Tetrabutyltin

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 December 2005 to 09 March 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Qualifier:

according to guideline

Guideline:

other: ISO 10706:2000: Determination of long term toxicity of substances to Daphnia magna Straus (Cladocera, Crustacea)' 2000-03-30

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: nominal 10, 22, 46, 100, and 220 µg/L
- Sampling method: Sampling volume was 100 mL
- Sample storage conditions before analysis: Not applicable; samples were transferred (at room temperature) to TNO Quality of Life immediately after sampling.
- Duplicate samples were taken from all test concentrations and the solvent-control during the study. Duplicate samples were taken at the beginning and the end of three intervals of 48 hours (nominal days 0 and 2, 14 and 16, 19 and 21) and interval of 72 hours (nominal days 9 and 12).

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The batch of TTBT was prepared three times a week. Volumes of 100 µL were added per litre of test medium, whilst stirring. Test vessels were preincubated with the respective test solution for 30 minutes. The preincubation solutions were then discarded and replaced by freshly prepared solutions.

- Controls: test medium without test substance but containing the solvent (TBA, 100 µL/L) used to prepare the stock solutions.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Test medium is M7, 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).

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (Crustacea, Cladocera)
- Strain/clone: Straus, 1820
- Source: In-house laboratory culture with a known history. Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs os stress such as mortality, >20 %, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.
- Age of parental stock (mean and range, SD): <24 hours
- Feeding during test
- Food type: suspension of fresh water green algae (Chlorella pyrenoidosa)
- Amount: 0.2 mg/C/daphnid/day
- Frequency:daily


ACCLIMATION
- Acclimation period:With newborn daphnids, i.e. less than 3 days old, by placing them individually into 50 mL of medium in an all-glass culture vessel.
- Health during acclimation (any mortality observed): maximum age of cultures is 4 weeks. After 7 days of cultivation half of he medium is renewed twice a week.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

The hardness value in blank test medium and the highest test concentration were fairly constant during the study period and were maintained at >140 mg CaCO3 per liter.

Test temperature:

The tempertures at their renewals varied between 19.8 and 20.7 °C. Room temperature (measured continuously in a temperature control vessel) remained within the range of 19.8-21.1 °C. Hence, the temperature was maintained within the limits described in the protocol.

pH:

The pH values remained within the range of 7.3 to 8.1 throughout the study and thus was maintained within the limits prescribed by the protocol. One deviating pH value of 6.2 was recorded in the remaining test vessel that contained the last dead parent at nominal 46 µg/L at the end of the test.

Dissolved oxygen:

The dissolved oxygen concentrations measured during the study remained >6.9 mg/L during the exposure period and thus complied to the protocol.

Nominal and measured concentrations:

solvent-control, 10, 22, 46, 100 and 220 µg/L
TWA - 0, 7.2, 14, 34, 78, 220 µg/L

Details on test conditions:

TEST SYSTEM

- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): 20

TEST MEDIUM / WATER PARAMETERS
-Total organic carbon: TOC at the start of the test was 0.5 mg/L.
- Intervals of water quality measurement: pH and oxygen measured at start and just before and after each renewal in all test solutions; temperature measured at the start of the test and just before and after each renewal, additionally, continuously in a temperature control vessel. Hardness measured once a week in fresh and old media of the control and the highest remaining concentration. TOC measured in duplicate for total dissolved organic carbon on day 0 from blank test medium.

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
- Test concentrations: 0.1 to 1000 µg/L
- Results used to determine the conditions for the definitive study: The 72 hour EC50 was estimated at 300 µg/L, being the rounded geometric mean of the concentrations causing 10 and 100 % effect, i.e., 100 and 1000 µg/L. The highest concentration to be tested in a reproduction study is generally set at the EC20 level obtained in the acute test. Consequently, a proposal for a range to be tested might be 10, 22, 46, 100 and 220 µg/L. Replacements of test solutions should preferably be performed at least every 48 hours.

