Hexamethylene diisocyanate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

Because of the rapid hydrolysis a water accommodated fraction (WAF) of Desmodur H rein was prepared by direct weighing:
- 120 mg of the test item were diluted in 1 litre of dilution water
- treated for 60 s at 8000 rpm with an ultra-turrax
- stirred for 24 hours on a magnetic stirrer
- finally undissolved particles removed by filtration using folded filters (pore size 7-12 µm)

The resulting solution was analyzed to its TOC content and was the only test concentration used. The test concentration obtained was determined to be 89.1 mg/l.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM:
- Parthenogenetic females, age 0 – 24 hours, laboratory bred at BAYER AG Leverkusen, cloned at the Federal Health Office (BGA), Berlin Germany
- Water for aquaculture: M4-medium according to Elendt, version of BGA (1992), originally described in Water Research 24 (9), Sept. 1990; 1157-1167

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

14.2 °dH (253.47 mg/l CaCO3)

Test temperature:

20.2 °C (after 48 hrs)

pH:

7.8 (after 48 hrs)

Dissolved oxygen:

8.2 mg/l (after 48 hrs)

Salinity:

No data

Nominal and measured concentrations:

Nominal concentration of test substance: 90 mg/l (Analytical value for organic carbon after 0 hour: 48 mg/l, after 48 hours: 51 mg/l, resp.)

Details on test conditions:

TEST SYSTEM:
- water for dilution: M4 -Medium according to Elendt and BGA (1992)
- control: M4 -Medium according to Elendt and BGA (1992)
- photoperiod: 16 hours light, 8 hours dark (illumination 1000 lux)
- cylindric test vessel: diameter 4.0 cm/height 6.5 cm, 20 ml test medium, not ventilated
- number of daphnids per beaker: 10 daphnids (neonates)
- test parameter: immobilization (death)
- method of administration: direct weighing
- test concentration: 1 (90 mg/l) plus 1 control
- replicate: 2 (per concentration/control)
- chemical analysis: TOC

Duration:

24 h

Dose descriptor:

EC0

Effect conc.:

>= 90 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

>= 89.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: arithmetic mean of day 1 and 2 d

Details on results:

The above test result refers to a concentration of the test substance which was calculated directly from analytically determined TOC values.

Validity criteria fulfilled:

yes

Remarks:

•The immobilisation and other abnormalities in the controls did not exceed 10% by the end of the test.•The dissolved oxygen concentration remained above 3 mg/L throughout the exposure period.

Executive summary:

The 48–hr acute toxicity of HDI to Daphnids (Daphnia magna) was studied under static conditions. The experiment was carried out in accordance with the EU Method C.2.The medium composition was compliant with the Guideline requirement. Considering the variable composition of the substance, a Water Accomodated Fraction (=WAF) procedure was used (ratio: 100 mg of the test item was added to 1 L of water).The result is expressed in terms of arithmetic mean of analytical values.Immobilization was observed daily. The48h-EC0 was found to be >= 89.1 100 mg/L, based on immobilization (Bayer AG, 2000).Based on the results of this study, hexamethylenediisocyanate (HDI) is not considered as harmful to aquatic invertebrates in accordance with the EU criterion (Directive 67/548/EC). This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis:

Test Organism: Daphnids.

Test Type : static

Limit test

48h-EC0: >= 89.1 mg/L

Endpoint Effected: mobility

Description of key information

For acute toxicity of HDI to Daphnia magna a 48 h-EC0 of >= 89.1 mg/l has been

determined (92/69/EEC C.2 (1992)) proceeding in the same way as described in the first fish test above. The pH of the test solution was 7.8 (Bayer AG, 2000b).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

89.1 mg/L

Additional information

Disregarded study:

In an earlier IUCLID dataset a test result was erroneously reported as a 24 -h EC0 < 0.33 mg/l (Bayer AG, 1989). No relation of concentration to effect-level was observed. So as a result of this test the advice was to test at first the hydrolysis behaviour of hexamethylene diisocyanate (HDI). However, according to international standard methods an exposure duration of 48 hours follows the state-of-the-art of science.