2-amino-2-(hydroxymethyl)propane-1,3-diol hydrochloride

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jan 18 - Mar 07, 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Principles of method if other than guideline:

none

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Landwirtschaft und Forsten

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 1000 mg lest item were dissolved in 200 mL deionized water. Thus, a concentration of 5 .0 g/L was obtained.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Species: activated sludge, micro organisms from a domestic waste water treatment plant.
Origin: supplied by the sewage plant Groß Zimmern, Germany

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

250 mg/L

Test temperature:

19 - 20 °C

pH:

saturated (7-8 mg/L)

Dissolved oxygen:

7.7 - 9.1 mg/L

Nominal and measured concentrations:

0, 10, 32, 100, 320, 1000 mg/L nominal

Details on test conditions:

Measurement of Respiration Rate:

For the measurement of the respiration rate a well-mixed sample of each test medium was poured into a Karlsruher flask after exactly 3 hours incubation time, and was not further aerated. The oxygen concentration was measured with an oxygen electrode, and was recorded for about ten minutes. During measurement, the samples were continuously stirred on a magnetic stirrer.
The oxygen consumption (in mg 02 per L per minute) was determined from the most linear part of the respiration curve.

Reference substance (positive control):

yes

Remarks:

DCP

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

-- Incolulum control:
The respiration rates of the two controls did not differ by more than 15 %.

-- Reference Item
The 3-hour EC 50 of the reference item 3,5-Dichlorophenol was determined to be 5.0 mg/L and is thus in the range of 5 to 30 mg/L for the used activated sludge batch.

-- Dissolved Oxygen
The concentration of dissolved oxygen did not drop below 2.5 mg 02/L during the incubation period, and just before the measurements of the respiration rates the oxygen concentrations were at least 6.9 mg 02/L.

--Determination of the Inhibitory Effects:
The 3-hour EC 50 of the reference item was calculated by Probit analysis. The 3-hour EC 20 and EC 50 of the test item could not be calculated due to the low toxicity of the test item to micro organisms under the tested conditions.

Results with reference substance (positive control):

The 3-hour EC 50 of the reference item 3,5-Dichlorophenol was determined to be 13.5 mg/L and is thus in the range of 5 to 30 mg/L for the used activated sludge batch.

Study design

The influence of the test item on the activity of activated sludge was evaluated by measuring the respiration rate under defined conditions. The respiration rate (oxygen consumption) of an aerobic activated sludge fed with a standard amount of synthetic sewage was measured in the presence of various concentrations (10, 32, 100, 320 and 1000 mg/L) of the test item after an incubation period of 3 hours. This study was conducted according to Good Laboratory Practice (GLP) and the method applied followed the OECD Guideline for Testing of Chemicals, Section 2, No.209: "Activated Sludge, Respiration Inhibition Test", adopted April 04, 1984.

Results

In comparison to the inoculum controls, the respiration rate of the activated sludge was inhibited by -5.6% and 7.4% at all tested concentrations up to nominal 1000 mg/L. Higher concentrations were not tested. Based on measured inhibition rates, the 3 hour EC20 and EC50 values of the test item could not be quantified as the inhibition at the highest nominal concentration of 1000 mg/L was less than 20%. However, the 3 -hour EC20 and EC50 are clearly higher than 1000 mg/L.

Conclusion

The 3 -hour EC50 of the test material was higher than 1000 mg/L under the present test conditions.

Validity criteria fulfilled:

yes

Description of key information

There is one microorganism study available for TRIS HCl. The study was conducted according to OECD guideline 209 and GLP (6.1.7 -1). Activated sludge of a predominantly domestic sewage was exposed to TRIS HCl for 3 hours, at nominal test concentrations of 10, 32, 100, 320 and 1000 mg/L. In comparison to the inoculum controls the respiration rate of the activated sludge was not or only slightly inhibited by -5.6 % to 7.4 % at all tested concentrations up to 1000 mg/L. The EC10 and EC50 values for the test substance are therefore greater than 1000 mg/L, the highest concentration tested.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L