Chlorocresol

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 Nov - 13 Dec 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

adopted in 1981

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

adopted in 1998

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Version / remarks:

adopted in 1992

Test guideline 4

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

adopted in 2009

Deviations:

yes

Remarks:

MMAD ranges from 3.09 - 4.2 µm

GLP compliance:

yes

Test type:

traditional method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Chlorocresol

EC Number:

200-431-6

EC Name:

Chlorocresol

Cas Number:

59-50-7

Molecular formula:

C7H7ClO

IUPAC Name:

4-chloro-3-methylphenol

Test material form:

solid: pellets

Details on test material:

Batch No.: CHP 0117

Test animals

Species:

rat

Strain:

other: Wistar (Hsd Cpb:WU (SPF))

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan-Winkelmann GmbH, Borchen, Germany
- Females nulliparous and non-pregnant: yes
- Age at study initiation: approximately 2 months
- Weight at study initiation: 192 - 218 g (males), 163 - 185 g (females); individual weights did not exceed ± 10% of the mean for each sex
- Housing: individual in conventional Makrolon® Type lla cages, type BK 8/15 low-dust wood granulate bedding (Ssniff, Soest, Germany)
- Diet: standard fixed-formula diet (KLIBA 3883 = NAFAG 9441), pelleted (PROVIMI KLIBA SA, Kaiseraugst, Switzerland), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 40 - 60
- Air changes (per hr): approximately 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

>= 3.09 - <= 4.2 µm

Geometric standard deviation (GSD):

>= 1.99 - <= 2.43

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: aluminum inhalation chamber with plexiglas exposure tubes
- Exposure chamber volume: about 3.8 L
- Method of holding animals in test chamber: plexiglas exposure tubes were designed so that the rat's tail remained outside the tube avoiding restrained-induced hyperthermia
- Source and rate of air: minimal air flow rate of 1.4 L/min
- Method of conditioning air: automatically by a VIA compressed air dryer
- System of generating particulates/aerosols: The test substance was compressed to a pellet using approximately 0.3-0.5 metric ton by a laboratory press. From this pellet defined amounts of test substance were scraped off, effectively dispersed using pressurized air (approximately 160 kPa), passed through a cyclone, and then entrained into the inhalation chamber. The airborne powder was then conveyed into the inner cylinder of the inhalation chamber.
- Method of particle size determination: The particle-size distribution was analyzed using a BERNER-TYPE AERAS low pressure critical orifice cascade impactor (Hauke, Gmunden, Austria). The individual impactor stages had been covered by an aluminum foil which was subjected to gravimetric analysis.
- Treatment of exhaust air: purification via cotton-wool and HEPA filters
- Temperature, humidity, pressure in air chamber: 22.0 - 22.6 °C, < 6 - 8%

TEST ATMOSPHERE
- Brief description of analytical method used: gravimetric analysis; a nominal concentration was not calculated since the construction and weight of the dust generator used did not allow for a precise measurement of the powder aerosolized
- Samples taken from breathing zone: yes (vicinity)

TEST ATMOSPHERE
Please refer to Table 1 under "Any other information on materials and methods incl. tables".

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gravimetric

Duration of exposure:

4 h

Concentrations:

2 and 3 mg/L (target concentration)
1.558 and 2.860 mg/L (analytical concentration)
1.337 and 2.871 mg/L (dust concentrations)

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Observations were conducted several times on the day of exposure and at least once daily thereafter. Body weights were measured before exposure, on days 3 and 7, and weekly thereafter.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, other: rectal temperature (directly after end of treatment), several reflex measurements (on the first post-exposure day)

Statistics:

R x C chi squared test with subsequent pair-wise Fisher test if differences occurred between groups (necropsy findings), means and standard deviation (body weights) and subsequent one-way ANOVA (body weight gains)

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 3 mg/L air (nominal)

Based on:

test mat.

