3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles. However, the study is limited by several restrictions: no standard guideling, use of solvent DMSO, no analytical monitoring, etc.

Principles of method if other than guideline:

Method: see Reference / Test Conditions

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

STOCK AND TEST SOLUTION AND THEIR PREPARATION
- Solvent: dimethyl sulfoxide, CAS No. 67-68-5
- Concentration of solvent: max. 0.1 ml per l

Test organisms (species):

other: Chaetogammarus marinus (Crustacea, marine)

Details on test organisms:

TEST ORGANISMS
- Breeding method: laboratory culture
- Age: young gammarids, 5 +/- 1 mm long
- Feeding: Fucus sp. and/or Tetramin

Test type:

semi-static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

15 °C +/- 1 °C

pH:

approx. 8 (between 7.8 and 8.3)

Dissolved oxygen:

"almost saturated for the whole study duration"

Salinity:

28 o/oo

Nominal and measured concentrations:

0.18; 0.32; 0.56; 1.0; 1.8; 3.2; 5.6; 10 mg/l

Details on test conditions:

TEST SYSTEM
- Renewal of test solution: once a day
- Exposure vessel type: 1 l glass beaker, covered with watch glass
- Number of replicates, individuals per replicate: 2, 10
- Feeding during test: some Fucus sp. and/or Tetramin; reason: to prevent  cannibalism

CONTROLS
- Control group: (1) blank seawater; (2) solvent in seawater

DILUTION WATER
- Source: natural seawater from Eastern Scheldt (NL), filtered through  sand, activated charcoal, and 0.2 um millipore filter
- Aeration: no

Reference substance (positive control):

not specified

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: any change from the control

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: CL: 3.5-4.5

Duration:

72 h

Dose descriptor:

LC50

Effect conc.:

4.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: CL: 4.3-5.5

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

5.5

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: CL: 5.0-6.1

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

6.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: CL: 6.0-7.9

Validity criteria fulfilled:

not specified

Conclusions:

The EC50 (96 hours) was determined as 4.0 mg/L indicating that the test substance may be toxic to marine invertebrates.

Executive summary:

The marine crustancean Chaetogammarus marinus was exposed to the test substance at nominal concentrations ranging from 0.18 mg/L to 10 mg/L for a period of 96 hours. The test solutions were renewed daily. The following endpoint was derived:

LC50 (96 hours): 4.0 mg/L; CL: 3.5 mg/L - 4.5 mg/L

The study was assessed as "reliable with restrictions".

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1999-09-14 to 1999-09-16

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions: Test substance not stable under test conditions; 3 instead of 5 treatment levels

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

(1992)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- at test start and after 48  hours of exposure

Vehicle:

no

Details on test solutions:

STOCK AND TEST SOLUTION AND THEIR PREPARATION
- Dispersion: ultra-turrax treatment for 60 seconds at 8000 rpm, followed  by stirring with a magnetic stirrer for 24 hours and filtration (folded filter)  at pore size 7-12 um
- Other procedures: 120 mg/l stock solution

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISMS
- Strain: Daphnia magna STRAUS, parthenogenetic females
- Source/supplier: Origin German Federal Health Office (BGA); laboratory  bred inhouse
- Age: 0-24 hours
- Control group: M4-Medium according to Elendt and BGA (1992)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20.0-20.4 degree C (at 48 hours)

pH:

7.9-8.0 (at 48 hours)

Dissolved oxygen:

8.1-8.4 mg/l (at 48 hours)

Nominal and measured concentrations:

- 18.5; 37; 74 mg/l (nominal)
- 12; 24; 47 mg/l (24 hours)
- 13; 25; 50 mg/l (48 hours)

Details on test conditions:

TEST SYSTEM
- Exposure vessel type: cylindrical test vessels, 4.0 cm diameter, 6.5 cm  height, with 20 ml test medium 
- Number of replicates, individuals per replicate: 2 replicates with 10  individuals each
- Photoperiod: 16 hours light / 8 hours dark

DILUTION WATER
- Hardness: 14.2 degree German hardness
- Holding water: M4-Medium according to Elendt and BGA (1992)

TEST PARAMETER
- number of immobile daphnids

Reference substance (positive control):

not specified

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

19 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

35 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 30.9-39.7

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

73 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The 48h-EC50 value was calculated using ToxRatProgram Version 2.09 (probit analysis). This value was derived from a re-calculation (2006) which
was required due to regulatory changes. However, this calculation was based on only 3 treatment levels limiting the reliablity of the statistical analysis.

