PARENT SESSION
Poster Session 37: Toxicology and Disease
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Approaches for establishing predicted-no-effect concentrations for population-level ecological risk assessment in the context of chemical substances management.

LIN, Bin-Le^*,1, Tokai, Akihiro, Nakanishi, Junko, ¹ Ecological Risk Analysis Team, Tsukuba, Japan

ABSTRACT- The establishment of rational frameworks for population-level ecological risk assessment (PLERA) in the context of chemical substances management is an important issue. We illustrate two feasible approaches for establishing predicted-no-effect concentrations (PNEC) for PLERA through a case study of 4-nonylphenol (4-NP) using life-cycle toxicity data for medaka (Oryzias latipes). We first quantified the potential impacts of 4-NP on medaka in terms of reduction of population growth rate (). An age-classified population matrix model (daily time-step) was developed and used to combine life-cycle survivorship and fecundity data obtained from individual-level responses of medaka exposed to 4-NP into population-level responses defined by the parameter . Thereafter, from the resulting s, two approaches for establishing population-level PNEC values were proposed and examined. The PNEC values for population-level impacts, based on a) the threshold concentration defined as the chemical concentration at which = 1, and b) the no-observed-effect concentration (NOEC) and the maximum-acceptable-toxic concentration (MATC), were then derived. The results suggest that PNEC values of 4-NP ranging between 0.82 and 2.10 ug/L affect medaka population growth. Although these approaches still have their limitations, current knowledge indicates that they are reasonable and practical for evaluating population-level impacts of chemicals, thereby serving as the case study for establishing PNEC values for PLERA in the context of chemical substances management and decision making.

Key words: Population Level Ecological Risk Assessment, Chemicals Risk Management