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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Phthalic acid has to be classified as readily biodegradable and is regarded as inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

There is only one study on ready biodegradability of phthalic acid available.

The test was conducted in 1973 according to a national standard method using closed bottles and results in 74% degradation after 30 days, indicating that the substance is readily biodegradable. The structural analogue phthalic anhydride is taken into account to describe the biodegradation behaviour of phthalic acid. Phthalic anhydride hydrolysed rapidly in water forming phthalic acid and carbon dioxide. In a modified MITI test comparable to OECD TG 301 C the biodegradation of phthalic anhydride was investigated (MITI, 1992). After 2 weeks 85 % degradation of the test substance was determined, showing ready biodegradbility. Based on this result, ready biodegradabaility of phthalic acid is considered to be confirmed and the substance has to be classified as readily biodegradable. Inherent biodegradability was documented with a degradation > 90 % within 4.5 days according to EU Method C.9 (Zahn, 1980).