1-[(4-chlorophenyl)methyl]-1-cyclopentyl-3-phenylurea

Endpoint summary

Description of key information

GLP- and guideline-compliant studies of acute oral, inhalation and dermal toxicity are available for pencycuron.

Test Species/Type	Results	Assessment	Reference
OECD 401 - Acute oral toxicity in the rat	The acute oral LD50 of pencycuron was found to be >5000 mg/kg bw under the conditions of this study.  Classification not required.	Key study	Sheets (1989)
None - Acute oral toxicity in the rat (single dose level of 1000 mg/kg bw)	The acute oral LD50 of pencycuron was found to be >1000 mg/kg bw under the conditions of this study.	- not considered acceptable	Ono and Iyatomi (1978)
None - Acute oral toxicity in the mouse	The acute oral LD50 of pencycuron was found to be >5000 mg/kg bw under the conditions of this study.	- not considered acceptable	Kawaguchi et al (1979)
OECD 403 - Acute inhalation study in the rat: head/nose exposure. MMAD 5.61 um	The acute inhalation LC50 of pencycuron was found to be >5.13 mg/L under the conditions of this study.  Classification not required.	Key study	Pauluhn (1990)
OECD 402 - Acute dermal toxicity study in the rat (occlusive, 24-h)	The acute dermal LD50 of pencycuron was found to be >2000 mg/kg bw under the conditions of this study.  Classification not required.	Key study	Sheets (1988)
None - Acute dermal toxicity in the rat	The acute dermal LD50 of pencycuron was found to be >2000 mg/kg bw under the conditions of this study.	- not considered acceptable due to deficiencies	Ono and Iyatomi (1978)
None - Acute dermal toxicity in the mouse	The acute dermal LD50 of pencycuron was found to be >2000 mg/kg bw under the conditions of this study.	- not considered acceptable due to deficiencies	Kawaguchi et al (1978)

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:

1988-08-02 to 1989-01-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 81-1 (Acute Oral Toxicity)

Version / remarks:

November 1984

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OTS 798.1175 (Acute Oral Toxicity)

Version / remarks:

July 1987

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Specific details on test material used for the study:

White powder

Species:

rat

Strain:

Sprague-Dawley

Remarks:

CD(SD)BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Females nulliparous and non-pregnant: yes
- Age at study initiation: approximately 15-18 weeks.
- All animals were fasted overnight prior to dosing.
- Housing: Animals were housed individually in stainless steel cages suspended over deotized animal cage board (DACB) bedding. Bedding was changed three times weekly and rats were transferred to clean cages every three weeks.
- Diet: ad libitum
- Water: municipal, ad libitum
- Acclimation period: at least six days.
- Method of randomisation in assigning animals to test and control groups: Rats were assigned to cages from a list of computer-generated random numbers. Animals were assigned to dose groups from consecutively numbered cages.

ENVIRONMENTAL CONDITIONS
- Temperature: 18 to 26°C
- Humidity: 40 to 70%
- Photoperiod: 12-hour light/dark cycle.

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Remarks:

PEG 400

Details on oral exposure:

DOSE VOLUME APPLIED: 10 mL/kg

Doses:

5000 mg/kg bw

No. of animals per sex per dose:

5/sex/group

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days.
- Frequency of observations and weighing: twice daily during the week and once daily on weekends. Rats were weighed on the day of treatment and on days 7 and 14 after treatment.
- Necropsy of survivors performed: yes
All animals were subjected to a gross pathologic examination as soon as possible following their death. Survivors were sacrificed by CO2 asphyxiation on day 14 after treatment.
- Clinical signs including body weight: The weight range for all animals was within ±20% of the mean for each sex.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

No deaths occurred at the oral limit dose (5000 mg/kg bw).

Clinical signs:

other: Urine stain

Body weight:

other body weight observations

Remarks:

Body weight increased for all animals from days 0-7 and for all but one female (8 g loss) from days 7-14.

Gross pathology:

No gross lesions were observed at necropsy.

