Irritants, Irritancy and Irritant Induced Asthma

Abstract

An irritant represents a non-corrosive chemical that causes a reversible non-immunologic inflammatory reaction after direct contact with the skin, eyes, nose and/or respiratory system. There are numerous reactions to irritants including change in spirometry, elevated exhaled breath levels of nitric oxide, enhancement of the response to allergen provocation and alteration of antioxidant defenses. Irritancy prompts an "inflammatory soup" of signaling molecules leading to tissue changes characterized by infiltration of mononuclear inflammatory cells, vascular congestion, augmented blood flow, contiguous edema with leaking of plasma, glandular hyper secretion and nervous hyperresponsiveness. Acute irritant-induced asthma, also referred to as Reactive Airways Dysfunction Syndrome (RADS), is a non-allergic type of asthma presenting without a prior time-period of latency. The manifestations of RADS begin within 24 h following a single massive exposure to an irritating gas, vapor or fume resulting in continuing airway inflammation, changed airway remodeling, persistent structural changes, neural disturbances and unrelenting airway hyperresponsiveness. Recommendation is that RADS or any serious inhalation exposure be handled in a hospital setting. Serial bronchoscopic assessments assist management decisions. Management requires astute judgment and skill for a rapidly changing clinical scenario. The influence of odors and emotion in the pathogenesis irritant-induced inhalational responses is significant.

Clinical Characteristics of Irritant-Induced Occupational Asthma

“…It has been speculated that the chemical properties of the irritant agent and the timing of inhaled cortisone initiation affect the prognosis of IIA. 50 In these data, the chemical classes were indistinguishable in respect of initial symptoms after exposure or asthma outcomes and lung function parameters at the control appointment. Oxidizing agents showed lower FVC and FEV1, but smoking history affected the individual values.…”