Potassium triboron pentaoxide

Endpoint summary

Additional information

In vitro gene mutation study in bacteria

In the key study, the following strains were tested with and without the presence of metabolic activation by S9-mix: TA 1535, TA 1537, TA 98, TA 100 and WP2uvrA. Positive and solvent controls were run concurrently. Two separate assays were performed as part of this study, both yielding similar results. No mutagenic response was observed in any of the five strains tested in either the presence or absence of metabolic activation up to a maximum concentration of 10,000 µg per plate; furthermore, no cytotoxicity was observed. Test material precipitate was observed on the plates at concentrations of 1000 µg per plate and above. Positive controls demonstrated the sensitivity of the assay and the metabolising activity of the S9 mix and all results were considered to be valid.

In the supporting study, the following strains were tested with and without the presence of metabolic activation by S9-mix: TA 1535, TA 1537, TA 98 and TA 100. Both the concurrent positive and solvent controls were valid, demonstrating the sensitivity of the assay and the metabolising activity of the S9-mix. There was no substantial increase in revertant colony numbers for any of the tester strains. However considerable test variability was encountered with the test material due to a variable chemical reaction, upon incubation at 37 ºC, between the test material and the agar at the higher test concentrations. This reaction produced a white material, resembling microbial contamination which obscured the evaluation of mutagenic potential at high concentrations. Under the specific conditions of the test, the test material is considered to have given a negative response.

Both of the studies available for this endpoint showed no evidence of the test material being mutagenic.

In vitro cytogenicity

A micronucleus assay was conducted in the key study with the test material suspended in peanut oil and dosed by intraperitoneal injection at 1250, 2500 and 5000 mg/kg. Ten animals (five males and five females) were assigned to each dose/harvest time group. The animals dosed with the test material and vehicle control were sacrificed approximately 24, 48 and 72 hours after dosing for extraction of the femur bone marrow. The animals dosed with the positive control were sacrificed approximately 24 hours after dosing for extraction of the bone marrow. The test material induced no statistically significant increase in micronucleated polychromatic erythrocytes over the levels observed in the vehicle controls in either sex or at any of the harvest times. A statistically significant decrease in the PCE:NCE ratio was observed in the 5000 mg/kg females at the 72 hour harvest time. Under the conditions of the assay, the test material did not induce a statistically significant increase in micronuclei and was considered negative in the mouse micronucleus assay.

Justification for selection of genetic toxicity endpoint
No single study could not be selected, as all studies are necessary in assessing the genotoxic potential of the test substance.

Short description of key information:
IN VITRO GENE MUATION STUDY IN BACTERIA
Orthoboric acid, potassium salt was determined to be negative in an Ames study performed in accordance with OECD 471, EU Method B13/14, EPA OPPTS 870.5100 and MOHW (Pharmaceutical Affairs Bureau Notification No. 24). This was confirmed in a supporting Ames study considered to be equivalent or similar to OCED 471.

IN VIVO CYTOGENICITY IN MAMMALIAN CELLS
Orthoboric acid, potassium salt was determined to be negative in a mouse micronucleus study performed in accordance with EPA OPPTS 870.5395.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

In accordance with the criteria for classification as defined in Regulation 1272/2008 and Directive /548/EEC, the substance does not require classification for genotoxicity.