Causal agents	Groups at risk	Clinical features and diagnosis	Prevention
Rhus genus (e.g., poison oak, poison ivy)	Firefighters and outdoor workers, including surveyors, maintenance workers, utility workers, farm workers, and landscapers	With first exposure, reaction in 5 to 28 days; with reexposure, reaction in 6 to 72 hours Appearance: vesicles and bullae in unilateral linear pattern; in severe cases, oozing blisters and pronounced edema Location: contact area, with spread to genitalia, face, and trunk (spares mucous membranes) Diagnosis: clinical appearance; limited usefulness for patch skin testing; 70% of persons are sensitive.	Workplace protection: respirators Personal protection: protective gloves and clothing, removal of exposed clothing and shoes, showering, effective laundering, instruction in recognizing members of Rhus genus; desensitization (limited usefulness): respirators
Epoxy resins	Workers in high-technology industries (e.g., computers, chemicals, electronics), wire and cable workers, floor layers, pipe workers	Appearance: vesicles, erythema, occasional bullae; unilateral, asymmetric Location: dorsum of hands, fingers, feet; lesions at distant sites (transfer by hands) Diagnosis: clinical improvement with removal of causal agent; patch skin testing	Workplace protection: isolation of epoxy mixing, use of less sensitizing resin, no smoking or eating in work area Personal protection: gloves and aprons during mixing, washing on contact, protection from sun (photosensitivity induced)
Nickel	Dental technicians, mechanics, cashiers, grinders, casters, jewelers, battery makers, electroplaters, miners, refiners, ceramic workers, computer workers, textile workers, electronic workers	Appearance: small eruption, often in shape of object contacted (e.g., button); spreads bilaterally and symmetrically Location: sun-exposed areas (phototoxic), frequently palmar; often widespread and chronic Diagnosis: clinical improvement with removal of causal agent; patch skin testing	Workplace protection: substitution of aluminum, covering tools with plastic Personal protection: gloves, measures that decrease sweating (to diminish solubilization)
Chromates	Arc welders, cutting oil users, painters, dyers, electroplaters, leather tanners, battery workers, cement workers, lithographers	Appearance: nummular eczema; often xerotic and lichenified Location: can become widespread and, over years, persistent Diagnosis: appearance; patch skin testing less helpful	Workplace protection: in electroplating, change hexavalent for less sensitizing trivalent chromium; use premixed cement; periodic examination of workers’ skin and mucous membranes; respirators Personal protection: gloves, work shoes; wash on contact; protection from sun (photosensitivity induced)
Acrylics	Dentists, dental technicians (denture making), printers, orthopedic surgeons (methyl methacrylate)	Appearance: eczematous eruptions, peripheral neuropathy Location: exposed areas Diagnosis: patch skin testing using low dilution	Workplace protection: heat curing rather than cold curing (cold curing is more often associated with skin disorders) Personal protection: wash on contact
Topical medications: neomycin (e.g., Neosporin), benzocaine (e.g., Anbesol, Hurricaine, Orajel), ethylenediamine (stabilizer)	Medical personnel, pharmacists, all workers	Appearance: pruritic eruption of erythematous vesicles Location: area of application Diagnosis: patch skin testing	Personal protection: use nonsensitizing topical medications (e.g., 5 percent doxepin cream [Zonalon])