- Nominal/ measured concentrations: 

nominal  /  0 hours  /  48 hours  / evaluation

test s.      /   TOC      /    TOC        /  test s.

----------------------------------------------

control    /    <2        /      <2     /    0 mg/l

 18.5       /    12       /      13     /   19 mg/l

 37         /    24       /      25     /   37 mg/l

 74        /    47      /      50     /   73 mg/l

TOC has to be multiplied with 1.5 to correspond with test substance. The  arithmetic means of the two analytical values were used for the  evaluation.

----------------------------------------------

- Effect data (Immobilization): 

---------------------------------------------

nominal / analytical  /  24 hours / 48 hours

---------------------------------------------

control /    0 mg/l   /  0 %     /   0 %

 18.5    /   19 mg/l   /  0 %    /    0 %

 37       /   37 mg/l   /  0 %    /   60 %

 74      /   73 mg/l    / 70 %  /  100 %

---------------------------------------------

 

EC0 (highest concentration without effect): 37 mg/l (24 h); 19 mg/l (48  h)

EC50: not determined (24 h); 35 mg/l (48 h) (95 % CL: 30.9 - 39.7 mg/l)

EC100 (lowest concentration with 100 % effect): >73 mg/l (24 h); 73  mg/l (48 h)

EC50 (48 h) was determined by probit analysis using nominal concentrations, since recovery rates of the analytical results were > 80 %. For this calculation, inhibitions of 0 % and 100 % were replaced by  0.1 % and 99.9 %, respectively.

Validity criteria fulfilled:

not specified

Conclusions:

The EC50 (48 hours) for Daphnia magna was calculated to be 35 mg/L indicating that the test substance may be harmful to aquatic invertebrates.

Executive summary:

Daphnia magna were exposed to the test item in a static 48-h test with three test concentrations ranging from 18.5 to 74 mg/L plus control. The test was conducted by Bayer AG (2000) according to EU method C.2. The following endpoint was derived:

EC50 (48h) Daphnia magna: 35 mg/L

The study was assessed as "reliable with restrictions".

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1995-05-09 to 1995-05-11

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions: Test substance not stable under test conditions (rapid hydrolysis)

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

(1992)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

STOCK AND TEST SOLUTION AND THEIR PREPARATION
- 1 g/l test substance was stirred for approx. 18 hours  in synthetic freshwater and filtered. DOC 279 mg/l = 430 mg test  substance/l.

STABILITY OF THE TEST CHEMICAL SOLUTIONS
- Hydrolysis was expected but not  quantified.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISMS
- Strain: Daphnia magna STRAUS clone 5
- Source/supplier: Hüls AG (inhouse)
- Breeding method: in 1 l jars with dechlorinated drinking water, water  renewal each 2-3 days, isolation of juveniles for further breeding each  
approx. 4 weeks
- Age: < 24 hours
- Feeding: Desmodesmus subspicatus, as much as consumed
- Pretreatment: Filtration of adults 24 h prior to testing

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

- Test temperature: 20 +/- 1 degree C

pH:

- pH: 7.8-8.0

Dissolved oxygen:

- Dissolved oxygen: 8.4-8.6 mg/l

Nominal and measured concentrations:

5.2; 8.6; 15; 26; 43; 73 mg/l (nominal)
0 h analysis: 2.8; 5.7;  9.8; 17.7; 34.2; 67.4 mg/l   
48 h analysis: 3.6; 5.9; 10.5; 18.0; 32.0; 62.2 mg/l

Details on test conditions:

