Terephthalaldehyde

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Terephthalaldehyde

EC Number:

210-784-8

EC Name:

Terephthalaldehyde

Cas Number:

623-27-8

Molecular formula:

C8H6O2

IUPAC Name:

benzene-1,4-dicarbaldehyde

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Batch (Lot) Number: 180401
Expiry date: 01 April 2020 (retest date)
Physical Description: Light yellow powder
Purity/Composition: 99.6%
Storage Conditions: At room temperature

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Samples for possible analysis were taken from all test concentrations and the control according to the schedule below. In addition, the filter containing the undissolved residue was kept for possible analysis.
Frequency at t=0 h and t=48 h
Volume 2.0 mL from the approximate centre of the test vessels
Storage Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.
At the end of the exposure period, the replicates were pooled at each concentration before sampling.
Additionally, reserve samples of 2.0 mL were taken for possible analysis. If not already used, these samples were stored in a freezer (≤-15°C) for a maximum of three months after delivery of the draft report, pending on the decision of the sponsor for additional analysis.

Test solutions

Vehicle:

no

Details on test solutions:

The batch of Terephthaldehyde tested was a light yellow powder with a purity of 99.6% and not completely soluble in test medium at the loading rate initially prepared. No correction was made for the purity/composition of the test item.
Preparation of test solutions started with a loading rate of 100 mg/L applying a three-day period of magnetic stirring to ensure maximum dissolution of the test item in test medium. Thereafter, the aqueous Saturated Solution (SS) was collected by filtration through a 0.45 µm membrane filter (RC55, Whatman) and used as the highest test concentration. Lower test concentrations were prepared by subsequent dilutions of the SS in test medium. All test solutions were clear and colorless at the end of the preparation procedure.
Any residual volumes were discarded.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

Species Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions.
Source In-house laboratory culture with a known history.
Reason for selection This system has been selected as an internationally accepted invertebrate species.
Validity of batch Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20% , presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.
Characteristics Daphnia, less than 24 hours old, from parental daphnids of more than two weeks old.

Breeding
Start of each batch Approximately 250 newborn daphnids, i.e. less than 3 days old, were placed into 5 litres of medium in an all-glass culture vessel.
Maximum age of the cultures 4 weeks
Renewal of the cultures After 7 days of cultivation, half of the medium twice a week.
Temperature of medium 18-22°C
Feeding Daily, a suspension of fresh water algae.
Culture medium M7, as prescribed by Dr. Elendt-Schneider
(Elendt, B.-P., 1990: Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33).
The following salts and vitamins were added to freshly prepared test medium (see section 4.8.2.2) to reach the following concentrations:

Salts: H3BO3 0.71 mg/L
FeSO4.7H2O 0.25 mg/L
MnCl2.4H2O 0.090 mg/L
LiCl 0.076 mg/L
RbCl 0.018 mg/L
SrCl2.6H2O 0.038 mg/L
Na2MoO4.2H2O 0.015 mg/L
NaBr 0.0040 mg/L
CuCl2.2H2O 0.0042 mg/L
ZnCl2 0.013 mg/L
CoCl2.6H2O 0.010 mg/L
KI 0.0032 mg/L
Na2SeO3 0.0022 mg/L
NH4VO3 0.00057 mg/L
Na2EDTA.2H2O 0.62 mg/L
Na2SiO3.5H2O 7.5 mg/L
NaNO3 0.27 mg/L
KH2PO4 0.14 mg/L
K2HPO4 0.18 mg/L
Vitamins: Thiamine hydrochloride 75.0 µg/L
B12 1.0 µg/L
Biotin 0.75 µg/L

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

The hardness of test medium expressed as CaCO3: 180 mg/L with a pH between 6 and 9.

Test temperature:

18-22°C

pH:

pH between 6 and 9.

Dissolved oxygen:

The dissolved oxygen concentration at the end of the test was ≥3 mg/L in control and test vessels.

Salinity:

N/A

Conductivity:

N/A

Nominal and measured concentrations:

Nominal concentrations: 10, 18, 32, 56, 100 mg/L

Details on test conditions:

The project started with a combined limit/range-finding test. Twenty daphnids per concentration (four replicates, 5 daphnids per vessel) were exposed to a control and a SS prepared at a loading rate of 100 mg/L. Test procedure and conditions were similar to those applied in the final test with the following exceptions:
• Ten daphnids per concentration (in duplicate, 5 per vessel) were exposed to solutions containing 1.0 and 10% of the SS in the combined range-finding test.
• Dissolved oxygen concentrations and pH were only measured in the control and the highest test concentration.

