Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, 2-ethylhexyl ester

Short-term toxicity to fish

Description of key information

No toxic effects occur at the range of solubility.

Additional information

Assessment of target substance

In a limit test, according to OECD guideline 203, no effects of substance at the test concentration of 100 mg/L on Chinese Rare Minnow was observed (2017). The test solution were prepared as water accomodated fractions (WAFs). Therefore, the test item is unlikely to cause acute effects towards fish.

Supporting assessment of similar source substance EC 406-040 -9

96 hour static test with vehicle (OECD 203):

The acute toxicity of the test substance towards zebra-fish was tested in a 96 hour static test according to OECD guideline 203 (CIBA-GEIGY 1989). The desired test substance and 4 mg/L sorbitan-fatty-acid-ester-polyglykol-ether were directly added to the test vessels. The initial measured test substance concentrations ranged from 78 -109%. After 96 hours the recovery rates were lower with 59 -87 % of the nominal concentrations. The following mortalities were observed: 0, 0, 2, 4, 1 dead fish at 10, 18, 32, 58 and 100 mg/L nominal concentrations. Therefore, the LC50 based on mean measured concentrations is >74 mg/L (>100 mg/L nominal). Though the dose response curve is not consistent the test was considered as valid, since the test is well documented and the analytical recoveries sufficient to assess the acute toxicity of the test substance towards fish.

14 days semi-static test without vehicle (OECD 204):

Furthermore, the toxicity of the test substance to

rainbow trout (Oncorhynchus mykiss) was investigated in a 14-day semi-static toxicity test according to the OECD Guideline No. 204, 1984 (RCC 2000). Additionally the growth parameters body wet weight and body length of the test fish was determined at the start of the test (Day 0) and at the end of the test (Day 14).

 

Due to the low water solubility of the test item, a supersaturated emulsion of the test item with a loading rate of 100 mg/l was continuously stirred over 6.5 days. This emulsion was filtered and the undiluted filtrate with the maximum concentration of dissolved test item was used as the highest test medium concentration and as stock solution for two dilutions in a geometric series differing by a constant factor of 3.2. Additionally, a control was tested in parallel.

 

At all preparation dates, the test item concentrations in the analyzed test medium (the undiluted filtrate of the supersaturated emulsion) were below the limit of analytical quantification of 0.03 mg/l. Therefore, all reported biological results are related to the loading rate of 100 mg/l of the test item.

 

In the control and up to the highest treatment (the undiluted filtrate, based on a loading rate of 100 mg/l) no mortality or other signs of intoxication were determined during the test. Furthermore no statistically significant effect on the fish growth (body length and wet weight) was determined after the exposure period of 14 days.

 

Therefore, the 14-day NOEC (highest concentration tested without toxic effects after the exposure period of 14 days) of the test item to rainbow trout was determined to be

at the loading rate of at least 100 mg/l. The 14-day NOEC might even be higher, but loading rates in excess of 100 mg/l have not been tested, according to the guideline. The 14-day LOEC (lowest concentration with toxic effects) and the 14-day LLC were clearly higher than the loading rate of 100 mg/l. These values could not be quantified, since the test item had no toxic effect on the test fish up to water solubility limit.

Supporting assessment of the major degradation product Metilox acid (CAS: 20170-32-5)

As a result of the short term toxicity test to zebra fish, the LC50 value was determined to be 130 mg/L (1989). Based on these data it can be concluded tha the test item is unlikely to cause acute effects towards fish.