl alcohol, glycidyl ethers, ethyl acetate, amyl acetate, butyl acetate, turpentine, ethyl ether, acetone, carbon dioxide, dimethyl sulfoxide, dioxane, styrene, metal working fluids, arsenic, oxalic acid, formic acid, salicylic acid, sodium hypochlorite, alkalis, anhydrides




  • Chemicals




    • Sodium, potassium, lithium, phosphorus, phenolic compounds, bromine, iodine, ethylene oxide, aluminum chloride, propylene glycol, sodium lauryl sulfate, butanediol diacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, anthralin, benzalkonium chloride, 2-chloroethyl sulfide, calcipotriol, 2-chlorovinyl arsine, epichlorhydrine, octyl gallate




  • Plants




    • Euphorbiaceae (spurges, crotons, poinsettias, machineel tree). Racunculaceae (buttercup), Cruciferae (black mustard), Urticaceae (nettles), Solanaceae (pepper, capsaicin), Opuntia (prickly pear), furocoumarins




  • Materials




    • Fiberglass, wool, rough synthetic clothing, fire-retardant fabrics, noncarbon copy paper




  • Airborne Irritants




    • Acids, alkalis, ammonia, anhydrous calcium sulfate, arsenic, calcium silicate, cement, dichlorvos, domestic cleaning products, epoxy resins, formaldehyde, fiberglass, industrial solvents, metallic oxide powders, paper, phenol formaldehyde resins, sawdust, silver, sodium sesquicarbonate, urea-formaldehyde insulating foam, dust foam, wool dust, tear gases




  • Others




    • Cosmetics, oils, greases, foods, medications (benzoyl peroxide, tretinoin, diclofenac, podophyllin), animal products




The most common irritants

Data from Amado A, Taylor JS, Sood A. Irritant contact dermatitis. In: Wolff K, Goldsmith LA, Katz SI, et al, editors. Fitzpatrick’s dermatology in general medicine. 7th edition. New York: McGraw-Hill; 2008. Available at: http://www.accessmedicine.com/content.aspx?aID=2950409 . Accessed April 15, 2011; and Taylor JS, Sood A, Amado A. Occupational skin diseases due to irritants and allergens. In: Wolff K, Goldsmith LA, Katz SI, et al, editors. Fitzpatrick’s dermatology in general medicine. 7th edition. New York: McGraw-Hill; 2008. Available at: http://www.accessmedicine.com/content.aspx?aID=3001176 . Accessed April 15, 2011.


Allergic contact dermatitis (ACD) is caused by an external agent acting as a specific antigen or allergen, producing the classic, delayed, T-cell–mediated (type IV) hypersensitivity response. As an immunologic phenomenon, it tends to involve the surrounding skin and can even spread beyond the initial exposure site. When the allergen elicits an incredible immune response, the skin eruption becomes generalized. Systemic ACD (SACD) describes a cutaneous eruption in response to a systemic exposure of a previously sensitized allergen. Several routes of exposure have been reported to elicit SACD such as subcutaneous, hematogenous, intravenous, intramuscular, inhalation, and oral ingestion. Table 1 lists the most common allergens responsible for ACD according to patch-test results from the North American Contact Dermatitis Group (NACDG) in 2005 to 2006.



Table 1

The most common allergens



































































Patch–Test Allergen Positive Reaction (%)
Nickel sulfate 19.0
Balsam of Peru 11.9
Fragrance mix 11.5
Quaternium-15 10.3
Neomycin 10.0
Bacitracin 9.2
Formaldehyde 9.0
Cobalt chloride 8.4
Methyldibromoglutaronitrile 5.8
p -Phenylenediamine 5.0
Potassium dichromate 4.8
Carba mix 3.9
Thiuram mix 3.9
Diazolidinylurea 3.7
2-Bromo-2-nitropropane-1,3-diol 3.4
Cinnamic aldehyde 3.1
Imidazolidinylurea 2.9
Propylene glycol 2.9
MCI/MI 100 ppm 2.8
Tixoorto-21-pivalate 2.7

Abbreviation: MCI/MI, methylchloroisothiazolinone/methylisothiazolinone.

Data from Zug KA, Warshae EM, Fowler JF, et al. Patch-test results of the North American Contact Dermatitis Group 2005–2006. Dermatitis 2009;20:149–60.


