Tungsten

Specific investigations: other studies

Administrative data

Endpoint:

cytotoxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non standard method and non-GLP. Well described methods.

Data source

Reference

Reference Type:

publication

Title:

Biocompatibility of corroding tungsten coils: in vitro assessment of degradation kinetics and cytotoxicity on human cells.

Author:

M. Peuster, C. Fink, C. von Schnakenburg.

Year:

2003

Bibliographic source:

Biomaterials 24 (2003) 4057-4061.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

An In vitro cell proliferation assay was used to assess the toxicity of tungsten using various cell lines.

GLP compliance:

not specified

Type of method:

in vitro

Endpoint addressed:

not applicable

Test material

Test material information

Constituent 1

Reference substance name:

Tungsten metal

IUPAC Name:

Tungsten metal

Constituent 2

Reference substance name:

Tungsten

EC Number:

231-143-9

EC Name:

Tungsten

Cas Number:

7440-33-7

Molecular formula:

W

IUPAC Name:

tungsten

Details on test material:

- Name of test material (as cited in study report): Tungsten ICP/DCP standard solution
- Substance type: Active

Test animals

Species:

other: Human pulmonary arterial endothelial cells, smooth muscle cells, and dermal fibroblasts

Administration / exposure

Route of administration:

other: in vitro

Vehicle:

water

Duration of treatment / exposure:

1, 3, 6 and 10 days

Frequency of treatment:

one time

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 0.1, 1, 10, 50, 100, 500, 1000, 2500 and 5000 ug/ml
Basis:
nominal conc.

Control animals:

yes, concurrent no treatment

Details on study design:

Cells were seeded at a concentration of 5 x 10^3 in 100 ul onto 96 well multiplates without coating. After 24 h, tungsten was added to the cell culture medium to result in the tungsten concentrations listed above. Cell proliferation was assessed using the WST-1-assay after 1, 3, 6, and 10 days. In brief, after incubation of the cells in the plates with the culture medium, 10 ul cell proliferation agent WST-1 was added to each well. The cells were then incubated for another 4h at 37 degrees C in a 5 % CO2 atmosphere. After 1 min of shaking, the multiplate was placed in an ELISA multiplate reader and measured against a background control consisting of 100 ul growth medium and 10 ul cell proliferation reagent WST-1 at a wavelength of 520 nm. The vitality of cultured cells was then expressed as activity in % by normalizing the units of absorbance of cells incubated at different tungsten concentrations to the units of absorbance of cells incubated without tungsten in the culture medium. All cell culture assays were repeated 5 times. The vitality of the cells at a given tungsten concentration was then expressed as the median of the 5 measurements.

Results and discussion

Any other information on results incl. tables

Assessment of metabolic activity demonstrated increasing toxicity with increasing tungsten concentrations in all cell lines examined. However, marked differences in susceptibility were found. Pulmonary arterial endothelial and smooth muscle cells showed a significant decrease in metabolic activity in relation to incubation time and incubation concentrations. In contrast, fibroblasts kept their metabolic activity despite prolonged exposure time. At a threshold tungsten level of 50 ug/ml, all cell types showed a decrease in metabolic activity and as before, fibroblasts were more resistant to higher tungsten levels in the culture medium. The highest toxicity of tungsten was demonstrated for human pulmonary arterial endothelial cells. The LD50 was 50 ug/ml for human pulmonary arterial endothelial cells, 100 ug/ml for human pulmonary smooth muscle cells and 1000 ug/ml for human dermal fibroblasts. In endothelial cells, irrespective of incubation time, a tungsten level of 500 ug/ml in the growth medium lead to complete cell death as reflected by the steep decrease of metabolic activity if compared to unexposed control cells regardless of incubation time. In pulmonary arterial smooth muscle cells, metabolic activity gradually decreased in relation to incubation time and this observation was pronounced with increasing tungsten concentrations in the culture medium. In contrast, fibroblasts retained their metabolic activity up to a tungsten concentration of 1000 ug/ml before they showed a marked decrease in metabolic activity.

Applicant's summary and conclusion

Conclusions:

Human pulmonary arterial endothelial cells were most susceptible to tungsten with a LD50 of 50 ug/ml. In contrast, the LD50 for the smooth muscle cells was 100 and 1000 ug/ml for the human dermal fibroblasts after 10 days of incubation. In conclusion, very high (>50 ug/ml[normal serum value 0.0002 ug/ml]) tungsten concentrations are needed to result in local cytopathologic effects on human pulmonary arterial endothelial cells, smooth muscle cells, and dermal fibroblasts.