Skin Exposure and Asthma: Is There a Connection?

Abstract

Numerous occupational and environmental exposures that increase asthma risk have been identified. Research and prevention have focused primarily on the respiratory tract. However, recent studies suggest that the skin may also be an important route of exposure and site of sensitization that contributes to asthma development. Factors that impair skin barrier function, such as filaggrin gene mutations or skin trauma, may facilitate allergen entry and promote Th2-like sensitization and subsequent asthma. Animal studies demonstrate that skin exposure to chemical and protein allergens is highly effective at inducing sensitization, with subsequent inhalation challenge eliciting asthmatic responses. A similar role for human skin exposure to certain sensitizing agents, such as isocyanates, is likely. Skin exposure methodologies are being developed to incorporate skin exposure assessment into epidemiology studies investigating asthma risk factors.Keywords: skin exposure; asthma; isocyanates; epidermal barrier function; sensitization Environmental and occupational asthma research and practice have focused primarily on the respiratory tract as the key route of exposure and pathogenesis. However, several lines of research support an important role for skin exposure in initiating and driving Th2-like immune responses and asthma. Human and animal studies of atopic dermatitis have identified skin epithelial barrier dysfunction, which may facilitate allergen entry, as a key factor in the development of atopic asthma and sensitization. This article highlights recent findings from a diverse literature that support the concept that skin may be an important site of exposure for certain occupational and environmental allergens.

An evaluation of respiratory health at a syntactic foam manufacturing facility.

“…Many chemicals that cause occupational asthma also induce allergic and contact sensitivity rashes in the skin. Skin exposure to chemicals called isocyanates has been found to be a risk factor for isocyanate asthma and may be relevant for other chemical causes of asthma [Bello et al 2007;Redlich 2010]. As such, the associations we found between production work and rashes suggest that exposure reduction in this facility should include both respiratory and skin protection.…”

Evaluation of lead and isocyanate exposure in a maintenance facility with small arms repair and vehicle painting shops.

“…The asthmatic reaction may occur minutes after exposure (immediate phase), several hours after exposure (late phase), or both (dual phase) [Lummus et al 2011]. After sensitization, any exposure, even to levels below OELs or below the level of detection, can produce an asthmatic response that may be life threatening [NIOSH 1978[NIOSH , 1996[NIOSH , 2006Redlich 2010]. The only effective intervention for employees with isocyanateinduced asthma is cessation of all isocyanate exposure.…”

Evaluation of exposure to crystalline silica, welding fume, and isocyanates during water heater manufacturing.

“…The most frequent respiratory effect associated with isocyanate exposure is asthma due to sensitization [Lockey et al 2015;Markowitz 2005]. Sensitization can occur from inhalation and from skin exposure [Arrandale et al 2012;Heederick et al 2012;Lummus et al 2011;Redlich 2010;Wisnewski 2007]. Skin exposure might even be more effective at causing sensitization than inhalation [Heederick et al 2012;Redlich 2010].…”

“…Sensitization can occur from inhalation and from skin exposure [Arrandale et al 2012;Heederick et al 2012;Lummus et al 2011;Redlich 2010;Wisnewski 2007]. Skin exposure might even be more effective at causing sensitization than inhalation [Heederick et al 2012;Redlich 2010]. Less common health effects of isocyanate exposure include contact dermatitis, rhinitis, and hypersensitivity pneumonitis [Lockey et al 2015].…”