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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

Log 96h-LC50 = -0.4581*number of carbon + 5.8266
With 11 carbons, 96h-LC50 = 6.13 mg/L

Key value for chemical safety assessment

LC50 for freshwater fish:
6.13 mg/L

Additional information

γ-undecalactone is a linear saturated 4-hydroxycarboxylic acid derived-lactones with 11 carbons. γ-nonalactone and γ-decalactone are structurally similar compounds of aliphatic lactones with 9 and 10 carbons, respectively.

A compilation of QSAR results (blue rhombus in the graph, see attached document) and experimental value (red triangle in the graph, see attached document) was made for these three lactones. QSAR results were obtained with ECOSAR v1.11 model (Ecological Structure Activity Relationships), which is a computerized predictive system that estimates the toxicity of chemical substances to aquatic organisms such as fish, aquatic invertebrates, and aquatic plants by using computerized Structure Activity Relationships (SARs). A correlation between the chemical acute toxicity on fish (96h-LC50) and the number of carbon was made, showing a decrease of toxicity value (increase of potential for toxicity) when carbon number increase. With experimental value, a slight overestimation of the toxicity was observed with QSAR model.

For γ-undecalactone, lactone with 11 carbons, only QSAR result was available. To estimate with greater precision the acute toxicity on fish, the equation log 96h-LC50 = -0.4581*number of carbon + 5.8266 (R² = 0.9734) was used. With 11 carbons, the 96h-LC50 was estimated at 6.13 mg/L. This value was chosen for the chemical safety assessment.