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Repeated dose toxicity: inhalation

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short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Study period:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
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-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
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:

Test material

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

other: Albino Charles River COBS strain
Details on test animals 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
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:
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
Doses / Concentrations:
0, 0.1, 1.0 mg/L
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:


Observations and examinations performed and frequency:
- Time schedule: daily
- Cage side observations checked in table [No.?] were included. No data


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

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

- 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)

- 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

- 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)
Other examinations:
No further information required
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 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

open allclose all
Dose descriptor:
Effect level:
0.1 mg/L air
Based on:
act. ingr.
Basis for effect level:
other: see 'Remark'
Dose descriptor:
Effect level:
1 mg/L air
Based on:
act. ingr.
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

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.