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Environmental fate & pathways

Additional information on environmental fate and behaviour

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Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Although not conducted according to an accepted guideline, this study followed written procedures with minor variations. Water levels were not maintained throughout the first experiment so a second experiment was run using deionised make-up water. The second experiment was not run in duplicate and did not have a water control.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1985
Report Date:
1985

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
The half-life of the test substance was determined in Haskell Laboratory well water under static aerated conditions at 25ºC. Measurements of the loss from solution was made by paired-ion reverse phase HPLC.
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Purity: 99.5%

Results and discussion

Any other information on results incl. tables

The concentrations of test substance measured in experiments 1 and 2 are shown in the table below. Day 21, experiment 1, values were analysed but the results were not reported because of unknown materials interfering with the HPLC analysis.

  

Concentrations (mg/L) of Remaining Test Substance

Time

Exp 1, 2.5 mg/L (Initial Conc.)

Exp 2, 2.5 mg/L (Initial Conc.)

Exp 1, 25 mg/L (Initial Conc.)

Exp 2, 25 mg/L (Initial Conc.)

0-hour

2.4

2.2

22.7

22.4

1 day

2.1

1.9

18.9

22.2

2 day

1.6

1.4

14.4

16.5

4 day

1

0.82

7.9

13

7 day

0.42

0.3

3

7

14 day

nq

nq

0.66

1.1

21 day

z

nm

z

nm

nm: not measured, nq: not quantifiable, z: analyzed but not reported, unkown materials in samples interfered with the analysis

 

 

The test substance was lost from solution in both experiments and at both concentrations. The loss from solution may not be due totally to oxidative processes since low levels of microorganisms were detected which may have played a small role in the degradation.

 

Physical-chemical measurements were taken for the H2O controls in each experiment. In experiment 1, nearly 80% of the initial volume was lost at the end of the 21-day test period. The alkalinity, hardness, and conductivity increases in experiment 1 are probably due to evaporation which concentrated these inorganic constituents. While not measured in the test substance solutions, the evidence indicates that these increases occurred in the test solutions as well. In experiment 2, the volume of solution was held constant by addition of deionised water which prevented these constituents from concentrating.

 

The statistical analysis is described in detail within the report. The data from experiment 2 was used. The regression lines that best fit the data were chosen for estimating the half-lives for the test substance. The loss of test material generally followed first order kinetics.

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Applicant's summary and conclusion

Conclusions:
The shortest oxidative half-lives were those of PPD (4.1 hours at 2.5 mg/L , k = 0.17/hr; 8.9 hours at 25 mg/L , k = 0.08/hr), followed by OPD (2.7 days at 2.5 mg/L, k = 0.26/day; 4.5 days at 25 mg/L, k = 0.16/day), and finally by MPD (13.4 days at 2.5 mg/L, k = 0.05/day; 33.6 days at. 25 mg/L, k = 0.02/day).
Executive summary:

The half-lives of o-phenylenediamine (OPD), m-phenylenediamine (MPD), and p-phenylenediamine (PPD) were determined in Haskell Laboratory well water under static aerated conditions at 25ºC. Measurements of the loss of each isomer from solution were made by paired-ion reverse phase HPLC. The shortest oxidative half-lives were those of PPD, followed by OPD, and finally by MPD. The loss of test material generally followed first order kinetics.

 

Haskell well water was selected for this study because the aquatic toxicities of OPD, PPD and MPD were previously determined in the same water. The water is monitored on a yearly basis for priority pollutants, selected organic pesticides, and inorganic constituents. The organic constituents are generally below the level of detection.

 

The study was conducted in two experiments. During the first experiment, which ran for 21 days, the volume of the test vessels decreased due to evaporation, leading to the possibility that some of the test substance solutions may have become concentrated. For this reason, a second experiment was implemented.

 

The conditions of the second experiment were identical to the first with several exceptions. There were no replicates and only one water control. The test vessel water levels were kept constant with deionised water. The study ran 14 days.

 

The oxidative half-life results were 2.7 days at 2.5 mg/L , k = 0.26/d and 4.5 days at 25 mg/L , k = 0.16/d.

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