Besides the major division of contact dermatitis as either irritant or allergic, other classifications of contact dermatitis as well as a spectrum of contact responses of the skin exist, and are often underreported to the physician or employer. Subjective irritancy describes idiosyncratic stinging and smarting reactions that occur within seconds to minutes of contact without visible skin changes, and last either momentarily or for several hours. Toxic or caustic burns are the most severe form of an acute irritant reaction wherein the skin undergoes necrosis. The most severe irritants, such as strong acids and bases and oxidizing and reducing agents, create toxic reactions even with a very small amount and brief exposure. Airborne ICD and ACD arise when irritating dusts, volatile chemicals, or allergens suspended in the air become exposed to skin, producing a contact dermatitis. Phototoxic and photoallergic reactions occur when a chemical or drug is absorbed into the skin via oral ingestion, subcutaneous injection, or topical application. The offending agent acts as an irritant or antigen only after exposure to and activation by ultraviolet (UV) light. Finally, occupational contact dermatitis describes any type of contact dermatitis caused by agents present at a place of employment or trade. ACD, ICD, and acute caustic chemical injuries are the most common toxin-related skin problems in the workplace. As such, occupational contact dermatitis (OCD) is the most common occupational skin disease in the United States and in many other countries.


Risk factors


Contact dermatitis is broadly classified into irritant and allergic reactions, thus skin exposure to potential irritants and allergens is a clear prerequisite for its development. However, the multifactorial etiology of contact dermatitis, with numerous extrinsic and intrinsic factors influencing its development, often makes the exact causative agent difficult to determine. Extrinsic factors include occupation, geographic and environmental factors, biochemical properties of allergens and irritants, and cultural factors, while intrinsic factors include age, sex, race, epidermal barrier integrity, atopic constitution, and genetics, all of which contribute to skin reactivity.


Occupation


Occupation is a key factor in the development of contact dermatitis, with 90% to 95% of all occupational skin diseases representing some form of contact dermatitis. OCD was found to be the most common among metalworkers, construction workers, professional hairdressers, waiters, cleaners, health care workers, agricultural workers, chefs, and food workers, with the highest prevalence found among cosmetologists. The most common sources of allergic sensitizations identified were metallic objects followed by drugs, cosmetics, and rubber. As expected, the most common occupations with ACD were hairdressers, construction workers, and metalworkers. In comparison, the most common occupations with ICD were health care workers, agricultural workers, and cleaners, most likely a result of repetitive contact with chemicals and water. Environmental and physical factors decrease the protective barrier of the skin, rendering it much more susceptible to the harmful effects of irritants and allergens. Professions whereby skin is constantly exposed to water lead to maceration of the skin, and repetitive cycles of wetting and drying causes scaling, fissuring, and cracking. These changes weaken the protective seal of the stratum corneum and permit increased cutaneous penetration of molecules. Indeed, “wet work” is the most commonly implicated exogenous factor in OCD, with affected professions including health care professionals, janitors, maids, bartenders, dishwashers, waiters, hair washers, bakers, cooks, and employees in the food service industry.


Environment


Low-humidity environments decrease ceramide levels in the stratum corneum, producing desiccation and disruption of the epidermal barrier. In hot, humid, or occlusive environments, perspiration causes soluble chemicals to dissolve, facilitating easier absorption into the skin. Microtraumatization of the skin also disrupts the protective epidermal barrier, especially in professions where repetitive friction, rubbing, or exposure to harsh, rough materials or fabrics occurs. Professionals who wear protective gloves can create a cycle of occlusion, perspiration, maceration, and subsequent irritation; therefore, its overuse or improper use paradoxically increases the risk of skin dysfunction, penetration by irritants and allergens, and risk of development of contact dermatitis.


Age and Sex


The frequency of positive patch-test results increases with age, reaching a peak between 60 and 69 years. In addition, compared with men (50–59 years), women become sensitized to allergens at a younger age (20–29 years). Age was also found to be associated with specific origins of contact dermatitis, including metals (10–59 years old), cosmetics (20–49 years), household products (30–59 years), and drugs (50–69 years). Regarding ICD, it has been suggested that susceptibility to irritants is enhanced in children, but appears to decline with age. Furthermore, self-reported dermatitis of the hands was most prevalent in young women and decreased with age; however, hand dermatitis in general is significantly more frequent in women than in men. Epidemiologic studies have shown that women carry an increased risk for the development of ICD. In fact, in comparison with men women have reported more intense irritant contact reactions when exposed to alkalis and detergents; however, other studies revealed no gender differences after exposure to certain irritants, thus the intrinsic effect of gender and the risk of ICD is still debatable. Despite this, an increased prevalence of contact dermatitis among women is widely accepted, most likely related to the increased extrinsic differences such as the occupational and domestic exposures between women and men, and less likely due to the intrinsic factors of skin susceptibility between sexes.


