Chlorothalonil

Endpoint summary

Description of key information

- Oral: LD50 > 5000 mg/kg bw, male/female, rat, according to EPA OPPTS 870.1100, Moore 2000

- Inhalation: LC50 = 0.10 mg/L, males/female, rat, according to EPA OPP 81-3, Shults 1993

- Dermal: LD50 > 5000 mg/kg bw, male/female, rat, according to OECD 402, Johnson 2000

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01 Feb 2000 to 07 Mar 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Version / remarks:

1998

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: young adult
- Weight at study initiation: males: 231 - 257 g; females: 153 - 199 g
- Housing: singly housed in a suspended stainless steel caging with mesh floors
- Diet: rodent chow
- Water: filtered tap water, ad libitum
- Acclimation period: 10 - 14 days

ENVIRONMENTAL CONDITIONS
- Temperature: 18 - 21 °C
- Photoperiod (hrs dark / hrs light): 12 hour light/dark cycle

IN-LIFE DATES: From: 01 Feb 2000 To: 07 Mar 2000

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

1% w/v aqueous

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 30 %

MAXIMUM DOSE VOLUME APPLIED: 5000 mg/kg bw

Doses:

5000 mg/kg bw

No. of animals per sex per dose:

6 females and 5 males

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: observation daily; body weight prior to test substance administration (initial) and again on Days 7 and 14.
- Necropsy of survivors performed: yes (Day 14). Gross necropsies were performed on all animals. Tissues and organs of the thoracic and abdominal cavities were examined .
- Clinical signs including body weight: gross evaluation of skin and fur, eyes and mucous membranes, respiratory, circulatory, autonomic and central nervous systems, somatomotor activity and behaviour pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhea and coma

Preliminary study:

Female - Range Finding Screen - 5000 mg/kg bw
The female survived and gained body weight during the 7-day observation period. There were no signs of gross toxicity, adverse pharmacologic effects or abnormal behaviour.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No mortality observed.

Clinical signs:

other: With the exception of ano-genital staining, soft faeces and/or diarrhea noted in all rats within 2 hours (in females) and 20 hours (in males) and Day 1 post-dosing, all animals appeared active and healthy over the 14-day observation period. There were no

Gross pathology:

No gross abnormalities were observed.

Table 1. Weight changes in animals treated with 5000 mg/kg bw test substance.

Animal	Sex	Body weight (g)
		Initial	Day 7	Day 14
1	F	162	200	233
2	F	159	202	239
3	F	170	207	246
4	F	167	205	224
5	F	153	194	209
6	M	257	307	350
7	M	232	318	353
8	M	231	308	343
9	M	242	325	366
10	M	233	290	315

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the findings from the study performed in compliance with GLP and following the OPPTS 870.1100 guideline, the acute oral LD50 of the test substance is greater than 5000 mg/kg bw of the test substance in both the male and female rat.

Executive summary:

An acute oral toxicity test was conducted in compliance with GLP and following the OPPTS 870.1100 guideline using rats to determine the potential for the test substance to produce toxicity via the oral route. Based on the results of this study, the acute oral LD50 of the test substance is greater than 5000 mg/kg of body weight in both the male and female rat. Initially, five thousand milligrams of the test substance per kilogram of body weight was administered to one healthy female rat by oral gavage. This animal was observed for 7 days. Due to the absence of mortality in this animal, a group of five females was administered the test substance at the same dose level. Since no females died, a group of 5 males was administered the test substance at 5000 mg/kg to assure that males were not the more sensitive sex. All animals were observed for mortality, signs of gross toxicity, and behavioural changes at least once daily for 14 days. Body weights were recorded prior to administration and again on Days 7 and 14 (termination). Necropsies were performed on all animals at terminal sacrifice.

