Registration Dossier

Administrative data

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: details on experimental conditions are lacking

Data source

Reference
Reference Type:
publication
Title:
Unnamed

Materials and methods

Test guideline
Deviations:
not specified
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified

Study design

Light source:
not specified
Details on light source:
UV light

Results and discussion

Dissipation half-life of parent compoundopen allclose all
DT50:
16 d
Test condition:
on solid surface
DT50:
5 d
Test condition:
in aqueous solution
DT50:
140 d
Test condition:
in soil at 1 mg/kg concentration
DT50:
280 d
Test condition:
in soil at 10 mg/kg concentration

Applicant's summary and conclusion

Conclusions:
On a solid surface, chlorendic acid was degraded by UV light (half-life = 16 days) to a number of unknown products. The irradiation of chlorendic acid in aqueous solution with UV light showed that the half-life in this system was 5 days. In soil, the half-life of 14C-chlorendic acid was found to be 140 ± 37 days at a soil concentration of 1 mg/kg and 280 ± 35 days at 10 mg/kg. Ozone seems quite effective in dechlorinating chlorendic acid. The rate of dechlorination is affected by pH, UV light and bicarbonate concentration. 80% dechlorination was achieved in 1h with a 125mg/min ozone at pH 7.4.
Executive summary:
              

  From a comparison of the characteristics of the cyclodiene

  derivatives, chlorendic acid would be expected, on theoretical grounds, to degrade by direct photolysis or by reactions with hydroxyl

   radicals and ozone (Parlar & Korte, 1977).

 

        An experimental study was conducted to investigate the use of

   ozone to dechlorinate chlorendic acid. The dechlorination and

   subsequent degradation of chlorendic acid by ozonation was influenced

   by the pH, applied ozone dose and bicarbonate concentration. A change

   in the initial chlorendic acid concentration to 50, 100 and

   200 mg/litre did not influence the rate of degradation of chlorendic

   acid. Ultraviolet (UV) radiation alone dechlorinates chlorendic acid.

   UV radiation was also shown to greatly enhance the oxidation of

   chlorendic acid in the presence of ozone. In a typical case, 80%

   dechlorination of chlorendic acid was obtained in 60 min when using an

   ozone dose of 125 mg/min ozone at pH 7.4. Conditions favouring

   radicals in solution, such as high pH and exposure to UV light,

   resulted in much faster dechlorination. The conditions which did not

   favour radicals, such as low pH and the addition of bicarbonate,

   resulted in slower dechlorination (Stowell & Jensen, 1991).

 

        The photolysis of chlorendic acid by UV light and sunlight has

   been determined on solid surface and in aqueous solution. On a solid

   surface, chlorendic acid was degraded by UV light (half-life = 16

   days) to a number of unknown products. The irradiation of chlorendic

   acid in aqueous solution with UV light showed that the half-life in

   this system was 5 days (Yu & Atallah, 1978).

 

        In soil, the half-life of14C-chlorendic acid was found to be

   140 ± 37 days at a soil concentration of 1 mg/kg and 280 ± 35 days at

   10 mg/kg. However, it should be noted that the labelled carbon atoms

  From a comparison of the characteristics of the cyclodiene

  derivatives, chlorendic acid would be expected, on theoretical grounds, to degrade by direct photolysis or by reactions with hydroxyl

   radicals

   chlorendic acid in the presence of ozone. In a typical case, 80%

   dechlorination of chlorendic acid was obtained in 60 min when using an

   ozone dose of 125 mg/min ozone at pH 7.4. Conditions favouring

   radicals in solution, such as high pH and exposure to UV light,

   resulted in much faster dechlorination. The conditions which did not

 

   half-lives are more representative of that moiety than of chlorendic

   acid itself. Chlorendic acid can thus be considered fairly persistent

   in soil (Butz & Atallah, 1979a).

   acid itself. Chlorendic acid can thus be considered fairly persistent

   in soil (Butz & Atallah, 1979a).