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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

One biodegradation study based on OECD 301F.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The ready biodegradability of Paraformaldehyde, oligomeric reaction products with 4-tert-butylphenol, m-phenylenebis(methylamine)was evaluated using the Organisation for Economic Co-operation and Development (OECD) Guideline No. 301F: Manometric Respirometry Test. Due to the low aqueous solubility of some components, the test material was coated onto silica gel to facilitate its dispersion in the biodegradation reaction mixtures at approximately 20.2 mg/L (53.3 mg/L as chemical oxygen demand [COD]). No biodegradation of the test material occurred over the duration of this test. However, cumulative oxygen demand in duplicateTest Suspensionscontaining the test material was lower than that in unamendedInoculum Blanks; indicating that the test material was toxic or inhibitory to the inoculum under these test conditions. Therefore, the test material does not meet OECD criteria for “ready biodegradability” in the Manometric Respirometry test. Because the test material was toxic/inhibitory to the inoculum under these conditions, further testing would be necessary to assess the intrinsic biodegradability of this material.

The results of this test met or exceeded each of the OECD-specified criteria for validation of the ready biodegradability tests. These include parameters such as viability of the inoculum, control of pH, temperature, and precision in percentage biodegradation recorded among replicate test mixtures. Biodegradation of a reference material aniline (99.9 mg/L, 240.3 mg/L as theoretical oxygen demand [ThOD]) exceeded 60% by 6.1 days, verifying the viability of the activated sludge inoculum. AToxicity Controlmixture, containing both aniline (99.9 mg/L, 240.3 mg/L as ThOD) and the test material (20.3 mg/L, 53.6 mg/L as COD), showed no evidence for inhibition of the microbial inoculum. Oxygen consumption and CO2evolution observed in the reaction mixtures could be attributed solely to biological activity, as no net O2consumption or CO2evolution was measured in anAbiotic Controlmixture containing the test material and a chemical sterilant (HgCl2).