Exp. duration:

4 h

Effect levels 2

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.86 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Effect levels 3

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.871 mg/L air

Based on:

test mat.

Remarks:

dust concentration (highest attainable concentration)

Exp. duration:

4 h

Mortality:

No mortality occurred during the study period.

Clinical signs:

other: 2 mg/L: - bradypnoea, laboured breathing pattern, dyspnoea, rales, stridor, nasal discharge (serous), nostrils reddened, nostrils: red encrustrations, piloerection, hair-coat ungroomed, motility reduced, limp, high-legged gait, cyanosis and tremor in mal

Body weight:

2 and 3 mg/L: decreased body weights in males and females on post-exposure day 3 with evidence of recovery thereafter

Gross pathology:

2 and 3 mg/L: increased incidence of macroscopic findings (less collapsed lung, trachea with abundant secretions)

Other findings:

- Other observations: Body temperatures of the treated animals were significant decreased compared to the control animals. Reflex measurements revealed a reduced tonus, righting response, and grip strength of the 3 mg/L group compared to the control animals.

Any other information on results incl. tables

Table 2:Results of acute inhalationl toxicity testing

Target concentration [mg/L air]	Toxicological results*	Duration of clinical signs (days)	Time of death	Mortality [%]	Rectal temperature [°C]
Males
0	0/0/5	---	---	0	38.0
2	0/5/5	0 - 9	---	0	26.5**
3	0/5/5	0 - 12	---	0	25.9**
Females
0	0/0/5	---	---	0	38.5
2	0/5/5	0 - 8	---	0	26.6**
3	0/5/5	0 - 14	---	0	26.7**

*number of dead animals/ number of animals with signs/ number of animals used

** p < 0.01

Applicant's summary and conclusion

Interpretation of results:

other: CLP/GHS criteria not met; no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

CLP: With regard to acute inhalation toxicity the test substance does not need to be classified. However, due to the irritant potential to the respiratory tract the test substance needs to be classified as STOT SE 3, H335: May cause respiratory irritation.

Executive summary:

A study for acute inhalation toxicity in the rat was conducted with the test substance according to the OECD Guideline 403 (1981) and in compliance with GLP.Five male and five female Wistar rats per dose group were nose-only exposed for 4 h to a solid aerosol (dust) of the test substance at target concentrations of 2 and 3 mg/L air. The analytical concentrations were 1.558 and 2.860 mg/L. The average dust concentrations reached were 1.337 mg/L and 2871 mg/L, which was the highest attainable aerosol concentration. 49% and 36.4% of the particles of the 2 and 3 mg/L group were smaller than 3 µm in aerodynamic diameter, respectively. Analysis of the aerosol particle-size distribution from the breathing zone samples demonstrates that the aerosol generated was within the respirable range. Detailed clinical observations were made several times on the day of exposure and at least once daily thereafter. Body weights were taken before exposure, on days 3 and 7, and weekly thereafter. Rectal temperatures were determined within 30 min after exposure and reflex-measurements were performed on the first post-exposure day. A complete gross pathological examination was conducted on each rat at the end of the 14 day post-exposure period. Exposure to the maximum technically attainable concentration of 2.871 mg/L did not result in mortality. The clinical signs observed were indicative of respiratory distress, associated with subdued demeanour, decreased body weights, emaciation, and hypothermia. In some rats the clinical signs lasted until the end of the 14 day post-exposure period. However, most rats showed evidence of recovery during the study period. Necropsy findings consisted of a less collapsed lung and secretions in the trachea. The hypothermia is considered to be related to upper respiratory irritation caused by the high concentrations of aerosol tested. According to the results, the test substance has an irritant potential to the respiratory tract, although it is of low acute inhalation toxicity to rats. Under the conditions of this study the LC50 value was considered to be > 2.871 mg/L for male and female rats corresponding to the highest attainable concentration. According to Regulation (EC) No 1272/2008 the test material does not need to be classified for acute inhalation toxicity.