N-1-naphthylaniline

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented publication which meets basic scientific principles.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Degradation of 14C-labelled PAN in soil and sediment after an incubation time of 11 days.

GLP compliance:

no

Test type:

laboratory

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

not specified

Soil no.:

#1

Soil type:

other: temperate soil

% Org. C:

2.3

pH:

7

Soil no.:

#2

Soil type:

other: soil suspension

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Soil preparation: 2 mm sieved; air dried

PROPERTIES OF THE SOILS (in addition to defined fields)
- Moisture: 75% field capacity (soil no. 1)
- composition: both soils were tested unsupplemented and plus 500 µg nutrient broth/g soil

Soil No.:

#1

Duration:

11 d

Soil No.:

#2

Duration:

11 d

Soil No.:

#1

Initial conc.:

1.54 other: ug (40 nCi)/g soil

Based on:

test mat.

Soil No.:

#2

Initial conc.:

0.77 other: ug (20 nCi)/mL

Based on:

other: suspension of test material

Parameter followed for biodegradation estimation:

radiochem. meas.

Soil No.:

#1

Temp.:

26°C

Soil No.:

#2

Temp.:

26°C

Details on experimental conditions:

EXPERIMENTAL DESIGN
- Soil condition: air dried
- Soil (g/replicate): 25 and 100
- No. of replication treatments: not specified
- Test apparatus (Type/material/volume): 250 mL Erlenmeyer flasks
- Details of traps for CO2 and organic volatile, if any: 0.1 N KOH was used as the CO2-trapping solution in the side arm.
- Identity and concentration of co-solvent: methanol

Test material application
- Volume of test solution used/treatment: 125 mL inorganic salts solution (pH 7.2, shaken for 1h at 26 °C and 150 rpm and settle)
- Is the co-solvent evaporated: yes

Experimental conditions
- Incubation: at 26 °C, shaken with 150 rpm
- Continuous darkness: Yes

SAMPLING DETAILS
- Sampling intervals: 2, 5, 8 and 11 days

Soil No.:

#1

% Degr.:

17

Parameter:

radiochem. meas.

Remarks:

(unsupplemented soil)

Sampling time:

11 d

Soil No.:

#2

% Degr.:

35

Parameter:

radiochem. meas.

Remarks:

(unsupplemented)

Sampling time:

11 d

Soil No.:

#1

% Degr.:

12.5

Parameter:

radiochem. meas.

Remarks:

(+ nutrient broth)

Sampling time:

11 d

Soil No.:

#2

% Degr.:

22

Parameter:

radiochem. meas.

Remarks:

(plus nutrient broth)

Sampling time:

11 d

Transformation products:

not specified

Evaporation of parent compound:

not specified

Volatile metabolites:

not specified

Residues:

not specified

Addition of nutrient broth resulted in a lower CO2 -production. From carbon-supplemented soil 3.5% and 12.5% of the initial radioactivity were evolved as 14CO2 after 2 and 11 days, respectively. Similar results were obtained with unsupplemented soil suspensions. After 2 days only 6% of radioactivity was recovered as 14CO2 while 22% was recovered as 14CO2 after 11 days from the nutrient broth-supplemented soil suspension.

Less than 2% of the 14C was released as 14CO2 in autoclavated soil and soil suspension indicating that degradation of 14C-PNA was attributed to the action of microorganisms in the respective ecosystems investigated.

The greater disappearance of 14C-PNA in unsupplemented soils and soil suspensions is explained due to higher adsorption of PAN to soil or suspended soil particles.

Conclusions:

The data indicate that PNA is degraded and mineralized by terrestrial microorganisms. The extent and rate of microbial attack is dependent on the amount of organic amtter present.

Description of key information

PNA is considered to be degraded and mineralized in the terrestrial environment.

Additional information

One study investigating the biodegradation of the substance in soil is available. In this study, the degradation of 14C-labelled N-phenyl-1-naphtylamine was investigated for 11 days at 26°C in the dark under aerobic conditions (Rosenberg 1983). Initial concentration of the test substance was 1.54 µg/g soil. In order to enhance 14C-N-phenyl-1-naphtylamine degradation, one set of flasks was amended with 500 µg of nutrient broth/g of soil. Possible non-biological transformation of 14C-N-phenyl-1-naphtylamine was assessed using soil previously sterilized for three successive days for 1h at 121°C.

In order to facilitate the demonstration of microbial transformation of 14C-N-phenyl-1-naphtylamine, soils suspensions were prepared in an additional experiment. One set of flasks was supplemented while another set of flasks received 500 µg of nutrient broth/mL of soil suspension. The suspensions were amended to a final concentration of 0.77 µg (20 nCi) of 14C-N-phenyl-1-naphtylamine/mL.

Addition of nutrient broth resulted in a lower CO2 evolution. From carbon-supplemented soil 3.5% and 12.5% of the initial radioactivity were evolved as 14CO2 after 2 and 11 days, respectively. Similar results were obtained with supplemented soil suspensions. After 2 days only 6% of radioactivity was recovered as 14CO2 while 22% was recovered as 14CO2 after 11 days from the nutrient broth-supplemented soil suspension. Less than 2% of the 14C was released as 14CO2 in autoclaved soil and soil suspension indicating that degradation of 14C-N-phenyl-1-naphtylamine was attributed to the action of microorganisms in the respective ecosystems investigated.