TEST SYSTEM
- Exposure vessel type: glass jars with 10 ml test solution
- Number of replicates, individuals per replicate: 4 replicates with 5 animals each (including control)

DILUTION WATER
- Source: Synthetic: CaCl2 x 2 H2O: 294 mg/l ;  MgSO4 x 7 H2O: 123 mg/l ;  NaHCO3: 63 mg/l;  KCl: 5.5 mg/l
- Ca/Mg ratio: 4:1
- Na/K ratio: 10:1
- Aeration: no

OTHER TEST CONDITIONS
- Feeding during test: no
- Control group: blank synthetic freshwater
- Adjustment of pH: no
- Photoperiod: darkness

STATISTICAL METHODS:
- EC50 values were calculated by graphic interpolation

Reference substance (positive control):

yes

Remarks:

potassium dichromate, CAS No. 7778-50-9

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

18 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

(DOC)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

27 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

(DOC)

Basis for effect:

mobility

Remarks on result:

other: CL: 18-33 mg/L

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 65 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

(DOC)

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

49 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

(DOC)

Basis for effect:

mobility

Remarks on result:

other: CL: 33-65 mg/L

Details on results:

- The EC0 was defined as the highest test concentration with an effect <=  10 %.

Results with reference substance (positive control):

- Concentrations: 1 mg/l; 2 mg/l
- Results: 40 %; 100 % immobilization after 24 hours

- evaluation (geometric mean of measured concentrations): 

3.2; 5.8; 10.0;  18.0; 33.0; 65.0 mg/l
- Effect data (Immobilization): 
  control; 3.2 mg/l; 5.8 mg/l: no immobilization
  10 mg/l: 0 % after 24 hours, 5 % after 48 hours
  18 mg/l: 0 % after 24 and 48 hours
  33 mg/l: 20 % after 24 hours, 75 % after 48 hours
  65 mg/l: 70 % after 24 hours, 95 % after 48 hours

Validity criteria fulfilled:

not specified

Conclusions:

The EC50 (48 hours) was determined as 27.0 mg/L indicating that the test substance may be harmful to aquatic invertebrates.

Executive summary:

Daphnia magna were exposed to the test item in a static 48 -h test. The test was conducted by Hüls AG (1995) according to EU method C.2. Six concentrations ranging from 5.2 to 73 mgL (nominal) were tested. The following endpoint was derived:EC50 (48h) Daphnia magna: 27 mg/L

Due to fast hydrolysis it is assumed that the observed effect is rather attributed to the hydrolysis product than to the parent substance. The study was assessed as "reliable with restrictions".

Description of key information

Daphnia magna were exposed to the test substance in a static test conducted by Hüls AG (1995) according to EU method C.2. Five concentrations ranging from 5.2 to 73 mg/L were tested over a period of 48 hours. The EC50 (48 hours) was determined as 27 mg/L. A second freshwater test with Daphnia magna was conducted by Bayer AG (2000) with an EC50 of 35 mg/L.

Another study was conducted with the marine crustacean Chaetogammarus marinus (Adema 1982). The study was not well documented and was characterised by some deficiencies (e.g. no standard protocol, no analytical monitoring, etc.). The EC50 (96 hours) was determined as 4.0 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

27 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

4 mg/L

Additional information

Among the two valid freshwater studies, the highest sensitivity was observed in the test which was conducted by Hüls AG (1995) and therefore this test was determined as key study. The test conducted with the marine crustacean Chaetogammarus marinus (Adema 1982) was also determined as key study, although its reliability is limited by some restrictions: no standard protocol, no standard organism, no analytical monitoring, use of a solubilizer.

In view of the low solubility in water (see chapter 4.9) and the liability towards hydrolysis (see chapter 5.1.2) of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, exposure to well-defined aquatic concentrations is difficult to achieve. Due to fast hydrolysis, the observed effect is expected to be the effect of the hydrolysis product. In the aquatic environment, only the chemically less reactive hydrolysis product is expected to be relevant. The methods used for the determination of the test substance concentration (DOC or TOC) do not differentiate between parent substance and hydrolysis product. Hence the analytical results should be treated with caution.