Desmedipham

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Type of information:

(Q)SAR

Remarks:

Estimation using Atkinson method.

Adequacy of study:

supporting study

Study period:

1992-06-05

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Data source

Reference

Reference Type:

other company data

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

QSAR - Atkinson calculation

GLP compliance:

no

Remarks:

GLP is not relevant for studies using QSAR models to calculate endpoints.

Test material

Test material information

Constituent 1

Reference substance name:

Desmedipham

EC Number:

237-198-5

EC Name:

Desmedipham

Cas Number:

13684-56-5

Molecular formula:

C16 H16 N2 O4

IUPAC Name:

ethyl 3´-phenylcarbamoyloxycarbanilate

Test material form:

solid: particulate/powder

Details on test material:

The test material is Desmedipham but the purity has not been specified.

Results and discussion

Any other information on results incl. tables

In the case of desmedipham, K_add does not apply as there are no unsaturated aliphatic groups. Therefore, K_OH is given by:

- k_abs = 1.44 x 10^-12 cm³ molecule^-1s^-1

- k_{arom 1} = 2.04 x 10^-11 cm³ molecule^-1s^-1; k_{arom 2} = 1.40 x 10^-11 cm³ molecule^-1s^-1; sum = 3.44 x 10^-11 cm³ molecule^-1s-1

- K_OH = (0.144 + 3.44) x 10^-11 = 3.58 x 10^-11 cm³ molecule^-1 s^-1.

 

Using the recommended global 24-h average for the concentration of OH radicals, 5 x 10⁵ molecules/cm³, a first rate constant k can be calculated:

k = K_OH x [OH] = 3.58 x 10^-11 x 5 x 10⁵ s^-1 = 6.44 x 10^-2 h^-1.

The correct [OH] has been applied for REACH

 

The corresponding half-life is:

t_1/2 = ln2/k = 0.693/6.44 x 10^-2 h = 10.75 h.

Applicant's summary and conclusion

Conclusions:

Results were presented in the Review Report for Desmedipham (SANCO/4061/2001-Final, 13 February 2004).

Executive summary:

The photochemical degradation of desmedipham in the atmosphere was estimated with the Atkinson method. Reaction with photochemically generated OH radicals can be expected to be the main phototransformation process for desmedipham in the atmosphere. The bimolecular OH radical rate constant was estimated according the incremental method of Atkinson to be > 3.58 x 10^-11 cm³ molecule^-1s^-1. Assuming the global 24-hour average for the concentration of OH radicals to be 5 x 10⁵ molecules/cm³, this value corresponds to a maximum half-life of 10.8 h for the photochemical-oxidative degradation of desmedipham in air.