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

14 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: reproductive output, mortality of parentals, body length

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

34 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: survival of parentals, reproduction, and body length

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

51 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks:

of parental daphnids

Duration:

21 d

Dose descriptor:

other: EC100

Effect conc.:

78 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks:

parental daphnid survival

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

34 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth

Remarks:

body length

Duration:

21 d

Dose descriptor:

other: EC0

Effect conc.:

14 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks:

parental survival

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

34 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

The values for reproduction observed at various concentrations of the test substance in water were expressed as mean number of living young per parent.

Exposure to TTBT induced statistically significant inhibition of the reproductive capacity of the parental daphnids at the three highest levels tested, The reproduction at the TWA concentration of 34 µg/L was slightly (but statistically significant) below that of the control. At 78 and 220 µg/L TTBT the decrease was caused by complete mortality of the parental daphnids.

A LOEC for body length could not be determined because parents did not survive at 78 µg/L (TWA) and higher.

Reported statistics and error estimates:

Statistical analysis included normality and homogenity of variance. The data were statistically tested using ANOVA, Bonferroni t-test, Tukey test, and Dunnett's test. The LC50 was determined as (AB)^1/2, where A is the concentration with no or 10 % mortality and B is the concentration with 100 % mortality. The average exposure concentrations were calculed with the geometric means of the concentrations of TTBT at the start of the 2 and 3 -day renewal periods.

Table 1: Summary of Mortality

Nominal Conc	TWA (ug/L)	Number Exposed	Cumulative # of dead parents on day:														Mortality (%)
			1	2	5	6	7	8	9	12	13	14	16	19	20	21
Solvent-control	0	20	0	0	0	0	0	0	0	0	0	0	0	1	1	1	5
10	7.2	10	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
22	14	10	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
46	34	10	0	0	0	0	0	0	0	0	0	0	0	0	1	1	10
100	78	10	0	0	0	0	1	1	1	1	1	3	3	8	9	10	100
220	220	10	0	0	0	0	2	6	9	10	10	10	10	10	10	10	100

Table 2: Summary of Body Length

Average Body Lengths (mm) of parental daphnids
Nominal TTBT (ug/L)	TWA (ug/L)	Average Length (mm)	SD	% Reduction
Solvent control	0	5.14	0.46
10	7.2	4.93	0.36	4.1
22	14	5.04	0.34	1.9
46	34	4.84	0.24	5.8
100	78	NA	NA	NA
220	220	NA	NA	NA

Validity criteria fulfilled:

not specified

Conclusions:

Exposure to TTBT induced statistically significant inhibition of the reproductive capacity of the parental daphnids at the three highest levels tested. The reproduction at the TWA concentration of 34 ug/L was slightly, but statistically significantly below that of the control At TWA concentrations of 78 and 220 µg/L, the decrease was caused by complete mortality of parental daphnids.

Executive summary:

A 21-day reproduction study with tetrabutylstannane (TTBT) was conducted according to guidelines. Exposure to TTBT induced statistically significant inhibition of the reproductive capacity of the parental daphnids at the three highest levels tested. The reproduction at the TWA concentration of 34 µg/L was slightly, but statistically significantly below that of the control. At TWA concentrations of 78 and 220 µg/L, the decrease was caused by complete mortality of parental daphnids.

21 day NOEC = 14 µg/L based on reproductive output, mortality of parentals, body length

21 day LC50 = 51 µg/L mortality of parental daphnids

Description of key information

21 day NOEC Daphnia magna = 14 µg/L (based on reproductive output, mortality of parentals, body length)

21 day LC50 Daphnia magna = 51 µg/L (based on mortality of parental daphnids

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

14 µg/L

Additional information

One study is available. In a 21 day study of daphnia magna, the following time weighted average concentration results were obtained:

21 day NOEC = 14 µg/L based on reproductive output, mortality of parentals, body length

21 day LC50 = 51 µg/L mortality of parental daphnids