Behrendt, H; Kramer, U; Schafer, T; Kasche, A; Eberlein-Konig, B; Darsow, U; Ring, J
Background: Allergy is a major health problem in most modern societies. Environmental pollution has been recognized to be harmful to human health, especially with respect to cytotoxicity, mutagenicity, and cancerogenicity. The role of environmental pollutants in allergy is still controversial. However, air pollutants are proposed to be at least one of the factors contributing to the increase of allergic diseases over the last decades. Methods/data base: Population-based epidemiological trials, animal experiments, clinical observation, and in vitro studies. Results: "Allergotoxicology" has been proposed as a research concept to study the influence of pollutants (toxic substances) upon induction, elicitation, and maintenance of allergic reactions. Clinical, epidemiological, and experimental studies (in vitro, in vivo, and in the atmospheric compartment, i.e., pollen in ambient air) have to be seen together. Many air pollutants enhance allergic reactions both at the level of sensitization (e.g., diesel exhaust particles) and by increasing the response in sensitized organisms. With regard to their effect upon allergies, different air pollution patterns have to be differentiated: Classical air pollution (type I) characterized by high SOSUB2 levels and large dust particles has not been found to be associated with allergy, in some studies there was even an inverse correlation (higher hay fever prevalence rates in former Eastern Germany compared to the West). However, modern type air pollution (type II) characterized by nitrogen oxides (NOSUBx), ozonr, volatile organic compounds (VOCs), tobacco smoke, fine and ultrafine particles has been found to be associated with higher prevalences of allergic sensitization and disease. In the ambient air, allergen carriers (e.g., pollen grains) also incorporate pollutants from the atmosphere, leading to alterations of the pollen surface and altered protein and allergen release. Furthermore, pollen grains secrete proinflammatory substances (eicosanoid-like substances) in aqueous conditions; this is greatly enhanced after exposure to VOCs or in pollen collected near roads with heavy traffic. In large-scale epidemiologic studies since 1988 in more than 30,000 pre-school children in different areas of Eastern and Western Germany, the following significant risk factors for atopy were found by multiple logistic regression analysis: genetic predisposition (stronger maternal influence than paternal), allergen exposure, pollutant exposure in the indoor (environmental tobacco smoke) and in the outdoor air (traffic exhaust), and socioeconomic status (higher allergy prevalence rates in children from parents with university degrees). Conclusion: There is increasing evidence that various environmental factors characteristic of a "modern society" (physical, chemical, biological, and psychosocial) can influence the development of allergy. It is important to distinguish the different levels at which pollutants may act (sensitization, elicitation, or chronification of allergic reactions). Only when the responsible substances have been characterized at the molecular level, can scientifically rational consequences for primary prevention of allergy be expected.
