6-Amino-5-chloro-2-cyclopyrimidine-4-carboxylic acid

Endpoint summary

Description of key information

Acute oral toxicity (OECD 401, GLP), mice: LD50 > 5000 mg/kg bw

Acute inhalation toxicity (OECD 403, GLP), rat: LC50 > 5.4 mg/L

Acute dermal toxicity (OECD 402, GLP), rat: LD50 > 5000 mg/kg bw

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:

14 March - 7 June 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)

Version / remarks:

Adopted: 2001

Deviations:

no

GLP compliance:

yes

Test type:

up-and-down procedure

Limit test:

yes

Species:

rat

Strain:

Crj: CD(SD)

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, North Carolina, USA
- Age at study initiation: 10 - 11 weeks
- Weight at study initiation: 227.1, 231.8 and 251.0 g
- Fasting period before study: approximately 16-18 h
- Housing: individually in stainless steel, wire-mesh cages suspended above cage boards
- Diet: PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002, ad libitum
- Water: ad libitum
- Acclimation period: at least 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 26
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

other: water (deionized)

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: 20 mL/kg bw

CLASS METHOD
- Rationale for the selection of the starting dose: according to EPA OPPTS 870.1100

Doses:

5000 mg/kg bw

No. of animals per sex per dose:

3 (The rats were dosed one at a time at a minimum of 48 h intervals.)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: daily observation for mortality and signs of illness, injury, or abnormal behavior, clinical signs were observed at the beginning of fasting, before dosing (test day 0), once during the first 30 min after dosing and 2 more times on the day of dosing, and once daily thereafter body weight was determined on Day -1, 0, 7 and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, organ weights

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortalities were observed.

Clinical signs:

other: One rat exhibites diarrhea on the day after dosing. No clinical signs of toxicity were observed in the remaining two rats.

Gross pathology:

Animals sacrificed at the end of the post-treatment observation period showed no evidence of gross lesions.

 Table 1. Table for acute oral toxicity.

Dose [mg/kg bw]	Toxicological results*	Duration of clinical signs	Time of death	Mortality (%)
Females
5000	0/1/3	Day 1 postdosing	---	0
LD50> 5000 mg/kg bw
* first number = number of dead animals
second number = number of animals with clinical signs
third number = number of animals used

 

Interpretation of results:

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

Conclusions:

In this acute oral toxicity study in female rats a LD50 value of > 5000 mg/kg bw was determined.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate, reliable (Klimisch score 1) and consistent study, and is thus sufficient to fulfil the standard information requirements set out in Annex VII, 8.5, of Regulation (EC) No 1907/2006.

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:

16 March - 01 June 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

adopted 12 May 1981

Deviations:

no

GLP compliance:

yes

Test type:

traditional method

Limit test:

yes

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, North Carolina, USA
- Age at study initiation: approximately 8 weeks (males and females)
- Weight at study initiation: 249 - 270 g (males), 181 - 197 g (females)
- Housing: individually in stainless steel, wire-mesh cages suspended above cage boards
- Diet: PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002, ad libitum
- Water: ad libitum
- Acclimation period: at least 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 26
- Humidity (%): 30 - 70
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

3.5 µm

Geometric standard deviation (GSD):

1.9

Remark on MMAD/GSD:

Particle size distribution:
2.2 - 2.5 % of aerosols: less than 1 µm MMAD
37 - 49 % of aerosols: less than 3 µm MMAD
86 - 87 % of aerosols: less than 10 µm MMAD

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: glass (cylindrical) exposure chamber
- Exposure chamber volume: 36 L
- Method of holding animals in test chamber: Animals were individually restrained in perforated stainless steel cylinders with conical nose pieces. The restrainers were inserted into a polymethylmethacrylate faceplate attached to the exposure chamber so that the nose of each animal extended into the exposure chamber.
- Source and rate of air: house air
- Method of conditioning air: The chamber atmosphere was generated by suspension of the test substance in air with a Fluid Energy Processing model 00 Jet-O-Mizer.
- System of generating particulates/aerosols: The test substance was metered into the jetmill with a K-Tron model T-20 Twin Screw volumetric feeder. Filtered, high-pressure air, metered into the jetmill, carried the resulting atmosphere through a 1-L glass cyclone and into the exposure chamber. Chamber concentrations of test substance were controlled by varying the test substance feed rate to the jetmill.
- Method of particle size determination: Sierra® series 210 cyclone preseparator/cascade impactor and Sierra® series 110 constant flow air sampler
- Treatment of exhaust air: The test atmosphere was exhausted through a high-capacity canister filter prior to discharge into the fume hood.
- Temperature, humidity, airflow range, oxygen concentration: 20-22°C, 45-49%, 20 L/min (34 air changes/h), 21%