Interpretation of results:

GHS criteria not met

Conclusions:

Pencycuron does not require classification for acute oral toxicity in any CLP category on the basis of this study. For both males and females the acute oral LD50 was >5000 mg/kg bw and the no-observed-effect level was <5000 mg/kg bw.

Executive summary:

The acute oral toxicity of pencycuron was tested in young adult male and female (5/sex) Sprague-Dawley rats using the oral limit dose (5000 mg/kg bw). Pencycuron was administered by gavage in polyethylene glycol (10 mL/kg). Animals were observed for 14 days post-dosing for mortality and clinical signs. Body weights were recorded on the day of treatment (day 0) and on days 7 and 14. On day 14 the animals were sacrificed and a gross necropsy was performed.

 

No deaths were observed at the oral limit dose, therefore, LD₅₀ estimates were not determined. Treatment related clinical signs, consisting of urine stain in four animals (three males and one female) and anal stain in one male, were resolved by day 3. Body weights increased for all animals from days 0-7 and for all but one female from days 7-14. No treatment-related gross lesions were observed at necropsy. For both males and females, the oral LD₅₀ for pencycuron was >5000 mg/kg bw.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 5 000 mg/kg bw

Quality of whole database:

A GLP- and guideline-compliant study of acute oral toxicity in the rat is available for pencycuron

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:

1989-08-28 to 1990-01-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPP 81-3 (Acute inhalation toxicity)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

traditional method

Limit test:

yes

Specific details on test material used for the study:

Storage conditions: room temperature.

Species:

rat

Strain:

Wistar

Remarks:

SPF-Cpb

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 2 to 3 months.
- Weight at study initiation: 180 g to 200 g.
- Housing: During the acclimatization period and the experimental period, the rats were housed conventionally in Type III Makrolon® cages (5 rats per cage).
All animals of one exposure group were placed in one animal room in each case. For reasons of capacity, rats from other toxicological studies were housed temporarily in the same animal room. Mix-ups with other animals Here avoided by adequate spacing and separation (different cage racks), a clear cage identification, and an appropriate scheduling of work.
- Diet: ad libitum.
- Water: ad libitum.
- Acclimation period: at least 5 days.
- Method of randomisation in assigning animals to test and control groups: The randomization lists were generated using a BASIC program. This program uses a random number generator with varying starting conditions as the algorithm. The animals were randomized by cage (5 rats per cage).

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2 °C
- Humidity: approx. 50%
- Air changes: approx. 10 times per hour.
- Photoperiod: 12 hours, artificial illumination.

Route of administration:

inhalation

Type of inhalation exposure:

nose only

Vehicle:

water

Remarks:

denoised water

Mass median aerodynamic diameter (MMAD):

>= 2.11 - <= 5.61 µm

Geometric standard deviation (GSD):

>= 1.54 - <= 2.21

Remark on MMAD/GSD:

The ranges are from the two studies done in this report. The MMAD for Aerosol and Dust exposure is 2.11 µm and 5.61 µm repectively, while the GSD values are 1.54 and 2.21 respectively.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION

- Volume of exposure chamber: approximately 20 liters.

- Method of holding animals in test chamber:
During the exposure, the animals were exposed to the exposure atmosphere in Plexiglas exposure tubes. The size of the exposure tubes was adjusted to the size of the rat. The exposure tubes were designed in such manner that the tail of the rat was outside the exposure tube. In this way, hyperthermic effects can be avoided.

- Method of conditioning air:
The compressed air was generated by two B06E compressors, Model SB 270/15/350D, connected in parallel. The fully automatic conditioning of the compressed air (i.e. removal of water, dust, and oil) was performed by means of a VIA compressed air dryer, Model A 110, connected downstream. The standard operating pressure of the compressors was 8 to 10 bar (800 to 1000 kPa). The working pressure was adjusted in each case by pressure-reducing valves.

