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Description of key information

Weight of evidence: Experimental results from subchronic studies using different species and published in scientific articles.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Test method equivalent or similar to OECD Guideline 413.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
Deviations:
yes
Remarks:
(Only two dose concentrations were tested in males).
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
not specified
Sex:
male/female
Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
CHAMBER DESCRIPTION: 1700-liter capacity water-sealed chambers.
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
114 days
Frequency of treatment:
7h/day, 5 days/week.
Remarks:
Doses / Concentrations:
400 ppm (females), 500 ppm (males and females) and 1000 ppm (males and females)
Basis:
nominal conc.
No. of animals per sex per dose:
500 and 1000 ppm-dose groups: 20 animals/sex/group.
400 ppm-dose group: 10 females.
Control animals:
yes, concurrent no treatment
Details on study design:
Since it was evident that female rats were the only group which was significantly affected by exposures to 500 ppm, it was deemed desirable to expose another group of female rats to 400 ppm to observe their response.
Positive control:
None
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes

BODY WEIGHT: Yes
- Time schedule for examinations: The animals were weighed twice a week until it was evident that growth was essentially normal and once a week thereafter.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at study termination.
- Animals fasted: Yes.
- How many animals: on representative animals of the unexposed group and the 1000 ppm dose group.
- Parameters checked in table [No.3] were examined: RBC, WBC and differential count of Neutrophils, Lymphocytes, Monocytes and Eosinophils.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at study termination.
- Animals fasted: Yes
- How many animals: on representative animals of all dose groups and control groups.
- Parameters checked in table [No. 2] were examined: blood bromide, blood urea-nitrogen (BUN) and blood non-protein-nitrogen (NPN).

Sacrifice and pathology:
SACRIFICE: all rats were fasted overnight and killed by decapitation the day following their last exposure.
GROSS PATHOLOGY: Yes (see table No. 1). After gross pathological examination was made, the lungs, heart, liver, kidney, spleen and testes were removed and weighed.
HISTOPATHOLOGY: Yes. Portions of the lungs, heart, liver, kidney, spleen, testes, pancreas and adrenals were examined microscopically.
Statistics:
The "t" test was used to determine the significance of the organ weight differenes. A probability (P) of 0.05 or less was considered as significant.
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
Bromide blood levels were elevated in males exposed at ≥500 ppm and females exposed at ≥ 400 ppm.
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Increase in weight of the liver in males exposed at ≥500 ppm and females exposed at ≥400 ppm.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
In males and females exposed to 1000 ppm.
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Females in the ≥500 ppm groups and males in the 1000 ppm group.
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY
Animals exposed to bromochloromethane were normal in appearance and activity.

BODY WEIGHT AND WEIGHT GAIN
The average body weight and growth of the exposed animals were normal.

HAEMATOLOGY
Hematological values were within normal limits.

CLINICAL CHEMISTRY
Blood bromide levels were elevated in females exposed to ≥400 ppm and in males exposed to ≥500 ppm.

ORGAN WEIGHTS
A small increase in weight of the liver was noted in males exposed to 500 ppm. Nevertheless, since no pathological changes were seen in the 500 ppm-dose group, it probably indicates that the organ was only under slight stress. The average liver weight in females exposed to 500 ppm was high. The average liver and kidney weights were elevaded in males and females exposed to 1000 ppm.

GROSS PATHOLOGY
Fatty and enlarged livers were seen grossly when female rats exposed to 1000 ppm were sacrified. Organs of exposed males appeared normal at autopsy.

HISTOPATHOLOGY: NON-NEOPLASTIC
A very slight proliferation of the bile duct epithelium with very slight portal fibrosis and inflammation was seen in males exposed to 1000 ppm. There was some cloudy swelling of the parenchymal cells in the midzonal areas spreading to the central areas of the lobule. Numerous parenchymal cells in the midzonal area and portal area contained many small vacuoles. Slight pathological changes were seen in females exposed to 500 ppm: bile duct epithelial proliferations and very slight portal fibrosis, together with occasional large and small vacuoles in parenchymal cells of the midzonal areas. Similar changes to those described for male rats were seen in females exposed to 1000 ppm, in addition of some portal fibrosis in the liver.
Dose descriptor:
NOAEC
Effect level:
500 ppm
Based on:
test mat.
Sex:
male
Basis for effect level:
other: histopathology (pathological changes in the liver) (equiv. to 2645.88 mg/m3)
Dose descriptor:
NOAEC
Effect level:
400 ppm
Based on:
test mat.
Sex:
female
Basis for effect level:
other: histopathology (pathological changes in the liver) (equiv. to 2116.71 mg/m3)
Critical effects observed:
not specified

Table 1. Summary of Terminal Average Body and Organ Weights of Animals Receiving Repeated 7-Hour Exposures to Bromochloromethane (CH2BrCl).

Specie

Sex

Group

Ratio of survival

Final average body weight, g

Organ Weights, g/100 g body weight

Lung

Heart

Liver

Kidney

Spleen

Testes

Rat

M

Unexposed control

19/20

341

0.55

0.31

2.46

0.68

0.29

0.87

M

1000 ppm

17/20

306

0.56

0.32

3.20d

0.75d

0.32

0.85

M

500 ppm

17/20

300

0.56

0.34

2.77d

0.69

0.32

0.82

F

Unexposed control

17/20

203

0.73

0.37

2.67

0.71

0.36

 

F

1000 ppm

19/20

206

0.70

0.38

3.65d

0.82d

0.35

 

F

500 ppm

19/20

210

0.70

0.38

3.05d

0.75

0.38

 

F

Unexposed control

12/12

215

0.64

0.39

2.70

0.76

0.28

 

F

Air exposed control

12/12

220

0.64

0.34

2.77

0.75

0.32

 

F

400 ppm

9/10

232

0.63

0.38

2.98bb

0.78

0.25

 

Probability values (P): a = P > 0.05; b = P = 0.01-0.05; bb = P ≈ 0.045; c = P = 0.001-0.01; d = P < 0.001.

