Bis(hydroxyethyl) terephthalate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

The basis for this read-across approach is that the target substance is expected to undergo transformation into terephthalic acid (CAS No. 100-21-0) and ethane-1,2-diol (CAS No. 107-21-1). The toxicity of the transformation products will accurately predict the toxicity of the bis(2-hydroxyethyl)terephthalate (CAS No. 959-26-2). Refer to the JUSTIFICATION FOR READ-ACROSS OF TOXICOLOGICAL INFORMATION in Section 13 of this dossier for further details.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Specific details on test material used for the study:

Prediction based on the toxicity of the transformation products terephthalic acid (100-21-0) and ethylene glycol (107-21-1)

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 2 131 mg/L

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 8.4 mmol/L

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 2 131 mg/L

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 8.4 mmol/L

Basis for effect:

inhibition of total respiration

Details on results:

The 16d EC50 for terephthalic acid following OECD TG 209 is reported as 1392.8 mg/L (16d EC50 = 8.4 mmol/L).

The 16h Pseudomonas putida TTC, which is comparable with EC5, for ethylene glycol is reported as > 10000 mg/L (16h TTC > 161.1 mmol/L)

Based on a conservative prediction, the 3h EC50 of BHET is predicted to be > 2131 mg/L (3h EC50 > 8.4 mmol/L)

Validity criteria fulfilled:

not applicable

Remarks:

Prediction based on analogue approach

Conclusions:

Based on a conservative prediction, the 3h EC50 of BHET is predicted to be > 2131 mg/L.

Executive summary:

No data was available regarding the ability of BHET to inhibit activated sludge respiration. A GLP-compliant OECD 209 study was conducted with terephthalic acid. The respiration rate of activated sludge was not inhibited at saturated concentrations during the range finding study. The reported 16d EC50 was 1 392.8 mg/L or 8.4 mmol/L. The activated sludge respiration inhibition of ethylene glycol was assessed according to DIN 38412-8 using Pseudomonas putida. The 16-hour toxic threshold concentration (TTC), comparable with an EC5, was reported to be greater than 10 000 mg/L or 161.1 mmol/L. The information on the source substances is for longer exposure times than the 3-hour exposure period required by OECD 209 and would be a conservative estimate of the 3-hour respiration inhibition concentration. Information on the source substances is considered to be directly applicable to an equivalent molar amount of the target substance; therefore, the conservative 3h EC50 of BHET was predicted to be greater than 8.4 mmol/L or greater than 2 131 mg/L.

Description of key information

Based on a conservative prediction, the 3h EC50 of BHET is predicted to be > 2131 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

2 131 mg/L

EC10 or NOEC for microorganisms:

2 131 mg/L