5-chloro-2-(4-chlorophenoxy)phenol;[DCPP]

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: screening tests

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study on Triclosan, suitable for read-across.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OTS 796.3140 (Anaerobic Biodegradability of Organic Chemicals)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Triclosan

EC Number:

222-182-2

EC Name:

Triclosan

Cas Number:

3380-34-5

IUPAC Name:

5-chloro-2-(2,4-dichlorophenoxy)phenol

Details on test material:

- Name of test material (as cited in study report): Triclosan
- Lot/batch No.: # 21738-037
- Radiochemical purity (if radiolabelling): 94.8 %
- Specific activity (if radiolabelling): 15 µCi/mg

Study design

Oxygen conditions:

anaerobic

Inoculum or test system:

anaerobic sludge

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): primary (anaerobic) sludge from Nut Island Wastewater Treatment Plant, Quincy Massachusetts, USA
- Pretreatment: 2 mm mesh sieved
- Concentration of sludge: 3000000 cfu/mL

Duration of test (contact time):

147 d

Initial test substance concentration

Initial conc.:

200 µg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS
- Composition of medium: 95 mL of prepared inoculated medium and the appropriate amount of test article or reference material
- Test temperature: 35 ± 1 °C




TEST SYSTEM
- Culturing apparatus: 150-mL Wheaton serum bottle capped with a butyl rubber serum-bottle stopper
- Number of culture flasks/concentration: 1



SAMPLING
- Sampling frequency: concentration of [14C]-Triclosan remaining in the test article vessels was determined on days 0, 7, 14, 21, 28, 42, 56, 70, 91, 119 and 147.
- Sampling method: 3 vessels were sacrificed for analysis by HPLC-RAM

Results and discussion

% Degradation

Parameter:

% degradation (radiochem. meas.)

Value:

< 10

Sampling time:

147 d

Details on results:

No concrete evidence for the biodegradation of Triclosan under anaerobic conditions was observed.
- The radioactivity distribution of extracts from test vessels receiving 200 µg/L Triclosan indicated that 90-92 % (mean: 91 %, n = 3) of extractable residues remained as [14C]-Triclosan after 147 days of incubation with anaerobic inoculum, under anaerobic conditions. The percent extractable decreased steadily with time, but with no concomitant appearance of Triclosan metabolites it is unlikely that mineralization to CO2 and methane occurred.
- Microbial analysis of the sludge during the study indicated that the sludge microbes were still viable.
- Testing performed with a reference material, ethanol, in the same anaerobic test solution resulted in mean cumulative gas production of 69 to 310% of theoretical during the 147-day test, when corrected for blank gas production. The high gas production may have resulted from respiratory stimulation of the microbes by the ethanol, or by consumption of carbon contaminants in the glass bottles; nevertheless, the reference article performance indicates an active microbial community capable of degrading simple organic compounds.