Final Test
Test Concentrations
Terephthaldehyde Solutions containing 10, 18, 32, 56 and 100% of the SS, prepared at a loading rate of 100 mg/L.
Control Test medium without test item or other additives.

Test Procedure and Conditions
Test duration 48 hours
Test type Static
Test vessels 60 mL, all-glass
Test medium The following salts (analytical grade) were added to tap water purified by Reverse Osmosis (RO-water, GEON Waterbehandeling, Berkel-Enschot, The Netherlands):
CaCl2.2H2O 211.5 mg/L
MgSO4.7H2O 88.8 mg/L
NaHCO3 46.7 mg/L
KCl 4.2 mg/L
The hardness of test medium expressed as CaCO3: 180 mg/L with a pH between 6 and 9.
Number of daphnids 20 per concentration
Loading 5 per vessel containing 50 mL of test solution.
Light A daily photoperiod of 16 hours.
Feeding No feeding
Aeration No aeration of the test solutions was applied.
Introduction of daphnids Within 18 minutes after preparation of the test solutions.

Measurements and Recordings
Immobility (including mortality) At 24 hours and at 48 hours.
pH and dissolved oxygen At the beginning and at the end of the test, for all concentrations and the control.
Temperature of medium Continuously in a temperature control vessel, beginning at the start of the test.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

ca. 27 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 9.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No immobility was observed in the control and at solutions containing 1.0 and 10% of the SS throughout the test, while all daphnids exposed to the undiluted SS were immobilized after 24 hours of exposure onwards.
Based on these results, samples taken from solutions containing 10 and 100% of the SS were analysed. The measured concentrations at the start of the test were 9.6 and 118 mg/L, respectively. During the exposure period, the concentrations remained stable, i.e. were at 82-92% relative to the initial concentrations at the end of the test. It was concluded that the undissolved material removed during the preparation of test solutions was not test item related.

All test conditions were maintained within the limits prescribed by the study plan.

Main Test
Samples taken from all test concentrations and the control were analysed. The measured concentrations at the start of the test were 9.7, 17, 30, 54 and 94 mg/L in solutions containing 10, 18, 32, 56 and 100% of the SS prepared at a loading rate of 100 mg/L, respectively. During the exposure period, the concentrations remained stable, i.e. were at 93-98% relative to the initial concentrations at the end of the test. It was concluded that the undissolved material removed during the preparation of test solutions was most likely not test item related. Since the measured concentrations were within the range of 80-120% relative to the nominal levels throughout the test, the effect parameters were consequenty expressed in terms of analytically confirmed nominal concentrations.


Immobility
Table 2 shows the responses recorded during the final test.
No immobility was observed in the control throughout the test. A concentration-related increase of immobility was observed at nominal concentrations of 10 mg/L and higher after 24 and 48 hours of exposure, resulting in 100% immobility at the three highest test concentrations at the end of the test.
The responses recorded in this test allowed for reliable determination of an EC50.

Any other information on results incl. tables

Table 1
Number of Introduced Daphnids and Incidence of Immobility in the
Combined Limit/Range-Finding Test

 

Time (h)	Replicate	Terephthaldehyde;%SS prep. at a loading rate of 100 mg/L
		Control	1.0	10	100
0	A	5	5	5	5
	B	5	5	5	5
	C	5			5
	D	5			5
	Total introduced	20	10	10	20
24	A	0	0	0	5^#
	B	0	0	0	5
	C	0			5
	D	0			5
	Total immobilised	0	0	0	20
	Effect %	0	0	0	100
48	A	0	0	0	5
	B	0	0	0	5
	C	0			5
	D	0			5
	Total immobilised	0	0	0	20
	Effect %	0	0	0	100

^#Microscopic observation revealed no test item attached to the daphnids.

