Decahydronaphthalene

Biodegradation in water: screening tests

Description of key information

Based on the four biodegradation tests conducted according to standard existing guidelines, the substance was found to be not readily biodegradable. Three of the four studies analyzing the ready biodegradability resulted in degradation rates of 1 -3 % within 28 days. In the fourth test, which studied the inherent biodegradability, a degradation rate of 5.5 % was found after 28 days.

The test item also showed biodegradation by 53% at day 28 in a Closed Bottle test according to ISO 10707 and OECD 301D using natural surface water. In the prolonged Closed Bottle test (enhanced biodegradability test) the test substance is biodegraded in excess of 63% at day 42.

Studies with aquatic or marine bacteria showed that they are able to degrade this chemical to some extent (up to 25%). In addition, the half-life for decahydronapthalene was calculated in another biodegradation study with biodiesel and the results indicate a disappearance in less than 30 days. QSAR calculations with some Biowin models also indicate a good degradability of the test item in the environment.

Altogether, these results would indicate that degradation of decahydronaphthalene in the environment may occur and even increase in presence of cometabolite substrates.

 

However, interpretation of these screening data is fraught with uncertainty, a significant amount of screening studies demonstrates weak or no biodegradation, other studies demonstrate biodegradation and cometabolisation to a certain extend. Due to the 53% biodegaradtion within 28 days in the Closed Bottle test and 63% after 42 days in the prolonged Closed Bottle test (enhanced biodegradability test) the test substance is regarded to be biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater