Pseudoephedrine

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Scientifically acceptable publication with analytical monitoring

Data source

Reference

Reference Type:

publication

Title:

Biotic and abiotic degradation of illicit drugs, their precursor, and by-products in soil

Author:

Raktim Pal, Mallavarapu Megharaj, K. Paul Kirkbride, Tunde Heinrich, Ravi Naidu

Year:

2011

Bibliographic source:

Chemosphere Vol. 85 (2011), p. 1002-1009

Materials and methods

Principles of method if other than guideline:

A specific guideline has not been mentioned in the paper. However, the test method applied has been described in detail.
The purpose of the paper has been to investigate the degradation of pseudoephedrine in laboratory scale over a 1 year testing period in three different South Australian soils both under non-sterile and sterile conditions.
The test procedure under sterile conditions has been conducted in order to gain a reference value with which the microbial degradation efforts in soil can be compared.

GLP compliance:

no

Test type:

laboratory

Test material

Test material information

Constituent 1

Reference substance name:

Pseudoephedrine

EC Number:

202-018-6

EC Name:

Pseudoephedrine

Cas Number:

90-82-4

Molecular formula:

C10H15NO

IUPAC Name:

(1S,2S)-2-(methylamino)-1-phenylpropan-1-ol

Details on test material:

- Name of test substance (as cited in study report): pseudoephedrine (PSE)
- Water solubility: 1.06E+5 mg/L

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Soil classification:

not specified

Soil properties

Soil properties 1

Soil no.:

#1

Soil type:

sandy loam

% Clay:

20

% Silt:

25

% Sand:

55

% Org. C:

1.11

pH:

8.91

CEC:

19.24 other: µg/ml

Soil properties 2

Soil no.:

#2

Soil type:

sandy loam

% Clay:

15

% Silt:

25

% Sand:

60

% Org. C:

2.88

pH:

5.98

CEC:

6.3 other: µg/ml

Soil properties 3

Soil no.:

#3

Soil type:

loam

% Clay:

15

% Silt:

42.5

% Sand:

42.5

% Org. C:

2.26

pH:

5.64

CEC:

17.42 other: µg/ml

Details on soil characteristics:

SOIL #1: COLLECTION AND STORAGE
- Geographic location: Mawson Lakes Campus of the University of South Australia
- Characteristics of sampling site: urban area
- Further details on soil: alkaline sandy loam
- Sampling depth (cm): 0-15 cm
- Storage conditions: storage in polyethylene buckets for transportation; final storage in fridge at 4°C
- Soil preparation (e.g., 2 mm sieved; air dried etc.): soil was screened to remove any plant parts or other artifacts and passed through 2 mm sieve

SOIL #2: COLLECTION AND STORAGE
- Geographic location: Sturt Gorge
- Characteristics of sampling site: native bush land
- Further details on soil: slightly acidic sandy loam
- Sampling depth (cm): 0-15 cm
- Storage conditions: storage in polyethylene buckets for transportation; final storage in fridge at 4°C
- Soil preparation (e.g., 2 mm sieved; air dried etc.): soil was screened to remove any plant parts or other artifacts and passed through 2 mm sieve

SOIL #3: COLLECTION AND STORAGE
- Geographic location: Waite Campus of The University of Adelaide, South Australia
- Characteristics of sampling site: agricultural land
- Further details on soil: slightly acidic loam
- Sampling depth (cm): 0-15 cm
- Storage conditions: storage in polyethylene buckets for transportation; final storage in fridge at 4°C
- Soil preparation (e.g., 2 mm sieved; air dried etc.): soil was screened to remove any plant parts or other artifacts and passed through 2 mm sieve

Duration of test (contact time)

Duration of test (contact time) 1

Soil No.:

#1

Duration:

1 yr

Duration of test (contact time) 2

Soil No.:

#2

Duration:

1 yr

Duration of test (contact time) 3

Soil No.:

#3

Duration:

1 yr

Initial test substance concentration

Initial test substance concentration 1

Soil No.:

#1

Initial conc.:

0.1 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 2

Soil No.:

#2

Initial conc.:

0.1 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 3

Soil No.:

#3

Initial conc.:

0.1 mg/kg soil d.w.

Based on:

test mat.

Details on experimental conditions:

1. EXPERIMENTAL DESIGN
- Soil preincubation conditions: at 25°C in a constant temperature room for 1 week; incubation in the dark to avoid photodegradation
- Moisture level of each soil: adjusted to 50 % of maximum water holding capacity (MWHC)
- Soil (g/replicate): 5
- Experimental conditions (non-sterile/sterile): 5 g sub-samples of pre-incubated soils were weighed into individual amber colored glass vials fitted with Teflon lined solid screw caps
- Additional experimental conditions (sterile): soils in individual vials were autoclaved at 121°C for 20 on three consecutive days; sterile conditions were maintained throughout study period
- No. of replication treatments: 2

2. PREPARATION OF STOCK SOLUTION
- Solution medium: water
- Additional procedures for sterile degradation: stock solutions were passed through sterile 0.45 µm filters and soils were spiked aseptically within a laminar airflow cabinet

3. FURTHER TEST CONDITIONS
- Moisture maintenance method: moisture contents of the soils (both in non-sterile and sterile) were maintained by aseptic addition of sterile Milli-Q water
- Continuous darkness: Yes
- Aeration: the vials for non-sterile degradation were aerated aseptically within a laminar airflow every week

Results and discussion

Half-life / dissipation time of parent compound

Half-life / dissipation time of parent compound 1

Soil No.:

#1

DT50:

3.7 d

Remarks on result:

other: non-sterile conditions

Half-life / dissipation time of parent compound 2

Soil No.:

#2

DT50:

30.1 d

Remarks on result:

other: non-sterile conditions

Half-life / dissipation time of parent compound 3

Soil No.:

#3

DT50:

5.44 d

Remarks on result:

other: non-sterile conditions

Details on results:

The degradation in sterile soils can be attributed to abiotic factors such as oxidation or hydrolysis whereas the degradation in non-sterile soil is indicative of the role of soil microbes.

Results with reference substance:

The sterile testing conditions can be regarded as reference for the degradation under non-sterile conditions. The results under sterile conditions are as follows:
Half-life in soil #1: 143 d
Half-life in soil #2: 502 d
Half-life in soil #3: 376 d