History and exam

Key diagnostic factors

common

occupational exposure to sensitizing agents or irritants

The patient may work with diisocyanates or acid anhydrides such as epoxy resins, polyurethane foam, plastic coatings, and spray paint for vehicles.

Current and previous occupational exposures, including frequency and intensity of exposure to the potential causal agent and timing of exposures relative to symptoms, are all supportive of a diagnosis of sensitizer-induced occupational asthma.[22]​​[36]​​​​

Colleagues in the same workplace may also be affected by respiratory symptoms.[22]​​[36]​​[53]

symptoms of asthma that improve during holidays

Conjunctivitis (lacrimation, itching, burning) and rhinitis (sneezing, rhinorrhea, congestion), usually present in cases of high molecular weight occupational asthma (occupational asthma [OA]; and to a lesser extent with low molecular weight OA).

Irritant upper respiratory and eye symptoms may occur at the time of an irritant exposure in those with irritant-induced OA.

Asthma symptoms such as cough, wheeze, chest tightness, and dyspnea are present.

initial onset of asthma symptoms during a work period

Symptoms of sensitizer-induced occupational asthma (OA) are typically temporally associated with specific exposure to substance(s) at the workplace.[36][74][75]

Advanced or long-standing sensitizer-induced OA may be associated with less temporal variability in symptoms with workplace exposure.

For irritant-induced OA, onset of symptoms typically follows an accidental workplace exposure to a high-level irritant.[22]​​[36]​​

Risk factors

strong

high-level exposure to sensitizer

High-level exposure is more likely to result in sensitization. Dose-response relationships have been shown for several agents.[21][46]​

There is, however, a lack of information regarding the risk of sensitization at low levels of exposure (the "no-effect" level).

atopy

Atopy is a risk factor for occupational asthma (OA) due to high molecular weight agents, such as animal proteins and plant products.[17][47]

Atopy does not appear to be a risk factor for OA attributable to low molecular weight agents.

weak

genetic factors

Certain genes (e.g., CTNNA3) have been associated with sensitizer-induced occupational asthma (OA).[35]​

HLA phenotype appears to be an important factor in response to exposure to stimuli such as acid anhydrides, diisocyanates, western red cedar, complex platinum salts, natural rubber latex, and animal proteins.[48][49][50]

OA associated with toluene diisocyanate exposure may be associated with certain glutathione S transferase genotypes (involved in protecting cells from oxidative stress products) and with certain N-acetyltransferase genotypes.[7][34]

smoking

Cigarette smoking increases the risk of sensitization associated with some high molecular weight agents such as coffee, snow crab, and platinum salts.[51]

A synergistic effect between smoking and atopy has been demonstrated in laboratory animal workers and in workers exposed to anhydride compounds.[7]

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