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Butyl 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoate (CAS 52449-44-2): Chironimus riparius: NOEC(28d): 1000 mg/kg sediment dw, EC50(28d) > 1000 mg/kg sediment dw, LC50(28d) > 1000 mg/kg (Goodband and Mullee, 2000) / Lumbriculus variegatus: NOEC(28d): 100 mg/kg sediment dw, LOEC(28d): 320 mg/kg sediment dw, EC50(28d)> 1000 mg/kg sediment dw (Goodband and Mullee, 2000) 

Key value for chemical safety assessment

Additional information

No data are available regarding sediment toxicity effects of Benzenepropanoic acid, 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-,C7 -9 branched alkyl esters (CAS 125643 -61 -0).

Two experimental results are available for the substance Butyl 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxybenzenepropanoate (CAS 52449 -44 -2), which can be considered as read-across possibility. Both are key studies with reliablility 1 (reliable without restriction) and conducted under certificated GLP compliance.

In the first study report, the toxicity to the sediment-dwelling larvae of Chironomus riparius was investigated according to the recommendations of the OECD Guidelines for Testing of Chemicals No. 218 (April 2004) “Sediment-Water Chironomid Toxicity Test using Spiked Sediment” (Goodband and Mullee, 2009a). Following a preliminary range-finding test, 120 larvae of Chironomus riparius (six replicates of 20 larvae) were exposed to formulated sediment spiked with test material at a single concentration of 1000 mg/kg (dry weight of sediment) for a period of 28 days. The numbers of emerged adult midges were recorded daily. Further 40 larvae (two replicates of 20 larvae) of each test group were prepared and sacrificed on Day 10 of the exposure period to determine the 10-Day larval survival and growth data.The 28-Day EC50(reduction in emergence) based on nominal test concentrations was greater than 1000 mg/kg. The No Observed Effect Concentration was 1000 mg/kg. The EC50(development rate) based on nominal test concentrations was greater than 1000 mg/kg. It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/kg. Analysis of the test sediment on Day -2 (the day of preparation) showed the measured concentration to be 106 % of nominal thereby indicating that the test system had been correctly dosed. Analysis of the test sediment on Day 0 (introduction of the test organisms) showed the measured concentration to be 102 % of nominal. Analysis of the overlying water on Day 0 showed the measured concentration to be 0.401 mg/L. Analysis of the interstitial water on Day 0 showed the measured concentration to be less than the limit of quantitation (LOQ) of the analytical method which was assessed down to 0.46 mg/L. Analysis of the test sediment on Day 28 showed the measured concentration to be 77 % of nominal. Analysis of the overlying and interstitial water on Day 28 showed the measured concentrations to be less than the LOQ (0.0065 mg/L) and 1.40 mg/L respectively. 

Another study was performed to assess the toxicity of the test material on reproduction to the sediment-dwelling oligochaete Lumbriculus variegatus (Goodband and Mullee, 2009d). The method was based on the OECD Guidelines for the Testing of Chemicals (2004), “Sediment-water Lumbriculus Toxicity Test using Spiked Sediment”, OECD Guideline No. 225, October 2007. Following a preliminary range-finding test, 40 worms of Lumbriculus variegatus (4 replicates of 10 worms) were exposed to formulated sediment spiked with test material at concentrations of 10, 32, 100, 320 and 1000 mg/kg (dry weight of sediment) for a period of 28 days. The numbers of worms and the dry weight data of these worms were recorded at the end of the test. Further replicates were prepared for the solvent control and each test group and sacrificed on Days 0 and 28 for chemical analysis of the sediment and overlying water. A positive control conducted approximately every six months used pentachlorophenol sodium salt (PCP-Na salt) as the reference material. The 28 -day-EC50 (reproduction) based on nominal test concentrations was greater than 1000 mg/kg. The No Observed Effect Concentration was 100 mg/kg and the Lowest Observed Effect Concentration was 320 mg/kg. Analysis of the test sediment on Day -5 (i.e. day of preparation before overlying water was placed above sediment) showed the measured concentrations to range from 102 % to 109 % of nominal for the 32, 100 and 1000 mg/kg test concentrations. The 10 and 320 mg/kg test concentrations showed measured concentrations of 55 % and 141 % of nominal respectively. These values were outside the 80 % to 120 % acceptance limits. Analysis of the corresponding frozen duplicate samples showed measured concentrations of 103 % and 140 % respectively.  Analysis of the sediment on Day 0 of the test (ie after 5 days equilibration period) showed the measured concentrations to range from 69 % to 140 % of nominal. Analysis of the interstitial (pore) water on Day 0 showed measured concentrations of less than the limit of quantitation (LOQ) of the analytical method which was assessed down to 0.46 mg/L. Analysis of the overlying water showed the measured concentrations to range from less than the LOQ of the analytical method (0.0065 mg/L) to 0.0265 mg/L. Analysis of the sediment on Day 28 of the test showed the measured concentrations to range from 27 % to 119 % of nominal. The decline in measured test concentrations was observed at the lower concentrations of 10 to 100 mg/kg and was considered to be possibly due to instability of the test material and/or possible binding of the test material to the sediment. The test material has an estimated Log Pow value of 6.53 (EPIWIN v4.0) and therefore it was considered that the test material may bind to the organic material and not dissolve into the aqueous phase. Analysis of the interstitial (pore) water on Day 28 showed measured concentrations to range from less than the LOQ (0.46 mg/L) to 0.811 mg/L. Analysis of the overlying water showed the measured concentrations of less than the LOQ (0.0065 mg/L).

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