tert-butyl methyl ether

Additional toxicological data

Administrative data

Endpoint:

additional toxicological information

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Detailed account of vapour test atmosphere generation methodology used for toxicity studies of gasoline and gasoline/oxygenate mixtures (including gasoline-MTBE), with extensive chemical analysis). Study in itself reliable, but of questionable relevance to toxicity assessment of MTBE.

Data source

Reference

Reference Type:

publication

Title:

Health assessment of gasoline and fuel oxygenate vapors: Generation and characterization of test materials

Author:

Henley M et al

Year:

2014

Bibliographic source:

Regulatory Toxicology and Pharmacology 70 (2014) S13–S17

Materials and methods

Type of study / information:

Description of test vapours produced from baseline gasoline and gasoline with added oxygenate (including gasoline + MTBE): methods used to generate vapours, collect vapour condensates and regenerate vapours used in various toxicological studies. Includes analytical characterisation of the vapour condensates.

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Development of methods for vapour generation compatible with specific EPA requirements (211b rule at CFR 79.57(f)(2)) but modified from that to permit safe and reproducible conditiond on testing laboratories

GLP compliance:

no

Remarks:

Not generally applicable, but GLP-compliant analyses included

Test material

Test material information

Constituent 1

Reference substance name:

Baseline gasoline (BG)

IUPAC Name:

Baseline gasoline (BG)

Constituent 2

Reference substance name:

Gasoline + MTBE (BG+MTBE)

IUPAC Name:

Gasoline + MTBE (BG+MTBE)

Constituent 3

Reference substance name:

Gasoline + other oxygenates also investigated: not further described here

IUPAC Name:

Gasoline + other oxygenates also investigated: not further described here

Test material form:

other: Vapours collected as condensates

Details on test material:

BG = Reformulated gasoline summer baseline fuel meeting CAA section 211(k)(10)(B)(i) specification (40 CFR 79.55)
BGVC = vapour condensate collected from BG
BG+MTBE = BG with MTBE added to create 2.7 wt% O2 content (corresponding to 14.9 vol% MTBE)
G/MTBE = vapour condensate from BG+MTBE

Results and discussion

Any other information on results incl. tables

Collected vapour condensates represented 16 vol% (BGVC) or 17 vol% (G/MTBE) of the initial liquids (BG or BG+MTBE respectively). Analysis of equilibrium vapour in headspace above BG+MTBE heated to 130F/54C in 20 ml vials indicated an MTBE vapour content of 19.3% (GC-FID, Chevron SE-30 analysis): using this as a target, MTBE vapour content of 21.3 vol% was measured during the large-scale generation of G+MTBE vapour for test article (G/MTBE vapour condensate) collection, using a slightly different GC-FID method under GLP.

Similarity of baseline gasoline vapour condensate to vapour above heated gasoline.

Carbon number component	Liquid gasoline	Equilibrium vapour above gasoline at 130F/54C (vol%)	BGVC condensate (vol%)
C3	0	0	0.1
C4	4.7	27.1	20.6
C5	16.3	40.9	46.4
C6	18.5	18.8	21.6
C7	19.1	8.0	9.0
C8	20.2	4.0	2.2
C9	10.6	0.8	0.2
C10	6.0	0.2	0
C11	2.8	0	0
C12	1.8	00.1	0

GC-FID analysis using proprietary (Chevron SE-30) analysis

Applicant's summary and conclusion

Conclusions:

A large-scale procedure for generation of vapours and collection of vapour condensates from gasoline alone and gasoline with added oxygenates (including MTBE) was developed and described. Composition of the vapour condensate so collected from gasoline was shown to be similar to that of equilibrium vapour above heated liquid gasoline.