TEST ATMOSPHERE
- Brief description of analytical method used: gravimetric analysis. The known volumes of chamber atmosphere were drawn from the sampling port through a 25 mm filter cassette containing a pre-weighed glass fiber (Type A/E) filter. The filters were weighed on a Cahn model C-30 Microbalance®. The atmospheric concentration of the test substance was calculated from the difference between the pre- and post-sampling filter weights divided by the volume of chamber atmosphere sampled. High performance liquid chromatography (HPLC) analysis was used to determine the percentage of active ingredient on the gravimetric filters. HPLC analysis showed that the mean DPX-MAT28 content on the filters was 90% of the collected mean gravimetric mass (8.6 g vs. 9.6 g). The average recovery of DPX-MAT28 active ingredient was 98%.
- Samples taken from breathing zone: yes

VEHICLE
- Composition of vehicle: air

TEST ATMOSPHERE
- Particle size distribution: 2.2 - 2.5 % of aerosols: less than 1 µm MMAD, 37 - 49 % of aerosols: less than 3 µm MMAD, 86 - 87 % of aerosols: less than 10 µm MMAD
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 3.5 μm ± 1.9

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Air samples were collected at 3 separate locations (faceplate) and at the reference port. All samples (faceplate) were within 20% of the overall mean and were homogenously distributed. Difference between faceplate measurements and reference port was <1%.

Duration of exposure:

4 h

Concentrations:

5.4 ± 0.9 mg/L (mean ± standard deviation)

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: daily for clinical signs and mortality, body weight at days 0, 1, 2, 7 and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight other: gross pathology examination included observation of the nasal passages

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.4 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortalities were observed.

Clinical signs:

other:

Body weight:

One day following exposure to the test substance, a slight, reduction in mean body weight was observed in males, but not in females. By post-exposure day 2, all rats gained body weight.

Gross pathology:

Animals sacrificed at the end of the post-treatment observation period showed no evidence of gross lesions.

Interpretation of results:

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

Conclusions:

In this acute inhalation toxicity study in rats a LC50 value of > 5.4 mg/L air was determined.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate, reliable (Klimisch score 1) and consistent study, and is thus sufficient to fulfil the standard information requirements set out in Annex VIII, 8.5, of Regulation (EC) No 1907/2006.

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:

07 March - 17 May 2007

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:

adopted (according to study report) 1987

Deviations:

yes

Remarks:

Limit dose higher than 2000 mg/kg bw/day (5000 mg/kg bw/day)

GLP compliance:

yes

Test type:

fixed dose procedure

Limit test:

yes

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, North Carolina, USA
- Females nulliparous and non-pregnant: not specified
- Age at study initiation: approximately 9 weeks (males), 10 weeks (females)
- Weight at study initiation: 290.2 g (males), 225.5 g (females)
- Housing: individually in stainless steel, wire-mesh cages suspended above cage boards
- Diet: water, ad libitum
- Water: PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002, ad libitum
- Acclimation period: at least 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 -26
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light): 12/12

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: shaved back from the scapular to the lumbar region (approximately 5 cm x 7.4 cm, 37 cm²)
- Type of wrap if used: test substance was covered with a 2-ply gauze patch. Rats were then wrapped with stretch gauze bandage and self-adhesive bandage.

REMOVAL OF TEST SUBSTANCE
- Washing: warm water
- Time after start of exposure: 24 h

TEST MATERIAL
- Amount applied: 5000 mg/kg bw moistened with 0.6 mL of deionized water
- For solids, paste formed: yes

Duration of exposure:

24 h

Doses:

5000 mg/kg bw/day

No. of animals per sex per dose:

5

Control animals:

not required

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: mortality and clinical signs of illness, injury, dermal irritation and abnormal behavior were made daily (weekends excluded for dermal irritation). Body weight was determined prior to treatment and on days 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight other: dermal irritation (Draize score)

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

No deaths occured during the 14 days test period.

Clinical signs:

other: No clinical signs of systemic toxicity were observed during the study period. Two male rats exhibited stained fur/skin or ocular discharge after test substance removal. These clinical signs are commonly seen in wrapped rats and therefore are not considere

Gross pathology:

Gross pathology did not reveal any abnormalities.

Other findings:

- Other observations: Erythema (score of 1 or 2) was observed in 9 rats and ulceration was observed in 4 rats on the day after application of the test substance. The erythema and ulceration may have been due to the gauze pads adhering to the test sites at the time of washing. No dermal irritation was observed in the remaining rat.

