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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

The potential genotoxicity of the test substance was assessed in an Ames test performed (2000). In accordance with OECD Guideline 471 the test strains S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 were tested with and without a metabolic activation system (rat liver S-9). The study included a standard plate test (40 - 10000 µg/plate) as well as a pre-incubation test (0.8 - 2500 µg/plate). Due to the good solubility of the test substance in water, water was selected as the vehicle. An increase in the number of his+ or trp+ revertants was not observed in the standard plate test or in the pre-incubation test either without S-9 mix or after the addition of a metabolizing system. No test substance precipitation was found. Cytotoxicity of the test material was observed at doses ≥ 5000 µg/plate and ≥ 500 µg/plate in the standard plate and pre-incubation test respectively. Under the experimental conditions chosen here, it is concluded that the test substance is not a mutagenic agent in a bacterial reverse mutation test.

The mutagenic potential of povidone-iodine (PVP-1) and some related compounds was studied using the L5178Y mouse (TK+/-) lymphoma assay (Kessler 1980). The study was performed in similar fashion to OECD guideline 490. Test concentrations were 100 and 500 µg/L, and 1, 5, and 10 mg/L. Drug-induced cytotoxicity was measured during a seven day growth study. Those doses of drugs which resulted in 50% cell viability compared to control values and the next four lower dose multiples were used in the mutagenicity assay. Mutagenicity was assessed using a modification of the technique developed by Clive and Spector (1975). Cell viability was assessed using trypan blue exclusion dye and by measurement of the cellular doubling time. Colony formation was scored after 10 days incubation at 37 °C. In all of the experiments, the cloning efficiency of the control plates was found to be greater than 85%. The number of mutant colonies/1E-5 cells was calculated for the media controls. The test substance did not significantly alter the Mutational Frequency (MF) in the absence of a metabolic activation system. The concentration of PVP-I of 100 mg/ml could not be evaluated due to severe cytotoxicity. In the presence of a metabolic activation system, a MF of 3.2 and 4.7 was observed at 10 mg/mL and 5 mg/ml, respectively. However, only at 5 mg/mL the MF was statistically different from control values (p<0.01). Furthermore, there was no dose-related increase in the MF in the presence of the S-9 fraction. Based on these observation the test substance was considered to be not genotoxic under the test conditions chosen herein.

The same publication (Kessler 1980) also reported on a BALB/c 3T3 transformation assay in which the test material was assessed for its transformational capacities. The tested concentrations were 100, 500 µg/mL, 1, 3, 5, and 10 mg/mL. Doses of the compound were tested for cytoxicity by plating 2E-2 cells in 25 cm² tissue culture flasks. The plating efficiency of the control was compared to that of the treated cells after seven days incubation. The doses that yielded 50% of the control value and the next two lower dose multiples were used in the transformation assay. The number of foci formed in the presence of the test compounds were compared to the media control values. Only foci that exhibited the typical criss-cross pattern with overlapping and piling up of cells were considered to be transformed. Values of 2.5 times greater than that observed in the negative controls were considered to be positive transformational events. The test substance tested at 5 mg/mL produced a statistically significant increase in the number of transformed foci observed (3.67, p<0.01). However, no dose-response relationship was observed. Since no dose-response relationships for the test substance was found when positive results were obtained, and since only marginally positive if any activity was observed, it was concluded that the test substance does not demonstrate a biologically relevant concern as a genotoxic compound.

The in vitro genotoxicity of the test substance was also assessed in a more recent publication (Muller 2006). The test substance was evaluated, using Chinese Hamster Ovary cells (CHO-K1 cells), in 3 different formulations namely Betaisodona solution containing 10% povidone-iodine with 11% available iodine, Betaisodona ointment containing 10% povidone-iodine with 10% available iodine and the liposomal hydrogel Repithel (3% povidoneiodine). The comet assay and chromosome aberration test were used to characterise the genotoxic potency within 4 h of contact with test cells. For the Comet assay, 6% Repithel, 5% Betaisodona ointment and 2% Betaisodona solution in culture medium with 10% fetal bovine serum were the highest concentrations tested. Higher concentration would result in higher than 60% cytotoxicity, as determined in preliminary investigations. All tested concentrations were found to be not genotoxic in the comet assay with and without the presence of a metabolic activation system (S-9, Aroclor 1254 induced). In the chromosome aberration test, 10% Repithel, 5% Betaisodona ointment and 2.5% Betaisodona solution in culture medium with 10% fetal bovine serum were the highest concentrations tested, which provided less than 60% cytotoxicity within 4 h of contact with the CHO-K1 cells. Using concentrations of 5–10% Repithel, 2.5–5% Betaisodona ointment and 1.25–2.5% Betaisodona solution, no chromosome aberrations were detected. Based on the results from the presented comet assay and chromosome aberration test to characterise the genotoxic potency of the test substance within 4 h of contact with CHO-K1 cells, it was determined that the substance had no chromosome damaging properties.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

The test substance was tested for mutagenic effects on Chinese hamsters when applied singly and five times intraperitoneally, using the bone marrow test (chromosome aberration assay) (1976). The test involved 15 groups of six male and six female Chinese hamsters each. This test was used for direct analysis of induced structural and numerical chromosome aberrations in somatic cells. Three groups of animals received a single 38.3 mg/kg (one-quarter LD50) or 82.5 mg/kg (one-half LD50) dose of povidone-iodine or 10 mL of saline solution/kg. Three groups remained untreated. Two other groups received five applications of 38.3 mg of povidone-iodine/kg or five 10 mL/kg applications of saline solution on 5 successive days. Another group of animals remained untreated. The animals were sacrificed 6, 24, or 48 hr after the single application or 6 hr after the fifth application. From each animal, 100 metaphases were counted out and evaluated. Where only individual metaphases were found in the smears, evaluation was not carried out. Under these test conditions, exposure to the test substance did not result in an increase in the number of aberrant metaphases following single or repeated intraperitoneal application. No changes as compared with the control animals were to be seen, either in the type of aberrations or in the percentual occurrence.

As a second test to evaluate the potential in vivo genotoxicity was a micronucleus test performed on 5 NMRI mice after two intraperitoneal applications (1976). There were also two control groups of 5 mice each. One group was treated twice with 10 mL doubly destilled water and the other group was left untreated. The applied dose was 36.0 mg/kg bw which corresponds with 1/10 of the LD50. Substance was administered to the animals twice, thirty hours and six hours before the animals were put to death. After application of substance, the animals were examined for externally recognizable symptoms of toxicity. On completion of the test the animals were put to death and examined macroscopically for any pathological changes in the internal organs. From each animal 2000 normochromatic erythrocytes, 1000 polychromatic erythrocytes and 1000 segmented granulocytes were analysed. The animals which received two applications of the test substance or aqua bidest intraperitoneally displayed no signs of toxicity. Neither did the untreated animals show any evidence of illness. With all the animals put to death, macroscopic examination revealed no pathological changes of the internal organs which could be attributed to the administered substance. Finally, under these test conditions, the test conditions did not cause an increase in the number of micronucleus - containing erythrocytes or granulocytes.

In a third investigation (1976) the Dominant Lethal Assay was performed in order to detect possible induced mutations in the germ cells of male NMRI mice. A single group of 20 male mice received 72 mg/kg bw of the test substance (one-fifth LD50). The administered volume was 10 mL/kg body weight. A second group of 20 male mice received 10 mL of distilled water/kg bw in a single application and the third group of 20 male mice remained untreated. The treated male mice were mated about 20 hours after a single intraperitoneal administration with 3 virginal animals for the duration of 7 days. Thereafter, the same male animals received seven other consecutive test series, each 7 days duration each 3 new virginal animals. The untreated animals were treated in analogous manner. The females were killed the 18th day after the beginning of each match week. The percentage of dead implants, based on total implants was determined per mating week. During the the mating periods, all parameters varied in a similar manner as in the control animals except for two occassions: the conception rate decreased significantly during the 1st week and an increase in the percentage of dead implants after the seventh pairing week. Both effects were considered to be incidental. Therefore, no dominant lethal mutation could be attributed to the test substance and the substance was considered to be non-genotoxic under these test conditions.

Additionally two earlier chromosome aberration assays were identified using Chinese hamsters (1976). However, in both studies, not only in the exposed animals but also in the untreated and in the saline control group chromosomal changes were observed which are normally rarely seen in these animals. Based on the very ambiguous results likely obtained thereof, the studies were judged unsuitable for further assessment.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

Justification for classification or non-classification

Based on the results obtained in a in vitro Ames test, mouse lymphoma assay, Balb/c 3T3 transformation assay, Comet assay and a chromosome aberration assay as well as an in vivo chromosome aberration assay, micronucleus test and a dominant lethal assay all showing negative results, the test substance was determined no be non-genotoxic. Therefore, classifiaction for genetic toxicity is not warranted in accordance with EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation No. 1272/2008.