Registration Dossier

Environmental fate & pathways

Mode of degradation in actual use

Currently viewing:

Administrative data

Endpoint:
mode of degradation in actual use
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 1d: study well described and experiments performed according to scientific principle and realistic normal composting procedure (field conditions, European climate, on relevant durations) and completed with semi-realistic study.

Data source

Reference
Reference Type:
publication
Title:
Recycling of sewage sludge and household compost to arable land: fate and effects of organic contaminants, and impact on soil fertility
Author:
Petersen S.O., Henriksen K., Mortensen G.K., Krogh P.H., Brandt K.K., Sorensen J., Madsen T., Petersen J. and Gron C.
Year:
2003
Bibliographic source:
Soil and Tillage Research, 72, 139-152

Materials and methods

Test guideline
Qualifier:
no guideline available
GLP compliance:
not specified
Type of study / information:
Impact of DEHP in contaminated sludge compost on soil fertilization

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Results and discussion

Any other information on results incl. tables

First experiment (3 year field study):

After 3 years, DEHP concentration ranged from below detection limit (<0.05mg/kg) to 0.103 mg/kg without significant differences among the treatment applied. Soil fauna showed no discernable differences between the two sludge treatment but densities were increased in compost and manure treatment.

No grain samples showed DEHP, while green parts of the plants contained between 0.065 and 0.787 mg/kg of DEHP. No relationship of this content was seen with the amount of DEHP in the different treatment applied, therefore it was concluded that this amount mainly derived from atmospheric deposition.

Second experiment (1 year plot study):

The regular sampling and analysis of DEHP content showed a degradation of DEHP slow during the 6 first weeks, and approximately 40% of the initial concentration was still present after 6 months. Degradation continued leaving 5 to 6% of initial DEHP at the end of the 12 months. Moreover no adverse effect on nitrification process was observed in both conditions toxic concentration in the sludge.

Third experiment (seedling pot experiment-1month):

No uptake was observed. Moreover sludge amended soil showed a faster degradation of DEHP than in spiked soil.

 

Applicant's summary and conclusion

Conclusions:
In the 3 test conditions, it is shown that DEHP is biodegraded in soil fertilized with contaminated sludge. 40% of the initial concentration remained after 6 months of experiment and 6% after 12 months (2nd study) therefore half life of DEHP is expected to be below 6 months (<180 days). Moreover the DEHP showed no toxic effect neither on arthropod fauna nor on plant seedling or growth. No bioaccumulation was observed.
Executive summary:

Peterson et al. studied the behavior of DEHP during fertilization process and potential effect on plant by 3 different methods under field and greenhouse conditions.

The first experiment is a 3-year field study using different types of soils: a sandy loam and a loamy sand from. Both were supplemented with 4 types of wastes:

-        two sewage sludge from a municipal WWTP with  high level of organic contaminant (SShigh) or low level of organic contaminant (SSlow).

-        An household compost from a municipal composting facility containing kitchen wastes mixed with shredded straw. (compost)

-        A solid pig manure from a local pig operation. (manure)

The wastes were amended once a year during 3 years. Assuming no biodegradation occurred the total amount input at the end of the study was 0.238, 0.092, 0.290 and 0.04 mg/kg in SShigh SSlow, compost and Manure trials respectively.

Crops were cultivated every year (spring barley and oat) with or without supplementary fertilizer (N requirement were set at 80% of the expected crop requirement).

On the 3rdyear, the crop harvest was analyzed for their contaminant.

Soil fertility, micro-arthropod population and level of contaminant in the soil were also checked.

The second experiment was a 1 year study consisting in a plot experiment with banded sludge. Sludge turnover and toxicity to crop was studied in details under semi-realistic conditions with the loamy sand soil. Five bands of SShigh and SSlow were placed at 6-10cm soil depth with a space of 0.5m between each band. Each treatment was controlled for the DEHP concentration in the sludge soil matrix.

The third experiment was a pot experiment with amended soil (SShigh) and soil spiked with DEHP at 55 mg/kg where seedling of oilseed rape was studied during 30 days. Plant uptake and soil concentrations were checked.

In the 3 test conditions, it is shown that DEHP is biodegraded in soil fertilized with contaminated sludge. 40% of the initial concentration remained after 6 months of experiment and 6% after 12 months (2nd study) therefore half life of DEHP is expected to be below 6 months (<180 days). Moreover the DEHP showed no toxic effect neither on arthropod fauna nor on plant seedling or growth. No bioaccumulation was observed.