Ethyl 9,9-dioctyl-4,7,11-trioxo-3,8,10-trioxa-9-stannatetradeca-5,12-dien-14-oate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

The target substance is a mono-constituent organotin substance that consists of a tin as central metal element with two octyl-ligands. The source substance Dioctyltin oxide (DOTO) (EC Number 212-791-1 and CAS 870-08-6) is also an organotin compound that has the identical structure elements as the target substance in respect of the tin-alkyl moiety.
According to WHO IPCS CIRCAD (2006) organotin compounds are characterized by a tin–carbon bond and have the general formula RxSn(L)(4−x), where R is an organic alkyl or aryl group and L is an organic (or sometimes inorganic) ligand. The organotin moiety is significant toxicologically. The anionic ligand influences physicochemical properties but generally has little or no effect on the toxicology.
Since the target substance and the source substances share the identical organotin moiety, and the organotin moiety is generally recognized as the relevant toxophore of organotins and the toxicity estimates (AE) respectively toxicity limits for organotins are expressed as tin, the overall ecotoxicity/systemic toxicity of the target can be interpolated by assessing the (eco-)toxicity of the source (WHO IPCS CIRCAD, 2006, BAUA AGS TRGS 900, 2014, Summer KH, Klein D and Greim H, 2003).
The purity of the source and target substance are expected to be similar, based on the manufacturing method. The impurity profile is not expected to have strong effects on substance properties and any impurity of (eco-)toxicological relevance of the source substances is expected to be present in the target substance. Consequently, the hazard profiles of the source substances, including those of their impurities, are intrinsically covered. Differences in impurities are not expected and thus do not have an impact on the (eco-)toxic properties.

References
BAUA (Bundesanstalt für Arbeitsschutz und Arbeitsmedizin (Federal Institute for Occupational Safety and Health)) AGS (Ausschuss für Gefahrstoffe (Committee on Hazardous Substances)) TRGS (Technical Rules for Hazardous Substances) 900 (2014). Begründung zu n-Octylzinnverbindungen, April 2014.
Summer KH, Klein D, Griem H (2003). Ecological and toxicological aspects of mono- and disubstituted methyl-, butyl-, octyl-, and dodecyltin compounds - Update 2002. GSF National Research Center for Environment and Health, Neuherberg, for the Organotin Environmental Programme (ORTEP) Association.
World Health Organization (WHO) International Programme on Chemical Safety (IPCS) Concise International Chemical Assessment Document (CICAD) 73 Mono- and disubstituted methyltin, butyltin, and octyltin compounds (2006). Published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organization, and the World Health Organization, and produced within the framework of the Inter-Organization Programme for the Sound Management of Chemicals

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.001 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.002 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.002 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Equivalent to 100 % saturated solution

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 February 1988 to 08 March 1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was performed to the OECD guideline 201. The test material DOTO (di-n-octyltin oxide) is in the same category of substances as the registration substance, as such it is considered acceptable to use a read-across approach to address this endpoint. Some deficiencies were present in the study, such as limited reporting and the concentrations of the test material were not maintained throughout the test. The study is therefore considered to be reliable with acceptable restrictions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
PHYSICO-CHEMICAL PROPERTIES
- Melting point: melting with decomposition from approximately 282 °C
- Vapour pressure: 0.00042 Pa at 25 °C
- Water solubility (under test conditions): <0.0000152 g/L at 20 °C
- Log Pow: Calculated estimate of 9.26 (method not validated for this class of material)

OTHER PROPERTIES (if relevant for this endpoint)
- Results of test for ready biodegradability: not readily biodegradable
- Results of short-term toxicity testing on invertebrates (Daphnia magna): 48 hour EC50 >water solubility under the conditions of the study (between 0.09 and 0.54 mg/L); EC50 >0.21 mg/L (geometric mean of the solubility of the test material).
- Results of short-term toxicity testing on fish (Brachydanio rerio): 96 hour LC50 >water solubility under the conditions of the study (between 0.05 and 0.18 mg/L); LC50 >0.09 mg/L (geometric mean of the solubility of the test material).

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 10, 18, 32, 58 and 100 % of saturated solution, sampled at 0 and 72 hours measured as Sn content

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 300 mg of the test material was added to 1500 mL water and stirred for 48 h then filtered through a glass filter D4 then through a membrance filter (Millipore Type HA 0.45 µm)
- Controls: A blank was included as a control

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: Cambridge 276/20
- Method of cultivation: In accordance with OECD 201

ACCLIMATION
- Culturing media and conditions: 3 days under test conditions

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 ± 2 °C

pH:

7.8-9.2

Nominal and measured concentrations:

Nominal: 0 (blank), 10, 18, 32, 58 and 100 of saturated solution %
Measured: 0, 0.00023, 0.00032, 0.00053, 0.00097 and 0.0018 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type : closed, stoppered with aluminium caps
- Material, size, headspace, fill volume: 100 mL
- Initial cells density: 1.2 E4 cells/mL
- Control end cells density: 1.95 E5
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, as detailed in OECD 201 (1984)

OTHER TEST CONDITIONS
- Photoperiod: Continuous illumination
- Light intensity and quality: 120 µE/m²sec ± 20 % (approx. 8000 Lux) cold white fluorescent light

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: Daily on TOA cell counter

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.002 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Equivalent to 100 % saturated solution

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.002 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.001 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
Figure 1 depicts the growth rate.
- Results with test material: Slight to no effects were noted on the algal growth during the course of the study.
- Concentration of the test material: Test concentrations were not maintained during the study, results are expressed as initial measured concentration.

Reported statistics and error estimates:

Comparisons for area under growth curve were performed in accordance with the guidance provided in the guideline.

Table 1: Cell density after 24 hours

Conc. (initial) mg/L	Relative cell densities						Mean Relative Density	Dilution Factor 1:	Mean Density N24h cells/mL*1000
	1	2	3	4	5	6
Blank	50	53	48	53	54	63	54	10	8.1
0.00023	59	58	55				57	10	8.6
0.00032	60	56	68				61	10	9.2
0.00053	60	59	55				58	10	8.7
0.00097	51	57	50				53	10	8.0
0.0018	52	55	64				57	10	8.6

 

Table 2: Cell density after 48 hours

Conc. (initial) mg/L	Relative cell densities						Mean Relative Density	Dilution Factor 1:	Mean Density N48h cells/mL*1000
	1	2	3	4	5	6
Blank	154	204	200	262	231	271	220	10	33.0
0.00023	215	194	207				205	10	30.8
0.00032	154	233	227				205	10	30.8
0.00053	203	180	157				180	10	27.0
0.00097	244	229	258				244	10	36.6
0.0018	238	271	312				274	10	41.1

 

Table 3: Cell density after 72 hours

Conc. (initial) mg/L	Relative cell densities						Mean Relative Density	Dilution Factor 1:	Mean Density N72h cells/mL*1000
	1	2	3	4	5	6
Blank	118	128	128	133	127	146	130	100	195
0.00023	125	139	141				135	100	203
0.00032	132	130	161				141	100	212
0.00053	140	144	146				143	100	215
0.00097	135	130	144				136	100	204
0.0018	67	71	81				73	100	110

Multiplication Factor N72h/N0h = 163

 

Table 4: Percentage inhibition

Conc. (initial) mg/L	Areas under growth curve				% Inhibition (IA 0-72h)
	A0-24h	A24-48h	A48-72h	A0-72h
Blank	83	464	2707	3254	0
0.00023	89	444	2777	3310	0*
0.00032	96	451	2885	3432	0*
0.00053	90	400	2875	3365	0*
0.00097	82	506	2858	3446	0*
0.0018	89	568	1784	2441	25
* promotion of algal growth in regard to Blank-Control denoted as: 0

 

Table 5: pH and analytical concentrations

Conc. in % of saturated solution	Measured concentrations*		pH
	0 h mg/L	72 h mg/L	0 h	72 h
Blank			8.1	9.2
0.00023	0.00023	<0.00021	7.8	8.9
0.00032	0.00032	<0.00021	7.8	9.0
0.00053	0.00053	0.00027	7.8	9.0
0.00097	0.00097**	0.00044	7.8	9.1
0.0018	0.0018	0.00079	7.8	9.1
* analytically determined values multiplied by a factor of 100/32.87; Sn content of test material: 32.87 % ** value of only one sample considered, all others are mean of two samples

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the test, the test material exhibited little or no difference on the growth rate of the algae Desmodesmus subspicatus (reported as Scenedesmus subspicatus) when tested up to a 100 % saturated solution. The ErC50 of the test substance is greater than the water solubility of the test material.

Executive summary:

The toxicity of the test material to aquatic plants was determined in a study conducted in accordance with the standardised guideline OECD 201, using the algal species Desmodesmus subspicatus (reported as Scenedesmus subspicatus). The study was conducted using a range of concentrations, tested up to the water solubility of the test material. The concentrations of the test material were not maintained in the solutions throughout the entire 72 hour test period, results were expressed as the initial concentration. Under the conditions of the study, the test material exhibited little or no difference on the growth rate of the algae, the ErC50 of the test material is considered to be greater than the water solubility of the test material.

Description of key information

72 hour EC50 = >0.0018 mg/L, dioctyltin oxide, OECD 201, Rufli 1988

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

0.001 mg/L

Additional information

The toxicity of the test material to aquatic plants was determined in a study conducted in accordance with the standardised guideline OECD 201, using the algal species Desmodesmus subspicatus (reported as Scenedesmus subspicatus), with the analogous test material dioctyltin oxide.

The study was conducted using a range of concentrations, tested up to the water solubility of the test material. The concentrations of the test material were not maintained in the solutions throughout the entire 72 hour test period, results were expressed as the initial concentration. Under the conditions of the study, the test material exhibited little or no difference on the growth rate of the algae, the ErC50 of the test material is considered to be greater than the water solubility of the test material, >0.0018 mg/L.

As the study was performed on a read-across substance in the same category as the registered substance (di-n-octyltin oxide), it was assigned a reliability score of 2 (reliable with acceptable restrictions) in accordance with the criteria for assessing data quality as outlined in Klimisch (1997) and considered suitable for assessment as an accurate reflection of the test material.