Pentyl nitrite

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Parameter followed for biodegradation estimation:

O2 consumption

Key result

Parameter:

% degradation (O2 consumption)

Value:

95.7

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Percentage of biodegradation at 28 days : 95.7 %
Conclusion : Readily biodegradable

Executive summary:

The objective of this study was to assess the aerobic ready biodegradability of test item by measurement of manometric respirometry over a 28-day period according to the OECD 301F guideline (July 1992).

The test item, at approximately 100 mg/L, as the sole source of carbon and energy, was incubated in a buffer-mineral salts medium which was inoculated with a mixed population of micro-organisms. The consumption of oxygen was determined from the change in pressure in the apparatus. Evolved carbon dioxide was absorbed in a solution of sodium hydroxide. The amount of oxygen taken up by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of ThODNH3.

As the test item is poorly soluble in test conditions and volatile, the test solutions were prepared by direct addition of the test item on the silica gel.

The study is valid since:

Based on a biodegradation rate higher than 60% in 14 days (experimental value: 78.9 and 69.1 % in 6 days) in the reference control, the test was carried out under good conditions.

At the end of the test, measurements of Biological Oxygen Demand (BOD) in two replicates of the test item solution did not show a difference of more than 20% (experimental value: 8.3 %).

The oxygen uptake of the control was not greater than 60 mg/l in 28 days (experimental value: 33.1 and 27.0 mg O2/L).

Based on a biodegradation rate higher than 25% in 14 days (experimental value: 97.4 % in 13 days) in the toxicity control, the test item was not toxic to micro-organisms.

Results are the following:

Percentage of biodegradation at 28 days : 95.7 %

Conclusion : Readily biodegradable

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

Justification for type of information:

SOURCE AND TARGET CHEMICAL(S)
The read-across has been performed between pentyl nitrite (CAS No. 463-04-7; target chemical) and isoamyl nitrite (CAS No. 110-46-3; source chemical). The RA is based on an experimental study performed on the source substance with a purity of 98.3% in accordance with the OECD TG 301F and under GLP conditions.

ANALOGUE APPROACH JUSTIFICATION
The source substance and the target substance have the same chemical formula (C5H11NO2) and belong to the alkyl nitrites family. Like other alkyl nitrites, chemical and biological properties are mainly due to the nitrite group. Both target and source substances have similar physico-chemical properties.
For all these reasons, it is expected that the registered substance pentyl nitrite will have similar environmental fate than the source substance isoamyl nitrite. The read-across approach between both alkyl nitrite substances is therefore considered relevant for this endpoint.
Isoamyl nitrite was found to be readily biodegradable with a biodegradation rate of 95.7% at 28 days. The study was performed according to the OECD TG 301F under GLP conditions and all validity criteria were successful. This experimental study was therefore considered acceptable.
Because of the high biodegradation rate of the source substance under the conditions of the study and the similarity between both target and source substances, it is expected that pentyl nitrite would be also found readily biodegradable if a test was performed.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (O2 consumption)

Value:

95.7

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Based on a read-across on an experimental study performed on another alkyl nitrite substance (isoamyl nitrite) in accordance with the OECD TG 301F and under GLP conditions, the registered substance pentyl nitrite is expected to be readily biodegradable.

Executive summary:

For that endpoint, a read-across was performed between pentyl nitrite (CAS No. 463-04-7; target chemical) and isoamyl nitrite (CAS No. 110-46-3; source chemical).

The source substance and the target substance have the same chemical formula (C5H11NO2) and belong to the alkyl nitrites family. Like other alkyl nitrites, chemical and biological properties are mainly due to the nitrite group. Both target and source substances have similar physico-chemical properties.

For all these reasons, it is expected that the registered substance pentyl nitrite will have similar environmental fate than the source substance isoamyl nitrite. The read-across approach between both alkyl nitrite substances is therefore considered relevant for this endpoint.

An experimental study performed on the source substance isoamyl nitrite was available, and was conduted according to the OECD TG 301F under GLP conditions.

In this study, the test item, at approximately 100 mg/L, as the sole source of carbon and energy, was incubated in a buffer-mineral salts medium which was inoculated with a mixed population of micro-organisms. The consumption of oxygen was determined from the change in pressure in the apparatus. Evolved carbon dioxide was absorbed in a solution of sodium hydroxide. The amount of oxygen taken up by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of ThODNH3.

As the test item was poorly soluble in test conditions and volatile, the test solutions were prepared by direct addition of the test item on the silica gel.

The study is considered valid since:

Based on a biodegradation rate higher than 60% in 14 days (experimental value: 78.9 and 69.1 % in 6 days) in the reference control, the test was carried out under good conditions.

At the end of the test, measurements of Biological Oxygen Demand (BOD) in two replicates of the test item solution did not show a difference of more than 20% (experimental value: 8.3 %).

The oxygen uptake of the control was not greater than 60 mg/l in 28 days (experimental value: 33.1 and 27.0 mg O2/L).

Based on a biodegradation rate higher than 25% in 14 days (experimental value: 97.4 % in 13 days) in the toxicity control, the test item was not toxic to micro-organisms.

Results were the following for the source substance:

Percentage of biodegradation at 28 days : 95.7 %

Conclusion : Readily biodegradable

Because of the high biodegradation rate of the source substance under the conditions of the study and the similarity between both target and source substances, it is expected that pentyl nitrite would be also found readily biodegradable if a test was performed.

Description of key information

Based on a read-across on an experimental study performed on another alkyl nitrite substance (isoamyl nitrite) in accordance with the OECD TG 301F and under GLP conditions, the registered substance pentyl nitrite is expected to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater