Reaction mass of dodecyl methacrylate and tridecyl methacrylate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-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:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar physicochemical, ecotoxicological and toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: methacrylate esters
• the metabolism pathway leads to comparable products (methacrylic acid and medium chain alcohol).

Therefore, read-across from the existing physicochemical, ecotoxicity and toxicity studies on the source substances is considered as an appropriate adaptation to the standard information requirements of REACH regulation

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see “Justification for read-across” attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see “Justification for read-across” attached to IUCLID section 13

4. DATA MATRIX
see “Justification for read-across” attached to IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Test organisms (species):

Daphnia magna

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

21 d

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 5.73 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

and immobilisation

Remarks on result:

other: test concentration above the water solubility

Details on results:

- Mortality of parent animals: No mortality of parental and control animals during the test period.
- No. of offspring produced per day per female: not applicable, due to production of offspring was done mainly on day 9, 12, 15/16 and 19 of the test period.
Mean number of offspring alive produced per parent animal after 21 days: 85 ± 4.27 (control group); 82.2 ± 2.30 (test group)
- Body length and weight of parent animals: Total length: 4.50 - 5.00 mm (treated animals); 4.50 - 5.25 mm (control animals)
Dry weight (mean value): 1.15 mg (treated animals; 1.19 (control animals)
No significant effects were determined.
- Type and number of behavioural abnormalities: none (test group and control group)
- Time to first brood release or time to hatch: mean day: 9.0 (control group); 8.8 (test group)

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels:
In order to prove the validity of the test system and test conditions at the testing facility, an acute immobilisation test according to DIN 38412 L11
was carried out with potassium dichromate as reference item once per month. The EC50 of the reference item at 1.84 mg/L (1.74 - 1.95
(95% confidence interval)) after 24 hours was within the validity range of 1.0 to 2.5 mg/L according to DIN 38412 L30.

Reported statistics and error estimates:

The NOEC at the limit concentration for the reproduction was determined directly from the results.
Significant deviations concerning reproduction were determined in comparison to the control group using statistical standard procedures (One Way Analysis of Variance, p < 0.05 for reproduction rate and intrinsic rate of natural increase and KRUSKAL-WALLISS ANOVA on Ranks, p < 0.05 for the
day of release of first brood). Significant deviations concerning the body length were determined in comparison with the control group using
KRUSKAL-WALLISS ANOVA on Ranks, p < 0.05.

Validity criteria fulfilled:

yes

Conclusions:

At the limit concentration of nominal 10 µg/L, corresponding to the time weighted mean measured concentration of 5.73 µg/L, above the water solubility level and > LOQ (< 1 µg/L) no effects of Dodecyl methacrylate on reproduction and immobilisation of daphnids was determined.

Description of key information

At the limit concentration of nominal 10 µg/l, corresponding to the time weighted mean measured concentration of 5.73 µg/l and above the water solubility level, no effects on reproduction and immobilisation of daphnids were determined in a 21-day-chronic toxicity study with Daphnia magna.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

5.73 µg/L

Additional information

No experimental data are available for the taregt substance Reaction mass of dodecyl methacrylate and tridecyl methacrylate. However, a long-term toxicity study in Daphnia was conducted with the closely related source substance Dodecyl methacrylate. A justification for read-across is given in the endpoint summary "Aquatic toxicity".

The 21-day-chronic toxicity of dodecyl methacrylate to Daphnia magna STRAUS was studied under semi static conditions according to OECD guideline 211. Daphnids were exposed to dodecyl methacrylate at a limit concentration of 10 µg/L (nominal).

This concentration is higher than the solubility in water (< 1 µg/L) but has, nevertheless, been chosen with regard to the feasibility of

attaining appropriate and detectable test concentrations at 10 µg/L.

10 test organisms, individually held were used for the limit concentration and control. At test start they were 2 to 24 hours old. The test method was semi-static. Test solutions were renewed daily.

Concentrations of dodecyl methacrylate in the stock solution, limit concentration and control of fresh (0 h) and old (24 h) media were determined via HPLC. Samples were taken and analysed on days 0, 7, 16, 20 (fresh media) and on days 1, 8, 17, 21 (old media). The test item concentrations decreased within 24 h. All effect values were given based on the time weighted mean measured concentration for the limit concentration of 5.73 µg/L.

The average number of juveniles per parent in the control group was 85 after 21 days. The reproductive output at the limit concentration was not statistically significant reduced compared to the control (One Way Analysis of Variance, p < 0.05).

The coefficient of variation around the mean number of living offspring produced per parent in the control group was 5.02 % and shows very small variances between the control replicates.

No winter eggs, males, ephippia, stillborn juveniles and aborted eggs occurred in control or test groups.

The mean day of release of first brood was 9 in the control group and the limit concentration. There was no difference between the two groups. At the limit concentration and the control group 4 broods were released during the test period.

The intrinsic rates of natural increase (IR) of the surviving parent animals accounting for generation time and offspring numbers were used for calculation of population growth. The mean IR of the surviving daphnids of the limit concentration was compared to the control by One Way Analysis of Variances (p < 0.05). There was no statistically significant difference. The intrinsic rate was comparable for the control and limit concentration.

The no observed effect concentration (NOEC) after 21 days based on reproduction capacity is the tested limit concentration of 5.73

µg/L. No statistically significant test item related effects were observed at the limit concentration when compared to the control

group. No immobilisation of parent animals occurred in the control or test group.

Water quality parameters as pH-value, dissolved oxygen, water hardness and temperature were determined to be within the acceptable limits.

In order to prove the validity of the test system and test conditions at the testing facility, an acute immobilisation test according to DIN 38412 L11 was carried out with potassium dichromate as reference item once per month. The EC50 of the reference item at 1.84 mg/L after 24 hours was within the validity range of 1.0 to 2.5 mg/L according to DIN 38412 L30.

The 21 day LC₅₀/EC₅₀based on reproduction/immobilisation was greater than 5.73 µg/L (mean measured concentration).The 21-day NOEC based on reproduction/immobilisation was 5.73µg/L (mean measured concentration). Production of offsprings in the treated groups indicated that Dodecyl methacrylate did not have an effect on the reproduction at concentrations greater than 5.73 µg/L.

 

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

 

Results Synopsis 

Test Organism Age: 2 to 24 hours old at test start

Test Type: Semi-static (renewal daily)

 

NOEC:  5.73 µg/L (based on time weighted mean measured concentration)                 

Endpoint(s) Effected:  reproduction/immobilisation