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Basic toxicokinetics

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basic toxicokinetics in vivo
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented study in peer-reviewed publication conducted by experienced testing laboratory.

Data source

Reference Type:
Metabolism of linear alkylate sulfonate and alkyl benzene sulfonate in albino rats
Michael, W.R.
Bibliographic source:
Toxicol. Appl. Pharmacol. 12:473-485

Materials and methods

Objective of study:
Principles of method if other than guideline:
The absorption, distribution, metabolism and elimination of LAS (radioactively labelled with 35S) were studied in male Charles River rats. LAS was administered as an aqueous solution.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Benzenesulfonic acid, C10-13-alkyl derivs., sodium salts
EC Number:
EC Name:
Benzenesulfonic acid, C10-13-alkyl derivs., sodium salts
Cas Number:
Molecular formula:
C16-19 H25-31 Na O3 S
sodium 4-undecylbenzenesulfonate
Constituent 2
Reference substance name:
C10-13 LAS
C10-13 LAS
Details on test material:
C10-13, LAS (CAS #68411-30-3); alkyl chain length predominately C11, C12 and C13; phenyl ring fairly randomly distributed between carbons 2 through 6 of the alkyl chains.
(radioactively labelled with 35S)

Test animals

other: Charles River albino
Details on test animals or test system and environmental conditions:
The animals were housed in individual cages which permitted the separate collection of urine and feces. Food and water were provided ad libitum after dosing.

Administration / exposure

Route of administration:
oral: gavage
Details on exposure:
Male rats (150-200 g) were fasted for 16 hours and given orally an aqueous solution containing LA35S. The dose was given in 1.0 mL volume. The urine was collected under toluene, removed daily, and refrigerated until it could be examined. The feces were removed each day and allowed to dry at room temperature. At the termination of the study, the animals were killed and selected organs and tissues were taken for radioassay.

Also, the route of absorption was determined by oral feeding of 40 mg of LAS to thoracic duct-cannulated rats. The lymph was collected from each animal in a single 42-hour fraction.

The enterohepatic circulation of the surfactant was quantified by oral feeding of 1.2 mg of LAS to bile duct-cannulated rats and to rats prepared in a manner similar to the dual rat study described by Boquet and Fromageot. A cannula was inserted into the proximal end of the bile duct of Rat A and into the distal end of the bile duct in Rat B such that the bile from Rat A could flow through the cannula into the bile duct, and finally into the intestine of Rat B. A second cannula was inserted into the proximal end of the bile duct of Rat B so that is bile could be collected. LA35S was fed orally to Rat A. Urine and feces of Rats A and B and bile of Rat B were collected for 90 hours after dosing.
Duration and frequency of treatment / exposure:
See details of exposure section
Doses / concentrations
Doses / Concentrations:
0.6, 1.2, 8.0 and 40.0 mg (averages of three animals for the two lower doses and five animals for the two higher doses) for the excretion test, 1.2 mg/rat for the absorption and enterohepatic circulation tests.
No. of animals per sex per dose / concentration:
Three or five males per dose for the excretion test, six males for the absorption and enterohepatic tests.
Control animals:
not specified

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
The compound was readily absorbed from the gastrointestinal tract (80-90% of the dose).
Details on distribution in tissues:
Primarily excreted in the urine.
Details on excretion:
Most of the absorbed 35S was eliminated within 72 hours and 60-65% of the absorbed dose was eliminated in the urine, 35% of the absorbed 35S was excreted in the bile and was reabsorbed completely from the gastrointestinal tract. Very little was found in the lymph, so transport of LAS is probably by way of portal venous blood.

Metabolite characterisation studies

Metabolites identified:
Details on metabolites:
Urine - sulfophenyl butanoic and sulfophenyl pentanoic acid. These metabolites were sufficiently polar to avoid being reabsorbed from the kidney tubules. Although the metabolites in the bile were not identified, it was shown that no unchanged LAS was eliminated via this pathway.

Applicant's summary and conclusion

Interpretation of results (migrated information): no bioaccumulation potential based on study results
LAS is readily absorbed by the gastrointestinal track and rapidly excreted with its metabolites, primarily in the urine.
Executive summary:

The absorption, distribution, metabolism and elimination of LAS (radioactively labelled with 35S) were studied in male Charles River rats. LAS was readily absorbed by the gastrointestinal tract and rapidly metabolized and excreted in the urine.