The risk behind the risk-The fine line between raising awareness and creating anxiety.

Abstract

Risks seem to dominate our perception of daily life. Risks are discussed that result from climate change, pesticides and other contaminants in food, electromagnetic fields, infrasound, living near animal confinement plants, exposure to ultrafine particles, endocrine disruptors in toys, and, of course, risks in the context of the indoor environment. This list is not exhaustive and could easily be extended. Indeed, many people are worried about these risks and look for information and orientation. Risk is a term with a widespread use in public discussions and in the public media. The increased presence of environmental and health topics in the public perception is at least partly attributable to the increased occurrence of these topics in the public media.1-3 Studies give evidence that permanent presence of information on environment-related diseases can facilitate the perception of subjective disorders.4 To which degree perception of adverse health effects can be manipulated just by information was demonstrated by Knasko and colleagues who exposed participants to nebulized water.5 Prior to exposure, suggestions of a pleasant, unpleasant, or neutral ambient odor were given to the participants. According to the given information, the number of reported physical health symptoms differed as a function of the hedonic quality of the feigned odor. The internet offers much information on all kinds of risks. But does this huge amount of information contribute to a better understanding and assessment of risks and improved feelings of certainty? Inconsistent and sometimes contradictory information often intensifies the feeling of uncertainty about a risk. The term “risk” itself is already associated with a threat. Independent of the definition of risk, the realization of a risk always includes the possibility of an adverse outcome. When people are exposed to, or even assumed to be exposed to a risk, this usually leads to uncertainty and anxiety, especially in individuals with a negative affectivity and when risks cannot be influenced. Anxiety is one of our strongest emotions and has potent influence not only on psychology but also on physiology and behavior. The reason that uncertainty and anxiety are so crucial is that both are associated with negative expectations. If people are worried about a certain outcome, for example, headache, itching skin, or respiratory disorders, their attention is directed towards looking if signs of illness can already be perceived. In such situations, even ordinary symptoms such as sneezing or a slight cough are interpreted as a proof of expectation, an outcome well-known as confirmation bias. The power of expectation is best illustrated by the renowned placebo effect, which is based on positive expectations. An impressive example is the randomized, placebo-controlled trial to evaluate the efficacy of arthroscopy for osteoarthritis of the knee.6 A total of 180 patients with osteoarthritis of the knee were randomly assigned to receive arthroscopic debridement, arthroscopic lavage, or placebo surgery. Patients in the placebo group received skin incisions and underwent a simulated debridement without insertion of the arthroscope. Even after two years, the outcomes after arthroscopic lavage or arthroscopic debridement were no better than those after a placebo procedure. This example underlines that perception can be largely determined by expectation. Positive expectations can be very powerful to disperse even severe symptoms. But, in the same way, negative expectations can be very powerful in eliciting the perception of severe adverse health outcomes. In contrast to the placebo (“it will help”) effect, perception of adverse health symptoms due to negative expectations is called nocebo (“it will hurt”) effect. Health symptoms attributable to negative expectations are widespread. A lot of experience with this phenomenon results from double-blind pharmaceutical studies and from laboratory exposure studies including feigned exposure, for example, to electromagnetic fields, chemical substances, or infrasound.7-10 As for the placebo group in pharmaceutical studies, participants reported adverse health symptoms under feigned exposure conditions. These studies underline the fact that negative expectations alone can be sufficient to elicit adverse health symptoms; actual exposure to hazardous impacts is not mandatory. Especially in cases with low-level exposure, such nocebo effects may offer a more conclusive explanation for reported health symptoms than trying to deduce health effects to exposure conditions in the range of natural background exposures. Indoor environment quality is receiving increasing attention, in research as well as in the public media. This increasing attention is, in part, paralleled by uncertainty and anxiety about whether indoor environmental living conditions may represent a health risk. One reason for this development is inappropriate coverage in the mass media. Headlines such as “Toxic mold is next asbestos,” “Mold may mean bad news for the brain,” or “Fungal disease as a national health crisis” contribute to an atmosphere of uncertainty and anxiety. Lay persons commonly lack the knowledge and experience to judge such information. This point is well illustrated by the famous poll by Apfelbaum with the question, “Should the use of dihydrogen monoxide be banned or at least restricted in the EU – yes, no or I don't know?”11 About three-quarters of the subjects questioned answered “yes,” probably because dihydrogen monoxide sounds like a hazardous chemical, not recognizing the chemical name for water. If individuals are convinced that they face a severe threat, this can lead to harsh consequences ranging from restrictions in daily life up to loss of home and the persistent feeling of being ill. An important term in the context of uncertainty and anxiety is “risk.” Risk is commonly defined as a function of hazard and exposure. Accordingly, the lower the exposure, the lower the risk, even in cases of chemical substances or other impacts with pronounced hazardous properties. In many cases, our knowledge of exposure in the indoor environment is limited to the detection of chemicals in the air, in dust, in building materials, etc, describing, at best, the external factors influencing exposure. Knowledge about health effects at low levels of exposure is rare and data on