In conclusion, the LD50 is greater than 5000 mg/kg bw for males and females.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

5 000 mg/kg bw

Quality of whole database:

GLP compliant EPA OPPTS 870.1100 study.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 Jul 1992 to 12 Aug 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 81-3 (Acute inhalation toxicity)

GLP compliance:

yes

Test type:

traditional method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Males about 6 weeks old; females about 8 weeks old
- Weight at study initiation: circa 200 g
- Housing: The holding cages (size 31 cm x 19 cm x 20 cm height) were made of stainless steel sheet and wire mesh and were suspended on a movable rack.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25
- Humidity (%): 40 to 70
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 15 Jul 1992 To: 12 Aug 1992

Route of administration:

inhalation: dust

Type of inhalation exposure:

whole body

Vehicle:

clean air

Mass median aerodynamic diameter (MMAD):

>= 2.5 - <= 3.6 µm

Geometric standard deviation (GSD):

>= 2.45 - <= 2.49

Remark on MMAD/GSD:

Respirable fraction (<6µm) 71.0 to 83.5%

Details on inhalation exposure:

A sample of the test substance was packed into the container of the Wright dust generator using a hydraulic bench press to assist packing. Even density of the powder was achieved by packing the container in stages and applying a force of 0.8 tons weight. The packed container was weighed. The dust generator was positioned on a stand beside the exposure chamber and the output connected to an inlet port in the top centre of the chamber by the elutriation column. The speed controller of the generator mechanism was set to give a concentration of dust that was expected to produce some deaths.

A supply of clean dried compressed air was connected to the dust generator and the supply pressure was adjusted to give a flow rate of 25 litres per minute measured at the generator outlet nozzle. The total chamber air supply was derived from the air flow through the dust generator. The first group of rats (5 per sex) to be exposed were placed into separate compartments of the exposure chamber so that male and female rats were at alternate positions. The powder container of the Wright dust generator was advanced manually until a trace of suspended dust was seen in the chamber. The gearing on the generator was then engaged and the generator motor switched on to start the exposure. After an 11-minute equilibration period, the exposure was timed for 4 hours. The generator was then switched off and the chamber allowed to clear before the rats were removed for examination.

The procedure was repeated, with appropriate settings of the speed controller, for each of the other test groups. Following exposure, the rats were returned to the holding cages and food and water supplies were restored. The test rats were kept in a ventilated cabinet overnight and then returned to the holding room for the remainder of the observation period. The control group was treated similarly but exposed to air only for 4 hours. The control rats were returned to the holding room at the end of the exposure procedure.

Five air samples were taken from the chamber during each exposure to determine the concentration of the test substance in the chamber air. Each air sample was withdrawn, at 4 litres per minute, through a weighed glass fibre filter mounted in an open face filter holder. The filters were removed and re-weighed. The volume of the air sample was measured with a wet-type gas meter. Four additional air samples were taken during each exposure using a Marple cascade impactor. The material collected on the stages of the sampler was weighed to determine the particle size distribution of the test substance in the test atmospheres. The nominal concentration of test substance in the exposure chamber was calculated from the amount of test substance dispersed in the generator and the total air flow through the generator.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

0.14, 0.08 and 0.21 mg/L

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

Clinical signs
The rats were observed continuously for signs of reaction to the test substance during exposure and at least twice daily throughout the observation period. The clinical signs were recorded at the end of the chamber equilibration period, at 0.25, 0.5 and 1.0 hours and then at hourly intervals during the exposure and for 2 hours post exposure. During the observation period, the clinical signs were recorded once in the morning and then as necessary following a later check for clinical signs.

Body weight
All rats were weighed daily from the day of delivery until the day of exposure and then on Day 7 and Day 14 of the observation period or following death.

Terminal studies
At the end of the 14-day observation period, the surviving rats were anaesthetised by intraperitoneal injection of pentobarbitone sodium and killed by exsanguination. All rats that died as a result of exposure and those killed at the end of the observation period were subjected to a detailed macroscopic examination. The lungs were removed, dissected clear of surrounding tissue and weighed in order to calculate the lung weight to body weight ratio. The lungs were infused with, and preserved in, buffered 10% formalin together with samples of the liver and kidneys for possible microscopic examination.

Statistics:

The concentration of the test substance likely to cause death in 50% of exposed rats following a single 4-hour exposure was calculated by the log probit method of Miller and Tainter.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

0.1 mg/L air (analytical)

Based on:

test mat.

