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Environmental fate & pathways

Phototransformation in water

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Administrative data

Endpoint:
phototransformation in water
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment. Reliability assessment as per that quoted in IUCLID 4 (2000) data review

Data source

Reference
Reference Type:
publication
Title:
Decomposition of organolead compounds in aqueous systems
Author:
Jarvie, A.W.P., Markall, R.N., Potter, H.R.
Year:
1981
Bibliographic source:
Environmental Research 25, 241-249

Materials and methods

Study type:
direct photolysis
Test guideline
Qualifier:
no guideline available
Deviations:
not specified
Principles of method if other than guideline:
Aqueous Solutions
After shaking for the appropriate time 50 cm3 of TEL/water solution (suspension) was transferred to a separating funnel, benzene was added and the mixture shaken. The layers were separated, the benzene layer was analyzed for TEL by GLC and the organolead salt in the aqueous layer was determined by a colorimetric technique

Decomposition of Organolead Compounds on Silica
Silica gel was suspended in water before the addition of TEL. Organolead salts were added to the suspension by suitable additions of an aqueous standard solution of the salt. Dilute solutions of TEL were prepared by adding to methanol; appropriate aliquots of this dilute solution were added to the silica. All suspensions were prepared in glass flasks with glass stoppers; mixtures were stored in the dark prior to analysis.

Analysis
The TEL/water suspension was transferred to a separating funnel and benzene was added. The sample was shaken to achieve maximum extraction of TEL. The aqueous suspension of silica was run off into a glass column and the benzene layer was analyzed for TEL by GLC, The organolead salts were eluted from the silica by slowly passing aqueous acetic acid through the column. Successive fractions were collected and neutralized by the addition of aqueous NaOH. The alkyllead content was determined by a colorimetric technique
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Light source:
sunlight
Duration of test at given test condition
Duration:
15
Initial conc. measured:
30 mg/L

Results and discussion

% Degradation
% Degr.:
99
Sampling time:
15 d
Test condition:
Direct photolysis

Applicant's summary and conclusion

Conclusions:
Jarvie et al found 90% of TEL was degraded after 15 days with a half life of 7.3 days.  Once formed the tri and diethyl salts decompose to the unstable monoethyl lead salt and then to inorganic lead.
Executive summary:

Jarvie et al(A. W. P. Jarvie, R. N. Markell and H. R. Potter, Decomposition of organolead compounds in aqueous systems, Environ. Res.,25,(1981), 241-249) found 90% of TEL was degraded after 15 dayswith a half life of 7.3 days.  Once formed the tri and diethyl salts decompose to the unstable monoethyl lead salt and then to inorganic lead.

Breakdown of TEL and the various intermediate organolead compounds to inorganic lead is promoted by sunlight sunlight and in any aqueous system exposed to sunlight decomposition would be rapid. Dark reactions in a pure water system would be slow. Natural water systems contain variety of anions and cations and sediments which would speed up the breakdown of organic lead to inorganic lead.

These conclusions are consistent with those of other such studies for this endpoint