Pirimiphos-methyl

Endpoint summary

Description of key information

- Oral: LD50 = 1414 mg/kg bw, male/female, rat, according to OECD TG 401, Johnson 1999
- Inhalation: Discriminating conc. >5.04 mg/L male/female, rat, similar to OECD TG 403 Lewis 1989
- Dermal: Discriminating conc. >2000 mg/kg bw, male/female, rat, according to OECD TG 402, Johnson 1999

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:

1 Jun 1999 to 27Jul 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Version / remarks:

1987

Qualifier:

according to guideline

Guideline:

EU Method B.1 (Acute Toxicity (Oral))

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Version / remarks:

1998

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

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: 8-12 weeks old
- Weight at study initiation: Males: 270-381 g, females: 191-241 g
- Fasting period before study: The rats were fasted overnight immediately prior to dosing.
- Housing: A maximum of 5 rats was housed per cage, sexes separately, in cages suitable for animals of this strain and the weight range expected during the course of the study.
- Diet and water: Supplied by an automatic system were available ad libitum.
- Acclimation period: The animals were housed under the experimental conditions for at least 5 days, prior to the start of the study.

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

IN-LIFE DATES: 1 Jun 1999 to 27Jul 1999

Route of administration:

oral: gavage

Vehicle:

maize oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 10 mg/kg

Doses:

500, 1000 and 2000 mg/kg

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 clinical signs: The animals were observed for signs of systemic toxicity twice following dosing on day 1. Subsequent observations were made daily, up to day 15.
- Frequiency of weighing: Prior to fasting (day -1), immediately before dosing (day 1) and on days 8 and 15.
- Clinical signs including body weight and systemic toxicity
- Post mortem: Examination of all thoracic and abdominal viscera. All abnormalities were recorded but tissues were not submitted for histopathological examination.

Statistics:

LC50 values and 95% confidence intervals were determined.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

1 414 mg/kg bw

Based on:

test mat.

95% CL:

> 1 000 - < 2 000

Mortality:

Following a dose of 500 mg/kg and 1000 mg/kg, none of the animals died. Following a dose of 2000 mg/kg, all the animals were killed in extremis on days 2 or 3. Overview of the results were provided in table 1 in “Any other information on results incl. tables”

Clinical signs:

other: Signs of slight or moderate toxicity were seen in all animals, with complete recovery by day 5 in the males and day 8 in the females (some females had stained fur until day 10/13)

Gross pathology:

Following a dose of 500 mg/kg, one female had pelvic dilatation of the kidney. This is a common spontaneous finding which is considered to be unrelated to treatment. Following a dose of 1000 mg/kg, there were no macroscopic abnormalities in any animal. Following a dose of 2000 mg/kg, treatment-related abnormalities comprised staining/discharge from the eye, red nares, fluid stomach contents and (in one female) reddening of the pancreas.

Table 1. Cumulative mortality data

Dose level (mg/kg)	Day Number	Number of Deaths
		Male	Female
500	-	0	0
	15 (total)	0/5	0/5
1000	-	0	0
	15 (total)	0/5	0/5
2000	2  3	5  0	2  3
	15 (total)	5/5	5/5

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

The acute oral LD50 of the test substance is estimated to be 1414 mg/kg (95% confidence limits 1000, 2000) to male and female rats.

Executive summary:

Groups of five male and five female Alpk:APrSD rats received a single oral dose of 500, 1000 or 2000 mg/kg of the test substance in a study performed under GLP according to OECD TG 401. 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. Animals in extremis and those surviving to the end of the study were killed and subjected to a macroscopic examination post-mortem.

Following a dose of 500 mg/kg, none of the animals died. Signs of slight systemic toxicity were seen in most animals, with complete recovery by day 5. All animals showed an overall body weight gain during the study. There were no treatment-related abnormalities at examination post mortem. Following a dose of 1000 mg/kg, none of the animals died. Signs of slight or moderate toxicity were seen in all animals, with complete recovery by day 5 in the males and day 8 in the females. All animals showed an overall body weight gain during the study. There were no macroscopic abnormalities at examination post-mortem. Following a dose of 2000 mg/kg, all the animals were killed in extremis on days 2 or 3. At examination post mortem, treatment-related abnormalities comprised staining/discharge from the eye, red nares, fluid stomach contents and (in one female) reddening of the pancreas.

