reaction mass of isomers of: C7-9-alkyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate

Toxicity to soil macroorganisms except arthropods

Description of key information

Benzenepropanoic acid 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-2 -ethyl-hexylester (CAS 144429-84-5): NOEC(14d): 1000 mg/kg, LC50(7d) > 1000 mg/kg, LC50(14d) > 1000 mg/kg (Goodband, 2010)
Butyl 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoate (CAS52449-44-2): NOEC(4wk): 100 mg/kg, LOEC(8wk): 320 mg/kg, EC50(8wk) > 259 mg/kg (Schmidt, 2009)

Additional information

Regarding toxicity effects to soil macroorganisms of Benzenepropanoic acid, 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-,C7 -9 branched alkyl esters (CAS 125643 -61 -0) neither experimental nor predicted results are available.

The substance Benzenepropanoic acid 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-2 -ethyl-hexylester (CAS 144429 -84 -5) can be considered as one read-across possibility. The acute toxicity to earthworms was tested according to OECD guideline 207 in a laboratory test with Eisenia foetida as test organism (Goodband, 2010). The study was conducted under certificated GLP compliance. The test duration was 14 days with a single substance concentration of 1000 mg/kg, since no mortalities were observed in the range-finding test at any of the test concentrations employed (0.1, 10, 100 and 1000 mg/kg). 500 mL of test item was dissolved in acetone, which was used as vehicle, and the volume was adjusted to 50 mL, resulting in a solvent stock solution of 5000mg/50mL. Chloroacetamide was used as positive control. The test temperature range was 20 - 23 °C under continuous illumination at a light intensity of 689 - 740 lux. Artificial soil was used as substrate, consisting of industrial quartz sand (70 % w/w), Kaolinite clay (20 % w/w) and Sphagnum moss peat (10 % w/w). The pH was adjusted to 6.0 +/- 0.5 with the help of calcium calbonate. The moisture content of each vessel was recorded at Days 0 and 14, giving the following values for the control and test item: 28 % of dry weight (day 0) and 27 % of dry weight (day 14). The vehicle control contained 29 % of dry weight at the beginning and 28 % of dry weight at the end of the test. The weight of each earthworm was recorded on Day 0 before addtition to the test or control vessels. Each suviving earthworm was weighed on Day 14 again. The LC50 values were calculated by the trimmed Spearman-Karber method (Hamilton et.al., 1977) on Days 7 and 14 using the ToxCalc computer software package (ToxCalc, 1999). When only one partial response is shown the trimmed Spearman-Karber method is appropriate. For the test item, both LC50 values (7 d and 14 d) are greater than 1000 mg/kg ww, the corresponding No Observed Effect Concentration (NOEC) is 1000 mg/kg ww. The LC50 for the reference substance was determined to be 32 mg/kg after 7 days as well as 14 days. The corresponding NOEC is 18 mg/kg. The normal range of the control is reached, it shall be between 10 - 50 mg/kg. All concentrations are nominal results, since no analysis was conducted to determine the homogeneity, concentration or stability of the test item formulation. This is an exception with regard to GLP and has been reflected in the GLP compliance statement. Statistical analysis was performed using Bartlett´s test for homogeneity of variance (Sokal and Rohlf, 1981) and a Studens t-test was carried out on the earthworm weight data. There were no significant differences (P>=0.05) between the solvent control, control and test item in terms of weight at Days 0 and 14.

The substance Butyl 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoate (CAS 52449 -44 -2) can be considered as another read-across possibility. A study report is available assessing toxicity effects on survival, growth and reproduction of the earthworm Eisenia fetida during an exposure time of eight

weeks (Schmidt, 2009). The experiment was based on the OECD Guidelines for Testing Chemicals, Test No. 222 (April 2004), the International Standards ISO 11268-2: 1998(E) and the BBA Guideline “Richtlinien für die Prüfung von Pflanzenschutzmitteln im Zulassungsverfahren“ Part VI, 2-2, January 1994.

The test substance was homogeneously mixed into artificial soil at the following test concentrations: 10, 32, 100, 320 and 1000 mg/kg dry soil. Additionally, a control and a reference item treatment were tested in parallel. Adult earthworms were exposed in treated soils for a period of four weeks. After this period, the adults were removed from the test vessels and the survival and growth rate were determined. The cocoons and juvenile earthworms remained in the vessels for additional four weeks. The reproduction rate was determined by counting the number of offspring hatched from the cocoons after this additional test period of four weeks. Considering survival rates, the changes in body weight and the reproduction rates ofthe exposed adult test organisms, the highest concentration of the substance tested without toxic effects after the test period (NOEC) for Eisenia fetida was determined to be 100 mg/kg dry soil. The lowest test item concentration tested with toxic effects (LOEC) amounted to 320 mg/kg dry soil due to a reduced reproduction rate of the worms at this test concentration.