(2R,3S)-butane-2,3-diol

Endpoint summary

Description of key information

Acute aquatic ecotoxicity

Algae: 72h-ErC50 (Pseudokirchneriella subcapitata, growth rate) > 100 mg/L (nominal)

Daphnia: 48h-EC50 (Daphnia magna, mobility) > 100 mg/L (nominal), 48h-EC50 (Daphnia magna, mobility) >= 147 mg/L (extrapolated)

Fish: 96h-LC50 (Pimephales promelas) = 2830 mg/L (in silico)

Chronic aquatic ecotoxicity

72h-NOErC (Pseudokirchneriella subcapitata, growth rate) >= 100 mg/L (nominal)

Microorganisms

Activated sludge microorganisms: 30min- EC50 > 1000 mg/L (nominal)

Additional information

Acute aquatic ecotoxicity

Available experimental and in silico data shows no or very low acute toxicity of the submission substance. No adverse effects were observed for algae and fish. Very low effects of mobility were observed in aquatic invertebrates at high concentrations. The overall conclusion is that the submission substance is of no or very low acute toxicity. The most sensitive species is Daphnia magna among the available test data.

Short-term toxicity to aquatic algae

The available key study investigated growth inhibition of 2,3 -butanediol((2R,3S)-rich) to the Green Alga, Pseudokirchneriella subcapitata. The study was conducted in accordance with the OECD No. 201 and in compliance with GLP. A limit test was performed at 100 mg/L test item under static test conditions, using 6 replicates for control and treatment group.

No negative effects on growth rate or yield of biomass were observed in any of the test cultures. Moreover, no abnormalities were detected in any of the cultures and there was no sign of contamination by foreign algal cells or protozoa. The derived 72-hr EC50 was >100 mg/L (nominal) for average growth rate and yield. The No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) were >= 100 mg/L (nominal) and >100 mg/L (nominal) for average growth and yield.

The study fulfilled the all validity criteria of the guideline, and was considered adequate and reliable for the environmental hazard assessment.

Short-term toxicity to aquatic invertebrates

In the available key study, acute toxicity to aquatic invertebrate Daphnia magna was investigated. The study was performed according to OECD guideline 202 (adopted 1984) and in compliance with GLP. No immobility of daphnids was observed at test concentrations 0 (control), 12.5 and 20 mg/L during exposure period of 24 hours and 48 hours. One daphnid was observed immobile at 50 mg/L after 48 hours of exposure, and two daphnids were observed immobile at 100 mg/L after 48 hours. The derived effect concentration was: 48h-EC50 (Daphnia magna, immobility) > 100 mg/L. Based on the new dose-response assessment of MOSAIC Surv-Standard, the 48h-EC50 value was estimated (extrapolated) at 147 mg/L (95% CI: 112 - 240). The validity criteria of the test guideline (adopted 1984) were fulfilled. Despite of some deficiencies with respect to the updated guideline, the study was considered adequate and reliable for environmental hazard assessment.

Short-term toxicity to fish

Acute toxicity of (2R,3S)-butane-2,3-diol to fish was predicted using the OECD QSAR Toolbox 4.2 automated workflow (data gap filling method: trend analysis, executed via Automated "Ecotoxicological Endpoint"). The estimated lethal concentration (96h-LC50) was 2830 mg/L for Pimephales promelas. Therefore, (2R,3S)-butane-2,3-diol is not expected to pose an acute toxic hazard to fish. The prediction was considered reliable and adequate for aquatic hazard assessment.

Chronic aquatic ecotoxicity

Long-term experimental data is available for algae. No negative effects on algae growth were observed over 72 house exposure period. Based on the available acute toxicity data with indication of low acute toxicity at high concentrations, no or only very low chronic toxicity potential may is expected. Furthermore, the submission substance is well soluble in water and the rapidly degradable. Therefore, potential long-term effects are out-ruled from substances with low water solubility and if released into water, the submission substance will be degraded fast. Therefore, no further testing was considered necessary.

Long-term toxicity to aquatic algae

Refer to Short-term toxicity to aquatic algae above.

Microorganisms

In the available key study respiration inhibition of activated sludge microorganisms was investigated according to OECD guideline 209 (adopted 1993). Domestic activated sludge was used as inoculum. No inhibition of respiration was observed under static test conditions. The effect concentrations EC20 and EC50 (respiration inhibition) were derived at > 1000 mg/L after 30 minutes of exposure. In conclusion, the test substance was considered to not inhibit respiration of activated sludge microorganisms. The validity criteria of the test guideline (adopted 1993) were fulfilled. Despite of some deficiencies with respect to the updated guideline, the study was considered adequate and reliable for environmental hazard assessment.