Teflubenzuron

Long-term toxicity to fish

Description of key information

In a flow-through test with O. mykiss following a method similar to OECD TG 215 the 28-day NOEC of the test item was determined to be > 0.0186 mg teflubenzuron/L (mean measured).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

NOEC

Effect concentration:

0.019 mg/L

Additional information

One study on the long-term toxicity of test item to fish is available. This study was submitted in the EU in accordance with Council Directive 91/414/EEC and summarized in the original Draft Assessment Report (DAR) Volume 3, B9 Ecotoxicology for teflubenzuron and its metabolites (2007). 

 

Key information

ECT (2003 ): A Study of the Juvenile Growth Inhibition of Freshwater Fish (Rainbow Trout) with BAS 309 I (teflubenzuron), unpublished report, report No. G3FQ, according to Draft Assessment Report (2007) according to Council Directive 91/414/EEC, crossreference: MCA 8.2.2/01

The long-term toxicity of test item to fish was assessed in a 28-day Juvenile Fish Growth Test according to OECD TG 215 with Onchorynchus mykiss. In this study 20 fish per treatment (4 vessels containing 5 fish for each test concentration and control) were used. Instead of a dose-response test, a limit test was performed. The fish were exposed at the water solubility limit of the test item under test conditions (0.01 to 0.02 mg/L).

Young trout of an age of approx. 8 weeks, with a weight of approx. 963 mg ± 53 mg (SD) per fish (day 0 of test) were acquired from a breeder and kept in a holding vessel. 15 days ahead of the begin of the test, the fish were acclimated under conditions similar to the test. During the test, 5 individuals were kept per vessel. Feeding occurred twice per day (on weekends once per day) with trout food Aller S6P493.

To achieve a water saturated concentration, a nominal concentration level of 10 mg/L reconstituted water was prepared and delivered to the test vessels by a peristaltic pump via a glass fibre filter. Four aerated stainless steel tanks with test solution and 4 tanks controls (approx. 15 L each) were kept at 15 ± 1 °C at a 16/8 h light dark photoperiod; pH, oxygen concentration, total hardness, and alkalinity were recorded weekly. Turnover rate was 4.5-7.4 (L*g/fish*d). Weight of the fish was recorded on day 0, 14 and 28 of the test. Individual fish-specific growth rates (r₁) were not determined since the small fish could not be identified individually throughout the test. Instead, the tank-average specific growth rates (r₂) and pseudo-specific growth rates (r₃) were used for analysis of results by regression (concentration-response modelling). Lengths of the fish were recorded on day 28 of the test and behaviour and mortalities were recorded daily. On day 1, 7, 15,and 23 (once per week) samples for chemical analysis of approx. 600 mL were taken from the test vessels, transferred to glass bottles, stored in the freezer at –18 to –25 °C and subsequently analysed by HPLC/UV with a quanti­fication limit of 0.01 mg/L.

The pH averaged 7.36 ± 0.08 (s.d.) in the test vessels, oxygen concentration averaged 10.4 mg/L (104.5 % O₂-satur.) ± 0.58 (s.d.), total hardness averaged 13.9 ± 0.14 (s.d.) °dH, and alkalinity averaged 1.2 ± 0.1 mmol/L. The temperature averaged 15.3 ± 0.28 °C in the test vessels and 21.8 ± 1.84 °C in the test room. All water characteristics fulfil the validity criteria.

The averaged analytical measured concentration was 0.0186 mg/L (min. 0.0174 mg/L; max. 0.0218 mg/L). This is assumed to be equivalent to the water solubility limit under the given test conditions.

One dead fish occurred in the controls and one in a treatment within the test period 0-14 days. Therefore, mortality is 5% in the controls and the treatments. The criterion for validity (mortality ≤ 10%) is fulfilled. In the exposed fish, behavioural differences from the control fish were not observed and no significant differences between the weight of the control fish and the treatment were measured. Statistical analysis of the variable of the tank-average specific growth rates (r₂) and of the pseudo-specific growth rates (r₃) of the three exposure periods showed no significant differences between the controls and the treatment for the test period 0-14, 14-28 and 0-28 days. Therefore, the LOEC is greater than 0.0186 mg a.s./L and the NOEC is equal or greater than 0.0186 mg a.s./L in this test. The study was regarded acceptable for the hazard and risk assessment under Regulation (EC) No 1907/2006. 

Conclusion

Based on information of a valid juvenile growth test with O. mykiss according to OECD TG 215 the 28-day NOEC (mortality) is considered to be  0.0186 mg a.s./L.