Based on these findings, the acute oral median lethal dose (LD50) of the test substance is estimated to be 1414 mg/kg (95% confidence limits 1000, 2000) to male and female rats.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 414 mg/kg bw

Quality of whole database:

GLP compliant OECD 401 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:

9 Aug 1989 to 23 Aug 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes

Test type:

traditional method

Limit test:

yes

Species:

rat

Strain:

Wistar

Remarks:

Alpk:APfSD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Approximately 7 weeks old
- Weight at study initiation: Females: 200-225 g, males: 225-257 g
- Housing: They were housed five to a cage (sexes separately). Each cage had the following approximate internal measurements: length 37 cm, width 33 cm and height 20 cm, and was suspended over a collecting tray lined with absorbent paper. The cages were contained in a single-sided mobile rat rack.
- Diet: ad libitum except during exposure.
- Water: ad libitum except during exposure.
- Acclimation period: 5 days prior to exposure

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 15 - 24
- Humidity (%): 50 ± 15
- Air changes (per hr): 20 - 30
- Photoperiod (hrs dark / hrs light): 12 /12

IN-LIFE DATES: 9 Aug 1989 to 23 Aug 1989

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

1.58 µm

Geometric standard deviation (GSD):

1.49

Details on inhalation exposure:

CHAMBER DESCRIPTION
The Chamber consisted of sections of PERSPEX tubing (6mm wall thickness) with an internal diameter of 28 cm and height of 15 cm. Each section was drilled with ten equidistant holes of 28 mm diameter into which the restraining tubes were pushed to give a good seal. There was also one sampling port. The chamber located on to a base-plate, fitted with castors for manoeuvrability. A conical aluminium lid ensured good distribution of the atmosphere across the chamber, the atmosphere having been generated from above. The conical lid and the base together had a volume of approximately 9.2 L. In this study two sections were connected, giving a volume of approximately 27.6 litres. Within the chambers the temperature ranged between 21.7-23.0 °C, and the relative humidity ranged between 36-40 % for the control group and 25-28 % for the test group.

TEST ATMOSPHERE
The atmospheric concentration of the test substance was determined by dissolving the material deposited on the VM-1 filters and the stages of the Cascade Impactor in ethyl acetate, ultrasonicating the solutions, further diluting with ethyl acetate as necessary and then analysing the resultant solutions by gas chromatography.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

5 mg/L

No. of animals per sex per dose:

Air control: 5 female and 5 male rats
Test concentration: 5 female and 5 male rats

Control animals:

yes

Details on study design:

- Duration of observation period following administration: All animals were examined before exposure for clinical abnormalities. During exposure they were observed frequently, and at the end of the four-hour exposure each rat was given a detailed clinical examination. The animals were also subjected to a detailed clinical examination on each day of the 14-day observation period.
- Frequency of weighing: All rats were weighed on day-1 (to ensure a similar distribution between groups), prior to exposure on day 1 and then on days 2, 3, 8 and 15.
- Necropsy of survivors performed: Yes
- Other examinations performed: Blood was taken on day 2 (bled from the tail vein) and at termination (bled by cardiac puncture) from all animals for the analysis of plasma and erythrocyte cholinesterase activities.
- Terminal procedures: At termination, animals were deeply anaesthetised by exposure to halothane BP vapour and killed by exsanguination via cardiac puncture. The rats were then subjected to a post-mortem examination with particular attention being given to abdominal and thoracic viscera. Lungs (with trachea and larynx attached) and liver were excised and trimmed, and the weights were recorded (following removal of the larynx from the lungs). The lungs, inflated with 10% neutral buffered formal saline (approximately 2 mL/100 g body weight), liver, and any abnormal tissue were preserved in 10% neutral buffered formol saline.

Statistics:

Where appropriate, test and control data were compared statistically using a two-sided Student's t-test. Body weight gains were calculated from the day 1 body weight value.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.04 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortality was present in this study

Clinical signs:

other: including salivation, lachrymation, hypoaesthesia, reduced breathing rate and increased breathing depth

Body weight:

Treated animals lost weight following exposure, although this loss was not statistically significantly different in terms of absolute body weight from controls. By day 15 there were no significant differences between test and control body weights.

Gross pathology:

One male exposed to 5.04 mg/L had pale lungs and another male in the same group had pale areas on the lungs. One female exposed to 5.04 mg/L had a red cervical lymph node and another female in the same group had pale spots on the spleen. These findings occurred as single incidences and are thought to be unrelated to treatment.

