2,2-bis(hydroxymethyl)butanoic acid

Endpoint summary

Description of key information

Aquatic Invertebrate (Daphnia magna)

A study was performed to assess the acute toxicity of DMBA to Daphnia magna under static exposure conditions. The study was conducted in accordance with EEC Method C2 and the OECD Guideline for Testing of Chemicals No. 202.

A group of twenty, first instar Daphnia, less than 24 hours old, was exposed to a single concentration of DMBA (nominally 100 mg/L dissolved in Elendt M4 medium), for 48 hours. The numbers of immobilised daphnids were recorded for the test and control group after 24 and 48 hours.

No immobolisation was recorded in control and test vessels. The 24 and 48-hour EC₅₀for DMBA to Daphnia magna was > 100 mg/L (nominal). The highest test concentration resulting in 0% immobilisation was 100 mg/L and the lowest test concentration resulting in 100% immobilisation was > 100 mg/L. All results are expressed in terms of nominal concentrations. The mean measured concentration was recorded as 98 mg/L.

 

Aquatic algae

A study was conducted to assess the inhibitory effect of DMBA on the growth of the unicellular green algaSelenastrum capricornutum, Strain No. CCAP 278/4. The study was conducted in accordance with EEC Method C.3 and the OECD Guideline for Testing of Chemicals No. 201.

Triplicate algal cultures were exposed to five test concentrations, nominally 4.6, 10, 22, 46 and 100 mg/L, plus one untreated control. Additional pH buffered test concentrations were prepared for the two highest concentrations where a substantial reduction in pH was observed at the start of the study.

An additional control series containing the pH buffer was also prepared. All the cultures were incubated in a Gallenkamp Orbital Incubator under continuous illumination at 23 °C for 72 hours. Cell numbers were counted daily to monitor growth.

Under the test conditions, DMBA inhibited the growth of algae at concentrations tested in excess of 23 mg/L. The following values were derived from the data: EbC50 (72 h): 30 mg/L; ErC50 (0-72 h): 42 mg/L and No Observed Effect Concentration (NOEC): 23 mg/L.

The following values were derived using data from treatment solutions buffered to remove any pH related effects: EbC50 (72 h): 81 mg/L; ErC50 (0-72 h): 105 mg/L and No Observed Effect Concentration (NOEC): 48 mg/L.

All results were based on mean measured concentrations, which ranged from 99- 106% in this study.

It was considered by the author that the inhibition observed in non-buffered solutions was partly due to the low pH of test solutions and was not wholly attributable to the direct toxicity of DMBA. For this reason, EC50 and NOEC values determined from buffered cultures were believed to be more indicative of the intrinsic biological activity of DMBA than the equivalent values derived from unbuffered test cultures.

 

Fish

Study was performed according to OECD 203 guidance under GLP condition as a limit test. The total duration of the test was 96 hours. The test with Oncorhynchus mykiss (previous name: Salmo gairdneri) was performed under static condition. The measured test concertation over the first and last 24 hours of the exposure period were 101 - 89.4 mg/l and 105 - 104 mg/l respectively. During whole testing period no mortalities or sublethal effects were seen. The LC 50 based on fish mortality was established as more than 100mg/L. The NOEC (no observed effect concertation) was established as 100 mg/L (based on fish mortality).

Additional information

The key studies are also supported with results from short term fish toxicity testing with Danio rerio, which was performed according to 92/69/EWG, C.1 guideline under semi-static test condition. The total duration was 96 hours. No mortality was seen during whole test duration, thus the LC 50 after 96 hours was established as more than 100 mg/l (NOEC = 100 mg/L).