Environmental risk assessment is divided into 2 main parts as “environmental hazard assessment" and "environmental exposure assessment;" and HQ (Hazard Quotient) is calculated and expressed as RCR (Risk Characterization Ratio), which is derived from PEC (Exposure assessment, Predicted Environmental Concentration) divided by PNEC (Hazard assessment, Predicted No-Effect Concentration) for each environmental media (air, water, soil, sediment). It is feasible to verify that the risk management measure is sufficient and appropriate, when RCR is less than “1”.

1. Environmental hazard assessment:

The hazard assessment for the environment determines the classification and labeling of the environmental hazards of the chemical; and the concentration of the chemical that is expected to have no adverse effects on the ecosystem within the environmental domain (water quality, sediment, soil and microbial activity). In other words, the evaluation is performed to derive Predicted No Effect Concentration (PNEC).

In order to derive predicted no effect concentration, acute toxicity values such as LC50 and EC50 or No Observed Adverse Effect Level / No Observed Effect concentration (NOAEL / NOEC) were selected based on the hazard information of the environment and applied the assessment factor (AF) considering uncertainty.

2. Environmental exposure assessment

Exposure assessment in exposure scenario involves identifying the own uses of chemical manufacturer•importer and the use of downstream users to determine how the chemical is manufactured and used throughout the life cycle, and how to control environmental exposure or to recommend the controlling method to the downstream users

There are several ways to estimate the environmental release, which mainly consist of three ways; such as directly determine according to the domestic guideline, using EU environmental release factor, using Environmental release category and etc.
Estimate the Predicted environmental concentration (PEC) value of the environment by using a Korean multi-media fate model (Simplebox) based on the information of the local / regional environmental release according to each scenario.

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