Registration Dossier

Administrative data

Endpoint:
mode of degradation in actual use
Type of information:
other: expert judgement
Adequacy of study:
supporting study
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study

Data source

Reference
Reference Type:
other: expert judgement statement
Title:
Unnamed

Materials and methods

Principles of method if other than guideline:
Not relevant
Type of study / information:
Expert judgement statement

Test material

Constituent 1
Chemical structure
Reference substance name:
Reaction mass of 3-[(diphenoxyphosphoryl)oxy]phenyl triphenyl 1,3-phenylene bis(phosphate) and tetraphenyl 1,3-phenylene bis(phosphate)
EC Number:
701-337-2
Cas Number:
not available
Molecular formula:
C30H24O8P2
IUPAC Name:
Reaction mass of 3-[(diphenoxyphosphoryl)oxy]phenyl triphenyl 1,3-phenylene bis(phosphate) and tetraphenyl 1,3-phenylene bis(phosphate)
Details on test material:
- Name of test material (as cited in study report): Fyrolflex RDP

Results and discussion

Any other information on results incl. tables

Proposed biodegradation pathway

If an organic compound is to serve as a carbon and energy source it has to be converted into a form that can enter the central metabolism of micro-organisms. Although micro-organisms capable of degrading compounds are immensely diverse, the central metabolism is remarkably similar. Kluyver and Donker (1926) first described this similarity known as the unity of biochemistry. This unity is the key to justification of proposing a biodegradation pathway for Fyrolflex RDP. The initial steps in the biodegradation process of Fyrolflex RDP have to be hydrolysis of the respective phosphate bonds resulting in the formation of phosphate, resorcinol and phenol. This is based on initial biodegradation steps of other organophosphates, i.e. hydrolyses by phosphatases. Phosphatase is the general name adopted for enzymes that transform organophosphates giving phosphate and alcohols (Kertesz et al, 1994). Either resorcinol or phenol liberated by hydrolysis, has to be utilized by the microorganisms immediately because the phosphatase reactions do not generate energy necessary for growth-linked biodegradation. It is, however, most probable that both resorcinol and phenol are immediately degraded upon liberation in the microbial cells because many pure cultures (both bacteria and fungi) have the capacity degrade both aromatic compounds (Gaal and Neujahr, 1979; Springer et al, 1998; Cejkova et al, 2005; Ngugi et al, 2005). Based on these properties, excretion of phenol and resorcinol by micro-organisms is not expected. Moreover, excretion of metabolites (intermediates) during growth-linked biodegradation is in general a very uncommon phenomenon. Ultimate degradation of the aromatic compounds, both naturally occurring has been demonstrated by their biodegradation pathways leading to carbon dioxide and water (Chapman and Ribbons, 1976; Gibson and Subramanian 1984; Heider and Fuchs, 1997).

Kinetics

Either phenol or resorcinol is excreted as biodegradation product when Fyrolflex RDP is degraded by microorganisms only capable of degrading one of these aromatic compounds. In this case complete degradation has to be achieved by consortia of microorganisms. Organic compounds are exposed to mixed microbial culture in both natural ecosystems (soil, sediments etc.) and engineered systems (wastewater treatment, landfills etc). Both resorcinol- and phenol-degrading microorganisms are ubiquitously present in these (eco)systems and resorcinol and phenol degrade rapidly under both aerobic and anaerobic conditions (Table).

Table Data from literature showing biodegradation of resorcinol and phenol in a wide range of ecosystems.

Phenol

Reference

(Eco)system

Rate

 

Subsoil

0.006 -0.72 days-1

Konopka and Turco, 1991

Subsoil

2.6 days-1

Aelionet al,1987

Subsoil

 

Frieset al,1997

Landfill leachate

0.00027 h-1

Deeleyet al,1985

Sewage

0.00064 h-1

Deeleyet al, 1985

Enrichment culture

0.28–0.37 days-1

Vaishnavet al,1989

Biofilm reactor (aerobic)

Rates comparable with acetate

Arcangeli and Arvin, 1995

River water

1.8-4.9 10-6M h-1

Bannerjeeet al, 1984

Resorcinol

 

Estuary

 

Milligan and Haggblom, 1998

Sludge

0.1 h-1

Klugeet al,1990

Sludge

0.11 h-1

Gornyet al,1992

Biofilm reactor (anaerobic)

6 g l-1day-1

Latkaret al, 2003

Resorcinol and phenol will only accumulate in these (eco)systems when the degradation of Fyrolflex RDP is NOT rate limiting. Biodegradation of the naturally occurring recorcinol and phenol in ready biodegradability tests occurs within two weeks (MITI 1992; Zgajnar Gotvajn and Zagorc-Koncan 2003) whereas the biodegradation of Fyrolflex RDP requires three to four weeks (see Figure 1 below). These results strongly indicate that under aerobic conditions the degradation of Fyrolflex RDP is rate limiting thereby excluding (transient) accumulation of phenol or resorcinol. The high rates and rapid degradation in many systems of the aromatic compounds also indicate that (transient) accumulation is very unlikely (Table). Finally, it is likely that also under anaerobic conditions the degradation of natural occurring aromatic compounds will be faster than Fyrolflex RDP. Anaerobic degradation has been described for phenol (Knoll and Winter 1989; Tschech and Fuchs 1989; Satsangee and Gosh, 1990) and resorcinol (Szewzyk and Pfennig 1985; Tschech and Schink 1985; Kluge et al, 1990; Gorny et al, 1992; Springer et al, 1998; Milligan and Haggblom, 1998;). Under anaerobic conditions, phenol and resorcinol degrading bacteria are capable of utilizing nitrate, sulphate and carbon dioxide (methanogenic conditions) as electron acceptor.

