2-butoxyethanol

Additional toxicological data

Administrative data

Endpoint:

additional toxicological information

Type of information:

other: review

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comprehensive review of all available acute toxicity data in a peer reviewed publication.

Data source

Reference

Reference Type:

publication

Title:

Acute toxicity classification for ethylene glycol mono-n-butyl ether under the Globally Harmonized System

Author:

Boatman R, Kelsey J, Ball N

Year:

2014

Bibliographic source:

Regulatory Toxicology and Pharmacology 68 (2014) 41–50

Materials and methods

Type of study / information:

Comprehensive review of all available acute toxicity data and a comparison against the CLP criteria for classification.

Principles of method if other than guideline:

Comprehensive review of all available acute toxicity data and a comparison against the CLP criteria for classification.

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

Results and discussion

Any other information on results incl. tables

Acute oral, dermal and inhalation toxicity classifications of chemicals under the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (GHS) should typically be based on data from rats and rabbits, with the tacit assumption that such characterizations are valid for human risk. However this assumption is not appropriate in all cases. A case in point is the acute toxicity classification of ethylene glycol mono-n-butyl ether (EGBE, 2-butoxyethanol, CAS 111-76-2), where acute toxicity data from rats or rabbits leads to an overly conservative assessment of toxicity. Hemolysis is the primary response elicited in sensitive species following EGBE administration and the proximate toxicant in this response is 2-butoxyacetic acid (BAA), the major metabolite of EGBE. The sensitivity of erythrocytes to this effect varies between species; rats and rabbits are sensitive to BAA-mediated hemolysis, whereas humans and guinea pigs are not. In this publication, a weight of evidence approach for the acute hazard classification of EGBE under GHS is presented. The approach uses acute toxicity data from guinea pigs with supporting mechanistic and pharmacokinetic data in conjunction with human experience and shows that adopting the standard method results in over-classification.

The authors concluded using a weight of evidence approach covering animal and human data and known sensitivities of certain species to effects not relevant to humans that the following classifications for acute toxicity were appropriate:

• Oral route: data consistent with a Category 4 classification.
• Dermal route: data consistent with a Category 5 classification under GHS (not classified under CLP.)
• Inhalation: not classified (no effects seen up to saturated vapour concentration.)