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Acute Toxicity: dermal

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Administrative data

Endpoint:
acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25 July 1989 to 9 August 1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Justification for type of information:
In accordance with REACH Annex XI, testing is not scientifically necessary as studies on synthetic amorphous magnesium silicate have been conducted by Dallas Group of America and show no acute toxicity via the dermal route. The particle size analysis performed on the Dallas and PQ corporation material show that they are sufficiently similar. The only difference between the materials are the molar ratios. The molar ratio of the tested Dallas material is within the range of the PQ Corporation registered substance. No additional testing is therefore required.
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report date:
1989

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Qualifier:
according to guideline
Guideline:
other: FHSA 16 CFR 1500
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes

Test material

Constituent 1
Reference substance name:
Silicic acid, magnesium salt
EC Number:
215-681-1
EC Name:
Silicic acid, magnesium salt
Cas Number:
1343-88-0
Molecular formula:
MgO.xSiO2, the molar ratio SiO2:MgO typically ranges from 1.4-4
IUPAC Name:
Synthetic amorphous magnesium silicate, with molar ratio (SiO2:MgO) range of 1.4-4
Details on test material:
The test material, Magnesium Silicate was a fine white powder.
Specific details on test material used for the study:
The test material, Magnesium Silicate was a fine white powder.

Test animals

Species:
rabbit
Strain:
New Zealand White
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: U.S.D.A. supplier
- Weight at study initiation: 2.3-3.0 kg
- Housing: individually in wire mesh suspension cages
- Diet : Purina Laboratory Rabbit Chow available ad libitum
- Water : available ad libitum
- Acclimation period: Four days

Animals were housed in a temperature and humidity controlled environment with 12 hours light/12 hours dark cycle.

Administration / exposure

Type of coverage:
occlusive
Vehicle:
physiological saline
Details on dermal exposure:
Prior to dosing, hair was removed from the trunk of each rabbit so that approximately 10% of the body surface area was exposed. For half of the treated rabbits (2 males and 3 females), the surface ofthe test site was abraded , for the remaining animals the test site was left intact. The sample, moistened with saline, was applied to the test site at a dose of 2 g/kg bw. The sample was introduced onto a sleeve of rubber dental dam which was wrapped around the truck of the animal and secured with staples.

At the end of the 24 hour exposure period, the wrapping was removed and any residual test material was removed by gentle sponging using a towel moistened with water.
Duration of exposure:
24 hours
Doses:
The dose level applied was 2 g/kg
No. of animals per sex per dose:
Ten rabbits (five female/five male)
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: checked daily for clinical signs and weighedon day of dosing and at termination
- Necropsy of survivors performed: yes

The test material moistened with an appropriate volume of physiological saline was administered to five male and five female rabbits at a dose level of 2 g/kg.

Each animal was observed daily for viability. Observations of any toxicologic signs were taken after dosing and daily thereafter for 14 days. Skin reactions or any evidence of irritation were noted.

Body weights were measured for each animal on the day of dosing and at the time of necropsy.

A gross necropsy was performed on each animal at the end of the 14 day observation period
Statistics:
Not applicable for a limit test

Results and discussion

Preliminary study:
No preliminary study performed.
Effect levels
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Mortality:
No deaths occurred during the observation period.
Clinical signs:
Exposed area appeared dry, no other clinical changes recorded.
Body weight:
There was an increase in body weight over the 14 day exposure period. The mean body weigh gain was 283 g for male rats and 381 g for female rats.
Gross pathology:
No gross changes observed.
Other findings:
No other findings to report.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The acute dermal LD50 value was found to be greater than 2.0 g/kg in male and female New Zealand White rabbits. The test material is not classified as toxic or harmful by dermal application.
Executive summary:

The acute dermal toxicity of magnesium silicate was evaluated by the addition of 2 g/kg to an area of skin for 24 hours on ten New Zealand white rabbits. The animals were observed for 14 days. The acute dermal LC50 was found to be greater than 2.0 g/kg. The test substance was found to be not toxic or harmful by dermal application. No classification is required under existing DPD (Directive 67/548/EEC, as subsequently amended) or GHS (Regulation 1271/2008) legislation.