2,4,6-tribromophenol

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

1977

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

This study was conducted before current guidelines were in place and as such does not meet current standards for testing protocols. The study uses whole-body exposure so that oral dosing is expected to confound the results, and there is no information on the size of the particles generated. Other than weight change, there were no results that differed from control and would therefore offer an index of the toxicologic response to the test compound.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1977

Report date:

1977

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Three groups of 10 albino rats, 5 males and 5 females, were exposed to either 0, 0.1, or 1.0 mg/l dust for 6 hours per day, 5 days per week for 3 weeks (15 exposure periods). Mortality, cageside observations ,and body weight were taken for all animals, and haematology, clinical chemistry, and urinalysis were noted for selected animals for all groups. A necropsy was performed on all animals, including histopathology on selected tissues and organs from the control and high dose groups.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,4,6-tribromophenol

EC Number:

204-278-6

EC Name:

2,4,6-tribromophenol

Cas Number:

118-79-6

Molecular formula:

C6H3Br3O

IUPAC Name:

2,4,6-tribromophenol

Details on test material:

Physical description: beige crystalline material, no lot number given
Analytical data for two lot numbers of tribromophenol are listed:
Lot 02136A - 99.5% pure, melting point 94.1 degrees C, appearance: contained brown specks
Lot 10196 - 99.7% pure, melting point 94.0 degrees C, appearance: clear

Test animals

Species:

rat

Strain:

other: Albino Charles River COBS strain

Sex:

male/female

Details on test animals or test system and environmental conditions:

Young adult rats were selected from a 5 day observation period, after being judged to be healthy. The animals were housed in stainless steel cages and given Wayne LAB_BLOX for Rats (Allied Mills, Inc., Chicago IL) plus water ad libitum except during the inhalation exposure period. There are no further details on holding or handling conditions.

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

whole body

Vehicle:

clean air

Remarks on MMAD:

MMAD / GSD: unknown

Details on inhalation exposure:

Comparatively few details are available.
The inhalation chambers had a capacity of 80 L, and animals were confined individually in the chambers. Control animals received no dust exposure. Test dust was generated with specially designed dust-shaking mechanisms capable of producing steady concentrations over a long period of time. Air was clean and dry (dewpoint -40 degrees C) when passed through the test powder. The resulting air and dust mixture was introduced into the exposure chambers at the top center and exhausted at the bottom of the exposure chambers. Air flow rats were measured with rotameters connected upstream of the dust feeders. The rotatmeters were calibrated with a bubble meter after completion of each exposure. Temperature and pressure of the chamber were recorded. Concentrations of test dust present in the exposure chamber were determined by sampling the test atmosphere in the breathing zone of the animals being exposed. The total weight of dust collected on a glass filter was divided by the total volume of air drawn through the filter during the sampling period. Air flow rates for sampling were regulated by calibrated limiting orifices.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analysis of the chamber atmosphere was conducted by a Hewlett-Packard 5711 gas chromatograph with dual FID and 3% Dexsil 300 on 90/100 mesh Anakrom Q column using Gelman Type A filters.
Chamber air was passed throiugyh the Gelman filter at a rate of 4 L/min for 2.5 minutes (total of 10 liters). The filter samples were weighed, then mixed with 10 ml of methanol to extract the tribromophenol. A 3 uL volume of each extraction was injected into the GC and the concentration in mg/ml was obtained from the calibrating graph.

Duration of treatment / exposure:

6 hours per day

Frequency of treatment:

5 days per week, for 3 weeks

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 0.1, 1.0 mg/L
Basis:
nominal conc.

No. of animals per sex per dose:

5 males and 5 females per dose group = 30 rats

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: not stated
- Rationale for animal assignment (if not random): random

Positive control:

None

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations checked in table [No.?] were included. No data

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations:before first exposure and weekly thereafter

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at termination of study
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 3 per sex per group
- Parameters checked in table [No.?] were examined. Tables VI - XI: Total leukocyte count, erythrocyte count, hemoglobin concentration, hematocrit, differential leukocyte count (neutrophils, lymphocytes, monoytes, eosinophils, basophils), erythrocytes indices (MCV, MCH, MCHC)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at termination of study
- Animals fasted: yes
- How many animals: 3 per sex per group
- Parameters checked in table [No.?] were examined. Tables XII - XIII: Glucose concentration, blood urea nitrogen, SAP activity, SGPT activity

URINALYSIS: Yes
- Time schedule for collection of urine: day 0 and at termination of treatment
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No data
- Parameters checked in table [No.?] were examined. Table XIV-XVII: blood, ketones, glucose, proteins, pH, leukocytes, erythrocytes, crystals

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see Table X)
HISTOPATHOLOGY: Yes (see Table X)

Other examinations:

No further information required

Statistics:

None reported

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

One male low dose and one female high dose animal died before the end of the study.

