Bentonite, acid-leached

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test performed according to GLP. 1 hour exposure rather than 4 hour (this has been accounted for in the calculation of the LD50 value). No analytical monitoring

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1985

Report date:

1985

Materials and methods

Principles of method if other than guideline:

Ten albino rats were expsoed to the test substance at an atmospheric concentration of 200 mg/L. Animals were observed for a total of 14 days.

GLP compliance:

yes

Test type:

fixed concentration procedure

Test material

Test material information

Constituent 1

Reference substance name:

Bentonite, acid-leached

EC Number:

274-324-8

EC Name:

Bentonite, acid-leached

Cas Number:

70131-50-9

Molecular formula:

unspecified for this UVCB substance

IUPAC Name:

Bentonite, acid-leached

Details on test material:

- Name of test material (as cited in study report): Copisil D4A10 (bentonite acid leached)

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Suitable licence dealer
- Age at study initiation: 6 - 9 weeks
- Weight at study initiation: 226-292 g
- Housing: Galvanized cages with indirect bedding
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: At least 7 days


ENVIRONMENTAL CONDITIONS
- Temperature: 65 - 75°F
- Photoperiod: 12 hrs dark / 12 hrs light

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

Animals were placed in a 95 L plexiglass chamber. A flow of air was passed through the chamber at a rate of 5 L/minute. The test article was introduced directly through the chamber inlet so it mixed with the incoming air.. The chamber was initially charged with the test article at a static concentration of 200 mg/L, and the test article introduced at regular intervals for a period of 1 hour so that a concentration of 200 mg/L was maintained for the 1 hour exposure

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

1 h

Concentrations:

200 mg/L

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: 1, 3, 6 and 24 hours after exposure and then daily for 14 days
- Necropsy of survivors performed: yes

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 200 mg/L air

Based on:

test mat.

Exp. duration:

1 h

Effect levels 2

Sex:

male/female

Dose descriptor:

LC50

Effect level:

50 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortalities occurred during the test

Clinical signs:

other: 1 animal had slight depression after 1 hour exposure. No clinical signs were noted thereafter

Body weight:

Bodyweights appeared normal at the end of the test

Gross pathology:

In animals 2 and 5 (males) an abscess was found on the left lobe of the lung; 2 cm in diameter, hard, yellow, pus filled. No gross changes were observed in the other animals.

Any other information on results incl. tables

Table 1: Acute inhalation toxicity (raw data)

Animal no and sex

Bodyweight (g)

1

3

6

24

2

3

4

5

6

7

8

9

10

11

12

13

14

Body weight (g)

1 M

274

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

422

2 M

282

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

396

3 M

280

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

356

4 M

258

SD

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

376

5 M

292

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

402

6 F

268

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

332

7 F

242

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

274

8 F

232

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

246

9 F

246

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

266

10 F

226

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

258

SD = Slight depression

N = Normal

The classification criteria for acute inhalation toxicity relate to a 4 hour experimental expousre period. Where LC50 values have been obtained in stuides using exposure durations shorter or longer than 4 hours these may be adjusted to a 4 hour equivalent using Habers law (Cn.t = k), where 'C' is the concentration, 'n' is a regression coefficient, t is the exposure time and 'k' is a constant. For extrapolation to longer duration it is recommended to set n = 1. Using Habers law the LC50 for the inhalation study is 50 mg/L.

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test material gave an LD50 of 200 mg/L after 1 hour exposure which can be extrapolated to an LC50 of 50 mg/L for a 4 hour exposure. Based on the classification criteria bentonite acid leached is not classified by the inhalation route in accordance with CLP Regulation (EC) no. 1272/2008