Table 2. Summary of Average Blood Bromide, Blood Urea-Nitrogen and Blood Non-Protein-Nitrogen Levels in Animals Exposed Repeatedly to the Vapours of Bromochloromethane in Air.

Specie

Sex

Months on exposure, day bled

Vapour conc. (ppm)

Blood Bromide

Blood Nitrogen

No. of animals

Mg Br-/ 100 ml

Analytical method

No. of animals

Urea N

Total NPN

mg/100 ml

mg/100 ml

Rat

M

4 Thurs.

0

3

8

W

2

14.8

 

M

4 Thurs.

1000

3

122

W

2

13.9

 

M

4 Thurs.

500

3

88

W

2

16.0

 

F

4 Fri.

0

3

5

W

2

15.2

 

F

4 Fri.

1000

3

122

W

2

15.9

 

F

4 Fri.

500

3

83

W

2

18.7

 

F

6 Wed.

0

3

0.9

S

8

20.8

48

F

6 Wed.

400

3

73

S

3

12.9

47

*Analytical method for blood bromide:

W Wuth’s: Hepler, O.E., Manual of Clinical Laboratory Methods, Charles C Thomas, Springfield, Illinois, 1951.

S Shrader’s: Shrader, S.A., et al., Ind. Eng. Chem. Anal. Ed. 14:1 (1942).

Table 3. Average Terminal Hematological Values for Animals Receiving Repeated 7-Hour Exposures to Bromochloromethane.

Treatment

Sex

No. of animals

RBC

x 106

WBC x 103

Differential Count (%)

Neutrophils

Lymphocytes

Monocytes

Eosinophils

Unexposed control

F

5

8.8

16.9

14.2

82.9

0.4

3.0

1000 ppm

F

10

8.7

14.4

18.9

79.5

1.0

1.5

Conclusions:
On the basis of the pathological changes observed in the liver, the inhalative NOAEC of bromochloromethane was established to be 500 ppm (2645.88 mg/m3) for males and 400 ppm (2116.71 mg/m3) for females.
Executive summary:

20 male and 20 female rats were exposed in 114 days to 500 and 1000 ppm. The exposures were for seven hours per day and given five days a week. Since it was evident that female rats were the only group which was significantly affected by exposures to 500 ppm, a 400 ppm-dose group was including only females was added. A fourth group was maintained in the animal quarters at all times as unexposed controls. The animals were weighed twice a week until it was evident that growth was essentially normal and once a week thereafter. Terminal hematological examinations were made on representative animals and all rats were subjected to gross pathological and histopathological examinations. Exposed animals were normal in appearance, activity and growth. Hematological values were within normal limits as were BUN levels. Blood bromide levels were found elevated in females exposed to ≥400 ppm and in males exposed to ≥500 ppm. Pathological changes in the liver were seen in males exposed to 1000 ppm of bromochloromethane: it was seen a very slight proliferation of the bile duct epithelium with very slight portal fibrosis and inflammation. Besides, there was some cloudy swelling of the parenchymal cells in the midzonal areas spreading to the central areas of the lobule and numerous parenchymal cells in the midzonal area and portal area contained many small vacuoles. Pathological changes in the liver were seen at a lower dose-level in females: females exposed to 500 ppm showed bile duct epithelial proliferations and very slight portal fibrosis, together with occasional large and small vacuoles in parenchymal cells of the midzonal areas. Similar changes to those described for male rats were seen in females exposed to 1000 ppm, in addition of some portal fibrosis in the liver. On the basis of the pathological changes observed in the liver, the NOAEC was established to be 500 ppm (or 2645.88 mg/m3) for males and 400 ppm (or 2116.71 mg/m3) for females.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEC
2 116.71 mg/m³
Study duration:
subchronic
Species:
rat
Quality of whole database:
Weight of evidence: the available information is sufficient for an adequate hazard characterisation.

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Several repeated dose studies performed in different species are available for bromochloromethane. In these studies, animals were exposed for 6 to 7 hours, 5 days a week to the test substance. The concentrations tested ranged from 500 to 1000 ppm (2645.88 to 5291.76 mg/m3) in both sexes. Besides, in one of the studies, female rats were also exposed to a dose concentration of 400 ppm (2116.71 mg/m3). No significant pathological effects attributable to the exposure to bromochloromethane were reported in both rat and dog studies performed by MacEwen J.D., et al.. In the studies published by Torkelson T.R., et al., pathological changes in the liver were seen in male rats when exposed at 1000 ppm (5291.76 mg/m3) of the test substance for seven hours per day, five days a week during 114 days. In the same study, female rats exhibited similar pathological changes in the liver when exposed to 400 ppm (2116.71 mg/m3) in the same inhalation exposure conditions. In the study conducted in guinea pigs and rabbits, testicular pathological effects were seen microscopically in males of the both species when exposed to 1000 ppm (5291.76 mg/m3). No significant pathological changes were reported for females of these species.


Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
The study in rats with lowest NOAEC was chosen.

Justification for classification or non-classification

Based on the available data, bromochloromethane is not classified for specific target organ toxicity by repeated exposure (STOT-RE) according to CLP Regulation (EC) no 1272/2008.