N4-Benzoyl-5′-O-(4,4′-dimethoxytrityl)-2′-deoxycytidine-3′-O-[O-(2-cyanoethyl)-N,N′-diisopropylphosphoramidite]

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Filtrate of nominal 100 mg test item/L

Basis for effect:

mobility

Remarks on result:

not determinable because of methodological limitations

Remarks:

Concentration was below LOD of 0.01 mg/L though a supersatured solution of the test item was prepared.

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Filtrate of nominal 100 mg test item/L

Basis for effect:

mobility

Remarks on result:

not determinable because of methodological limitations

Remarks:

Concentration must be below LOD of 0.01 mg/L though a supersatured solution of the test item was prepared.

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Filtrate of nominal 100 mg test item/L

Basis for effect:

mobility

Remarks on result:

not determinable because of methodological limitations

Remarks:

Concentration must be below LOD of 0.01 mg/L though a supersatured solution of the test item was prepared.

Details on results:

- Behavioural abnormalities: No
- Observations on body length and weight: No
- Other biological observations: No
- Mortality of control: No mortality occurred in the control
- Other adverse effects control: No
- Abnormal responses: No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: See details on test solution. During the test no irregularities in the medium were observed.
- Effect concentrations exceeding solubility of substance in test medium:

Results with reference substance (positive control):

In the most recent test with the reference item potassium dichromate performed in January 2018 (study code 88299220), the EC50 after 24 hours was determined to be 1.06 mg test item/L, indicating that the sensitivity of the daphnids was consistent with the level proposed by the OECD 202 guideline (EC50-24 h between 0.6 and 2.1 mg potassium dichromate/L).
In the reference test performed in June 2017 (study code 88298220) with the reference item potassium dichromate, the EC50 after 24 hours was determined to be 1.58 mg test item/L and the EC50 after 48 hours was determined to be 1.07 mg test item/L.

Reported statistics and error estimates:

No statistical analysis was performed.
The EC50 could not be quantified due to the absence of toxicity of the test item. The NOEC and the LOEC were determined directly from the raw data.

Validity Criteria of the Study
Control Immobilisation Rate:	0 %, no daphnid showed signs of disease or stress; thus the validity criterion was met.
Dissolved Oxygen Concentration:	³ 8.3 mg O2/L in the control and test vessels at the end of the test; thus validity criterion was met.
Biological Results
Signs of Intoxication after 48 Hours:	After 48 hours of exposure no immobilisation of the test animals was observed in the control and in the only test concentration of the filtrate of 100 mg test item/L (see Table 1).
	Table 1. Influence of 5′-O-[bis(4-methoxyphenyl)phenylmethyl]-2′-deoxythymidine, 3′-[2-cyanoethyl N,N-bis(1-methylethyl)phosphoramidite] on the Mobility of Daphnia magna
	Treatment group	% of immobilised daphnids after
	[mg test item/L]	24 hours	48 hours
	Control	0	0
	Filtrateof 100	0	0
	The EC50, EC20and EC10could not be calculated due to the low effects of the test item. Therefore the 72-hourEC50, EC20and EC10was determined to be higher than the limit of water solubility of the test item, represented by the filtrate of nominal 100 mg test item/L. TheNOECwas determined to be at least the filtrate of 100 mg test item/L. The LOEC wasestimated to behigherthan the filtrate of 100 mg test item/L.
Analytical Results
	Table 2. Summary of Analytical Results   Sample description   Nominal % of RSD [mg test item/L] nominal^1 [%] n         Control n.a. n.a. 8 Filtrate of 100 <LOD n.a. 8           ^1mean value of all measured samples per treatment group RSD: relative standard deviation per treatment group n: number of analysed samples n.a.: not applicable LOD (=Limit of Detection): 0.01 mg test item/L

 

Validity criteria fulfilled:

yes

Conclusions:

In an acute toxicity test conducted as Limit test according to the OECD guideline 202 Daphnia magna were exposed to 100 mg/L (nominal) 5′-O-[bis(4-methoxyphenyl)phenylmethyl]-2′-deoxythymidine, 3′-[2-cyanoethyl N,N-bis(1-methylethyl)phosphoramidite]. As the test substance is hardly soluble, less than the limit of detection was dissolved in the medium (LOD = 0.01 mg/L), although the test solution was stirred for 48 hours. No effect was observed.

Executive summary:

The 48-hr-acute toxicity of 5′-O-[bis(4-methoxyphenyl)phenylmethyl]-2′-deoxythymidine, 3′-[2-cyanoethyl N,N-bis(1-methylethyl)phosphoramidite] to Daphnia magna was studied under semi-static conditions. Test species were exposed to control and test chemical at nominal concentration of 100 mg a.i./L. for 48 hr. As the test substance is hardly soluble, less than the limit of detection was dissolved in the medium (LOD = 0.01 mg/L), although the test solution was stirred for 48 hours. Mortality/immobilisation and sublethal effects were observed daily.  No effect were observed up to the limit of the test item solubility.

 

Based on the results of this study, 5′-O-[bis(4-methoxyphenyl)phenylmethyl]-2′-deoxythymidine, 3′-[2-cyanoethyl N,N-bis(1-methylethyl)phosphoramidite] would be classified as not toxic to D. magna in accordance with the classification system of the EU.

 

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates. 

 

Results Synopsis

 

Test Organism Age (e.g. 1^stinstar): < 24 h

Test Type (Flowthrough, Static, Static Renewal): Static

Table1. Summary of Biological Results
Nominal Concentration	% of immobilised daphnids after
[mg test item/L]	24 hours	48 hours
Control	0	0
Filtrateof 100	0	0
EC50[mg test item/L]:	> filtrate 100	> filtrate 100
95 % CI [mg test item/L]:	n.d.	n.d.
EC20[mg test item/L]:	> filtrate 100	> filtrate 100
95 % CI [mg test item/L]:	n.d.	n.d.
EC10[mg test item/L]:	> filtrate 100	> filtrate 100
95 % CI [mg test item/L]:	n.d.	n.d.
NOEC [mg test item/L]:	≥filtrate 100	≥filtrate 100
LOEC [mg test item/L]:	> filtrate 100	> filtrate 100

 

Endpoint(s) Effected:mobility, mortality

This information is used in a read-across approach in the assessment of the target substance.For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Description of key information

In an acute toxicity test conducted as Limit test according to the OECD guideline 202 Daphnia magna were exposed to 100 mg/L (nominal) 5′-O-[bis(4-methoxyphenyl)phenylmethyl]-2′-deoxythymidine, 3′-[2-cyanoethyl N,N-bis(1-methylethyl)phosphoramidite] for 48 h. As the test substance is hardly soluble, less than the limit of detection was dissolved in the medium (LOD = 0.01 mg/L), although the test solution was stirred for 48 hours. No effect was observed.

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the attached report in section 13 of IUCLID.