95% CL:

>= 0.07 - <= 0.14

Exp. duration:

4 h

Sex:

male

Dose descriptor:

LC50

Effect level:

0.1 mg/L air (analytical)

Based on:

test mat.

95% CL:

>= 0.03 - <= 0.18

Exp. duration:

4 h

Sex:

female

Dose descriptor:

LC50

Effect level:

0.1 mg/L air (analytical)

Based on:

test mat.

95% CL:

>= 0.05 - <= 0.15

Exp. duration:

4 h

Mortality:

In Group 2 (0.14 mg/L), one female rat died 10 minutes post exposure. Two male rats died overnight following exposure. One male rat and 2 female rats were found dead on Day 2 (a.m.) of observation period.
In Group 3 (0.08 mg/L), one male rat and one female rat died overnight following exposure and were found dead on Day 1 (a.m.). One female rat died on Day 1 (p.m.). One male rat was found dead on Day 2 (a.m.) of the observation period.
In Group 4 (0.21 mg/L) two female rats died on Day 1 (a.m.) and two male rats and two female rats died on Day 1 (p.m.). One male rat and one female rat were found dead on Day 2 (a.m.) and one male rat died on Day 2 (p.m.) of the observation period.

Clinical signs:

other: See description in "Any other information on results incl. tables'.

Body weight:

There were moderate reductions in the rate of body weight gain during the first week following exposure. Subsequently, weight gain for rats that survived exposure to the test substance was similar to that of the control rats.

Gross pathology:

The findings for rats that died as a result of exposure to te test substance were typified by congestion of the lungs. The stomachs of a number of decedents were found to be gas-filled and a white frothy fluid was found in the trachea. There were no abnormalities in rats that survived exposure to the test substance.

Verification of test atmosphere concentrations

The nominal concentrations were calculated from the amounts of the test substance dispersed and the total volumes of air supplied to the exposure system. The measured concentrations were between 9 and 21% of nominal.

Clinical signs

- During the exposure: The signs seen during exposure were considered to be consistent with inhalation of an irritant aerosol and included partial closing of the eyes, wetness around the eyes, exaggerated respiratory movements and restless behaviour. Gasping was seen in rats exposed at 0.14 mg/L or 0.21 mg/L.

 

- During the observation period: Clinical signs evident during the 2-hour period included exaggerated respiratory movements, wet fur, gasping and a discharge from the eyes. Most of these signs and also brown staining were seen on Day 1. Exaggerated respiratory movements persisted or recurred for several days. Deaths as a result of exposure occurred on Days 0 - 2 of observation. Recovery from the effects of exposure was evident from Day 4 and the majority of rats surviving exposure to the test substance were normal by Day 9 of the observation period.

Table 1. Mortality

Group	Mean measured concentration (mg/L)	Mortality (males)	Mortality (females)
1	Control	0/5	0/5
2	0.14	3/5	3/5
3	0.8	2/5	2/5
4	0.21	4/5	5/5

Interpretation of results:

Category 1 based on GHS criteria

Remarks:

Including STOT-SE Cat. 3 for respiratory irritation

Conclusions:

Based on the mortality data for all groups and sexes from this study (EPA FIFRA 81-3 guideline and GLP), the LC50 estimate and corresponding 95% confidence limits (CL) were calculated from the actual (measured) concentrations: 0.10 mg/L air (0.07 – 0.14 mg/L).

Executive summary:

The acute inhalation toxicity of the test substance was assessed by exposing 3 groups of rats, each for a period of 4 hours, to aerosols produced from the test substance following the EPA FIFRA 81-3 guideline and GLP. A fourth group was exposed to air only. The animals were exposure using whole-body exposure. The observation period was 14 days post exposure.

