1,1'-methylenebis(4-isocyanatobenzene) and its oligomeric reaction products with butane-1,3-diol, 2,2'-oxydiethanol and propane-1,2-diol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well documented report but with some deviations from standard method and no analytical monitoring reported.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

Test substance added to test vessels and dispersed by slight stirring with a glass rod.

Test organisms (species):

activated sludge

Details on inoculum:

Strain/source: activated sludge from laboratory plant
Breeding method: bacteria fed with synthetic sewage consisting of peptone meat extract urea and some inorganic salts as in guideline.
Control: yes.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Test parameter: inhibition of respiration.

Nominal and measured concentrations:

1, 10 and 100 mg/l.

Details on test conditions:

no details provided.

Reference substance (positive control):

yes

Remarks:

3.5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

Exposed: 0% inhibition of respiration with any of the tested concentrations. (respiration rate 0.5 mg/l min).
Control: respiration rate: 0.5 mg/l min

Results with reference substance (positive control):

Respiration rate with 1 mg/l: 0.4 mg/l min
respiration rate with 100 mg/l: 0 mg/l min

Description of key information

Based on the respiration rate using activated sludge, the 3h-EC50 for the test substance  was found to be >100 mg/L (Caspers et al, 1986), following an OECD 209 Activated Sludge, Respiration Inhibition Test. 

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

The test substance is covered by the category approach of methylenediphenyl diisocyanates (MDI). Hence, data of the category substances can be used to cover this endpoint. The read-across category justification document is attached in IUCLID section 13. It is important to note that the MDI category approach for read-across of environmental and human hazards between the MDI substances belonging to the MDI category is work in progress under REACH. Therefore the read-across document should be considered a draft.

An OECD 209 Activated Sludge, Respiration Inhibition Test is available for PMDI. Based on the respiration rate using activated sludge, the 3h-EC50 was found to be >100 mg/L, which was the highest concentration tested (Caspers et al, 1986). This value may be used for the derivation of a PNECstp.