Formamide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004, Oct 06-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

other: activated sludge from laboratory waste water plant treating municipal sewage

Details on inoculum:

- Method of cultivation: activated sludge from laboratory waste water plant treating municipal sewage
- Preparation of inoculum for exposure: Inoculum was washed, brought to a concentration of 5 g/L dry substance and aerated during the night.
- Initial biomass concentration: Concentration of dry substance 1 g/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Test temperature:

20 +-2 °C

pH:

7.5

Dissolved oxygen:

- oxygen concentration during aeration:  > 2.5 mg/L
- oxygen concentration immediately before measurement:  > 6.5 mg/L

Nominal and measured concentrations:

1000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL nominal volume Erlenmeyer vessel
- Material, size, headspace, fill volume: 250 mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 8 mL/vessel 100-fold concentrated OECD medium

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- duration of the measurement of oxygen consumption:  8-10 min

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol: 100, 10, 1 mg/L

Key result

Duration:

30 min

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

30 min

Dose descriptor:

other: EC20

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

30 min

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes

- Relevant effect levels: Effect concentrations for the reference substance:

EC20 (30 min): ca.  2.5 mg/L  
EC50 (30 min): ca. 17   mg/L  
EC80 (30 min): ca. 92   mg/L

Oxygen consumption         

	Inhibition
	mg O2/L*h	%
Blank (mean value)	17	-
Test substance 1000 mg/L	17	0
Reference substance 1 mg/L	16	6
Reference substance 10 mg/L	10	41
Reference substance 100 mg/L	3	82

Validity criteria fulfilled:

yes

Conclusions:

The NOEC and EC 50 at 30 minutes was greater than 500 mg/L.

Reference 2

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedure according to National Standard with acceptable restrictions (e.g. exposure concentrations in the test and the stability of formamide were not confirmed by chemical analysis)

Qualifier:

according to guideline

Guideline:

other: German Industrial Standard DIN 38412, Part 8 (draft)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Pseudomonas putida

Details on inoculum:

- Laboratory culture: DSM 50026
- Method of cultivation: at 24°C in 100 mL AK-medium according to DIN 38412, Part 8 (draft)in 300 mL-Erlenmeyer flasks (1 baffle)
- Pretreatment: 24 °C (297 K +- 1 K), 150 rpm for 7+/-1 h
- Initial biomass concentration: 1 mL pre-culture (adjusted to 10 TE/F)

Test type:

static

Water media type:

freshwater

Total exposure duration:

17 h

Test temperature:

20°C (292 K), 150 rpm for 17 h

pH:

7.1-7.2

Nominal and measured concentrations:

0 (control), 156.25, 312.5, 625, 1250, 2500, 5000, 7000, 10000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 ml-Erlenmeyer flasks, 1 baffle
- Material, size, headspace, fill volume: 10 mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates):4 and blank (w/o cells): 1 per concentration and control

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: AK-medium according to DIN 38412, Part 8 (draft)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : photometric determination at 436 nm and pH at test start and after 17 h

Key result

Duration:

17 h

Dose descriptor:

EC10

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth inhibition

Key result

Duration:

17 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth inhibition

Key result

Duration:

17 h

Dose descriptor:

other: EC90

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth inhibition

Effects on growth:

Concentration-related growth stimulation was observed up to a concentration of 7500 mg/L rather than growth inhibition:

Nominal test concentration (mg/L)	Growth stimulation (%)
0	-
156.25	-2.7 (1)
312.5	3.7
625	1.9
1250	10.5
2500	21.3
5000	35.3
7500	35.8
10000	20.5

EC-values (17 h) are based on the nominal concentrations

EC10 > 10000 mg/L
EC50 > 10000 mg/L
EC90 > 10000 mg/L


pH:

pH at the start (0 h; w/o cells) and after 17 h (w cells):

Nominal test concentration (mg/L)	pH (1 h) (w/o cells)	pH (48 h) (w cells)
0	7.1	4.9
156.25	7.2	4.9
312.5	7.2	4.9
625	7.2	5.0
1250	7.2	5.0
2500	7.2	5.3
5000	7.2	6.5
7500	7.2	6.9
10000	7.2	7.0

Validity criteria fulfilled:

yes

Conclusions:

At 17 hours, the EC10, EC50 and EC90 were all greater than 1000 mg/L.

Description of key information

In a 30 min respiration inhibition test according to OECD 209 performed as a limit test, the effect of formamide on the respiration rate of activated sludge from an laboratory sewage treatment plant was investigated using the following nominal test concentration of 1000 mg/L. An inhibition of the respiration rate was not observed. The NOEC (30 min) was 1000 mg/L (Key study).

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L