During exposure: signs consistent with exposure to an irritant aerosol, including partial closing of the eyes, wetness around the eyes, exaggerated respiratory movements and restless behaviour. During observation period: signs seen in rats exposed to the test substance included abnormal respiration, wet fur, brown staining around the snout and jaws, discharges from the eyes and deaths. Recovery from the effects of exposure was evident from Day 4 and the majority of surviving rats were normal by Day 9 of observation. Reduced rate of body weight gain during the first week following exposure. Subsequently weight gain was generally similar to that for control rats. The lungs of the majority of rats that died as a result of exposure were congested and the stomachs were gas-filled. A white frothy fluid was found in the trachea of a number of rats. There were no macroscopic abnormalities in rats surviving exposure to the test substance.

In conclusion, from the mortality data for all groups and sexes, the LC50 estimate and 95% confidence limits (CL) were calculated from the actual (measured) concentrations: 0.10 mg/L air (0.07 – 0.14 mg/L).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

100 mg/m³ air

Quality of whole database:

GLP compliant EPA OPP 81-3 study.

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 Jan 2000 to 27 Jan 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

1987

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Version / remarks:

1998

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

other: Alpk:APfSD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 8 to 12 weeks
- Weight at study initiation: Males: 352-393 g. Females: 211-249 g
- Housing: The rats were housed individually, in cages suitable for animals of this strain and the weight range expected during the course of the study.
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 to 70
- Air changes (per hr): A minimum of 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 12 Jan 2000 To: 27 Jan 2000

Type of coverage:

occlusive

Vehicle:

water

Details on dermal exposure:

The day prior to application of the test substance, the hair was removed with a pair of veterinary clippers from an area, at least 7 cm x 7 cm, on the dorso-lumbar region of each animal. The appropriate amount of the test substance was weighed onto a plastic weighing boat and, to allow good skin contact, was moistened to a dry paste with a small amount (0.9 - 1.3 mL) of water. The amount applied was calculated for each animal according to its weight at the time of dosing. The estimated amount applied per unit area of skin exposed was 47.9 - 53.5 mg/cm2 for males and 28.6 - 33.8 mg/cm2 for females.
The test substance was applied to the shorn back of each animal and was kept in contact with the skin for approximately 24 hours using an occlusive dressing wrapped around the trunk of the animal. Each dressing consisted of a foil backed gauze patch to cover the treated area and was held in position by a cohesive bandage secured with two pieces of surgical tape.
At the end of the 24-hour contact period, the dressings were carefully cut, using blunt tipped scissors, removed and discarded. The skin, at the site of application, was cleansed free of any residual test substance using clean swabs of absorbent cotton wool soaked in clean warm water and was then dried gently with clean tissue paper.

Duration of exposure:

24 hours

Doses:

5000 mg/kg bw/day

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

CLINICAL OBSERVATIONS
Prior to the start of the study, all rats were examined to ensure that they were physically normal and exhibited normal activity. The animals were observed twice following dosing on day 1 (only gross abnormalities were noted at this time as the presence of the dressings may have affected the behaviour and movement of the rats). Subsequent observations for signs of systemic toxicity and skin irritation were made once daily up to day 15.

BODY WEIGHTS
The animals were weighed immediately before dosing (day 1) and on days 8 and 15.

TERMINATION
All rats were killed by exsanguination under terminal anaesthesia induced by halothane vapour.

MACROSCOPIC EXAMINATION
All animals were examined post mortem. This involved an external observation and a careful examination of all thoracic and abdominal viscera. All abnormalities were recorded but tissues were not submitted for histopathological examination.

Statistics:

The acute dermal median lethal dose was estimated from the mortality data.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

>= 5 000 mg/kg bw

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

None of the animals died and there were no significant signs of systemic toxicity.

Clinical signs:

other: Slight or moderate skin irritation was seen in all animals. Signs of skin irritation had resolved in all the females by day 14, but was still apparent in four of the males at the end of the study.

Gross pathology:

At examination post mortem, compound-related abnormalities comprised scabs at the application site of two males. One male had stained nares. This is considered to be a non-specific finding which is incidental to treatment.

Interpretation of results:

GHS criteria not met

Conclusions:

Based on this study, the acute dermal median lethal dose of the test substance is estimated to be in excess of 5000 mg/kg to male and female rats.