Table 1. Table for acute dermal toxicity.
Dose [mg/kg bw]	Toxicological results*	Duration of clinical signs	Time of death	Mortality (%)
Males
5000	0/5/5	stained (red) skin/fur chin, ulceration, black discharge eye bilateral, Day 1	/	0
Females
5000	0/1/5	Hair loss (forelimb bilateral), Day 11 -14	/	0
LD50 = > 5000 mg/kg bw
* first number = number of dead animals
second number = number of animals with clinical signs
third number = number of animals used

Table 1. Results of skin irritation parameters (Draize score)
Observation time	Rabbit no.
	1 (male)		2 (male)		3 (male)		4 (male)		5 (male)		6 (female)		7 (female)		8 (female)		9 (female)		10 (female)
	Erythema	Edema	Erythema	Edema	Erythema	Edema	Erythema	Edema	Erythema	Edema	Erythema	Edema	Erythema	Edema	Erythema	Edema	Erythema	Edema	Erythema	Edema
1 Day	0	0	2	0	2	0	2	0	2	0	1	0	1	0	2	0	1	0	2	0
Day 2-14	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

Interpretation of results:

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

Conclusions:

In this acute dermal toxicity study a LD50 value of > 5000 mg/kg bw was determined in male and female rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate, reliable (Klimisch score 1) and consistent study, and is thus sufficient to fulfil the standard information requirements set out in Annex VIII, 8.5, of Regulation (EC) No 1907/2006.

Additional information

Acute oral toxicity

Acute toxicity of the test substance, dissolved in deionized water, was tested in Crl:CD(SD) rats according to OECD TG 425 and GLP (2011a). Groups of 3 female rats each were exposed to 5000 mg/kg bw (20 mL/kg bw) via gavage. No mortality was observed until the end of the observation period of 14 days. One rat exhibited diarrhea on the day after dosing. No clinical signs of toxicity were observed in the remaining two rats. No effects on body weight or body weight development and no gross pathological findings were identified. Thus, a LD50 > 5000 mg/kg bw was derived.

 

Acute inhalation toxicity

Acute inhalation toxicity was tested in Crl:CD(SD) rats according to OECD Guideline 403 and in compliance with GLP (2011b). 5 male and 5 female rats were exposed (nose only) to an aerosol (dust) of the test substance at an average concentration of 5.4 ± 1.9 mg/mL air for 4 h. The aerosol generated was of adequate respirability with a MMAD ca. 3.5 µm (GSD ca. 1.9 and MMAD of at least 87%<10 μm). After exposure, animals were examined for a period of 14 days. Examinations included daily observation of clinical signs, determination of body weights and gross pathology examination. No mortalities were observed during the observation period. One female rat had discharge from the eyes on the day of exposure (day 0) and 3 males and 2 females demonstrated stained skin/fur on days 0 and 1. These signs disappeared and the rats were normal by 2 days post-exposure. Body weights in males were slightly reduced one day following exposure to the test substance. However, 2 days post-exposure all rats gained body weight. No effect on body weight was observed in females. Gross pathology analyses did not reveal any abnormalities. No test substance related mortality was observed, thus a median lethal concentration (LC50, aerosol, 4 h) of > 5.4 mg/L was determined for both sexes.

 

Acute dermal toxicity

Acute dermal toxicity of the test substance was tested in Crl:CD(SD) rats according to OECD Guideline 402 and in compliance with GLP (2011c). Five rats per sex were exposed to the test substance moistened with 0.6 mL deionized water at a dose of 5000 mg/kg bw (5 cm x 7.4 cm, 37 cm²) under semi-occlusive conditions. After an exposure period of 24 h the test substance was removed with warm water. Subsequently animals were examined for a period of 14 days. Examinations included daily clinical observations and determination of body weights prior to treatment (days 0) and at days 7 and 14. At the end of the observation period, gross pathology was performed. Two male rats exhibited stained fur/skin or ocular discharge after test substance removal. These clinical signs are commonly seen in wrapped rats and therefore are not considered as test substance related. Hair loss observed in 1 female rat was considered incidental. No further clinical signs of systemic toxicity were observed at the maximum dose of 5000 mg/kg bw. Effects on body weight were not observed and gross pathology examinations did not reveal test-substance-related grossly visible organ lesions. None of the exposed rats died, thus a dermal LD50 of >5000 mg/kg bw was determined for both males and females.

 

Overall conclusion

In summary, the available data on acute toxicity following oral, dermal and inhalation exposure consistently indicate a very low level of acute toxicity in rats. Therefore the test substance is not considered as hazardous after acute exposure.

Justification for classification or non-classification

The available data on the test substance for acute toxicity following oral, dermal and inhalation exposure do not meet the criteria for classification according to Regulation (EC) No. 1272/2008. Data are therefore conclusive but not sufficient for classification.