Tetrakis(hydroxymethyl)phosphonium chloride, oligomeric reaction products with urea

Biodegradation in water: screening tests

Description of key information

Tetrakis(hydroxymethyl)phosphonium chloride, oligomeric reaction products with urea is not readily biodegradable in accordance with the criterion in EU system (Directive 67/548/EC).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Available biodegradation information

Several study reports record experimental results on biodegradation properties of [Tetrakis(hydroxymethyl)phosphonium chloride, oligomeric reaction products with urea]. An overview of the biodegradation dataset is provided in the table below.

Method	Duration	Inoculum	Test conditions	Parameter	Result	Reference	Flag (reliability)
OECD 302C	28 d	AS (domestic, industrial) 100 mg ss/L	30 mg/L Aerobic, Dark 25°C	O2 consumption DOC ThOD = 15.99 mg O2/L (test material)	%Degr.=0% (O2cons-Day 28) %Degr.=0% (DOC-Day 28)	Mead, 1996a	Key Study (1)
OECD 301B	28 d	AS(domestic) 30 mg ss/L	24.6 mg/L (equivalent to 5 mg C/L) Aerobic, Dark 21°C	CO2 production	%Degr.=8% (on Day 28)	Mead, 1996b	Key Study (2)
OECD 302B	14 d	AS 300 mg ss/L	121 mg/L (equivalent to 21 mg DOC/L) 293 mg/L (equivalent to 50 mg DOC/L)	DOC Removal	%degr.=29%(on Day 14) but toxicity observed	Gottfried E, 2010	Supporting study (2)
OECD 301D	28 d	AS (domestic)	20 mg/L Aerobic, Dark	O2 consumption	%Degr.=11% (on Day 28)	Handley & Sewell, 1992	N/A (2)
5day- BOD (UK Guid.)	5 d	Sludge from a sewage treatment plant	1:19 dilution of 500 mg/L	BOD COD	BOD5= 10.10 mgO2/L COD= 115 mgO2/L	Handley & Mead, 1992	N/A (1)

Guid.: Guideline ; AS: Activated Sludge

Ready biodegradation study

Three available study reports (Handley & Mead, 1992; Handley and Sewell, 1992; Mead, 1996b) record experimental result from ready biodegradation test. Handley & Mead (1992) found that the test material was not readily biodegradable using a 5-day BOD Testing.

Handley & Sewell (1992) performed a ready biodegradation test on [Tetrakis(hydroxymethyl)phosphonium chloride, oligomeric reaction products with urea] according to OECD Guideline No 301D. The following treatments were applied: abiotic control (culture medium without inoculum), control (culture medium with inoculum), test material (inoculum + test material), reference substance (inoculum + sodium benzoate).

The biodegradation of test material was determined at 11% based on oxygen depletion. The percentage of biodegradation of the reference substance (sodium benzoate) attained 72% on day 5, 94% on day 15 and 97% on day 28 (based on oxygen depletion).

Mead (1996b) performed a ready biodegradation test on [Tetrakis(hydroxymethyl)phosphonium chloride, oligomeric reaction products with urea]. The following treatments were applied: control (inoculum), test material (inoculum + test material), reference substance (inoculum + sodium benzoate) and toxicity control (inoculum + test material + sodium benzoate). The percentage of biodegradation of test material was determined at 8% based on inorganic carbon after 28 days of exposure. The percentage of biodegradation of the toxicity control attained 28% on day 6, 31% on day 14 and 88% on day 28. The percentage of biodegradation of the reference substance (sodium benzoate) attained 73% on day 6, 94% on day 14 and 98% on day 28 (based on inorganic carbon). The biodegradation of the reference substance was a little bit delayed and reduced in the toxicity control but the experimental results are compliant with the OECD Guideline No 301B requirements.

Inherent Biodegradation study

Mead (1996a) performed an inherent biodegradation test on [Tetrakis(hydroxymethyl)phosphonium chloride, oligomeric reaction products with urea]. The following treatments were applied: control (inoculum), test material (inoculum + test material), abiotic control (test material + deionised water), reference material (inoculum + aniline) and toxicity control (inoculum + test material + aniline). The percentage of biodegradation of both test material and abiotic control was determined at 0% based on BOD after 28 days of exposure. The percentage of biodegradation of the toxicity control was determined at 88% based on BOD after 28 days of exposure. The percentage of biodegradation of the reference substance (aniline) attained 44% on day 7, 71% on day 14 and 91% on day 28 (based on BOD). Aniline attained 99% of biodegradation calculated from the results of the DOC analyses. The biodegradation of aniline was reduced in the toxicity control by comparison with the reference material. A screening test was performed recently to confirm the inhibitory effect of test material (Gottfried, 2010). Under the conditions of the test, the registered substance was found toxic to microorganisms at concentrations of 121 and 293 mg/L.

Conclusion

Under the conditions of this study, Tetrakis(hydroxymethyl)phosphonium chloride, oligomeric reaction products with urea would be considered as not readily biodegradable in accordance with the criterion in EU system (Directive 67/548/EC). This limited potential for biodegradation is expected to result from the inhibitory effect of registered substance.