Race and Ethnicity


A clinical consensus has established that black skin is less reactive than white skin, which is less reactive than Asian skin; however, one review found that this rarely reached statistical significance. African Americans have greater compaction of the lipid content in their stratum corneum, which most likely confers greater barrier protection from susceptibility to potential allergens and irritants. Reduced rates of sensitization to weaker allergens such as nickel and neomycin in African Americans compared with Caucasians, as well as an overall reduced rate of ICD in African Americans has been reported. This protection is secondary to increased lipid production rather than a genetic predisposition or immunologic-mediated advantage. In white and black patients patch tested by members of the NACDG, no differences were found in the overall response rate to allergens. However, some differences were found in response to specific allergens, yet it was unclear if these differences were attributable to a genetic basis by race or mere difference in ethnicity of potential exposures between the two groups. One study found a similar incidence rate of allergic reactions between Japanese and Caucasian people, but Japanese people exhibited more severe allergic reactions. Patch testing Japanese and German women with sodium lauryl sulfate revealed no significant differences in skin reaction or barrier function in the measurements of several physiologic parameters after 24 hours; however, Japanese women had significantly more subjective sensory complaints. Although racial differences in the speed of penetration could not be excluded, ethnic differences owing to cultural behaviors could be responsible for these increased feelings of irritation. Furthermore, a comparison of white Europeans patients with Fitzpatrick skin types I to IV with Indian, Pakistani, and Bengali patients with skin type V, who all lived in the same community, resulted in a lower incidence of positive patch-test results among the races of the Indian subcontinent, although no significant difference between the detected responsible allergens was found among these two groups. The decreased incidence of positive reactions is still unclear, but different exposures between these groups as opposed to an innate difference in susceptibility is likely responsible for such findings.


Atopy


Atopic dermatitis (AD) is associated with a higher rate of contact allergy and irritancy, due to disturbed barrier function that heightens the susceptibility to skin irritants and allergens. Numerous studies have repeatedly shown that AD is the single most important risk factor for the development of hand eczema ; however, the association between AD and ACD is largely controversial, and the relationship between the two remains unclear. While a history of atopy increases the risk of developing ACD, there is no evidence suggesting that ACD is more prevalent among atopic patients. Furthermore, the rates of positive patch tests in atopics as compared with nonatopics are either similar or not significantly different. In fact, no significant difference in patch-test results was elucidated in atopics versus nonatopics among hairdressers, except for increased sensitization to fragrance mix 1 and nickel sulfate within the atopic group. Although atopy may increase the risk of contact dermatitis, patch testing benefits anyone with an unclear etiology of dermatitis regardless of its association with atopic diathesis.




Incidence and prevalence


Contact dermatitis is a significant public health concern. According to the National Health and Nutritional Examination Survey (NHANES) the prevalence of contact dermatitis in the United States was 136 per 10,000 individuals, determined using data collected over a 1-year period between 1999 and 2006; however, this figure was underreported in comparison with the documented physical examination findings. The National Ambulatory Medical Care Survey conducted in 1995 estimated 8.4 million outpatient visits to American physicians for contact dermatitis, rating it the second most frequent dermatologic diagnosis. The majority of epidemiologic data regarding contact dermatitis has been extrapolated or inferred from government reports on prevalence and incidence, and their impact on occupational skin diseases. Therefore, the remainder of this section focuses on the epidemiology of contact dermatitis in the occupational setting.


While occupational skin diseases encompass a variety of cutaneous pathologies including neoplasms, infections, and injuries, contact dermatitis is by far the most common work-related skin disorder, accounting for 90% to 95% of all cases. Hands are the most commonly affected area and account for 80% to 90% of cases, while only 10% involve the face. The 2 major subtypes of OCD are irritant and allergic. It is widely quoted in the literature that ICD is responsible for 80% of all OCD cases, with the remaining 20% caused by ACD ; however, a wide variation exists in this distribution. In fact, the NACDG has reported significantly more occupational ACD (60%) then ICD (32%) in the United States.


Specific data on national occupational disease and illness in the United States are available from the United States Bureau of Labor and Statistics (BLS) collected through annual surveys of approximately 160,000 employers selected to represent all private industries nationwide. According to the most recent 2009 survey results, BLS data estimated 25,900 cases of occupational skin diseases or disorders and an incidence rate of 2.9 cases per 10,000 full-time workers. These figures showed a downward trend in comparison with 2008 BLS data, which estimated 35,800 cases and an incidence rate of 3.8 per 10,000 full-time workers. Several studies have examined BLS survey limitations, and the number of actual occupational skin diseases may be on the order of 10 to 50 times higher than figures reported by the BLS, theoretically raising the number of occupational skin disease cases to between 250,000 and 1.25 million.


