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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Not reported
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Guideline study with acceptable restrictions. The study was not conducted under GLP and exposure concentrations were not measured.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The study consisted of triplicate runs of a 21-day test. Each run consisted of duplicates for control and all test concentrations. Each duplicate started with five 24-48 hour old Daphnia magna. Concentrations of 0.01, 0.03, 0. 1 , 0.3 and 1.0 ppm were selected for the test. First generation Daphnia mortality was recorded throughout the test and their reproductive function was assessed by counting the total number of young produced through day 21.
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The substance was added directly to 600 mL beakers, each containing 400 ml of hard reconstituted fresh water.
Test organisms (species):
Daphnia magna
Details on test organisms:
- Source: The test daphnids were from a laboratory culturing. The original colony of Daphnia magna was obtained through the Dow Chemical Company, which obtained their colony from the Duluth Laboratory of the United States Environmental Protection Agency.

- Culture medium: The colonies were maintained under static conditions in reconstituted hard water (EPA 660/3-75-009) made-up from glass-distilled water. Before culture inoculation, the reconstituted water was aerated for 2-4 hours.

- Culture conditions: The colonies were maintained in five-gallon glass aquaria under approximately 1000 foot-candle illumination (18/6 hour light/dark) in an environmental chamber designed to maintain 22+/-1°C.

- Feeding: The food for the Daphnia. magna is prepared each week by blending 0.25 g alfalfa meal, 4.0 g trout chow and 400 mL distilled water. This solution is allowed to settle and the supernatant is used as food.

- Test organisms; A number of egg-bearing daphnia were isolated prior to each test for a period of 24-48 hours. Five 24-48 hour old
Daphnia magna produced in the period prior to the test were introduced into each test concentration along with the untreated control group.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
No data
Test temperature:
22+/-1°C
pH:
No data
Dissolved oxygen:
No data
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations: 0 (Control), 0.01, 0.03, 0.1, 0.3 and 1.0 ppm
Details on test conditions:
Five 24-48 hour old Daphnia magna were introduced into each test concentration along with the untreated control group.

The test consisted of triplicate runs of the 21-day test. Each run consisted of duplicates for control and all test concentrations, each duplicate started with five 24-48 hour old Daphnia magna.

The daphnia were fed 0.25 ml of daphnia food each day except weekends throughout the 21-day study.

Observations were made each day for each of the test concentrations and control groups for mortalities and young produced.

The daphnia were transferred to fresh test and control vessels weekly throughout the 2l-day study.

Survival of the first generation daphnids was recorded throughout the test. The reproductive function of the first generation daphnia was assessed by counting the total number of young produced through day 21.

Comparison between test vessels and controls were made for first generation survival, fecundity, and survival of the second generations. General observations of behaviour and abnormalities were also made.
Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 other: ppm
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: reproduction and mortality
Details on results:
Control parental daphnia survival after 21 days: 96.7%

There were no statistically significant differences in survival and reproductive output between the Controls and any of the treatments.
Reported statistics and error estimates:
The levels of effect on survival and reproduction were insufficient to determine ECx values.

Differences in reproductive output were assessed by t test with p<0.05

Table 1. Test results

 

Nominal concentration (ppm)

Survival of parental daphnia (%)

Total young produced +/-Stand Dev

Young produced per female +/-Stand Dev

Initial survival of offspring (%)

0 (Control)

96.7

52.7+/-25.3

10.72+/-4.81

99.7

0.01

100

47.7+/-23.3

9.53+/-4.66

98.3

0.03

100

46.0+/-28.1

9.20+/-5.63

100

0.1

100

52.2+/-25.3

10.43+/-5.07

99.7

0.3

100

44.2+/-29.0

8.83+/-5.81

99.6

1.0

90

33.5+/-17.1

6.93+/-3.19

99.5

 

Validity criteria fulfilled:
yes
Conclusions:
A 21-day NOEC of =1 ppm has been determined for the effects of the test substance on survival and reproduction of Daphnia magna. The results are expressed relative to nominal concentrations of the test substance. However the substance is subject to rapid hydrolysis and under the test conditions it is therefore likely that exposure will have been to its hydrolysis products (methanol and trisilanols).

Description of key information

21-day NOEC: =1 ppm (=1 mg/l), survival and reproduction of Daphnia magna; equivalent to =0.8 mg/l as N-(3-(trihydroxysilyl)propyl)ethylenediamine.

Key value for chemical safety assessment

Additional information

No reliable long-term toxicity to aquatic invertebrates data are available with 3-(trimethoxysilyl)propylamine (CAS 13822-56-5), therefore good quality data from an appropriate structural analogue, N-(3-(trimethoxysilyl)propyl)ethylenediamine (CAS 1760-24-3), have been read across. The substance rapidly hydrolyses to N-(3-(trihydroxysilyl)propyl)ethylenediamine and methanol. N-(3-(trihydroxysilyl)propyl)ethylenediamine is a structural analogue of the silanol hydrolysis product of the registration substance, 3-aminopropylsilanetriol.

 

A 21-day NOEC of =1 ppm (=1 mg/l) has been determined for the effects of N-(3-(trimethoxysilyl)propyl)ethylenediamine (CAS 1760-24-3) on survival and reproduction of Daphnia magna. The results are expressed relative to nominal concentrations of the test substance. However the substance is subject to rapid hydrolysis and under the test conditions it is therefore likely that exposure will have been to its hydrolysis products (N-(3-(trihydroxysilyl)propyl)ethylenediamine and methanol).

The results may be expressed in terms of concentration of the hydrolysis product N-(3-(trihydroxysilyl)propyl)ethylenediamine by applying a molecular weight correction: (MW of silanol = 180.28 / MW of parent = 222.36) *=1 mg/l ==0.8 mg/l. This value is read across to 3-(trimethoxysilyl)propylamine (CAS 13822-56-5) without further correction.

Refer to the IUCLID Section 6 endpoint summary (Section 7.0 of the CSR) for further discussion of the approach to chemical safety assessment for this registration substance, and justification for read-across used.