- System of generating particulates/aerosols:
In order to attain maximum respirability of Pencycuron for the test species, it was nebulized (20% in deionized water as vehicle).
Using a binary nozzle and conditioned compressed air (10 liters of air per minute; dispersion pressure approximately 600 kPa), 5000 µl/min of the spray solution were constantly nebulized into the preseparator of the inhalation chamber.

- Method of particle size determination: ANDERSEN cascade impactor.

- Treatment of exhaust air: The exhaust air from the hoods was purified via an absolute filter.

- Temperature, humidity, pressure in air chamber: 21°C, Rel. humidity / Aerosol approx. 93%, Rel. humidity / Dust approx. 32%, The dispersion pressure was about 200 kPa, The standard operating pressure of the compressors was 8 to 10 bar (800 to 1000 kPa).

TEST ATMOSPHERE
- Brief description of analytical method and equipment used:
* Aerosol Atmosphere:
A total of 3 air samples were taken from the inhalation chamber: at the start of the test (after attaining concentration equilibrium), at the middle of the test, and toward the end of the test. The total air volume per analysis was 10 liters (sampling rate: 2 liters/minute).

* Dust Atmosphere:
To the extent technically feasible, 3 air samples Here taken from the inhalation chamber in the breathing zone of the rats: at the start of the test (about 30 to 90 minutes after the start of exposure), at the middle of the test, and toward the end of the test.

- Samples taken from breathing zone: yes

Analytical verification of test atmosphere concentrations:

yes

Remarks:

The concentration in the exposure atmosphere was determined by High Performance Liquid Chromatography (HPLC). The actual test substance concentration (mg NTN 19701/m3 air) in the breathing zone of the rats was assessed gravimetrically.

Duration of exposure:

4 h

Remarks on duration:

For the inhalation toxicity tests with dust, this is the air control group. In the aerosol tests, the water control was considered to be an appropriate control group.

Concentrations:

Aerosol (nominal) concentration: 10000 mg/m3 air.
Aerosol analytical concentration: 239.9 - 283.6 mg/m3 air.
Dust analytical concentration: 5020 - 5210 mg/m3 air.

No. of animals per sex per dose:

5/sex/concentration

Control animals:

yes

Remarks:

Both air control and vehicle controls

Details on study design:

- Duration of observation period following administration: 14 days

- Frequency of observations and weighing:
The appearance and behavior of the individual rats were evaluated several times on the exposure day, in the morning and in the evening on work days starting on the first day of recovery, but not during exposure (tube exposure). The rats were also evaluated once per day on weekends.

The body weights of the rats were manually determined prior to exposure, on Days 3 and 7 of the recovery period, and once per week thereafter.
The recovery period amounted to 2 weeks.

- Necropsy of survivors performed: yes

- Clinical signs including body weight
At the end of exposure, the rats are evaluated primarily for the following signs (at hourly intervals if necessary):
- Appearance of the visible mucosae of eyes and respiratory tract.
- General condition of the rhinarium and pinna of the ear, condition of the hair coat, preening activities.
- Respiration.
- Circulation (to the extent assessable)
- Somatomotor activity and behavior pattern (including tremor, convulsions, hypersalivation, dyspnea, diarrhea, lethargy, sedation, and coma)
- Central nervous and autonomic signs.

Since these signs can be adequately evaluated only for animals that can move freely, no specific evaluation of the rats is performed a priori during the tube exposure.
The following reflexes were tested: corneal reflex, pinnal reflex, myotactic reflex, pupillary reflex, righting reflex, startle reflex (reaction to external stimuli).


- Other examinations performed: clinical signs, body weight, organ weights, histopathology, other:
At the end of the recovery period, the rats were sacrificed with pentobarbital (approximately 100 to 150 mg/animal, i.p. administration) and subjected to gross pathological examination.

Statistics:

Gross Pathological Findings:
The more frequently observed findings pertaining to the respiratory tract were statistically evaluated using the "Pairwise Fisher's Test" with preferred RxC Chi Square Test. The Fisher Test was performed only when there was a difference between the groups in the RxC Chi Square Test or when a frequency value of < 5 was obtained. A symmetrical distribution (p - one-tailed = (p - two-tailed)/2) was assumed when calculating the one-tailed p value.