Table 2
Number of Introduced Daphnids and Incidence of Immobility in the Final Test

 

Time (h)	Replicate	Terephthaldehyde; Nominal conc. (mg/L)
		Control	10	18	32	56	100
0	A	5	5	5	5	5	5
	B	5	5	5	5	5	5
	C	5	5	5	5	5	5
	D	5	5	5	5	5	5
	Total introduced	20	20	20	20	20	20
24	A	0	0	0(1)	2	5*	5
	B	0	0	0	5	5	5
	C	0	0	0	5	5	5
	D	0	0	1	5	5	5
	Total immobilised	0	0	1	17	20	20
	Effect %	0	0	5	85	100	100
48	A	0	4	5	5	5	5
	B	0	2	4	5	5	5
	C	0	2	5	5	5	5
	D	0	4	5	5	5	5
	Total immobilised	0	12	19	20	20	20
	Effect %	0	60	95	100	100	100

( ) Number of daphnids observed to be trapped at the surface of the test solutions. These organisms were reimmersed into the respective solutions before recording of mobility.
^#Microscopic observation revealed no test item attached to the daphnids.
* The dissolved oxygen concentration was measured to be 9.1 mg/L after the observations on immobility were made.

  Determination of Effect Concentrations

Table 3shows the effect parameters based on analytically confirmed nominal concentrations.

Table 3
Effect Parameters

Parameter	Terephthaldehyde Nominal conc. (mg/L)	95%-confidence interval (mg/L)
24h-EC50	27	24 – 29
48h-EC50	9.2	4.9 – 11

1.1.1.                 Experimental Conditions

The results of measurement of pH and oxygen concentrations (mg/L) are presented inTable 4. These test conditions remained within the limits prescribed by the study plan (pH: 6‑9, not varying by more than 1.5 units; oxygen:>=3 mg/L at the end of the test).

The temperature continuously measured in a temperature control vessel varied between 20 and 21°C during the test, and complied with the requirements as laid down in the study plan (18‑22°C, constant within±1°C).

Table 4
pH and Oxygen Concentrations (mg/L) During the Final Test

Terephthaldehyde Nominal conc. (mg/L)	Start (t=0 h)		End (t=48 h)
	O2	pH	O2	pH
Control	8.5	8.0	8.8	8.3
10	8.7	8.0	8.8	8.2
18	8.8	8.0	8.9	8.2
32	8.8	8.0	8.8	8.2
56	8.7	8.0	8.9	8.2
100	8.7	8.0	9.0	8.2

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the 48h-EC50 for Daphnia magna exposed to Terephthaldehyde was 9.2 mg/L based on analytically confirmed nominal concentrations (95% confidence interval between 4.9 and 11 mg/L).

Executive summary:

The objective of the study was to evaluate Terephthaldehyde for its ability to generate acute toxic effects on the mobility ofDaphnia magnaduring an exposure period of 48 hours and, if possible, to determine the EC₅₀at 24 and 48 hours of exposure.

The study procedures described in this report were based on the OECD guideline No. 202, 2004.In addition, procedures were based on the test methods described in the OECD series on testing and assessment number 23, 2000.

The batch of Terephthaldehyde tested was a light yellow powder with a purity of 99.6% and not completely soluble in test medium at the loading rate initially prepared.

A Saturated Solution (SS) was prepared at a loading rate of 100 mg/L and used as the highest concentration. Lower concentrations were prepared by diluting the highest concentration in test medium.

A final test was performed based on the results of a preceding combined limit/range-finding test. Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to solutions containing 10, 18, 32, 56 and 100% of the SS prepared at a loading rate of 100 mg/L. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test.

Samples taken from all test concentrations and the control were analysed. The measured concentrations at the start of the test were 9.7, 17, 30, 54 and 94 mg/L at solutions containing 10, 18, 32, 56 and 100% of the SS prepared at a loading rate of 100 mg/L, respectively. During the exposure period, the concentrations remained stable, i.e. were at 93-98% relative to the initial concentrations at the end of the test. Based on these results, the effect parameters were expressed in terms of analytically confirmed nominal concentrations.

No immobility was observed in the control throughout the test. A concentration-related increase of immobility was observed at nominal concentrations of 10 mg/L and higher after 48 hours of exposure, resulting 100% immobility at the three highest test concentrations.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

In conclusion, the 48h-EC₅₀for Daphnia magna exposed to Terephthaldehyde was 9.2 mg/L based on analytically confirmed nominal concentrations (95% confidence interval between 4.9 and 11 mg/L).