Benzoic acid

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 14 March to 11 April 1980

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study run to a method comparable with current guidelines and GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1981

Report date:

1981

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Principles of method if other than guideline:

This study consisted of four groups, each containing ten male and ten female albino rats. One group served as an air exposed control while the other three were exposed to one of three different dust concentrations of the test substance. Exposures were for 6 hours per day five days per week for four consecutive weeks. At various times during the study body weights and observations for pharmacotoxic signs were recorded. After four weeks of exposure various serum biochemical, hematologic, organ weight and histopathologic evaluations were conducted.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Benzoic acid

EC Number:

200-618-2

EC Name:

Benzoic acid

Cas Number:

65-85-0

Molecular formula:

C7H6O2

IUPAC Name:

benzoic acid

Details on test material:

Batch No.: 52930350Purity: not specified

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS- Source: Charles River Breeding Laboratories, Inc.- Age at study initiation: At the time of receipt the rats were 42 days of age.- Weight at study initiation: males 194-201 g, females 148-163 g- Housing: caged individually - Diet: ad libitum for non-exposure hours- Water: tap water, ad libitum for non-exposure hours- Acclimation period: yesENVIRONMENTAL CONDITIONS- Temperature (°F): 71.6-74.7°F- Humidity (%): 41.0-51.0%- Air changes (per hr):- Photoperiod (hrs dark / hrs light): 12 hour photoperiodIN-LIFE DATES: From: 14 March 1980 To: 11 April 1980

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

whole body

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: A mean equivalent aerodynamic diameter of 4.7 µm was defined.Group 2, EAD of 4.6 µm, ag of 3.1Group 3, EAD of 4.4 µm, ag of 2.1Group 4, EAD of 5.2 µm, ag of 2.1

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION- Exposure apparatus: Exposures were conducted in 1 cubic meter glass and stainless steel exposure chambers.- Method of holding animals in test chamber:- Source and rate of air: Air for chamber ventilation was supplied from an HVAC system separate from general laboratory systems.- Method of conditioning air:- System of generating particulates/aerosols: The test material was ground in an Oster@ blender in order to produce a more respirable particle. The blender jar was filled approximately one third full with the test substance and run at high speed for one to two minutes. The ground compound was separated from the remaining flakes by using a flour sifter. The flakes were returned to the blender jar and reground. The procedure was continued until enough material for two exposure days had been prepared.- Temperature, humidity, pressure in air chamber:- Air flow rate: Chamber air flow rate varied between one 145 and 310 liters per minute depending on desired exposure concentrations.- Air change rate:- Method of particle size determination: The particle size distribution of the test material in a sample of the chamber atmosphere was determined using an Andersen 8 stage cascade impactor.- Treatment of exhaust air:TEST ATMOSPHERE- Brief description of analytical method used: Nominal concentrations were determined by weighing the amount of test material placed in the generator reservoir prior to exposure and then again after exposure. The difference in weight was the nominal concentration. Actual exposure concentrations were determined by standard gravimetric techniques. Exposure atmospheres were drawn through pre-weighed glass fiber filters at a known flowrate for a known time. The filters were reweighed, and the difference was divided by the total air volume to yield the actual concentrations.- Samples taken from breathing zone: yes/noVEHICLE (if applicable)- Justification for use and choice of vehicle:- Composition of vehicle:- Type and concentration of dispersant aid (if powder):- Concentration of test material in vehicle:- Lot/batch no. of vehicle (if required):- Purity of vehicle:

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Both nominal and analytical exposure concentrations were determined for this study. Nominal concentrations were determined by weighing the amount of test material placed in the generator reservoir prior to exposure and then again after exposure. The difference in weight was divided by the total air passed through the chamber during the exposure period resulting in the nominal concentration. Actual exposure concentrations were determined by standard gravimetric techniques. Exposure atmospheres were drawn through pre-weighed glass fiber filters at a known flowrate for a known time. The filters were reweighed and the difference was divided by the total air volume to yield the actual concentrations.Group 2, desired concentration 0.02 mg/L, nominal concentration 0.31 mg/L, actual concentration 0.025 mg/LGroup 3, desired concentration 0.2 mg/L, nominal concentration 2.2 mg/L, actual concentration 0.25 mg/LGroup 4, desired concentration 2.0 mg/L, nominal concentration 16.5 mg/L, actual concentration 1.2 mg/L

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

Animals were exposed for 6 hours per day, 5 days per week for 4 weeks.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:25, 250, 1200 mg/m3Basis:analytical conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:310, 2200, 16500 mg/m3Basis:nominal conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:20, 200, 2000 mg/m3Basis:other: Desired concentration

No. of animals per sex per dose:

10 male and 10 female per dose

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: - Rationale for animal assignment (if not random): The animals were randomized into the four groups based on body weight.- Rationale for selecting satellite groups: - Post-exposure recovery period in satellite groups: - Section schedule rationale (if not random):

Positive control:

None stated

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes - Time schedule: once each week- Cage side observations checked in table [No.?] were included.DETAILED CLINICAL OBSERVATIONS: Yes- Time schedule: Twice each day prior to exposure and again after each exposureBODY WEIGHT: Yes - Time schedule for examinations: prior to exposure and after 1, 2, 3 and 4 weeks of exposureFOOD CONSUMPTION:- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No dataWATER CONSUMPTION: No dataOPHTHALMOSCOPIC EXAMINATION: No dataHAEMATOLOGY: Yes- Time schedule for collection of blood: after four weeks of exposure- Anaesthetic used for blood collection: No data- Animals fasted: No data- How many animals: all survivors- Parameters: Hematocrit, Hemoglobin Concentration, Erythrocyte count, Leucocyte Count (total and differential), Platelet Count, MCV, MCH, MCHCCLINICAL CHEMISTRY: Yes- Time schedule for collection of blood: after four weeks of exposure- Animals fasted: No data- How many animals: all survivors- Parameters: Blood Urea Nitrogen, Serum Alkaline Phosphatase, Serum Glutamic Pyruvic Transaminase, Serum Glutamic Oxaloacetic Transaminase, Blood GlucoseURINALYSIS: No dataNEUROBEHAVIOURAL EXAMINATION: No data

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, heart, kidney, lungs/trachea, brain, liver, spleenHISTOPATHOLOGY: Yes, adrenal, nasal turbinate, brain, pancreas, colon, pituitary, esophagus, prostate/uterus, eye with optic nerve, submaxillary salivary gland, testis (both), ovary, jejunum, Harderian glands, spleen, heart, sternum (bone marrow), kidney, stomach, liver, thymus, lungs (5 lobes), thyroid/parathyroid, bronchial lymph node, urinary bladder, mammary gland

Other examinations:

None stated

Statistics:

Body weight data, clinical chemistry data, hematology data and organ weight data are presented on both an individual animal basis and as a group mean and standard deviation summary. Not all parameters were statistically evaluated at all intervals. Some parameters at some intervals were evaluated statistically after a review of the data indicated that a possible exposure related effect may have been present. All statistical analyses compared the treatment groups with the control group by sex.Body weights (weeks 1, 2, 3 and 4), hematological parameters (week 4) and absolute and relative organ weights (terminal sacrifice) were compared by analysis of variance (one-way classification), Bartlett's test for homogeneity of variances and the appropriate t-test (for equal or unequal variances) as described by Steel and Torrie using Dunnett's multiple comparison tables to judge significance of differences.

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):

not specified

Food efficiency:

not specified

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

not specified

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:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITYReddisch discharge around the nares was seen in the mid and high dose groups (starting from Day 4). Two high dose animals died during the study (on Day 6 and Day 15).BODY WEIGHT AND WEIGHT GAINHigh dose males and females showed a decreased body weight gain.HAEMATOLOGYA statistically significant decrease in platelets was seen in high dose males and femalesCLINICAL CHEMISTRYRandom statistical differences were observed in the biochemical data. These differences were not considered to be exposure related nor of toxicological significance.ORGAN WEIGHTSChanges in absolute and relative weights of liver, kidneys and lungs were noted in high dose males or females.GROSS PATHOLOGYNo changes in gross pathology were noted.HISTOPATHOLOGY: NON-NEOPLASTICCompound related microscopic lesions were confined to the lung. An increased incidence and intensity of interstitial inflammatory cell infiltrate interstitial fibrosis was noted in low, mid and high dose animals.

Effect levels

1

Dose descriptor:

NOAEC

Effect level:

<= 25 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Pulmonary fibrosis and inflammatory cell infiltrate at lowest dose level

2

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

250 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Only very slight organ weight and body weight decreases noted.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

All test concentrations induced local effects: nasal redness and discharge and pulmonary fibrosis and inflammatory cell infiltrates in the lungs that can be related to the irritant properties of the test substance. No systemic effects were noted at 25 mg/m3. At 250 mg/m3 a very slight decrease in absolute kidney weighth was seen in females only. At the highest dose level mortality, decresed body weights as well as decreased liver kidney and lung weights were reported. No histopathological findings except in the lungs were reported . No systemic effects were noted at this dose level. At 250 mg/m3 a very slight decrease in absolute kidney weighth was seen in females only. At the highest dose level mortality, decresed body weights as well as decreased liver kidney and lung weights were reported. No histopathological findings except in the lungs were reported .

Executive summary:

This study consisted of four groups, each containing ten male and ten female albino rats. One group served as an air exposed control while the other three were exposed to one of three different dust concentrations of the test substance. Exposures were for 6 hours per day five days per week for four consecutive weeks. At various times during the study body weights and observations for pharmacotoxic signs were recorded. After four weeks of exposure various serum biochemical, hematologic, organ weight and histopathologic evaluations were conducted.

All test concentrations induced local effects: nasal redness and discharge and pulmonary fibrosis and inflammatory cell infiltrates in the lungs that can be related to the irritant properties of the test substance. No systemic effects were noted at 25 mg/m3. At 250 mg/m3 a very slight decrease in absolute kidney weighth was seen in females only (body weight was also slightly lower (not significantly) than in control females). At the highest dose level mortality, decresed body weights as well as decreased liver kidney and lung weights were reported. No histopathological findings except in the lungs were reported . The NOAEL for local effects is < 25 mg/m3; The NOAEL for systemic effects is 250 mg/m3.