Methyl chloroformate

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Reference 2

Reference Type:

other: Notification

Title:

No information

Author:

BASF Corp.

Year:

1993

Bibliographic source:

US EPA; TSCATS: 8ECP, Doc. I.D: 88-930000347

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Methyl chloroformate

EC Number:

201-187-3

EC Name:

Methyl chloroformate

Cas Number:

79-22-1

Molecular formula:

C2H3ClO2

IUPAC Name:

methyl chloroformate

Details on test material:

- Name of test material (as cited in study report): Chloroformic aci methyl ester
- Physical state: colorless liquid
- Analytical purity: 99.2%
- Expiration date of the lot/batch: 1990-10-31
- Stability under test conditions: stable
- Storage condition of test material: dark at room temperature

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charle River (USA)
- Age at study initiation: approx. 6 weeks
- Weight at study initiation: 1180-195 (males), 144-159 (females)
- Fasting period before study: no
- Housing: in groups of five
- Diet (e.g. ad libitum): ad libitum, except at exposure (Biosure diet LAD1 Lavander Mill, Manea, England)
- Water (e.g. ad libitum): ad libitum, except at exposure
- Acclimation period:


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 2
- Humidity (%): 30 - 61 %
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Vapor generation: Vapor was generated by metering the test material to a sintered glass disc through which air was passed. The vapor was carried to a stainless steel manifold fitted with 5 T junctions containing metering valves. Delivery of vapor to each of the exposure chambers was controlled by each of the metering valves. The vapor entered the chamber at the top via the inlet air duct. Waste vapor was removed by passage through activated charcoal.
Exposure chambers were constructed form stainless steel and glass and had an internal volume of approximately 2.4 m³. Inlet air (650 lpm) was introduced into the inlet duct set at a tangent into the top of each chamber. Air flow was monitored continuously by measuring the pressure differential across a venturi nozzle set into the air inlet of each chamber. Chamber pressure was monitored continously using a magnehelic pressure gauge and recorded at approximately 30-minute intervals.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Continuous infra-red monitoring of each chamber allowed for adjustments to be made so that target concentrations could be reached.
Concentrations present in each chamber were recorded at least hourly. Samples of test atmosphere were withdrawn from each chamber into the sample loop of one of two infra-red gas analyzers. The absorbance at a known wavelength was measured and recorded by a flat-bed chart recorder. Due to the system design and the loss of a significant proportion of the vapor through the exhaust line, it was not possible to calculate nominal concentrations.

Duration of treatment / exposure:

28 Tage

Frequency of treatment:

5 Tage/Woche; 6 Std/Tag

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0 (air) 0.52; 1.48; 3.94; 12.14; 34.46 mg/m³
Basis:
analytical conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0 (air), 0.5, 1.5, 4.0, 12.0 or 35.0 mg/m³
Basis:
nominal conc.

No. of animals per sex per dose:

5

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: no

Positive control:

not necessary

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

WATER CONSUMPTION: Yes

HAEMATOLOGY: Yes
Samples of blood were collected from the orbital sinus under light ether anesthesia from all rats during week 4. All rats were fasted the night before blood collection.
Parameters: measured in the blood included packed cell volume, hemoglobin, red cell count, mean corpuscular hemoglobin concentration, mean corpuscular volume, mean corpuscular, hemoglobin, total and differential white blood cell counts, thrombotest.

CLINICAL CHEMISTRY: Yes
Samples of blood were collected from the orbital sinus under light ether anesthesia from all rats during week 4. All rats were fasted the night before blood collection.
Parameters measured in the plasma for glucose, glutamic-pyruvic transaminase, glutamic-oxaloacetic, transaminase, total protein, albumin, globulin, albumin/globulin ratio, urea nitrogen, alkaline phosphatase, total bilirubin, creatinine, sodium , potassium, calcium, inorganic phosphorus, chloride, and cholesterol

Sacrifice and pathology:

Sacrifice:
After the 28-day exposure period, all rats were sacrificed over 2 days. Those rats not sacrificed on the first day received an additional exposure.

The following tissues were fixed: adrenals, aorta, brain, cecum, colon, duodenum, eyes, eyelids, exorbital lachrymal gland, femur with joint, Harderian gland, head (nasal passages), heart, ileum, jejunum, kidneys, larynx, liver, lungs, lymph nodes (cervical, mediastinal and tracheobronchial), mammary glands, esophagus, optic nerve, ovaries, oviduct, pancreas, pharynx, pituitary, prostate, rectum, salivary gland, sciatic nerve, seminal vesicles, skeletal muscle, skin, spinal column, spinal cord (entire), spleen, sternum/ribs, stomach, testes (with epididymides), thymus, thyroids (with parathyroids), tongue, trachea (with bifurcation), ureter, urinary bladder, uterus and vagina.

