PARENT SESSION

PT16 Biological Testing Data in Sediment Management Decisions
Exhibit Hall
8:00 AM - Tuesday

(PT261) Statistical evaluation of the chronic toxicity data on aquatic organisms: The Chemicals Toxicity Distribution Approach.

González-Doncel, M.¹, Ortiz, J.¹, Martín de Madariaga, B.¹, Sánchez, P.¹, Izquierdo, J.J.¹, Tarazona., J.V.¹, ¹ Department of the Environment.Spanish National Institute for Agriculture and Food Research and Technology, INIA., MADRID., SPAIN.

ABSTRACT- The harmonized system for the hazard classification of chemical substances is based on the acute toxicities in combination with lack of rapid degradation and/or bioaccumulative potential. Our work focuses on a new approach for setting hazard identification triggers based on the Chemicals Toxicity Distribution (CTD). A CTD is the distribution obtained through statistical fitting of the data employed by regulatory bodies for setting hazard-based classifications. In this case the values correspond to the lowest NOEC of each chemical. A review of different toxicological databases was carried. The chronic toxicity values from each database were collected and a database was developed. Distributions for fish, invertebrates and algae were handled separately. The collected values were grouped according to the specific source and a final database containing all values (>700) was developed. Each database was analyzed and the CTDs were constructed. All databases fitted similar log-normal distributions and the cut-off categories proposed were: chronic I: <0.01 mg/L, chronic II 0.01-0.1 mg/L and, chronic III 0.1-1 mg/L. This approach results in a simple classification scheme where most chemicals are covered in one of the categories. This system also facilitates a clear distribution of the chemicals among the three different categories of chronic toxicity.

Key words: Aquatic environment, Hazard classification, NOEC, Chemicals Toxicity Distribution.