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Additional toxicological data

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Endpoint:
additional toxicological information
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Study period:
1985
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Publicly available literature without indication of guideline and GLP
Cross-reference
Reason / purpose for cross-reference:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1985

Materials and methods

Type of study / information:
Type: tissue toxicitynon-standard studyFemale guinea pigs were shaved and depilated. A gauze pad was placed over the upper dorsum and held in place with surgical mesh. At 8-hour intervals the gauze was soaked with 0.1 or 0.5 % sodium hypochlorite solution freshly prepared each day by dilution of Clorox bleach. Area covered: 5 x 5 cm
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Public available literature. No guideline indicated. For details on method see materials and methods section in IUCLID5 dossier.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Sodium hypochlorite
EC Number:
231-668-3
EC Name:
Sodium hypochlorite
Cas Number:
7681-52-9
Molecular formula:
ClO.Na
IUPAC Name:
sodium hypochlorite
Details on test material:
Sodium hypochlorite (Clorox bleach) Content: 5.25 %

Results and discussion

Any other information on results incl. tables

For the 0.5 % sodium hypochlorite solution, no significant differences in basal cell viabilities between control and treated areas were noted through 1 week of treatment. However, a 15 % decrease in basal cell viabilities was observed after 2 weeks of treatment. In contrast, the 0.1 % solution yielded no significant differences in basal cell viabilities between control and treated skin throughout the 2-week period. When the isolated basal cells were grown in tissue culture, the cells from untreated areas grew to confluency in 4 to 7 days. Basal cells isolated from areas treated for 7 days with 0.5 % sodium hypochlorite and for 14 days with 0.1 % sodium hypochlorite also were able to grow to confluency, although at a somewhat slower rate than that observed in control cells. In contrast, cells isolated from skin treated with 0.5 % solutions for 14 days were unable to reach confluency even after 12 days in culture.

No significant morphological changes were noted after 1 or 4 days of treatment with 0.1 and 0.5 % solutions. However, a marked epidermal hyperplasia with an influx of inflammatory cells into the papillary dermis was noted after 7 and 14 days of treatment with the 0.5 % solution and 14 days with the 0.1 % solution, which are likely to due to its irritation potential.

Applicant's summary and conclusion

Conclusions:
Sodium hypochlorite has cytotoxic properties and can affect the physiology of the cell which is caused by a change of pH and/or its oxidising properties.
Executive summary:

Female guinea pigs were shaved and depilated. A gauze pad was placed over the upper dorsum and held in place with surgical mesh. At 8-hour intervals the gauze was soaked with 0.1 or 0.5 % sodium hypochlorite solution freshly prepared each day by dilution of Clorox bleach. Animals were sacrificed on day 1, 4, 7 or 14. The treated area and an untreated sample of skin were excised and shaved again. The epidermis and the upper layer of the dermis were removed with a dermatome. The epidermal tissue was trypsinated and incubated for 1 hour. The epidermis was teased away from the dermis and minced. The viabilities of the cells from treated and untreated samples were determined. The cells were then plated and incubated for 7 to 12 days.

Tissue biopsies were taken with a dermal punch from each treated and untreated area at the time of excision and were fixed in formalin. The tissue was dehydrated, embedded in paraffin, cut in sections and stained.

A 15 % decrease in basal cell viabilities was observed after 2 weeks of treatment with the high concentration, i.e. 0.5 % sodium hypochlorite. Cells isolated from skin treated with 0.5 % solutions for 14 days were unable to reach confluency even after 12 days in culture, whereas confluency in control cell cultures was reached within 4 to 7 days and in a somewhat longer time in cells for 7 days with 0.5 % sodium hypochlorite and for 14 days with 0.1 % sodium hypochlorite. All other cell samples did not show significant differences from controls.

Morphological changes in cells were observed after 7 and 14 days of treatment with the 0.5 % solution and 14 days with the 0.1 % solution.

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