The software (Fisher Test and RxC Chi Square Test) was validated by means of data sets from the literature.

Body weights:
The following were calculated from the body weights: mean and standard deviation. The body weight means are plotted as a function of time, separately for males and females.

Since, in acute studies, the individual group means can differ prior to the start of the study, the body weight gain was statistically evaluated by means of an analysis of variance.

In this parametric method, a normal distribution of the data is checked by comparing the median and mean. The groups Here compared at the level of confidence of (1 - alpha) = 957., (p = 0.05). The test for homogeneity of the variances between the groups was performed using BOX'S test. This test is preferred to BARTLETT's test when using a small sample size. If the above mentioned F test shows that the variation within the group is larger than that between the groups, this is stated in the Appendix by entering "no statistical difference between the groups." If a difference is found, a pairwise post hoc comparison of the groups (one- and two-tailed) is performed using the GAMES and HOWELL modification of the TUKEY-KRAMER test for significance.

The software was validated by means of data sets from the literature.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 268 mg/m³ air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Aerosol exposure

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5 130 mg/m³ air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Dust exposure

Mortality:

No mortalities accoured

Clinical signs:

other: No treatment-related findings

Body weight:

When compared to the rats exposed to the air control, those exposed to the dust atmosphere showed a slight, transitory reduction in body weight gain. Based on the fact that, in comparison to the vehicle control, there was no statistically significant difference pertaining to a reduction in body weight gain, the observed changes in body weight are not considered toxicologically relevant.

Gross pathology:

Rats sacrificed at the end of the recovery period:
Gross pathological examination did not reveal any indication of gross organ damage.

Interpretation of results:

GHS criteria not met

Conclusions:

Both as an aerosol (high respirability) and as a dust (lower respirability), Pencycuron exhibited no acute inhalation toxicity to rats. The study results show that, when the product is handled, there is no acute hazard to humans. Pencycuron does not require classification for acute inhalation toxicity in any CLP category on the basis of this study

Executive summary:

Tests were performed to determine the acute inhalation toxicity of Pencycuron in accordance with OECD Guideline No. 403. Two methods were used to generate atmospheres containing respirable particles of pencycuron. Rats were initially exposed to pencycuron as an aerosol generated by mixing with water. This method gave a relatively low maximum achievable concentration but with a high proportion of respirable particles. The second exposure used solid pencycuron (dust) and gave a higher exposure concentration but with a lower proportion of respirable particles.

LC₅₀ Inhalation (Aerosol):
Rat, male and female (exposure: 4h): >268 mg/m³ air
(= maximum technically achievable concentration).

Signs: The exposure was tolerated without clinical signs and without Mortality.

LC₅₀ Inhalation (Dust)
Rat, male and female (exposure) 4h): > 5130 mg/m³ air
Signs: The exposure was tolerated without clinical signs and without mortality.

Assessment:
The test substance as an aerosol (high respirability, i.e. 98% of the particles ≤5 pm) and the test substance as a dust (lower respirability, i.e. 45% of the particles ≤5 pm) did not exhibit any acute inhalation toxicity to the rat. Pencycuron does not require classification for acute inhalation toxicity in any CLP category on the basis of this study.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

> 5.13 mg/L air

Physical form:

inhalation: dust

Quality of whole database:

A GLP- and guideline-compliant study of acute inhalation toxicity is available for pencycuron

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:

1988-08-02 to 1988-12-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 81-2 (Acute Dermal Toxicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OTS 798.1100 (Acute Dermal Toxicity)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

The most important deviations from the guideline was that an occlusive dressing instead of a porous gauze dressing was used. As the use of an occlusive dressing would increase effects, this deviation does not influence the conclusions of the study.

