Registration Dossier

Environmental fate & pathways

Additional information on environmental fate and behaviour

Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
other: Applicant summary
Adequacy of study:
other information
Reliability:
other: Applicant summary
Rationale for reliability incl. deficiencies:
other: Applicant summary from EU risk assessment ( Intake from plants )

Data source

Referenceopen allclose all

Reference Type:
secondary source
Title:
3,4-dichloroaniline (3,4-DCA)
Author:
EU-Risk Assessment Report
Year:
2006
Bibliographic source:
EUR 22235 EN; ISSN 1018-5593
Reference Type:
publication
Title:
Herbizide und ihre Rückstände. Stuttgart 1971.
Author:
Maier-Bode (1971)
Year:
1971
Bibliographic source:
Stuttgart 1971.
Reference Type:
publication
Title:
not stated
Author:
Sandermann Jr H, Musick TJ and Aschbacher PW
Year:
1992
Bibliographic source:
J. Agric. Food Chem. 40, 2002-2007.
Reference Type:
publication
Title:
Soil-Bound 3,4-Dichloroaniline: Source of contamination in rice grain.
Author:
Still CC, Tsung-Shih, Hsu and Batha R (1980)
Year:
1980
Bibliographic source:
Bull. Environ. Contam. Toxicol. 24, 550-554.
Reference Type:
publication
Title:
Weed Res. 9, 218. Cited in Still, C.C., Tsung-Shih, Hsu and Batha R. (1980): Soil-Bound 3,4-Dichloroaniline: Source of contamination in rice grain.
Author:
Still CC and Mansager ER (1969)
Year:
1969
Bibliographic source:
Bull. Environ. Contam. Toxicol. 24, 550- 554.
Reference Type:
publication
Title:
Studies on the nature and identity of bound chloroaniline residues in plants.
Author:
Still CC, Balba HM and Mansager ER
Year:
1981
Bibliographic source:
J. Agric. Food Chem. 29, 739-746
Reference Type:
study report
Title:
Unnamed
Year:
1997
Reference Type:
study report
Title:
Unnamed
Year:
1989
Reference Type:
study report
Title:
Unnamed
Year:
1995

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
applicant summary
GLP compliance:
no
Type of study / information:
Applicant summary from EU risk assessment ( Intake from plants )

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Any other information on results incl. tables

Intake from plants

3,4-DCA can reach plants by two pathways:

- The plant protection agents which are its subsequent products are degraded in soil (see Section 3), and 3,4-DCA is taken up by the plant.

- The plant protection agent is taken up by the plant where it is metabolised.

