Risk perception and the acceptability of human exposure to pesticides: Expert workshop report

The Science Advice for Policy by European Academies (SAPEA) consortium and the Institute for Advanced Sustainability Studies (IASS) organised a joint workshop on risk perception and the acceptability of human exposure to pesticides on 20 December 2017 in Berlin. The objective was to facilitate an exchange of experiences and research results among regulators and natural and social scientists in the field of pesticide regulation. While the distribution of pesticides continues to grow on a global level, society is becoming more sensitive to health hazards and environmental impacts associated with alimentation. Risk perception deviates from statistical data-based risk assessment results, often overestimating the levels of exposure and the severity of risk associated with certain products.

The EU authorisation process for plant protection products and the toxicological risk assessment are based on the premise “that substances or products produced or placed on the market do not have any harmful effect on human or animal health or any unacceptable effects on the environment”, as written in the EU Regulation N° 1107/2009. New active substances for plant protection need to apply to the European Food Safety Authority (EFSA), which conducts a comprehensive and periodical evaluation, including separate risk assessments from EU Member States and consultations of experts and the public. The risk assessment approach has four steps:

• Hazard Classification: Examines the potential of an active substance to cause harm to human health and the environment.

• Dose-Response-Assessment: Determines the probability of harm as a function of dose leading to an assessment of the maximum amount of active substance absorbable by humans.

• Exposure Estimation: Estimates the exposure of the population and specific subpopulations (children, operators, workers…) to the active substance.

• Risk Assessment: The combination of Hazard Classification, Dose-ResponseAssessment and Exposure Estimations determines the risk of an active substance to cause harm to human health and the environment. 

Assessing the causal and temporal relationships causing risk is very complex and constitutes a severe challenge to human intuition. The uncertainty, inherent in risk assessment, causes irritation about scientific claims and their precision. Risk perception is oriented by simple causality models and the reliance on trust where immediate experience is missing.

Risks are perceived differently according to its origin and characteristics. Social science defined several risk perception clusters of which mainly two correspond to pesticides and pollutants:

• Pending Risk: The risk of pending dangers consists in the randomness of its occurrence. Severe harm occurs rarely but unpredictable and it can affect everyone.

• Creeping Risk: Creeping dangers are not recognisable by human senses until they cause harm. There can be a long time span between trigger and effect. Humans rely on information by third parties to assess and evaluate the seriousness of risks to which they are exposed.

Individuals tend to avoid these kinds of risk, because of their complexity and uncertainty. Possible risk-benefit trade-offs rely on external information, which is also perceived differently. Individual risk perception is influenced by a set of intuitive heuristics and biases:

• Availability: People assess the frequency or probability of an event by the ease with which instances or occurrences come to mind.

• Representativeness: The degree to which “A” is similar to “B” leads us to estimate a probability or frequency that is insensitive to base rates.

• Affect: Quick, subconscious evaluation of the “goodness” or “badness” of a stimulus. • Confirmation bias: People give greater weight to information that confirms their beliefs and disregard information that disagrees with their beliefs.

• Motivated reasoning: People interpret and process incoming information in a way that reinforces their predispositions.

• Information seeking: Not everyone is disposed to pay attention to new information.

For successful risk communication, trust is vital. Trust is essential for communicating complex information to society. Only sources considered trustworthy by individuals are able to change their perceptions of risks. Unfortunately, the inherent uncertainty of scientific research and the vast amount of contradicting sources can destroy trust and it is difficult to rebuild it. Modern virtual reality can amplify risk perception and result in a plurality of truth claims, eroding trust.

Risks and uncertainty are perceived differently by risk assessors and the public. Hazard assessments produce clear messages about potential threats and are therefore commonly perceived more trustworthy. Comprehensive and complex risk assessments, on the other hand, include a permanent component of uncertainty and produce ambiguous messages for risk-benefit tradeoffs. Therefore, they are often ignored or considered less trustworthy, albeit they have substantial socio-economic benefits over hazard based approaches, avoiding unnecessary and exaggerated precautions.

The toxicological risk assessment in the EU in its current form produces diverging messages and uncertainty. The underlying uncertainties in the regulatory objectives and assessment procedures leads to an uncertain level of protection provided by the current regulations. The magnitude and impact of uncertainty in risk assessments is rarely transparent and separated from the final decision-making. Therefore, the assessed levels of risk are ambiguous, often resulting in diverging assessment results by different authorities.

Considering the importance of risk perception for successful risk management, the risk assessment process should be sensitive to the perception of uncertainty. They should:

• Avoid diverging interpretations of the assessment results by relating the results to the legally defined regulatory objectives and approaches. • Quantify levels of uncertainty in risk assessments to avoid ambiguous interpretations.

• Establish a scientific arbitration process to evaluate significant divergence.

Risk communication should react to the mechanisms of risk perception and deliver clear trust-building messages that are:

• Empowering and action-oriented,

• Emphasising benefits,

• Fair and transparent,

• Resolving conflict and approaching divergence and

• Holistic, including multiple “trustworthy” stakeholders.