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Specific details on test material used for the study:

Physical Appearance: White powder

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 19 weeks.
- Weight at study initiation: 2.99 to 3.79 kg.
- Housing: individually in stainless steel cages with flat rod floors suspended over pelletized wood bedding or Alfa-cobs.
- Diet: ad libitum.
- Water: municipal, ad libitum.
- Acclimation period: at least six days.
- Method of randomisation in assigning animals to test and control groups: Rabbits were assigned to cages using a list of computer-generated random numbers. Animals were assigned to dose groups from consecutively numbered cages

ENVIRONMENTAL CONDITIONS
- Temperature: 18 to 24°C
- Humidity: 40 to 70%
- Photoperiod: 12-hour light/dark cycle.

Type of coverage:

occlusive

Vehicle:

water

Remarks:

The test material was moistened with municipal tap water

Details on dermal exposure:

TEST SITE
- Area of exposure: The back of each rabbit.
- coverage: 240 cm2 shaved area of the back.
- Type of wrap if used: The exposed area was covered with a square of gauze secured with hypoallergenic tape. The gauze was covered with a square of plastic secured with tape and adhesive bandage. A plastic collar was placed on the rabbits to prevent removal of the test material.

REMOVAL OF TEST SUBSTANCE
- The collar, tape, plastic and gauze were removed approximately 24 hours after treatment and the back was wiped using a paper towel dampened with tap water to remove all visible residue.
- Time after start of exposure: 24 hours.

TEST MATERIAL
- The test material was moistened with municipal tap water.

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5/sex/group

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days.

- Frequency of observations and weighing: Clinical observations: twice daily on weekdays and once daily on weekends. Animals were weighed on the day of treatment and on days 7 and 14 after treatment. Terminal body weights were obtained on all animals. The body weight range on the day animals were treated was 2.99 to 3.42 kg for males and 3.27 to 3.79 kg for females.

- Necropsy of survivors performed: All animals were subjected to a gross pathologic examination. All rabbits which died during the study were necropsied as soon as possible. Survivors were sacrificed on day 14 after treatment.

- Other examinations performed: clinical signs, body weight, organ weights, histopathology, other:

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No treatment-related deaths occurred at the dermal limit dose (2000 mg/kg bw), therefore, LD50 estimates were not determined. One male was found dead on day 2. This animal appeared to have died from a terminal Pasteurella multocida infection, as indicated by the lesions observed at necropsy. Further evidence that this animal did not die from the treatment include the absence of toxic signs in all animals and the absence of deaths and toxic signs in rats and mice administered this dose by the dermal route.

Clinical signs:

other: Lacrimation

Body weight:

other body weight observations

Remarks:

Body weight increased an average 0.11 kg from days 0-7 and from days 7-14

Gross pathology:

Lesions observed at gross necropsy were limited to lesions in the animal that was found dead on day 2.

Interpretation of results:

GHS criteria not met

Conclusions:

The acute dermal LD50 of pencycuron was found to be greater than 2000 mg/kg bw for rabbits, irrespective of sex. Pencycuron does not require classification for acute inhalation toxicity in any CLP category on the basis of this study.

Executive summary:

The acute dermal toxicity of pencycuron was tested using the dermal limit dose (2000 mg/kg bw) in young adult male and female New Zealand White rabbits (5/sex). There was no treatment-related mortality or clinical signs. Bodyweights were unaffected by treatment. The dermal LD₅₀ was >2000 mg/kg bw for males and females. Pencycuron does not require classification for acute inhalation toxicity in any CLP category on the basis of this study.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 2 000 mg/kg bw

Quality of whole database:

A GLP- and guideline-compliant study of acute dermal toxicity in the rabbit is available for pencycuron

Justification for classification or non-classification

The acute oral LD₅₀ of pencycuron in the rat is >5000 mg/kg bw

The acute inhalation LC₅₀ (4-hour, nose-only) of pencycuron in the rat is >5.18 mg/L

The acute dermal LD₅₀ of pencycuron in the rabbit is >2000 mg/kg bw

Pencycuron has no harmonised classification for acute toxicity.  The results of the available studies confirm that pencycuron does not require classification for acute oral, inhalation or dermal toxicity in any CLP Category.