Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Terpinyl acetate multi is readily biodegradable based on read-across from alpha-Terpinyl acetate which was tested in OECD TG 301F. In this study activated sludge was exposed to 100 mg/L alpha-Terpinyl acetate for 28 days. In this test 63% biodegradation was observed at day 28 (58% biodegradation was observed already at day 2). For support alpha-Terpinyl Acetate and Terpinyl Acetate gamma are both predicted in BIOWIN 5 and 6 and these predictions are very similar. Therefore, the substance is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

No data is available for Terpinyl acetate multi. Therefore read-across is performed to the close structural analogue alpha-Terpinyl acetate. First the ready biodegradability test of Terpinyl Acetate alpha is presented after which a summarised read across justification is presented.

 

Terpinyl Acetate alpha ready biodegradability

In the ready biodegradability test with alpha-Terpinyl acetate the biodegradation exceeds 60% but the 10-day window is missed by a few %. According to CLP Annex I section 4.1.2.9.5. and OECD guidance for the testing of chemicals; Section 3 introduction (2006), if the substance is a UVCBs or a complex multi-constituent with structurally similar constituents, and it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test. Though alpha-Terpinyl acetate is a mono-constituent according to ECHA criteria, it contains 13% structural homologues of the main constituent for which indeed sequential biodegradation may be anticipated to occur. Based on this the 10-day window condition for alpha-Terpinyl acetate is waived and the pass level applied at >60% biodegradation in 28 days and the substance is considered readily biodegradable.

 

Terpinyl Acetate multi biodegradation prediction from Terpinyl Acetate alpha

The hypothesis is that Terpinyl Acetate multi is assumed to have the same ready biodegradability as Terpinyl Acetate alpha because both substances contain the same constituents. There are no structural differences between the constituents. The difference is the percentages of the constituents as presented in the table below. All constituents are expected to be similarly biodegradable based on the structural similarities, bioavailability and degradable fragments. This is supported with BIOWIN prediction for Terpinyl Acetate alpha and gamma, being the key constituents of both Terpinyl acetates. In the table below, these predictions show very comparable probabilities for ready biodegradation. The Terpinyl Acetate gamma shows slightly higher probability for BIOWIN 6 and therefore the ready biodegradability is unlikely to be underestimated.

 

 

Cas no.

Concentration in substance in % alpha/gamma

Biowin 5

Biowin 6

Terpinyl Acetate alpha

80-26-2

87/9

0.619

0.596

Terpinyl Acetate gamma

10235-63-9

64/20

0.62

0.67