Tin bis(2-ethylhexanoate)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance is inorganic

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

restrictions: non-GLP; instead of secondary effluent as recommended by the guideline, the primary effluent of a municipal sewage treatment plant was used as inoculum for this study. The authors justified this by referring (1) to the microbial concentration in the secondary effluent that was too low for the purpose of the study, and (2) to the possible presence of chemical residues within the secondary effluent that may interfere with the biological activity.

Justification for type of information:

Read across to an analogue based on structural similarity. An analogue justification is attached to section 13 of the dataset.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

GLP compliance:

no

Parameter:

% degradation (DOC removal)

Value:

99

Sampling time:

28 d

Parameter:

% degradation (DOC removal)

Value:

90.1

Sampling time:

7 d

Details on results:

Kinetic of test substance:
= 67% after 2 day(s)
= 91% after 5 day(s)
= 91% after 7 day(s)
= 95% after 14 day(s)

Degradation products: not measured

Results with reference substance:

Kinetic of control substance:
= 84% after 2 day(s)
= 98% after 5 day(s)

Abiotic and adsorption tests were poisoned with 15 mg/L Na azide to prevent bioactivity. The dosage was not sufficient to stop microbial growth in test vessels, and so the tests were interrupted as the preliminary results showed at the same time that these factors are not likely to interfere the biodegradation of the test substance.

Biodegradation (% relate to DOC)
	0 d	2 d	5 d	7 d	14 d	28 d
test substance (mean)	0	67.2	91.4	90.7	94.9	99.2
reference substance	0	83.8	97.8	95.6	96.8	99.3
toxicity test	0			76.1		98.2

 

	Biodegradation		10d-window
	10%	70%
test substance (mean)	0.3 d	2.3 d	0.3-10.3 d
reference substance	0.2 d	1.7 d	0.2-10.2 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In an OECD 301 E biodegradation study, 2-ethylhexanoic acid is readily biodegradable:
- biodegradation (28 d) > 70 %
- Pass level reached in 10-d window.

The tin bis(2 -ethylhexanoate) substance is known to dissociate into its 2-ethylhexanoate and Sn(II) components upon introduction to water. The 2-ethylhexanoate portion of the substance has been shown to be readily biodegradable, while the Sn(II) will speciate initially as Sn(OH)2, and spontaneously oxidize in oxygenated water to form the insoluble inorganic solid Sn(IV)O2.

Description of key information

2-EHA
Biodegradation: OECD 301E- readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The tin bis(2 -ethylhexanoate) substance is known to dissociate into its 2-ethylhexanoate and Sn(II) components upon introduction to water. The 2-ethylhexanoate portion of the substance has been shown to be readily biodegradable, while the Sn(II) will speciate initially as Sn(OH)₂, and spontaneously oxidize in oxygenated water to form the insoluble inorganic solid Sn(IV)O₂.