References mentioned:

* CM Aelion, CM Swindoll and FK Pfaender 1987, Appl Environ Microbiol, 53, 2212-2217.

* J-P Arcangeli and E Arvin 1995, Wat Sci Tech, 31, 117-128.

* F Bak and F Widdell 1986, Arch Microbiol, 146, 177-180.

* S Banerjee, PH Howard, AN Rosenberg, AE Dombrowski, H Sikka and DL Tullis 1984, Environ Sci Technol, 18, 416-422.

* PJ Chapman and DW Ribbons 1976, J Bac, 125, 985-998.

* A Cejkova, J Masek, V Jirku, M Vesely and J Nesvera 2005, World J Microbiol Biotechnol, 21, 317-321.

* GM Deeley, P Skierkowski and JM Robertson 1985, Appl Environ Microbiol, 49, 867-869.

* ECRA (2007) Biodegradability of Fyrolflex RDP in the Closed Bottle test Internal report F07020 (GLP).

* MR Fries, LJ Forney and JM Tiedje 1997, Appl Environ Microbiol, 63, 1523-1530.

* A Gaal and HY Neujahr 1979, J Bac, 137(1), 13–21.

* DT Gibson and V Subramanian 1984, Microbial degradation of organic compounds. Ed Gibson, Marcel Dekker, New York pp 181-252,

* N. Gorny, G. Wall, A. Brune and B. Schink, 1992, Arch Microbiol, 158, 48-53.

* J Heider and G Fuchs 1997, Eur J Biochem, 243, 577-597.

* C Kluge, A Tschech and G Fuchs 1990, Arch Microbiol, 155, 68 -74.

* MA Kertesz, AM Cook and T Leisinger 1994 FEMS Microbiol Rev, 15, 195-215.

* Konopka and R. Turco 1991, Appl Environ Microbiol, 57, 2260-2268.

* AJ Kluyver and HJL Donker 1926, Chemie der Zelle und Gewebe, 13: 134-190.

* G Knoll, and J Winter 1989, Appl Microbiol Biotechnol, 30, 318-324.

* M Latkar, K Swaminathan and T Chakrabarti 2003, Biores Technol, 88, 69-74.

* PW Milligan and MM Häggbom 1998, Env Toxicol Chem 17, 1456-1461.

* MITI 1992, Data of existing chemicals based on the CSCL Japan. Tokyo, Ministry of International Trade and Industry, Chemicals Inspection & Testing Institute, Japan Chemical Industry Ecology-Toxicology & Information Center, pp. 3–19.

* DK Ngugi, MK Tsanuo and HI Boga 2005, African J Biotechnol, 4(7), 639-645.

* R Satsangee and P Ghosh 1990, Appl Microbiol Biotechnol, 34, 127-130.

* N Springer, W Ludwig, B Philipp, B Schink 1998, Int J Sys Bac, 48, 953 956.

* A Tschech and B Schink 1985, Arch Microbiol ,143, 52-59.

* A Tschech and G Fuchs 1989, Arch Microbiol, 152, 594-599.

* R Szewzyk and N Pfennig 1987, Arch Microbiol, 147, 163-1168.

* DD Vaishnav, L Bahue and ET Korthals 1989, J Ind Microbiol, 4, 307-314.

* A Zgajnar Gotvajn and J Zagorc-Koncan J 2003, Arh Hig Toksikol, 54, 189-195.

Applicant's summary and conclusion

Conclusions:
Under both aerobic and anaerobic conditions it is highly improbable that resorcinol and phenol will accumulate during the (bio)degradation process of Fyrolflex RDP. Excretion can be excluded when both aromatic compounds are degraded by one organism. If one of the aromatic compounds is excreted during the degradation of Fyrolflex RDP, accumulation of this aromatic compound will only occur if hydrolysis of Fyrolflex RDP is not the rate limiting step in the biodegradation process. Biodegradation of the recorcinol and phenol is proven to be faster than the degradation of Fyrolflex RDP (demonstrated in ready biodegradability tests). These arguments based on science show that the statement “recorcinol and phenol accumulate during Fyrolflex RDP degradation under environmental conditions” has to be untrue.
Executive summary:

In this theoretical exercise, the proposed biodegradation pathway and kinetics of Fyrolflex RDP is discussed. It has been suggested that resorcinol and phenol would accumulate during the biodegradation of this substance. The document leads to the conclusion that under both aerobic and anaerobic conditions it is highly improbable that resorcinol and phenol will accumulate during the (bio)degradation process of Fyrolflex RDP.