1,2,4-trichlorobenzene

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms, other

Type of information:

other: EU Risk Assessment

Adequacy of study:

other information

Reliability:

other: EU Risk Assessment

Rationale for reliability incl. deficiencies:

other: no reliability is given as this is a summary entry for the EU RAR

Principles of method if other than guideline:

EU Risk Assessment

GLP compliance:

not specified

EU Risk Assessment (2003):

 

EC50 values for short-term toxicity to sludge microorganisms differ in a wide range between 0,91 mg/l (Yoshioka et al., 1985, species: Tetrahymena pyriformis) and 500 mg/l (Yoshioka et al., 1986, species: activated sludge).

 

Using activated sludge from a municipal STP, the reduction in oxygen uptake for 12 hours was measured. The inhibition of oxygen uptake rate, IC50, was observed to be 35 mg/l during 12 hours. Using the polytox freeze dried culture, IC50(6 h) was 23 mg/l (Nirmalakhandan et al., 1994).

 

The toxicity to each of the 3 bacterial groups: aerobic heterotrophic bacteria, Nitrosomonas, and methanogenic bacteria, was studied by Blum and Speece (1991). All assays were carried out in sealed serum bottles under similar conditions. The aerobic heterotrophs predominate in the activated sludge systems and natural aerobic environment, converting organic material to CO₂ and water. Methanogenic bacteria convert organic matter to CO₂ and methane in anaerobic environments. The heterotrophs, Nitrosomonas, and methanogenic bacteria inoculum were obtained from the mixed liquor of an activated sludge wastewater treatment plant. The 50% inhibition concentration relative to controls (IC₅₀) was 210 mg/l for Nitrosomonas and 120 mg/l for methanogens. IC50 for aerobic heterotrophs was 7,700 mg/l which is limited by the solubility. The value in a Microtox test was cited to be 2.3 mg/l (Blum and Speece, 1991).

Executive summary:

EU Risk Assessment (2003):

 

EC₅₀ values for short-term toxicity to sludge microorganisms differ in a wide range between 0,91 mg/l (Yoshioka et al., 1985, species: Tetrahymena pyriformis) and 500 mg/l (Yoshioka et al., 1986, species: activated sludge).

Using activated sludge from a municipal STP, the reduction in oxygen uptake for 12 hours was measured. The inhibition of oxygen uptake rate, IC₅₀, was observed to be 35 mg/l during 12 hours. Using the polytox freeze dried culture, IC₅₀(6 h) was 23 mg/l (Nirmalakhandan et al., 1994).

The toxicity to each of the 3 bacterial groups: aerobic heterotrophic bacteria, Nitrosomonas, and methanogenic bacteria, was studied by Blum and Speece (1991).  The 50% inhibition concentration relative to controls (IC50) was 50-210 mg/l for Nitrosomonas and 120 mg/l for methanogens. IC₅₀ for aerobic heterotrophs was 7,700 mg/l which is limited by the solubility. The value in a Microtox test was cited to be 2.3 mg/l (Blum and Speece, 1991).

Reference 2

Endpoint:

toxicity to microorganisms, other

Type of information:

other: BUA report

Adequacy of study:

other information

Reliability:

other: BUA report

Rationale for reliability incl. deficiencies:

other: no reliability is given as this is a summary entry for the BUA report

Principles of method if other than guideline:

BUA report

GLP compliance:

not specified

BUA report (1987):

 

A harmful effect on bacteria is seen at 0,2 (DABAWAS, 1983) - 500 mg/l (Yoshikoa et al., 1986) depending on the test method.

Executive summary:

BUA report (1987):

 

A harmful effect on bacteria is seen at 0,2 (DABAWAS, 1983) - 500 mg/l (Yoshikoa et al., 1986) depending on the test method.

Reference 3

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Principles of method if other than guideline:

=> testing of biodegradation of 1,2,4-TCB by municipal sewage (activated sludge) in closed vessels
=> inhibition effects on microorganisms were measured by reductions in oxygen uptake (BOD)

Activated-Sludge Test Cultures:
The activated sludge test cultures were obtained daily from the Las Cruces Wastewater Treatment Plant, which receives mainly municipal sewage. The reactor (test vessels) received 10 ml of activated sludge each. The test reactors were topped with tap water to reach the final volume of 60 ml, and the control reactors were topped up to 62 ml. All the reactors were then capped with potassium hydroxide pellets in holders attached to the caps. The tests were conducted at the endogenous phase, without any additional growth substrate.

