Isopropyl 4-hydroxybenzoate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation toxicity study was performed to determine the mutagenic nature of Isopropyl p-hydroxybenzoate. The study was performed using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 with and without S9 metabolic activation system. The test was performed as per the preincubation assay at six different concentration with 1 mg/plate being the maximum concentration. Preincubation was performed for 20 mins and the exposure duration was for 48 hrs. The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated). Isopropyl p-hydroxybenzoate failed to induce a doubling of revertant colonies over the control using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

Data is from peer reviewed publication

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

Gene mutation toxicity study was performed to determine the mutagenic nature of Isopropyl p-hydroxybenzoate

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

- Name of test material: Isopropyl p-hydroxybenzoate
- IUPAC name: isopropyl 4-hydroxybenzoate
- Molecular formula: C10H12O3
- Molecular weight: 180.202 g/mol
- Substance type: Organic
- Physical state: No data

Target gene:

Histidine

Species / strain / cell type:

S. typhimurium, other: TA92, TA1535, TA100, TA1537, TA94 and TA98

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not specified

Cytokinesis block (if used):

No data

Metabolic activation:

with and without

Metabolic activation system:

The liver microsome fraction (S-9) was prepared from the liver of Fischer rats

Test concentrations with justification for top dose:

6 different concentrations were used; 1 mg/plate was the maximum concentration

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The chemical was soluble in DMSO

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

not specified

Positive control substance:

not specified

Details on test system and experimental conditions:

METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 mins
- Exposure duration: 48 hrs
- Expression time (cells in growth medium): 48 hrs
- Selection time (if incubation with a selection agent): No data
- Fixation time (start of exposure up to fixation or harvest of cells): No data

SELECTION AGENT (mutation assays): No data
SPINDLE INHIBITOR (cytogenetic assays): No data
STAIN (for cytogenetic assays): No data

NUMBER OF REPLICATIONS: Duplicate

NUMBER OF CELLS EVALUATED: No data

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: No data

OTHER EXAMINATIONS:
- Determination of polyploidy: No data
- Determination of endoreplication: No data
- Other: No data

OTHER: No data

Rationale for test conditions:

No data

Evaluation criteria:

The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated).

Statistics:

No data

Species / strain:

S. typhimurium, other: TA92, TA1535, TA100, TA1537, TA94 and TA98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Additional information on results:

The maximum dose for negative results represents the highest non-cytotoxic dose used in the experiment

Conclusions:

Isopropyl p-hydroxybenzoate failed to induce a doubling of revertant colonies over the control using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

Executive summary:

Gene mutation toxicity study was performed to determine the mutagenic nature of Isopropyl p-hydroxybenzoate. The study was performed using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 with and without S9 metabolic activation system. The test was performed as per the preincubation assay at six different concentration with 1 mg/plate being the maximum concentration. Preincubation was performed for 20 mins and the exposure duration was for 48 hrs. The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated). Isopropyl p-hydroxybenzoate failed to induce a doubling of revertant colonies over the control using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Gene mutation in vitro:

Various peer reviewed publications were reviewed to determine the mutagenic nature of p-hydroxybenzoate. The studies are as mentioned below:

Gene mutation toxicity study was performed by Ishidate et al (Food and chemical toxicology, 1984) to determine the mutagenic nature of Isopropyl p-hydroxybenzoate (CAS no 4191 -73 -5). The study was performed using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 with and without S9 metabolic activation system. The test was performed as per the preincubation assay at six different concentration with 1 mg/plate being the maximum concentration. Preincubation was performed for 20 mins and the exposure duration was for 48 hrs. The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated). Isopropyl p-hydroxybenzoate failed to induce a doubling of revertant colonies over the control using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

In the same study by Ishidate et al (1984), Chromosomal aberration study was performed to determine the mutagenic nature of Isopropyl p-hydroxybenzoate (CAS no 4191 -73 -5). The cells were exposed to the test material at three different doses with 0.125 mg/mL being the maximum concentration for 48 hr. Colcemid (final concn 0.2µg/ml) was added to the culture 2 hr before cell harvesting. The cells were then trypsinized and suspended in a hypotonic KCI solution (0.075 M) for 13 min at room temperature. After centrifugation the cells were fixed with acetic acid-methanol (1:3, v/v) and spread on clean glass slides. After air-drying, the slides were stained with Giemsa solution for 12-15 min. A hundred well-spread metaphases were observed under the microscope. In the present studies, no metabolic activation systems were applied. The incidence of polyploid cells as well as of cells with structural chromosomal aberrations such as chromatid or chromosome gaps, breaks, exchanges, ring formations, fragmentations and others, was recorded on each culture plate. Untreated cells and solvent-treated cells served as negative controls, in which the incidence of aberrations was usually less than 3.0%. The results were considered to be negative if the incidence was less than 4.9%, equivocal if it was between 5.0 and 9.9%, and positive if it was more than 10.0%. The test chemical induced 3.0% polyploidy and 1.0% structural aberration. Isopropyl p-hydroxybenzoate did not induce chromosomal aberration in chinese hamster fibroblast cell line CHL and hence is not likely to classify as a gene mutant in vitro.

In vitro clastogencity study was performed by Ishidate et al (Mutation Research, 1988) to determine the mutagenic nature of Isopropyl p-hydroxybenzoate. The study was performed using CHL, a clonal sub-line of fibroblasts derived from lung tissue and at dose levels of 125 µg/ml (0.64mM) in the absence of S9 metabolic activation system. The cell line was exposed to the chemical for 48 hrs followed by a sampling without a recovery period being included. Isopropyl p-hydroxybenzoate did not induce clastogenic effects in CHL cell line used for the study and hence the test chemical is negative for gene mutation in vitro.

Based on the data available for the target chemical, p-hydroxybenzoate does not exhibit gene mutation in vitro. Hence the test chemical is not likely to classify as a gene mutant in vitro.

Justification for classification or non-classification

Based on the data available for the target chemical, p-hydroxybenzoate does not exhibit gene mutation in vitro. Hence the test chemical is not likely to classify as a gene mutant in vitro.