Other findings:

- Plasma Cholinesterase Activity: Inhibition was observed at day 2 to the extent of 53 % in the males and 80 % in the females. At the end of the observation period there was no significant difference between control and treated animals.
- Erythrocyte Cholinesterase Activity: At day 2 inhibition was apparent to the extent of 29 % in the males and 44 % in the females. At the end of the observation period significant depressions were still apparent in that the males showed a 20 % reduction and females a 12 % reduction.
- Organ weights: There were no effects on organ weight or organ:body weight ratio.
See table 1 and table 2 in ''Any other information on results incl tables''.

Table 1. Clinical observations during exposure (sexes combined)

Group	Time Into Exposure (mins)	Abnormalities
1 Control	45-164     195-225	Some animals have wet fur, some have stains around the snout.   As for 45-164 mins, except all have wet fur and most have stains around the snout.
2 5.04 mg/mL	3   15     46-226	All animals are salivating and have reduced breathing rate.   As for 3 mins, plus all have lachryrnation and reduced response tosound.   As for 15 mins, plus all have wetfur and increased breathing depth.

Table 2. Target Particulate Concentration mg/L test substance

Time into Exposure (mins)	Total Particulate Concentration (mg/L)	Analysed test substance concentration (mg/L)	% Total Particulate
10	5.02	4.75	94.6
35	5.09	4.77	93.7
60	5.10	4.74	92.9
84	5.16	4.85	94.0
110	4.87	4.57	93.8
141	4.94	4.59	92.9
168	5.13	4.68	91.2
199	5.06	4.67	92.3
228	5.00	4.65	93.0
Mean Standard Deviation	5.04 0.09	4.70 0.09	93.2 1.0

Interpretation of results:

GHS criteria not met

Conclusions:

Nose-only expoure for 4 hours to a particulate atmospheric concentration of the test substance exceeds the median lethal concentration of 5.04 mg/L.

Executive summary:

A group of 5 male and 5 female rats was exposed nose-only for a single four-hour period to the test substance at a target particulate concentration of 5 mg/L in a GLP compliant study following the principles of the OECD TG 403. A concurrent control group was similarly treated but was exposed only to air. The particulate concentration achieved was measured gravimetrically and found to be 5.04 mg/L (± 0.09). The atmospheric concentration of the test substance, analysed using gas chromatography, was 4.70 mg/L (± 0.09). The test atmosphere had a mass median aerodynamic diameter of 1.58 µm and a geometric standard deviation (GSD) of 1.49; the inhalable content (<15 µm AED) was 99.99% and the respirable content (<2.5 µm AED) was 86.85%.

Clinical signs indicative of irritancy and of a depressant effect on the nervous system were observed immediately after exposure. This depression was consistent with the initial reduction in plasma and erythrocyte cholinesterase activity in treated animals. By the end of the study this enzyme activity in the plasma was not significantly lower than controls, although the erythrocyte activity had not returned to control levels.
It is concluded that the median lethal concentration of the test substance exceeds 5.04 mg/L.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating conc.

Value:

> 5.04 mg/L air

Physical form:

inhalation: aerosol

Quality of whole database:

GLP compliant simliar to OECD 403 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:

23 Jun 1999 to 8 Jul 1999

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:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Version / remarks:

1998

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

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: Approximately 8-12 weeks old at the start of the study.
- Weight at study initiation: Males weighed 275-307 g and the females weighed 189-232 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 (%): 30-70
- Air changes (per hr): A minimum of 15 changes
- - Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: FROM: 23 Jun 1999 TO: 8 Jul 1999

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Preparation of the test site: 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.
- Area of exposure: The estimated amount applied per unit area of skin exposed was 9.8 - 14.5 mg/cm^2 for males and 6.7 - 8.2 mg/cm^2 for females (dorso-lumbar region)
- Coverage: Each dressing consisted of a foil backed patch (approximately 7 cm x 7 cm) to cover the treated area and was held in position using cohesive bandage (approximately 15 cm x 7.5 cm) around which was secured two pieces of surgical tape (approximately 2.5 cm wide).

REMOVAL OF TEST SUBSTANCE
- 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.

