Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Not specified; published in 1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non GLP, near guideline study, published in peer reviewed literature, minor restrictions in design and / or reporting but otherwise adequate for assessment.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1986

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
data are not presented as the number of revertant colonies per plate, no data are available on individual plate counts
Principles of method if other than guideline:
Salmonella preincubation assay, which is a modification of the standard plate incorporation assay. This test was performed according to OECD guideline 471, except for some differences (e.g., data are not presented as the number of revertant colonies per plate, no data are available on individual plate counts).
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
Purity: 97.8%
Source: Eastman Chemical products

Method

Target gene:
Not applicable.
Species / strain
Species / strain / cell type:
other: Salmonella typhimurium TA98, TA100, TA1535, TA1537
Details on mammalian cell type (if applicable):
Salmonella strains TAI535, TAI537, TA97, TA98, and TA100 were kept frozen in a -70°C freezer. For overnight inoculation, a loopful of cells were transferred into Columbia broth, maintained on Columbia agar slants at 4°C, or the entire 1 mL thawed bacterial culture was inoculated into minimal glucose medium [Vogel and Bonner, 1956] supplemented with an excess of biotin and histidine. All bacterial cultures were grown overnight for 12-15 hr at 37°C on a shaker, and their phenotypes were analysed as recommended by Ames et al [1975].
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
S-9 fraction from Aroclor 1254 treated male Sprague Dawley rats and male Syrian hamsters.
Test concentrations with justification for top dose:
0, 33, 100, 333, 1000, 3333, 6666 µg/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Remarks:
potassium chloride
Negative solvent / vehicle controls:
yes
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
other: 9-aminoacridine hydrochloride H20, 4-nitro-o-phenylenediamine, and tris(1,3-dichloro-2-propyl)phosphate
Remarks:
none
Details on test system and experimental conditions:
This test is performed according to OECD guideline 471, except for some differences (e.g., data are not presented as the number of revertant colonies per plate, no data are available on individual plate counts).

Furfural was assayed for mutagenicity in the preincubation assay [Haworth et aI, 1983]. To each of 13 X 100-mm test tubes maintained at 37 degrees C were added in the following order: 0.5 ml of S-9 mix or 0.1 M P04 buffer (pH 7.4), 0.05 ml of the overnight culture, and 0.05 ml of solvent or chemical dilution. The mixture was mixed and allowed to incubate without shaking at 37 degrees C for 20 min, at which time 2.0 ml of molten (45°C) top agar supplemented with 0.5 mM L-histidine and 0.5 mM D-biotin were added. The contents of the tubes were mixed and. poured onto 25 ml of minimal glucose bottom agar [Vogel and Bonner, 1956] in I5 X 100-mm plastic petri dishes. When the top agar had solidified, the plates were inverted and incubated at 37 degrees C for 48 hr.

Concurrent solvent and positive controls were tested with and without the metabolic activation systems. At least five dose levels of the chemicals were tested, with three plates per dose level. All assays were repeated no less than 1 wk after completion of the initial test.
Evaluation criteria:
Furfural was blindly tested and evaluated as coded chemical by each laboratory.

1) mutagenic response: a dose-related, reproducible increase in the number of revertants over background,
even if the increase was less than twofold;
2) non-mutagenic response: when no increase in the number of revertants was elicited by the chemical;
3) questionable response: when there was an absence of a clear-cut dose-related increase in revertants; when the dose-related increases in the number of revertants were not reproducible; or when the response was of insufficient magnitude to support a determination of mutagenicity.

When negative results were obtained in the initial assay, the chemicals were retested in all strains with and without activation. Chemicals that
produced a mutagenic response were retested only in the strain(s) and activation system(s) that gave the positive result. Flexibility was allowed in the protocol of the repeat test to adjust doses to better define or clarify a mutagenic response and/or toxicity.
Statistics:
No.

Results and discussion

Test results
Species / strain:
other: Salmonella typhimurium TA98, TA100, TA1535, TA1537
Metabolic activation:
with and without
Genotoxicity:
ambiguous
Remarks:
Tested negative in one laboratory and tested weakly positive in the other laboratory
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
Subtle differences in assay conditions between the laboratories existed (e.g. differences in dose levels, age of cultures, and S-9 mixtures (morning vs afternoon use) and incubation time and temperature (no further details provided). The use of a non statistical approach to evaluate results could also contribute to the apparent inconsistency.
The lack of knowledge about the chemical structure, in addition to not knowing how the chemical or its analogues behave in other biological systems, does not allow for selection of the optimum protocol. It is possible therefore that furfural reported as non mutagenic may have been reported mutagenic by other researchers. The discrepancy in the inter- and intra-laboratory results are most likely attributable to the testing of coded chemicals by a fixed protocol.
Remarks on result:
other: strain/cell type: Salmonella typhimurium TA98, TA100, TA1535, TA1537
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Case Western Reverse University: negative in all
strains.
SRI International: TA100 without S9: equivocal response
(nearly 2-fold increase) at 1 mg/plate. At the highest two
dose levels (3333 and 6666 µg/plate) furfural was toxic.
No dose-related increases are seen in Salmonella with S9.

The authors concluded that the discrepancies between the two
laboratories and other researchers were most likely
attributable to the testing of coded chemicals by a fixed
protocol and not the optimum protocol.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
other: Tested negative in one laboratory and tested weakly positive in the other laboratory

In an Ames test (Salmonella TA98, TA100, TA1535 and TA1537), furfural elicits an ambiguous response with regard to genotoxicity in presence of metabolic activation.
Negative results are shown in TA 98, TA1535 and TA1537 with and without metabolic activation and in TA100 with metabolic activation. A positive result was obtained without metabolic activation.
Executive summary:

This paper includes data of Salmonella Mutagenicity results on 270 coded chemicals, including furfural, performed under contract to the National Toxicology Program.

 

Furfural was incubated for 20 minutes at 37°C before the addition of soft agar supplemented with L-histidine and -biotin and subsequent plating on minimal glucose agar plates. Incubation was continued for an additional 48 hours. A total of 8 doses was tested. Metabolic activation obtained from Aroclor 1254-induced male Sprague-Dawley rats or Syrian hamsters. Positive and negative controls were used. The test was performed in two different laboratories (Case Western Reverse University and SRI International).

 

Case Western Reverse University: negative in all strains.

 

SRI International: TA100 without S9: equivocal response (nearly 2-fold increase) at 1 mg/plate. At the highest two dose levels (3333 and 6666 µg/plate) furfural was toxic. No dose-related increases are seen in Salmonella with S9.

 

The authors concluded that the discrepancies between the two laboratories and other researchers were most likely attributable to the testing of coded chemicals by a fixed protocol and not the optimum protocol.

It was concluded, therefore, that furfural was ambiguous for genotoxicity.