Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
other information
Study period:
Sep to Oct 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well reported GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1996

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): hydrocortisone (ZK 5191)
- Analytical purity: 99.3%
- Lot/batch No.: 024H0502

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Duration of test (contact time):
>= 28 d
Initial test substance concentration
Initial conc.:
ca. 20 mg/L
Based on:
DOC

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
>= 96
Sampling time:
22 d
Details on results:
The degradation of hydrocortisone was rapid after a lag phase of more than 8 days and reached ca. 96% within day 28. 60% degradation was reached approximately by day 19, 6 days after start of degradation (10% degradation).
The reference substance sodium acetate was degraded to 99% on day 5. The biodegradation of the toxic control reached 96%.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The toxicity control did not indicate any inhibiting effect.Thus, hydrocortisone is ready biodegradable.
Executive summary:

The aerobic biodegradation of hydrocortison was studied in a modified OECD screening test according to test guideline OECD 301E. The test compound was incubated over 28 days at a concentration of 20 mg/L as DOC. Hydrocortioson was degraded to more than 90% at day 28. 60% degradation was reached approximately by day 19, 6 days after start of degradation (10% degradation). The reference compound sodium acetate was degraded to 99% on day 5, the toxicity control did not indicate any inhibiting effect. Thus, hydrocortisone is ready biodegradable.