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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance was found to be readily biodegradable after achieving 75% degradation at 28 days in an OECD 301F guideline study.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Studies are available for both ready and inherent biodegradability. The test substance was found to be readily biodegradable.

Ready biodegradability:

A 28-day ready biodegradability test was performed using octanal to determine the biodegradability of the substance in an aqeuous medium. The test was performed in accordance with OECD guideline 301F. The test item, at a concentration of 30 mg test item/L, was exposed to activated sewage sludge microorganisms for 30 days. The degradation of the test item was assessed by the continous determination of O2consumption. The test item otained 75% degradation after 28 days and therefore is considered to be readily biodegradable.

A further supporting study (OECD 310) showed 46% biodegradation after 28 days.

Inherent biodegradability:

The inherent biodegradability of octanal was investigated in a 28-day OECD 302C study. The test was conducted at a nominal concentration of 30 mg/L in 1000mL flasks inoculated with mineral medium. The consumption of oxygen was measured using a respirometer and compared to the oxygen consumption in the control vessels in order to determine the degradation of the test substance. The respirometer used was a Bioscience BI-1000 and the test temperature was 25 ±1oC.

Octanal was found to be 77% degraded after 28 days and was over 50% degraded within the first 2 days of the test. As such, octanal is considered to be inherently biodegradable.