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Endpoint:
additional toxicological information
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study is well documented and meets general and acceptable scientific principles

Data source

Reference
Reference Type:
publication
Title:
Toxicity of Metal Oxide Nanoparticles in Mammalian Cells.
Author:
Jeng, H.A. and Swanson, J.
Year:
2006
Bibliographic source:
Journal of Environmental Science and Health Part A, 41:2699–2711

Materials and methods

Test guideline
Qualifier:
no guideline available
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Zinc oxide
EC Number:
215-222-5
EC Name:
Zinc oxide
Cas Number:
1314-13-2
Molecular formula:
OZn
IUPAC Name:
oxozinc
Test material form:
solid: nanoform
Details on test material:
Zinc oxide
Mean particle size: 50-70 nm
Surface area: 15-25 m2/g

Results and discussion

Any other information on results incl. tables

Dramatic changes in the cell morphology were observed after exposure to ZnO for 24 hours, particularly at concentrations greater than 50 µg/mL. The cells became irregular and shrank. At the concentration of 50 µg/mL, some cells retained an intact plasma membrane indicating that apoptosis occurred. At the concentration of 100 ?g/mL, they became necrotic and detached from the culture dishes. At concentrations below 10 µg/mL, no distinct change in morphology of cells was observed.

At concentrations of 50 to 100 µg/mL, ZnO nanoparticles caused 15% to 50% of the cells to die as detected by the trypan blue dye method. However, cell viability was not affected by ZnO exposure at a concentration of less than 25 ?g/mL for 48 hours.

The MTT results showed that ZnO exhibited more toxicity than other metal oxide nanoparticles. A dose-dependent increase in reduction of mitochondrial function was observed with ZnO exposure. After 24 hours of exposure, ZnO at a concentration of 100 µg/mL reduced the mitochondrial function >80% as compared to the control cells. At a concentration of 10 µg/mL, ZnO showed insignificant effects on the mitochondrial function.

A significant increase in LDH leakage was observed with exposure to ZnO. At 4 hours of incubation, cells treated by ZnO at a concentration of 50 µg/mL started showing a decrease in mitochondrial function and LDH leakage. At lower concentrations, the effect appeared after 6 hours of contact time.

Applicant's summary and conclusion

Executive summary:

This paper studied the toxicity of metal oxide nanoparticles in mammalian cells. Dramatic changes in the cell morphology were observed after exposure to ZnO for 24 hours, particularly at concentrations greater than 50 μg/mL. The cells became irregular and shrank. At the concentration of 50 μg/mL, some cells retained an intact plasma membrane indicating that apoptosis occurred. At the concentration of 100 μg/mL, they became necrotic and detached from the culture dishes. At concentrations below 10 μg/mL, no distinct change in morphology of cells was observed. At concentrations of 50 to 100 μg/mL, ZnO nanoparticles caused 15% to 50% of the cells to die as

detected by the trypan blue dye method. However, cell viability was not affected by ZnO exposure at a concentration of less than 25 μg/mL for 48 hours. The mitochondrial function (MTT) results showed that ZnO exhibited more toxicity than other metal

oxide nanoparticles. A dose-dependent increase in reduction of mitochondrial function was observed with ZnO exposure. After 24 hours of exposure, ZnO at a concentration of 100 μg/mL reduced the mitochondrial function >80% as compared to the control cells. At a concentration of 10 μg/mL, ZnO showed insignificant effects on the mitochondrial function.

A significant increase in LDH leakage was observed with exposure to ZnO. At 4 hours of incubation, cells treated by ZnO at a concentration of 50 μg/mL started showing a decrease in mitochondrial function and LDH leakage. At lower concentrations, the effect appeared after 6 hours of contact time.