the intake and internal exposure are usually not available. Thus, it is generally not possible to deduce a risk fully from indoor environmental measurements. Another aspect is the assessment of exposure data. The assessment of exposure is often hampered by the lack of health-based criteria such as threshold values. Although for many substances information is available from in-vitro tests, cell cultures, etc, providing evidence for potential adverse health effects, a conclusive assessment remains difficult. In this situation, the precautionary principle is usually adduced, leading to the conclusion that a health risk cannot be excluded. However, although this conclusion is principally correct, it should be used cautiously because it includes the possibility of negligibly small risks. In particular, the information may contribute to certain individuals becoming anxious, adding to the likelihood of stimulating the vicious circle of negative expectation, focused attention on bodily sensations, and perception of non-specific symptoms. As a first step, we have to acknowledge that adverse health symptoms can be perceived as a consequence of information that is disturbing even in the absence of an external hazard, especially in subjects with negative affectivity. Therefore, we need more commitment towards the careful presentation of study results, especially in cases of low-level exposure. The following aspects should help in avoiding nocebo effects. Risk is always associated with the possibility of a negative outcome. The term “risk” can be frightening, especially for individuals with a negative affectivity. However, the sole presence of hazardous impacts is not necessarily equal to a risk. As long as no assessment criteria such as health-based threshold limits exist and no information about internal exposure is available, we should describe the situation as it is: as the presence of a hazard together with its cause and not as a risk. In cases where a risk should be described nevertheless, outline the limitations of the assumptions underlying the risk assessment. In many cases, information on the potentially hazardous properties of chemical compounds is based only on results from in-vitro studies using cell cultures or animal tests, often at the level of proinflammatory effects. However, the concentrations applied in such tests are often much higher than the concentrations observed in the indoor environment. If such tests are used for risk assessment, information about the respective concentrations is necessary. Also, progress in analytical methods can contribute to uncertainty and anxiety because the list of chemicals that can be detected in the indoor environment has meanwhile increased substantially. Recent analytical methods offer deeper insights into the complexity of exposure conditions and the presence of substances that were previously undetectable. However, the discovery that more substances are present than has been supposed up to now does not change the exposure conditions or the health risk. The only thing that has changed is our knowledge. Obviously, association is not equal to causality. Nevertheless, a distinct differentiation is not always given. There is an urgent need to address the difference to avoid misunderstanding and anxiety. Many studies show an association between exposure parameters and health symptoms in the indoor environment. This large number tempts us to infer causality. But, studies based on self-reported exposure and health symptoms are biased by the fact that individuals with a negative affectivity participate to a higher degree compared to individuals with a normal or even positive affectivity. Two decades ago, Berglund and Gunnarsson already stated in this journal that the influence of person-related factors in sick building syndrome is significant and must be included in future research.12 Studies using questionnaires without considering the affectivity of the participants should be used cautiously. Mass media have a strong impact on the perception of risks in the population. Although an easy target, it is too short-sighted to blame only the mass media, not least because mass media base their news in part on scientific reports. Instead of criticizing the mass media for their way of reporting risks, we should seek for a deeper cooperation. This could be a part of the strategy to communicate science more effectively as outlined by Notman and Carslaw in a former editorial.13 Additionally, this can contribute to an improved public perception of ISIAQ. Odors play an important role in the perception of indoor air quality. Surely, everybody has experienced the situation of entering a room with an unpleasant odor. The immediate reaction is nearly always that the smell is unhealthy, triggering corresponding negative expectations. However, although easily perceivable, the concentrations of the odors are usually far below toxic levels. In such cases, the negative expectations can be sufficient to elicit the perception of adverse health effects. In a review, Mendell and Kumagai observed that mold odor had the strongest association with development of asthma and with rhinitis of all specific observable dampness and mold indicators.14 In future, we have to consider the relevance of unpleasant odors as promotor of negative expectations more seriously. In an editorial for Indoor Air, Corsi called for a broader thinking to open up our minds to the consolidation of otherwise disparate knowledge.15 His plea that we do better at connecting things must include knowledge of the effects of negative expectations and the underlying findings of psychoneuroimmunology and related fields. Creating awareness instead of creating anxiety is a difficult balancing act. Of course, negative expectations can only explain a part of the reported health symptoms. Other factors like individual predisposition to atopy and allergies, preexisting asthma, and autoimmune disorders are among the reasons why individuals may react differently to low levels of pollutants. Nevertheless, keeping in mind that adverse health symptoms can be perceived just as a consequence of information will at least in part help to minimize nocebo effects. Increasing awareness for a healthy indoor environment, especially among the public, demands an increasing awareness for an appropriate presentation of study results. The author would like to thank William Nazaroff for his valuable comments on an earlier version of this editorial.