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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

The highest toxicity to fish for fossil diesel fuel (CAS no 68334-30-5). The 96 h LL50 (mortality) to Oncorhynchus mykiss: 21 mg/l with 95 % CI:  12-40 mg/l (OECD 203; GLP)

Key value for chemical safety assessment

LC50 for freshwater fish:
21 mg/L

Additional information

There are no acute toxicity studies on fish available for the substance. The testing was considered unjustified because there is enough evidence on acute toxicity to fish available from similar fossil diesel fuels. The read-across data was also used to avoid unnecessary animal testing. Read-across justifications are presented in annex 1 of the CSR. The read-across approach was justified because the fate and ecotoxicological properties of renewable hydrocarbons of wood origin (diesel type fraction) are considered similar to fossil diesel fuels based on the similar composition and physical-chemical properties.

The results of Girling, A and Cann, B. (1996) were used as a key study for CSA for renewable hydrocarbons of wood origin. The study was considered reliable (2) as it was conducted following the OECD 203 in compliance with GLP. The results of this study were selected as key value for CSA because of the highest toxicity observed over the supporting studies presented in the CSR.

In the key study a sealed, 96 h semi static, toxicity test was carried out with daily renewal of the test WAFs. Fish mortality was observed at 24 h intervals. LL50 values (loading rates of gasoil resulting in 50% mortality) were determined to be as follows: 24 h LL50 = >100 mg/L, 48 h LL50 = 28 mg/L, 72 h LL50 = 21 mg/L and 96 h LL50 = 21 mg/L. The key value for CSA was the 96 -h LL50 of 21 mg/L with 95% CI 12 - 40 mg/L.

In the supporting study (OECD 203, GLP) conducted for diesel fuel, the LL50 values (loading rates of gasoil resulting in 50% mortality) were determined to be as follows: 24 h LL50 > 1000 mg/L, 48 h LL50 180 mg/L, 72 h LL50 150 mg/L and 96 h LL50 65 mg/L.

In the supporting study Khan et al. (2007) evaluated the sublethal and lethal toxicity of diesel, neat biodiesel and different biodiesel blends on Oncorhynchus mykiss (96-hour test). Studies were conducted according to EPA guidelines outlined in Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms.

Based on the study results diesel fuel was the most toxic test substance (72 h LC50; 133.52 mg/l), followed by biodiesel and fossil and biodiesel blends (B20, B50 and B5) with LC50 values between 541.27 to 234.47 mg/l, whereas 100-% biodiesel (B100) was the least toxic (72 h LC50; 555.19 mg/l). The results of this study were used as supporting information for CSA to present the difference on acute toxicity of fossil diesel and biodiesel and the blends of diesel and biodiesel.

Based on the available data, fossil diesel fuel toxicity to fish varies between 21 to 133.52 mg/l. The results on biodiesel fuels used as supporting studies also indicate that biodiesel or biodiesel blends with fossil diesels are less toxic to fish than conventional diesel fuels. Since there are no studies conducted for the substance itself, the highest toxicity response of the fossil fuels was selected as a key study.