Executive summary:

A group of five male and five female Alpk:APfSD (Wistar-derived) rats received a single 24 hour dermal application of 5000 mg/kg of the test substance (OECD 402, GLP). The animals were assessed daily for the following 14 days for any signs of systemic toxicity and their body weights were recorded at intervals throughout the study. At the end of the study all the animals were killed and subjected to a macroscopic examination post mortem.

None of the animals died and there were no significant signs of systemic toxicity. All except one animal showed an overall body weight gain during the study. At examination post mortem, compound-related abnormalities comprised scabs at the application site of two males. Slight or moderate skin irritation was seen in all animals. Signs of skin irritation had resolved in all the females by day 14, but was still apparent in four of the males at the end of the study.

In conclusion, the acute dermal median lethal dose of the test substance is estimated to be in excess of 5000 mg/kg to male and female rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

2 000 mg/kg bw

Quality of whole database:

GLP compliant OECD 402 study.

Additional information

Acute oral toxicity

An acute oral toxicity test was conducted in compliance with GLP and following the OPPTS 870.1100 guideline using rats to determine the potential for the test substance to produce toxicity via the oral route. Based on the results of this study, the acute oral LD50 of the test substance is greater than 5000 mg/kg of body weight in both the male and female rat. Initially, five thousand milligrams of the test substance per kilogram of body weight was administered to one healthy female rat by oral gavage. This animal was observed for 7 days. Due to the absence of mortality in this animal, a group of five females was administered the test substance at the same dose level. Since no females died, a group of 5 males was administered the test substance at 5000 mg/kg to assure that males were not the more sensitive sex. All animals were observed for mortality, signs of gross toxicity, and behavioural changes at least once daily for 14 days. Body weights were recorded prior to administration and again on Days 7 and 14 (termination). Necropsies were performed on all animals at terminal sacrifice.

Acute inhalation toxicity

The acute inhalation toxicity of the test substance was assessed by exposing 3 groups of rats, each for a period of 4 hours, to aerosols produced from the test substance following the EPA FIFRA 81-3 guideline and GLP. A fourth group was exposed to air only. The animals were exposure using whole-body exposure. The observation period was 14 days post exposure.

During exposure: signs consistent with exposure to an irritant aerosol, including partial closing of the eyes, wetness around the eyes, exaggerated respiratory movements and restless behaviour. 0.14 mg/L. During observation period: signs seen in rats exposed to the test substance included abnormal respiration, wet fur, brown staining around the snout and jaws, discharges from the eyes and deaths. Recovery from the effects of exposure was evident from Day 4 and the majority of surviving rats were normal by Day 9 of observation. Reduced rate of body weight gain during the first week following exposure. Subsequently weight gain was generally similar to that for control rats. The lungs of the majority of rats that died as a result of exposure were congested and the stomachs were gas-filled. A white frothy fluid was found in the trachea of a number of rats. There were no macroscopic abnormalities in rats surviving exposure to the test substance.

In conclusion, from the mortality data for all groups and sexes, the LC50 estimate and 95% confidence limits (CL) were calculated from the actual (measured) concentrations: 0.10 mg/mL air (0.07 – 0.14 mg/L).

Acute dermal toxicity

A group of five male and five female Alpk:APfSD (Wistar-derived) rats received a single 24 hour dermal application of 5000 mg/kg of the test substance (OECD 402, GLP). The animals were assessed daily for the following 14 days for any signs of systemic toxicity and their body weights were recorded at intervals throughout the study. At the end of the study all the animals were killed and subjected to a macroscopic examination post mortem.

None of the animals died and there were no significant signs of systemic toxicity. All except one animal showed an overall body weight gain during the study. At examination post mortem, compound-related abnormalities comprised scabs at the application site of two males. Slight or moderate skin irritation was seen in all animals. Signs of skin irritation had resolved in all the females by day 14, but was still apparent in four of the males at the end of the study.

In conclusion, the acute dermal median lethal dose of the test substance is estimated to be in excess of 5000 mg/kg to male and female rats.

Justification for classification or non-classification

 Based on the result of the acute inhalation study, the substance is classified as acute toxicity category 2; H330: Fatal if inhaled in accordance with EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation No. (EC) 1272/2008.