There are several investigations dealing with the 3,4-DCA content as a consequence of the application of plant protecting agents which are its subsequent products: Propanil is used as selective herbicide for weed control in rice fields. 3,4-DCA has been detected in all tested marketed rice samples. It has been estimated that marketed rice might contain as much as 1µg 3,4-DCA/g (Still and Mansager, 1969). This could be confirmed by experiments (Still et al., 1980) were plants treated with 14C-3,4-DCA quantities to approximate those that would result from propanil treatment at recommended field application levels. Leaf and soil treatment resulted in the same amount of radioactivity in the whole plants. No significant radioactivity was detected in grains of the leaf-treated rice plants whereas in the grains of soil-treated plants 0.4 µg 3,4-DCA/g could be found after 120 days. The authors interpret the radioactivity in the rice grains as 3,4-DCA that was temporarily immobilised in soil as complex with humic substances and was made bioavailable for root uptake during the grain ripening period by the microbial cleavage of these humic complexes. This interpretation is also supported by the results of Still and Mansager (1969) who found 3,4-DCA in the grain of rice plants that were never treated with herbicide, but grew in soil that had a history of propanil treatment. In pre-emergence application studies with linuron residue data for different plants from supervised trial were obtained (Stumpf, 1995). The herbicide was applied by spraying. The residues were calculated as linuron and analysed as 3,4-DCA (DCA is formed from linuron by alkaline hydrolysis during sample preparation). All metabolites which were cleaved by alkaline hydrolysis to 3,4-DCA were obtained. To differentiate between 3,4-DCA pre and post hydrolysis is not possible from this study. The maximum residue amount was found for parsley, onions and celery. Application rates were 0.475 and 0.713 kg a.s./ha for parsley, from 1.5 to 3 kg a.s./ha and 0.71 to 1.9 kg a.s./ha for celery. The residue levels in the leaves of parsley were 0.37 mg/kg at most after 90 days, in the root residues ranged between 0.1 and 0.29 mg/kg after 180 days. For onions concentrations of residues in bulb and leaves were 0.1 and 0.2 mg/kg after 89 and 66 days. After 105 days the residues in the bulb were below the determination limit of 0.02 mg/kg. For celery 42 days after treatment maximum values of residues of 1.15 mg/kg in the leaves and 0.72 mg/kg in the bulb could be found. At latest 48 days after treatment residues in the leaves of celery were below 0.5 mg/kg. In the bulb of rooted celery residues after 42 days exceeded 0.5 mg/kg in some trials. In other studies similar results for linuron could be found (Maier-Bode, Härtel, 1981). Additionally high residues were found after application of linuron in soybeans (after 65 days 1.3 mg/kg in the forage), carrots (after 82 days 0.41 mg/kg in the roots) and in clover (after 163 days 1.1 mg/kg in the dried). In a study of diuron in rotational crop the soils were treated with 2,600 g a.i./ha (A) and 1,900 g a.i./ha (B) (Stevenson, 1989). After treatment, the soils were aged aerobically in greenhouse for either 4 months (A), or 12 months (B). At the end of the aging periods, lettuce, wheat, and turnips were planted and grown to maturity. Soil samples at treatment, planting and plant harvest were extracted with different organic solvents, 1N HCl and 0.1 N NaOH. It could found that the extractable soil concentration of 14C-diuron decreased from 1.12 (B: 1.01) ppm at treatment to 0. 253 (B:0.212) ppm at planting, and to 0.209-0.237 (B: 0.078-0.194) at harvest. The soil concentration of extractable radioactive residues in diuron equivalents were 1.126 (B: 1.113) ppm at treatment, 0.675 (0.511) ppm at planting, and 0.651-0.735 (0.31-0.448) ppm at harvest. The unextractable radioactive residues in the soil increased from 5 - 6% at treatment to 11 - 16% at planting to 20 - 28% at the time of harvest. The crops were harvested and analysed for total radioactive residues. The concentrations of extractable radioactive diuron in edible portions of the harvested plants were 0.041 (B: 0.04) ppm. The extractable radioactive residues in the edible portions of the harvested plants were 0.235 (B: 0.157) ppm. Unextractable radioactive residues could be found in the range of 10%. No radioactive TCAB or TCAOB were found in the soil or the plants with the detection limit of 0.002 ppm. A study of the residue pattern in rotational crops and the degradation behaviour in soil under field conditions was also performed with a linuron application rate of 950 g linuron/ha, (nominal) (Sochor and Wrede, 1997). The initial concentrations determined experimentally were between 0.55 mg/kg and 0.29 mg/kg on the day of application. The residues in the crops were determined by the method of Bleidner. The results of degradation and binding of the degradation products of urea-herbicides in the soil are in relation with the other findings. An uptake of the active ingredient from soil occurred only at the early crop stage in carrots and lettuce in the range of 0.02 - 0.19 mg linuron/kg. Summarising, it must be said, that the results of the studies are very different. More or less amounts of 3,4-DCA were found in the different parts of the plants. But all investigation with radioactive material show that only 50% of the starting radioactivity could be found, that means the other part is bound in an unextractable manner to the matrix - as also found for the soil compartment (see Section 3.1.1). The results of Still et al. (1981) on the identity of bound chloroaniline residues in plants indicate that the chloroanilines may be bound covalently to lignin via 1,6-addition to a quinone method intermediate during the lignin synthesis as also could be shown for the soil. This can be confirmed by an animal bioavailable study (Sandermann et al., 1992). Treatment of intact wheat plants and excised shoot tissues with [14C]-3,4-DCA led to 55-65% incorporation of the radioactivity into the ¿insoluble¿ residue. A sequential solubilisation revealed that approximately 85% of the 14C-label was associated with the operationally defined lignin fraction. When the insoluble wheat metabolite residue was fed to rats and lambs, 11-20% of the bound radioactivity was released in soluble form. Re-feeding the lamb fecal residue to rats released another 7% of the bound radioactivity. A 3,4-DCA-lignin metabolite prepared enzymatically has been previously shown to be more extensively solubilised by rats (66%). Mild acid hydrolysis under simulated stomach conditions resulted in a strong release of free 3,4-DCA (30%) only from the previously used lignin metabolite. A review of monitoring data of 3,4-DCA in plants treated with linuron is available (Maier-Bode and Härtel, 1981). The measured DCA-concentrations in more than 200 samples were generally in the range between lower detection limit to 0.1 mg/kg, in some cases up to 0.7 mg/kg. The respective application amounts were between 0.5 and 4.5 kg linuron/ha (in two cases 7.5 kg/ha). It has to be considered that the results may overestimate the 3,4-DCA-concentration: due to the analytical method (which starts with alkaline hydrolysis), residual linuron as well as mono- and desmethyllinuron are hydrolysed to 3,4-DCA. As this publication gives the best available database, it is used for the exposure estimation.

As a worst case approach, it is assumed that the contribution of linuron, mono- and desmethyllinuron to the detected 3,4-DCA concentrations can be neglected.

An average concentration of 0.1 mg/kg plant (leaf and root crops) is assumed:

- DOSEstem = 1.7 · 10-3 mg · kg bw-1 · d-1

- DOSEroot = 5.5 · 10-4 mg · kg bw-1 · d-1

- DOSEstem + DOSEroot = 2.3 · 10-3 mg · kg bw-1 · d-1

This scenario is based on the assumption that all food plants are treated with linuron. On the other hand, further plants are treated with diuron and propanil. These agents are used in the same concentration range, so the respective 3,4-DCA concentrations are assumed to be similar. The scenario could be improved if it would be based on a more precise consume pattern for the different plants and their specific 3,4-DCA concentrations. The EUSES calculation of the human intake results for the regional scale

- DOSEstem = 8.8 · 10-8 mg · kg bw-1 · d-1

- DOSEroot = 1.3 · 10-11 mg · kg bw-1 · d-1

Applicant's summary and conclusion