The aforementioned BLS figures represent incidence rates and total cases for all occupational skin diseases or disorders and not cases of contact dermatitis specifically. In most countries, the reported incidence rate for OCD varies between 5 and 19 cases per 10,000 full-time workers per year. To determine the OCD incidence rate in the United States based on 2009 BLS data, the extrapolated figures for OCD alone are 23,310 cases (assuming 90% of all occupational skin diseases are due to OCD) and an incidence rate of 2.6 cases per 10,000 full-time workers per year (using the BLS equation to calculate incidence rate). To verify these calculations, the most recent data were obtained by using the searchable BLS databases online. Statistics were pooled from cases coded as (1) dermatitis, (2) ICD, (3) ACD, (4) contact dermatitis and related eczema, (5) dermatitis unspecified, and (6) dermatitis N.E.C. (nowhere else classified), resulting in 6200 total OCD cases and an OCD incidence rate of 0.5 per 10,000 full-time workers. Herein lies a discordance between values reported in the literature and the national statistical data, underscoring the challenge in estimating the incidence rate of OCD, which is especially relevant in the United States.


Many investigators have discussed the possible reasons for such disparate incidence rates including variations in the types of industries in a geographic area, the age and sex distribution of the patients assessed, selection biases inherent among patients referred to tertiary dermatologic centers, the ability of the health care provider to fully assess the worker by patch testing, and the national regulations, reporting, and data collection systems. For instance, milder cases of OCD are never registered or brought to medical attention, and therefore never calculated in the epidemiologic data. In addition, a lack of standardization in case definitions could certainly influence the underestimation of OCD incidence rate.


OCD prevalence provides information on the number of workers affected by contact dermatitis at any one time (eg, point prevalence) or over a defined period of time (eg, period prevalence). In 2005, the ACD prevalence rate was 15% in individuals under the age of 18, and 28% for those over the age of 18. Therefore, the overall period prevalence rate for contact dermatitis estimated 2440 cases per 10,000 individuals per year. OCD prevalence estimates, like OCD incidence rates, vary widely. Such distributions are largely due to differing definitions of contact dermatitis in classifying the allergic type versus the irritant type. Despite these variabilities, a 10% 1-year prevalence and 20% lifetime prevalence are consistently reported estimates in the context of OCD. Investigators who take interest in the accurate determination of OCD prevalence often use hand dermatitis as a clinical surrogate. The first epidemiologic study specifically designed to assess the prevalence of chronic hand dermatitis, as well as its impact on patient-reported outcomes and economic costs in a United States managed care population, projected a 16% prevalence for chronic hand dermatitis nationwide after standardization against the general population with regard to distributions for age, gender, and race.


To collect more precise epidemiologic data for contact dermatitis, many countries have created programs to exercise better surveillance of gathered data to help minimize discrepancies. Such programs include the Health and Occupation Reporting network (THOR) in conjunction with a more specific surveillance scheme called EPI-DERM, both used in the United Kingdom, while the Danish National Board of Industrial Injuries Registry (DNBIIR) is used in Denmark. Data from EPI-DERM gathered between 1993 and 2004 indicated approximately 80% of occupational skin disease cases were caused by contact dermatitis, which closely compares with the estimated 90% in the United States. Slightly lower than the projected prevalence of 16% for hand dermatitis in the United States, the prevalence for hand dermatitis in Europe is between 6.7% and 10.6%.


As regards the United States, a sector of the Centers for Disease Control and Prevention (CDC) known as the National Institute of Occupational Health (NIOSH) also publishes historical data on the epidemiology of OCD in addition to the annual data reported by the BLS and other organizations such as NHANES and NACDG. The most recently updated statistics from NIOSH are based on data collected from 1992 to 2001, and provide an overview of the most common occupations and industries with the highest incidence of OCD. Two occupational groups accounted for 56% of all dermatitis cases in 2001: operators, fabricators, and laborers (28.4%), and service workers (27.6%). The specific industries with dermatitis incidence rates higher than the private sector incidence rate of 0.5 per 10,000 full-time workers reported in 2001 included agriculture, forestry, and fishing (1.3 per 10,000 full-time workers), manufacturing (0.7), transportation and public utilities (0.7), and services (0.6). Agriculture had consistently higher incidence rates than other industry sectors during 1992 to 2001 and experienced a 78% rate reduction over this period. A couple of years later, an influential report outlined several key issues, including multiple specialties treating patients, survivor bias, and the plethora of cases never documented, all complicating the epidemiology of OCD and its analysis. These pitfalls are of paramount importance and should be revisited whenever critically evaluating the literature for incidence and prevalence estimates of contact dermatitis.

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Feb 12, 2018 | Posted by in Dermatology | Comments Off on Contact Dermatitis in the United States: Epidemiology, Economic Impact, and Workplace Prevention

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