Research Prof. Siegrist


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About the Authors


Maria Spillmann is a first year PhD student at the chair of Consumer Behavior. She graduated in psychology from the University of Zurich. Her PhD focuses on nutritional risk perception.


Dr. Carmen Keller, is a Senior Research Associate at the chair of Consumer Behavior. Her research focuses on the risk perception of new technologies and nutrition and on the communication of high and low-probability risks.


Prof. Michael Siegrist has been Associate Professor of Consumer Behavior at ETH Zurich since April 2007. His research focuses on risk perception, risk communication, the acceptance of new technologies and decision making under uncertainty. He is especially interested in food and consumer behavior.

How do consumers perceive chemicals in food?

Maria Spillmann, Dr. Carmen Keller, and Prof. Michael Siegrist

In a study conducted by the chair of Consumer Behavior, various facets of consumers’ perceptions of chemicals in food were investigated. Diet patterns were identified and studied in relation to these perceptions. The findings show that consumer knowledge about food additives and contaminants is inaccurate and that food chemical acceptance correlates with consumer diet patterns.

The fact that much of our everyday food is interspersed with chemicals is probably no news to consumers. The nature of their presence in food varies between chemicals. Besides additives, which are consciously added in order to enhance food quality, there are residues, agricultural and environmental chemicals that enter food in a rather uncontrolled way and that provide no direct benefit to food quality. Many consumers are concerned about chemicals in food. These concerns are reinforced by occasional food scares in the media.

Our Study

At the beginning of 2008, we conducted a questionnaire survey in a random sample of the German-speaking population of Switzerland. The goal of our study was to gain an understanding of Swiss consumers’ perceptions and acceptance of chemicals in food. We focused on phthalates, a contaminant that may migrate from food contact materials into food. A second aim of the study was to explore how perceptions about chemicals are associated with consumers’ dietary behavior. This study was conducted in close collaboration with Matthias Wormuth and Christiane Lorenz of the Safety and Environmental Technology Group of the Institute for Chemical and Bioengineering.

Two consumer diet patterns were indentified. The first diet pattern was characterized by frequent consumption of fresh and natural foods (fruit, cereals, yoghurt), the other by processed foods and meat (ready meals, frozen pizza, red meat).

Consumers’ acceptance of chemicals was associated with these diet patterns. The more frequently consumers ate processed foods and meat, the higher their acceptance of chemicals. In turn, the stricter consumers followed the “natural and fresh” diet pattern, the lower their chemical acceptance.

We assessed consumers’ sensitivity to dose-response relationships in the context of the health effects of chemicals. We expected that consumers could be classified as more or less sensitive to the fact that “the dose makes the poison”. To our surprise, we found that for consumers, the perceptions that "any contact with chemicals equals danger" and that "the dose makes the poison" were not mutually exclusive. Most consumers showed high levels of concern about chemical contacts (see graph). Those consumers who ate more processed foods and meat showed less concern about contact with chemicals than consumers who stuck to a natural and fresh diet.

Further study was dedicated to consumers’ risk perceptions of 12 chemicals contained in food. For consumers, phthalates belonged to the same category of chemicals as artificial colorants, preservatives and flavorings. Thus, consumers perceive phthalates as additives. This perception is inaccurate, as phthalates are not subject to intended inclusion in food and they have no direct benefit to the quality of food. Phthalates were perceived as an intermediate risk.

The chemical that was perceived as most risky was dioxin. Over half of the respondents perceived dioxin as a very high risk. Antibiotic residues and pesticides were perceived as a very high risk by more than a third of respondents. Natural chemicals were perceived as no risk by most respondents, while their synthetic siblings mostly received intermediate risk scores (see graphs).

Risk perception was also associated with diet patterns. The more a respondent adhered to the natural and fresh diet pattern, the higher the risk perception was of contaminants and additives in food. In turn, the processed foods and meat pattern was related to lower risk perception.

Consumer perceptions of risks and benefits are influenced by trust in those who have the responsibility to handle and communicate a hazard. We asked our respondents how much they trusted chemical companies, food producers, food retailers and regulatory authorities (Federal Office of Public Health (FOPH), Cantonal Chemical Laboratories). We observed that the regulatory authorities were trusted most, whereas chemical companies received the least trust from consumers (see graph). Generally, higher trust in various bodies was related to lower risk perception from chemicals in food.


We have concluded from our findings that consumer knowledge about phthalates is inaccurate, as phthalates are perceived as food additives rather than contaminants. The types of chemicals evoking the highest level of consumer risk perception are agricultural chemicals and contaminants. No risk is perceived from natural chemicals. Regarding dose-response relationships, consumers seem to believe that a single contact with a chemical is dangerous, no matter how small the amount, but if there is even more of this chemical, it is still more dangerous. This thinking might compromise consumers’ understanding of “No observable adverse effect levels” (NOAELs) and similar chemical parameters. Consumer trust lowers their risk perception of chemicals in food. Consumers’ perceptions of chemicals are reflected in the choice of their diet. We observed consistent differences in the acceptance of chemicals and in the risk perception of chemicals in food between the adherents of a natural and fresh diet pattern and the followers of a processed and meat diet pattern.

Further information about this project can be found on the Consumer Behavior website.


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