'Hidden' Occupational Allergens Such as Additives

Santiago Quirce; Darío Antolín-Amérigo; Javier Domínguez-Ortega


Curr Opin Allergy Clin Immunol. 2018;18(2):67-72. 

In This Article

Abstract and Introduction


Purpose of review: With the development of innovative technologies, new agents are continually introduced to the workplace. Some of these agents can act as hidden allergens whenever they are not declared in the product labels or whenever their health hazards are unknown. This review article focuses on the identification and description of unusual and/or hidden allergens recently incriminated in occupational diseases.

Recent findings: Occupational exposure is an important global health issue that can induce respiratory and cutaneous disorders, as well as life-threatening anaphylaxis. Apart from the classic forms of occupational exposure, reports have emerged from nonconventional or newly identified allergens or additives. These compounds are substances added to another in order to alter or improve the general quality or to counteract undesirable properties, and some of them may behave as potent and frequently hidden allergens. These highly uncommon and/or hidden allergens belong to several categories: foods, spices, cosmetics, insects, enzymes, chemicals, drugs, preservatives, and coloring agents, among others.

Summary: A high level of suspicion and awareness about the potential hidden allergens is necessary to ascertain the allergens implicated. It is of utmost importance to identify the specific eliciting agents of the occupational diseases in order to avoid strictly further exposure to them.


Agents involved in occupational allergy are commonly classified into high-molecular weight (HMW) and low-molecular weight (LMW) agents.[1] These agents can give rise to respiratory (rhinitis, asthma) or skin conditions, and occasionally can induce anaphylaxis. HMW allergens such as seeds, grains, foods, spices, and insects, and LMW agents such as chemicals and additives, are commonly reported in the literature as a cause of occupational allergy, but their presence in the products or source material used at work is not always obvious. Hidden allergens are so named because of the difficulty in identifying their presence in the final products or material sources, because they are not recognized as such, they do not appear on the product label, they contaminate other products, or they are new ingredients/components in a compound that previously did not contain them.[2] In a retrospective study of 530 food reactions in adults in Spain, approximately 22.4% were attributed to hidden allergens, of which 32% were anaphylactic.[3] Hidden and unsuspected causes of anaphylaxis[4] and new occupational agents of HMW and LMW have been recently reviewed,[5] but new cases are continuously being reported. Their knowledge is important for physicians to stay alert and suspect uncommon and/or hidden occupational allergens.