Respirometric Test Procedure:
The tests were run on a 12-reactor, computer-interfaced Comput-OX Respirometer (N-CON Corporation, N.Y.). Except of the control, each reactor was administered with different volumes of the toxicant. The toxicant dose was prepared by dissolving the toxicant in 2 ml of acetone and injecting into the liquid phase in each reactor. The capped reactors were placed in the respirometer water bath, maintained at 25°C with continued supply of oxygen. The data acquisition system was then initiated to monitor and record the oxygen uptake of each reactor; for the next 12 hours.
The inhibition effects were measured in IC50 terms. The percent inhibition at different concentrations of the toxicant was taken as reductions in oxygen uptake rates of spiked reactors compared to that of the control reactor. These percent inhibition values were then plotted against the respective concentrations, and from linear regression analysis of these plots in the range of 20¿80% inhibition, the concentration causing 50% inhibition, IC50 was determined.

GLP compliance:

not specified

Analytical monitoring:

not specified

Details on sampling:

The tests were run on a 12-reactor, computer-interfaced Comput-OX Respirometer (N-CON Corporation, N.Y.). Details of this system have been presented elsewhere (Cadena et al., 1988). The data acquisition system was initiated to monitor and record the oxygen uptake of each reactor; for the next 12 hours.

Vehicle:

not specified

Test organisms (species):

activated sludge of a predominantly domestic sewage

Test type:

static

Water media type:

freshwater

Total exposure duration:

12 h

Test temperature:

25°C
[The capped reactors were placed in the respirometer water bath, maintained at 25°C with continued supply of oxygen.]

Details on test conditions:

Test System:
- Type: closed
- Aeration: continued supply of oxygen


All the reactors were then capped with potassium hydroxide pellets in holders attached to the caps.
The reactor (test vessels) received 10 ml of activated sludge each. The test reactors were topped with tap water to reach the final volume of 60 ml,
and the control reactors were topped up to 62 ml.

Reference substance (positive control):

no

Duration:

12 h

Dose descriptor:

IC50

Effect conc.:

35 mg/L

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Validity criteria fulfilled:

not specified

Executive summary:

Sun, 1994

The inhibition effects at IC₅₀ and 12h is 35mg/L. 

Description of key information

For transported isolated intermediates according to REACh, Article 18, this endpoint is not a data requirement. However, data is available for this endpoint and is thus reported under the guidance of "all available data".

 

Generally, following EC50 values have been reported for the toxicity to microorganisms:

EC₅₀: 0.91 - 500 mg/L

The values were obtained under different test conditions. It is not always stated whether and which guideline was used.

 

BUA report (1987):
A harmful effect on bacteria is seen at 0.2 (DABAWAS, 1983) - 500 mg/L (Yoshikoa et al., 1986) depending on the test method.

EU Risk Assessment (2003):
EC50 values for short-term toxicity to sludge microorganisms differ in a wide range between 0.91 mg/L (Yoshioka et al., 1985, species: Tetrahymena pyriformis) and 500 mg/L (Yoshioka et al., 1986, species: activated sludge).
Using activated sludge from a municipal STP, the reduction in oxygen uptake for 12 hours was measured. The inhibition of oxygen uptake rate, IC50, was observed to be 35 mg/L during 12 hours. Using the polytox freeze dried culture, IC50(6 h) was 23 mg/L (Nirmalakhandan et al., 1994).
The toxicity to each of the 3 bacterial groups: aerobic heterotrophic bacteria, Nitrosomonas, and methanogenic bacteria, was studied by Blum and Speece (1991). All assays were carried out in sealed serum bottles under similar conditions. The aerobic heterotrophs predominate in the activated sludge systems and natural aerobic environment, converting organic material to CO2 and water. Methanogenic bacteria convert organic matter to CO2 and methane in anaerobic environments. The heterotrophs, Nitrosomonas, and methanogenic bacteria inoculum were obtained from the mixed liquor of an activated sludge wastewater treatment plant. The 50% inhibition concentration relative to controls (IC50) was 210 mg/L for Nitrosomonas and 120 mg/L for methanogens. IC50 for aerobic heterotrophs was 7.700 mg/L which is limited by the solubility. The value in a Microtox test was cited to be 2.3 mg/l (Blum and Speece, 1991).

Sun, 1994:
The inhibition effects at IC50 and 12h is 35mg/L.