Caffeine

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1989-03-16 to 1989-04-20

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: OECD guideline study with 2 concentrations only, no GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Principles of method if other than guideline:

The selection of the concentration of test group 2 was based on the limit test, OECD-Guidelines, method 403. The selection of the concentration of test group 1 was based on available information about the toxicity of the substance.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Caffeine

EC Number:

200-362-1

EC Name:

Caffeine

Cas Number:

58-08-2

Molecular formula:

C8H10N4O2

IUPAC Name:

1,3,7-trimethyl-3,7-dihydro-1H-purine-2,6-dione

Details on test material:

- Name of test material (as cited in study report): Coffein, wasserfrei, Pulver 200 (i.e. powdered anhydrous caffeine)
- Physical state: solid (white crystals or powder)
- Analytical purity: 99.5 - 100.5% referring to dried substance
- Lot/batch No.: 97757, date of production: March 1988
- Stability under test conditions: stability was ensured for at least the study period
- Storage condition of test material: stored at room temperature, air-tight and protected from light
No further data.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
male and female Wistar rats (strain: SPF Wistar/Chbb:THOM)
- Source: Dr. K. Thomae GmbH, D-7950 Biberach, Germany
- Age at study initiation: 8 - 9 weeks
- Weight at study initiation: mean weights +/- SD: 271 +/- 9.7 g (males); 191 +/- 9.2 g (females)
- Housing: 5 per cage in cages type D III of Becker. Deviation: From day 4 onward the male rats of the test group 2 and from day 1 onward the male rats of the test group 1 were housed individually in cages type D III of Becker (reason: indications of aggression).
- Diet (ad libitum): KLIBA rat/mouse laboratory diet 24-343-410 mm pellets, Klingentalmühle AG, CH-4303 Kaiseraugst, Switzerland
- Water (ad libitum): tap water

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): 30-70%
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

other: Test substance was mixed with Aerosil R 972

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Head-nose inhalation system INA 20 (glass-steel construction, BASF Aktiengesellschaft)
- Exposure chamber volume: ca. 55 l

VEHICLE
For technical reasons the test substance was mixed with Aerosil R 972 (2 wt % of test substance).

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

2.48, 4.94 mg/l (analytical concentration)

No. of animals per sex per dose:

5 males and 5 females per group

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The body weight of the animals was checked before the beginning of the test, after 7 days and at the end of the observation period. Clinical findings were recorded several times during exposure and at least once on each workday in the observation period. A check for dead animals was made daily.
- Necropsy of survivors performed: yes. At the end of the 14-day observation period the surviving animals were sacrificed with CO2 and were subjected to gross-pathological examination like all other animals which had died before.
- Other examinations performed: clinical signs, body weight, gross pathology

Statistics:

Calculation of LC50: Probit analysis.
Calculation of particle size distribution: DIN 66141 (Darstellung von Korngrößenverteilungen), DIN 66161 (Partikelgrößenanalyse)

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

ca. 4.94 mg/L air (analytical)

Exp. duration:

4 h

Mortality:

Six out of 10 animals of the high dose group died. Late deaths were observed. See table 2 below

Clinical signs:

other: During exposure, irregular/accelerated/intermittent/gasping respiration, eyelid closure, salivation, restlessness, attempts to escape, reddish nasal discharge, apathy, and decreased pain reflex were reported. During the observation period, accelerated/in

Body weight:

The body weight gain of female rats in the test group 1 compared with a historical control collective, was not affected by the substance over the total observation period. The body weight gain of male rats in the test group 1, compared with a historical control collective, was slightly retarded in the first week of the observation period and adjusted to normal in the second week of the observation period.
The body weight gain of male and female rats in the test group 2, compared with a historical control collective, was reduced in the first week of the observation period and adjusted to normal in the second week of the observation period.
See table 3 below.

Gross pathology:

In decedents, the following findings were observed at necropsy:
- general congestion
- bloody ulcers in the glandular stomach (2 animals)
- intensified hyperemia in the lungs of some animals.
No pathologic findings were noted in survivors sacrificed at the end of the observation period.

Any other information on results incl. tables

Analytical results

Table 1: Test concentrations

	Group 1	Group 2
Analytical concentration (mean +/- SD) [mg/l]; mean of 8 samples	2.48 +/- 0.243	4.94 +/- 0.185
Nominal concentration [mg/l]	11.27	28.6

Particle size analysis:

The MMAD 50% = 3.6 µm (geometrical standard deviation = 3.1) was calculated from the results of the particle size analysis.

A respirable dust fraction that might reach the alveolar region of 83% was obtained from the results of the particle size analysis.

Animal data

Table 2: mortality

Cumulated lethality on day	Test group (concentration)
	1 (2.48 mg/l)		2 (4.94 mg/l)
	m	f	m	f
0	0/5	0/5	1/5	2/5
1	-	-	-	3/5
2	-	-	-	4/5
7	-	-	2/5	-
14	-	-	-	-
Total at end of the study	0/10		6/10

Table 3: body weight

Mean body weight		before the study		after 7 days		after 14 days
		male	female	male	female	male	female
Test group 1	Weight in g Number of animals	268 5	188 5	285 5	203 5	324 5	223 5
Test group 2	Weight in g Number of animals	273 5	193 5	270 3	181 1	325 3	197 1
Historical (air) control	Weight in g	248	177	285	196	318	211

Applicant's summary and conclusion

Executive summary:

LC50 (4 h, dust aerosol): ca. 4.94 mg/l

Groups of 5 male and 5 female rats were exposed for 4 hours to a dust aerosol of the test substance at concentrations of 2.48 and 4.94 mg/l and were observed for 14 days.

No deaths were observed in the low dose group; 6/10 high dose rats died. Late deaths were observed. Numerous signs of toxicity, partially persisting throughout the observation period were noted in both groups. Body weight gain was decreased in low dose males as well as in high dose males and females. Gross pathology revealed general congestion, bloody ulcers in the glandular stomach, and intensified hyperemia in the lungs whereas no pathologic findings were noted in survivors sacrificed at the end of the observation period.