TEST MATERIAL
- Amount applied: To achieve the required dose of 2000 mg/kg, the volume applied was adjusted to take into account the specific gravity of the test substance. (As the specific gravity was 1.15, a dose-volume of 1.74 mL/kg was applied). The volume of the dose was calculated for each animal according to its weight at the time of dosing

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Frequency of observations and weighing: The animals were observed twice between one and five hours after application (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. The animals were weighed immediately before dosing (day 1) and on days 8 and 15.
- Necropsy of survivors performed: yes. 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:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

None of the animals died

Clinical signs:

other: No signs of systemic toxicity

Gross pathology:

One male had a speckled thymus. This is considered to be spontaneous finding which is incidental to treatment with the test substance.

Interpretation of results:

GHS criteria not met

Conclusions:

The acute dermal LD50 of the test substance is estimated to be in excess of 2000 mg/kg to male and female rats.

Executive summary:

A group of 5 male and 5 female Alpk:APrSD (Wistar-derived) rats received a single dermal occlusive application of 2000 mg/kg of the test substance in a study performed under GLP and according to OECD TG 402. 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 signs of systemic toxicity. Signs of slight skin irritation were seen in all animals but had completely resolved by day 7. All animals showed an overall body weight gain during the study. There were no compound-related abnormalities at examination post-mortem.

Based on these findings, the acute dermal LD50 of the test substance is estimated to be in excess of 2000 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 toxicity: oral
In an acute oral toxicity study, groups of 5 male and 5 female Alpk:APrSD (Wistar-derived) rats received a single oral dose of 500, 1000 or 2000 mg/kg of the test substance in a study performed under GLP according to OECD TG 401. 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. Animals in extremis, and those surviving to the end of the study were killed and subjected to a macroscopic examination post-mortem. Following a dose of 500 mg/kg, none of the animals died. Signs of slight systemic toxicity were seen in most animals, with complete recovery by day 5. All animals showed an overall body weight gain during the study. There were no treatment-related abnormalities at examination post mortem. Following a dose of 1000 mg/kg, none of the animals died. Signs of slight or moderate toxicity were seen in all animals, with complete recovery by day 5 in the males and day 8 in the females. All animals showed an overall body weight gain during the study. There were no macroscopic abnormalities at examination post-mortem. Following a dose of 2000 mg/kg, all the animals were killed in extremis on days 2 or 3. At examination post mortem, treatment-related abnormalities comprised staining/discharge from the eye, red nares, fluid stomach contents and (in one female) reddening of the pancreas.
Based on these findings, the acute oral median lethal dose (LD50) of the test substance is estimated to be 1414 mg/kg (95% confidence limits 1000, 2000) to male and female rats.

Acute toxicity: inhalation
In an acute inhalation toxicity study, a group of 5 male and 5 female Alpk:APrSD (Wistar-derived) rats was exposed nose-only for a single four-hour period to the test substance at a target particulate concentration of 5 mg/L in a GLP compliant study following the principles of the OECD TG 403. A concurrent control group was similarly treated but was exposed only to air. The particulate concentration achieved was measured gravimetrically and found to be 5.04 mg/L (± 0.09). The atmospheric concentration of the test substance, analysed using gas chromatography, was 4.70 mg/L (± 0.09). The test atmosphere had a mass median aerodynamic diameter of 1.58 µm and a geometric standard deviation (GSD) of 1.49; the inhalable content (<15 µm AED) was 99.99% and the respirable content (<2.5 µm AED) was 86.85%. Clinical signs indicative of irritancy and of a depressant effect on the nervous system were observed immediately after exposure. This depression was consistent with the initial reduction in plasma and erythrocyte cholinesterase activity in treated animals. By the end of the study this enzyme activity in the plasma was not significantly lower than controls, although the erythrocyte activity had not returned to control levels.
It is concluded that the median lethal concentration of the test substance exceeds 5.04 mg/L.

Acute toxicity: dermal
A group of 5 male and 5 female Alpk:APrSD (Wistar-derived) rats received a single occlusive dermal application of 2000 mg/kg bw of the test substance in a study performed under GLP and according to OECD TG 402. 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 signs of systemic toxicity. Signs of slight skin irritation were seen in all animals but had completely resolved by day 7. All animals showed an overall body weight gain during the study. There were no compound-related abnormalities at examination post-mortem.
Based on these findings, the acute dermal LD50 of the test substance is estimated to be in excess of 2000 mg/kg bw to male and female rats.

Justification for classification or non-classification

Based on the result of the acute oral toxicity study, the test substance is classified as Acute Tox Oral Cat. 4; H302 harmful if swallowed, in accordance with EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation No. (EC) 1272/2008. Classification for the dermal and respiratory route is not warranted.