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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1992-01-21 to 1992-03-04
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed to appropriate guideline under GLP.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Specific details on test material used for the study:
Trimellitic anhydride
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
Temperature: 23 +/- 1 degrees C.
pH:
adjustement stable for about 4hours at approx. 8.0
Nominal and measured concentrations:
Nominal concentrations: 62.5, 125, 250, 500 and 1000 mg TMA/L
Measured concentrations are reported as trimellitic acid equivalents. In the definitive test the analytically determined initial concentrations of the test material were between 73% and 110% of nominal. Residual concentrations at test-end were between 71% and 87% of nominal in the treatments that were analysed.
Details on test conditions:
There were four replicate vessels per treatment, each initially inoculated with an algal cell density of 10,000 cells/mL
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
> 739 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The 96 hour NOEC based on growth rate was ≥739 mg/L based on initial measured concentrations.
It is thought that trimellitic anhydride was hydrolysed under the test conditions. As a result it is believed that under test conditions and after pH adjustment that trimellitic anhydride and trimelltic sodium salt were the test materials investigated in this study.
The samples of 1000 mg/L were accidentally destroyed in the laboratory and so the NOEC is based on initial measured test concentrations.
Results with reference substance (positive control):
Not stated.
Reported statistics and error estimates:
There were no statistically significant differences in algal cell densities (Bonferroni's test following ANOVA and Bartlett's test, p<0.05) between the control and all of the TMA treatments during the test.

Table 1: Effects on the growth of Scenedesmus subspicatus following 96 -hour exposure to trimellitic anhydride

Nominal TMA conc., (mg/L)

Mean algal density
(cells
×104/mL)

Integrated biomass (AUGC)

Specific growth rate

(0 -96 h)

24 h

48 h

72 h

96 h

mean

% inhib.*

mean

% inhib.*

0 (control)

5.8

39.3

89.3

345.0

7281.6

-

0.056746

-

62.5

6.3

39.3

93.0

315.0

7022.4

4

0.054334

4

125

6.0

38.0

86.8

342.5

7165.2

2

0.056174

1

250

6.5

42.0

94.8

327.5

7285.2

0

0.054440

4

500

5.5

38.3

89.3

340.0

7190.4

1

0.057281

-1

1000

7.3

38.5

89.0

350.0

7351.2

-1

0.053751

5

 * Negative inhibition values signify enhanced growth, relative to the untreated control.

Table 2: Measured concentrations of trimellitic anhydride during a 96 -hour, static growth inhibition test with Scenedesmus subspicatus

Nominal trimellitic anhydride conc. (mg/L)

0 hours

96 hours

Measured mg TMA/L

% of nominal

Measured mg TMA/L

% of nominal

62.5

48.5
56.5

79
92

53.4
51.9

87
85

250

269.3
218.5

110
89

199.6
174.3

81
71

1000

713.3
764.9

73
78

sample lost

-

 

Validity criteria fulfilled:
yes
Conclusions:
The static 96-hour EbC50 and ErC50 of trimellitic anhydride (converted to the sodium salt(s) of trimellitic acid prior to exposure) to Scenedesmus subspicatus) were both >739 mg/L, based on the mean measured concentrations at the maximum treatment applied. The NOEC was 739 mg/L (mean measured).
Executive summary:

Desmodesmus subspicatus (formerly known asScenedesmus subspicatus) was exposed in a static test system over a period of 96 hours to trimellitic anhydride after its conversion to the sodium salt(s) of trimellitic acid. The nominal concentrations applied in the definitive test were 62.5, 125.0, 250.0, 500.0 and 1000.0 mg trimellitic anhydride/L. There were four replicate vessels per treatment, each initially inoculated with an algal cell density of 10,000 cells/mL. Exposure concentrations were verified analytically at the start of the test and re-checked at test-end in three of the treatments. The analytically determined initial concentrations of the test material were between 73% and 110% of nominal. Residual concentrations after 96 hours were between 71% and 87% of nominal.

There were no statistically significant differences in algal cell densities (Bonferroni's test following ANOVA and Bartlett's test, p<0.05) between the control and all of the trimellitic anhydride treatments. The NOEC was therefore 1000 mg trimellitic anhydride/L (nominal), the highest concentration tested, equivalent to 739 mg/L, mean measured. The EC50 endpoints based on integrated biomass and specific growth rate could not be determined, but both exceeded 1000 mg trimellitic anhydride/L (nominal), equivalent to 739 mg/L, mean measured.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The read across justification is described in the document attached in the scetion 13.

Reason / purpose:
read-across source
GLP compliance:
yes
Specific details on test material used for the study:
4-chloroformylphthalic anhydride
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
> 739 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Validity criteria fulfilled:
not applicable
Conclusions:
The static 96-hour EbC50 and ErC50 of trimellitic anhydride (source substance) (converted to the sodium salt(s) of trimellitic acid prior to exposure) to Scenedesmus subspicatus) were both >739 mg/L, based on the mean measured concentrations at the maximum treatment applied. The NOEC was 739 mg/L (mean measured).
Executive summary:

Desmodesmus subspicatus (formerly known as Scenedesmus subspicatus) was exposed in a static test system over a period of 96 hours to trimellitic anhydride (source substance) after its conversion to the sodium salt(s) of trimellitic acid. The nominal concentrations applied in the definitive test were 62.5, 125.0, 250.0, 500.0 and 1000.0 mg trimellitic anhydride/L. There were four replicate vessels per treatment, each initially inoculated with an algal cell density of 10,000 cells/mL. Exposure concentrations were verified analytically at the start of the test and re-checked at test-end in three of the treatments. The analytically determined initial concentrations of the test material were between 73% and 110% of nominal. Residual concentrations after 96 hours were between 71% and 87% of nominal.

There were no statistically significant differences in algal cell densities (Bonferroni's test following ANOVA and Bartlett's test, p<0.05) between the control and all of the trimellitic anhydride treatments. The NOEC was therefore 1000 mg trimellitic anhydride/L (nominal), the highest concentration tested, equivalent to 739 mg/L, mean measured.

Based on the close structural similarity of trimellitic anhydride (source substance) and trimellitic anhydride mono-chloride (target substance), these results can be taken into account for the target substance.

Description of key information

Read-across, OECD guideline 201, GLP, key study, validity 1:

Algal growth inhibition: NOEC 739 mg/L based on the mean measured concentrations.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
739 mg/L

Additional information

One reliable study addresses the short-term toxicity of trimellitic anhydride to unicellular aquatic algae. In this study (Knacker et al., 1993b) trimellitic anhydride was first treated with aqueous NaOH solution, to convert the acid anhydride to the sodium salt(s) of trimellitic acid, and exposure in this study was consequently to sodium trimellitate (following neutralisation of excess alkali).

Based on hydrolysis rate of Trimellitic anhydride acid chloride (TMAC) and its close structural similarity, rapid hydrolysis is anticipated for trimellitic anhydride (TMA), which is also expected to undergo almost instantaneous conversion to trimellitic acid (TMLA) on contact with aqueous matrices in the environment and in vivo in exposed humans and other organisms.

No toxicity was observed under these conditions: D. subspicatus 72 hour NOErC: 739 mg trimellitic acid and trimellitic sodium salts-equiv/L. This value is a mean measured value and represents the highest concentration applied.

Trimellitic anhydride and the more environmentally relevant trimellitic acid exhibit very low toxicity to unicellular aquatic algae.

Based on the close structural similarity of trimellitic anhydride (source substance) and trimellitic anhydride mono-chloride (target substance), these results can be taken into account for the target substance.

No classification is required for toxicity to algae.