2-butoxyethanol

Direct observations: clinical cases, poisoning incidents and other

Administrative data

Endpoint:

direct observations: clinical cases, poisoning incidents and other

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Published study in peer reviewed journal

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

A human exposure study to investigate biological monitoring methods for 2-butoxyethanol

Author:

Jones K, Cocker J

Year:

2003

Bibliographic source:

Biomarkers, 8, (5), 360-370

Materials and methods

Study type:

study with volunteers

Endpoint addressed:

basic toxicokinetics

Principles of method if other than guideline:

Assessment of potential biomarkers as indicators of butoxyethanol exposure. Volunteers were exposed to 2-butoxyethanol vapour for 2hrs and the time course of butoxyethanol and its metabolite butoxyacetic acid followed in blood and urine.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

2-butoxyethanol

EC Number:

203-905-0

EC Name:

2-butoxyethanol

Cas Number:

111-76-2

Molecular formula:

C6H14O2

IUPAC Name:

2-butoxyethanol

Method

Type of population:

general

Subjects:

- Number of subjects exposed: 2 male, 2 female.

Ethical approval:

confirmed, but no further information available

Route of exposure:

inhalation

other: dermal exposure to vapour.

Reason of exposure:

intentional

Exposure assessment:

not specified

Details on exposure:

50ppm vapour exposure for 2 hours.
Combinations of exposure: whole body, dermal only (subjects fed clean air via face mask).

Examinations:

- Urine analysis: collected at 0, 4, 6, 8, 10, 12, 22, 26 30, 24 hours. Analysis in duplicate. Creatinine levels determined. Analysed for free and total 2-butoxyacetic acid
- Haematology: collected by forearm cannula in vein at 0, 0.5, 1, 1.5 and 2hrs (end of exposure) then every 20 mins for a further 2 hours. Analysis in duplicate. Analysed for butoxyethanol.
- Other: Breath samples provided a 0, 2hrs then every 10-15 mins for a further 2 hours.

Results and discussion

Results of examinations:

- Urine analysis: Peak excretion 6-12 hours post exposure. Half life average 4hrs. Conjugation variable between individuals but does not slow elimination.
- Haematology: Average peak blood concentration of 2-butoxyethanol: 7µM. Half life average: 56min. Butoxyacetic acid :peaked 20 mins after exposure at average of 35µM and an average half life of 13 mins.
- Other: Dermal absorption based on butoxyacetic acid measurements: 12%
- Other: Breath measurements. Maximum value only 12x LOD, so not deemed a reliable technique to quantify exposure.

Any other information on results incl. tables

Inter individual variations

Absorption	Percentage update of vapour uptake via the skin	9 – 145	x1.6 range
Metabolism/Elimination	Half life	41-84 min	x2.0 range

Applicant's summary and conclusion

Conclusions:

Total free and conjugated butoxyacetic acid in urine is the most reliable biological marker to use as a proxy for 2-butoxyethanol exposure.

Executive summary:

In a study of the assessment of potential biomarkers as indicators of butoxyethanol exposure, 4 volunteers were exposed in a number of experiments to 2-butoxyethanol vapour for 2hrs and the time course of butoxyethanol and its metabolite butoxyacetic acid followed in blood and urine. In urine, peak excretion of butoxyacetic acid occured 6-12 hours post exposure with a half life of 4hrs. Conjugation was variable between individuals but did not slow elimination Average peak blood concentration of 2-butoxyethanol was 7µM with a half life of 56min. Butoxyacetic acid in blood peaked 20 mins after exposure at 35µM with an average half life of 13 mins. The study concluded that total free and conjugated butoxyacetic acid in urine is the most reliable biological marker to use as a proxy for 2-butoxyethanol exposure.