Sections of the adrenals, masal passages, heart, kidneys, larynx, liver, lungs, spleen and trachea were examined microscopically.
The brain, lungs, testes (male), ovaries (female), pituitary, adrenals, liver adn kidneys were examined grossly and weighed.

Statistics:

All statistical analyses for male and females were carried out separately. Bartlett's test (Proc Roy Soc A 160:268-282, 1937) for heterogeneity of variance was applied to the data. If significant, data were log transferred. If no significant heterogeneity was found or if the transformation was satisfactory, data were analyzed by one-way analysis of variance (ANOVA), followed by the Student's t-test and Williams' test (Biometrics 27:103-117 and 28:519-531, 1952/3). The Kruskal-Wallis analysis of ranks (J Amer Statis Ass 47:583-621 and 48:907-912) was used to analyze heterogeneous data. These data were further analyzed by the Shirley's test (Biometrics 33: 386-389, 1977). Analysis of covariance was used in place of ANOVA for organ weight data (with body weight as the covariant) in an attempt to negate the influence of body weight on organ weight.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Effect levels

1

Dose descriptor:

NOAEL

Remarks:

local

Effect level:

3.94 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: --

2

Dose descriptor:

NOAEC

Remarks:

systemic

Effect level:

12.14 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: --

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

35 mg/m³: Two males and 1 female exposed to 34.46 micrograms/ml died prior to blood sampling during the final week of exposure. Clinical signs observed during

exposure included blinking, hunched posture and rapid breathing. Rats in this group had noisy, apparently nasal breathing between exposures. Rats surviving to study termination had a rapid breathing pattern. Males and females had reduced weight gain for the first 2 weeks of exposure. Animals that died lost weight between weeks 2 and 3. A marked reduction in food consumption occured during the first 2 weeks of exposure. Results of hematological studies showed increased
packed cell volume, hemoglobin concentration, and numbers of red blood cells (both males and females), neutrophils (females and 1/3 of the males), eosinophils (males) and monocytes (males). Mean corpsucular hemoglobin concentration and mean corpsucular hemoglobin were slightly decreased in males. Results of biochemical analyses showed increased total protein in males and increased globulin and cholesterol, decreased albumin, and a decreased albumin/globulin ratio in both sexes. Small changes in electrolytes were within normal ranges and therefore were not concsidered to be significant. The following pathological changes were seen in rats killed after 4 weeks of exposure: lungs that did not collapse upon opening of the thoracic cavity (3/3 males and 4/4 females), congestion of the lungs (1/3 males and 1/4 females), enlarged mediastinal lymph nodes (3/3 males and 3/4 females), and enlarged tracheobronchial lymph nodes (3/3 males and 3/4 females). Similar findings were seen in the animals that died before study termination. Lung weights of males and females and adrenal weights of males were increased. Pituitary and ovary weights of females were decreased. Microscopic examinations revealed exudative sinusitis in the nasal turbinates of 4/5 males and 5/5 females (but no evidence of degenerative or erosive lesions); localized areas of minimal squamous metaplasia of the epithelia overlying the arytenoid processes of the larynx in 3/5 males and 4/5 females (with occasional areas of ventral epithelial erosion and inflammation in some rats); localized squamous metaplasia of the ventral epithelia of the larynx in 3/5 females; minimal inflammatory changes with some minimal epithelial hyperplasia in the trachea (1/5 males); minimal to marked areas of pneumonitis in the lungs with intra-alveolar
exudation and aggregation of alveolar macrophages (all males and females); brohchiolitis (number of animals was not stated); squamous metaplasia of terminal bronchilar
epithelia with occasional focal necrosis, edema and congestion (number of animals was not stated); and granulomatous lesions (1 female).

12.0 mg/m³: One male rat had noisy nasal breathing for 4 days during week 2 of exposure. Minor, localized squamous metaplasia of laryngeal arytenoid process epithelia
was noted in 2/5 males and 1/5 females. One female had exudative sinusitis.

4.0 mg/m³ : Minor, localized squamous metaplasia of laryngeal arytenoid process epithelia was noted in 1/5 males.

1.5 mg/m³: No effects were observed.

0.5 mg/m³ : No effects were observed.

Control: Focal squamous metaplasia of laryngeal arytenoid process epithelia was noted in 1/5 females