Risk assessment, ecological

Risk is defined as the likelihood and magnitude of adverse effects, and risk assessments are science-based methodologies designed for quantifying the level of risk associated to specific or generic actions, interventions or activities. In the field of toxicology, risk assessment methods were introduced in the mid-20th century. The initial focus was for assessing the effects of chemicals on human health, and later were extended to environmental assessments to cover the effects on ecosystems. Two terminologies, environmental risk assessment and ecological risk assessment are used, frequently considered as synonyms, while conceptually, the first is broader, covering other environmental impacts, in addition to adverse consequences on ecosystems. This chapter describes the main typologies of ecological risk assessments, and how modern tools are being incorporated gradually in regulatory and non-regulatory assessments. Level 1 risk assessments have been designed for assessing the presence or absence of unacceptable risk levels; are based on tiered approaches, and mostly deterministic. Level 2 risk assessments move to the next step, and according to the definition of risk, are designed to quantify the probability and magnitude of adverse effects, usually at population level, and frequently including explicitly temporal and/or spatial variabilities. Level 3 are retrospective assessments, adapting the risk assessment methodology for investigating effects observed in the environment, and its association with specific chemicals or activities. The next level is currently “under construction”, and maximizes the use of massive data tools in the exposure assessment, population modeling, and New Approach Methodologies (NAMs); it is frequently referred as Next Generation Ecological Risk Assessments.