Pyrocatechol

Phototransformation in air

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

The publication does not describe an experimental study. It reports an overview of ambient measurements and atmospheric transformation data on 189 chemicals listed in the Clean Air Act Amendment (CAAA) of the US-EPA. In this context, data are reported on the atmosheric transformation of catechol via reaction with OH radical. However, the experimental methodology applied to obtain these information is not known. Due to this last restriction, a reliability score of 2 was attributed to this data.

Principles of method if other than guideline:

The publication deals with 189 chemicals. The methodology used to obtain the data on atmospheric transformation is not precised for each chemicals. Instead, it is indicated that, depending on the products, the estimated atmospheric lifetimes either came from literature, or were calculated by the authors for the purpose of the current publication using rate constants obtained through measurement or derived from structure-reactivity relationship.

GLP compliance:

not specified

Estimation method (if used):

It is not known if it the case for catechol, but the authors estimated atmospheric lifetime for some chemicals, using the following characteristics:

PHOTOCHEMICAL REACTION WITH OH RADICALS
- Concentration of OH radicals: 3 x 10E6 molecules/cm3.
- Degradation rate constant: not reported in the publication.
- Temperature for which rate constant was calculated: not reported in the publication.
- Computer programme: not reported in the publication.

No further data.

Light source:

not specified

Reference substance:

not specified

DT50:

< 1 d

Transformation products:

not specified

The atmospheric lifetime of catechol is estimated to be less than 1 day. The primary mechanism influencing its lifetime is the OH radical reaction. the publication contains no information on its transformation products.

Validity criteria fulfilled:

not specified

Conclusions:

Catechol presents an estimated atmospheric lifetime of less than one day; revealing it is rapidly transformed or removed.

Executive summary:

Here is reported an overview of ambient measurements and atmospheric transformation data on 189 chemicals listed in the Clean Air Act Amendment (CAAA) of the US-EPA. The methodology used to obtain the data on atmospheric transformation is not precised for each chemicals. Instead, it is indicated that, depending on the products, the estimated atmospheric lifetimes either came from literature, or were calculated by the authors for the purpose of the current publication using rate constants obtained through measurement or derived from structure-reactivity relationship. In the case of catechol an estimated atmospheric lifetime of less than one day is reported; revealing catechol is rapidly transformed or removed.

Description of key information

Atmospheric half-life < 1 day.

Additional information

Two publications, scored of reliability 2 (Kelly et al., 1994) and 4 (CEPA, 2008) according to Klimisch, give consistent results in terms of photodegradation. Both report atmospheric half-life inferior to 1 day; revealing that catechol is rapidly transformed or removed in air through reaction with OH radicals.