Mortality:

mortality observed, treatment-related

Description (incidence):

One male low dose and one female high dose animal died before the end of the study.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Females exposed to low dose, and males exposed to the high dose, exhibited lower mean body weight gains when compared with those of untreated controls.

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:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

At necropsy, 4/5 male rats and all 5 female rats from the high treatment gropu were emaciated. An area of tan discoloration was observed on the kidney of 1 male rat in the high treatment group, and an area described as fibrotic was observed in the liver

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathologic evaluation of rats in the high treatment group revealed dilation of renal tubules in 3/5 rats of each sex, and a solitary area of submassive hepatic necrosis in 1 female rat.

Histopathological findings: neoplastic:

not examined

Details on results:

Treatment-related effects included reduced weight gain in males and females at 1 mg/l. Other treatment-related effects were hypoactivity and salivation on all exposure days (except Day 4 in the low dose group), and isolated instances of red nasal discharge and lacrimation.

Effect levels

1

Dose descriptor:

NOAEC

Effect level:

0.1 mg/L air

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

2

Dose descriptor:

LOAEC

Effect level:

1 mg/L air

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: Effects seen in kidney, liver, and on body weight.

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

		Treatment group, number of animals affected
Observation	Gender	Control	0.1 mg/l	1.0 mg/l
Hypoactivity	Male	-	10	10
	Female	-	10	10
Salivation	Male	-	10	10
	Female	-	10	10
Lacrimation	Male	-	1-2 daily	1-3 daily
	Female	-
Body weight at Day 21	Male	345 g	343 g	242 g
	Female	230 g	216 g	172 g
Body weight change	Male	113 g	90 g	-16 g
	Female	35 g	17 g	-22 g
Dilation of renal tubules	Male	0	0	3/5
	Female	0	0	3/5
Discolored kidney spot	Male	0	0	1
	Female	0	0	0
Fibrotic area on liver	Male	0	0	0
	Female	0	0	1
Hepatic necrosis (submassive)	Male	0	0	0
	Female	0	0	1

Applicant's summary and conclusion

Conclusions:

In this study, inhalation of 1.0 mg/l air containing 2,4,6-tribromophenol dust for 21 days resulted in reduced weight gain, dilation of kidney tubules, and individual liver effects. These effects were not seen at 0.1 mg/l under the same experimental conditions. The kidney and liver are organs seen to be affected at high doses after other routes of exposure, so this study is consistent with other studies with systemic expsoure to tribromophenol. The NOEL is determined to be 0.1 mg/l (no mg/kg bw calculated), and the LOEL is 1.0 mg/l.

Executive summary:

Five rats/gender/dose were repeatedly exposed for 21 days (15 doses total) to 2,4,6 -tribromophenol dust in individual whole-body inhalation chambers. The doses were 0, 0.1, and 1.0 mg/l clean, dry air, and the exposure was for 6 hours/day, 5 days/week. Data was taken for physical reactions from dosing, body weight, maematology, clinical chemistry, urinalysis, gross pathology, and histopathology. There was one low dose male and one high dose female that died after 10 and 11 doses, respectively. Animals in both treatment groups exhibited hypoactivity, salivation, lacrimation, and red nasal discharge during testing. Hypoactivity, lacrimation, and nasal discharge are symptoms consistent with exposure to dust particulates without regard to the compound itself. Salivation has been noted as a transient symptom after exposure to tribromophenol specifically. Low dose animals showed similar weight gain to controls, but high dose animals exhibited visibly lower weight gain than controls. Additionally, dilation of renal tubules was seen in 3 of 5 high dose animals of both genders, and one high dose female had two liver lesions (submassive necrosis and fibrosis).

Based on the above observations, the NOAEL is set at 0.1 mg/l (transient salivation is not considered adverse), and the LOAEL is set at 1.0 mg/l. This study is considered adequate to determine target organs and order of magnitude to find effects, but does not meet current standards for study design or documentation of results. This dose is also expected to be inaccurate based on oral exposure from grooming during and after the whole-body exposure in the inhalation chamber.