Fatty acids, C16 and C18-unsatd., polymers with bisphenol A, Bu glycidyl ether, epichlorohydrin and triethylenetetramine

Biodegradation in water: screening tests

Description of key information

The percentage biodegradation of MonoFA_TETA_PAA_BADGE_BGE_Adduct reached a maximum of 5% over the course of the 28 day incubation and therefore failed to meet the requirements for ready biodegradability. Thus, MonoFA_TETA_PAA_BADGE_BGE_Adduct cannot be classified as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The ready biodegradability of MonoFA_TETA_PAA_BADGE_BGE_Adduct was assessed by measurement of the amount of dissolved oxygen consumed during mineralisation of the test substance in completely filled, sealed bottles under standard conditions. The procedure followed was that described in OECD Guideline 301D, Closed Bottle Test (adopted July 1992).

The test substance was dissolved in a buffered mineral salts medium inoculated with microorganisms derived from a sample of sewage treatment plant effluent, not previously exposed to the test substance.

The test vessels were filled completely with mineral medium and closed prior to incubation in the dark at 22 ±2 °C for 28 days. At intervals during the incubation, duplicate vessels were sacrificed and a dissolved oxygen electrode placed in each vessel to measure residual dissolved oxygen (DO) concentrations. The differences between the initial DO readings and those made during the course of the incubation, allowed determination of the oxygen uptake. These data were corrected for blank uptake and expressed as a percentage of the theoretical oxygen demand (ThOD).

The activity of the inoculum and the experimental procedure were checked by inclusion of a series of vessels containing a standard reference substance, sodium benzoate. In addition a series of toxicity control vessels were prepared, containing both the test and reference substances, to determine whether MonoFA_TETA_PAA_BADGE_BGE_Adduct had an inhibitory effect on the microbial activity of the effluent.

In order for the test substance to be defined as 'readily' biodegradable, the percentage biodegradation must amount to at least 60% of ThOD, both within the 28-day incubation period and within 10 days of first reaching 10% biodegradation. The percentage biodegradation of MonoFA_TETA_PAA_BADGE_BGE_Adduct at Day 28 was 5%. Therefore, monoFA_TETA_PAA_BADGE_BGE_Adduct cannot be considered to be readily biodegradable.

Biodegradation of the reference substance, sodium benzoate, was 73% on Day 14 and 76% at the end of the test. These data show that the inoculum was viable and exerted normal degradative activity. In the toxicity control group, biodegradation of sodium benzoate was slightly lower at 61% and 64% on Day 14 and Day 28, respectively, suggesting that the test substance was exerting a small inhibitory effect on the microbial degradation of the reference substance.

All validity criteria were satisfied and the results of this study are therefore considered to be valid.