Nitrapyrin

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

other: Supporting information on product containing nitrapyrin

Adequacy of study:

key study

Study period:

5 June 2007 to 27 July 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to valid guidelines, and the study was conducted under GLP conditions. Since the study was conducted with a formulation, containing only 17.9 % w/w registered substance, the data have been used in a read-across approach and the study has been assigned a reliability score of 2.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Reported as European Economic Community; Methods for the Determination of Toxicity; Official Journal of the European Communities, Vol. 35, No. L 383 A, December 29 1992.

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: JMAFF, Acute Inhalation Toxicity Study (2000)

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

GF-2017

IUPAC Name:

GF-2017

Test material form:

other: liquid (unspecified)

Details on test material:

- Appearance: liquid, tan opaque

Test animals

Species:

rat

Strain:

other: F344/DuCrl

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately 9 weeks at the time of exposure
- Housing: The animals were housed two/three per cage in stainless steel cages during the acclimation period and, after assignment, animals were housed one per cage in stainless steel cages. Cages had wire mesh floors and were suspended above absorbent paper. Non-woven gauze was placed in the cages to provide a cushion from the flooring for the rodents' feet. The gauze also provided environmental enrichment.
- Diet: ad libitum except during the 2-hour acclimation period the day prior to exposure and during the 4-hour exposure period.
- Water: Municipal water was provided ad libitum except during the 2-hour acclimation period the day prior to exposure and during the 4-hour exposure period.
- Acclimation period: Animals were acclimated to the laboratory for at least one week prior to the start of the study. Animals were also acclimated to the nose cones for at least two hours on the day preceding exposure to the test material.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 1 °C
- Humidity (%): 40 - 70 %
- Air changes (per hr): 12 - 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours of darkness / 12 hours of light (06:00 to 18:00)

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

CHAMBERS
A modified 42 L, ADG nose-only chamber [30 cm in diameter by 60 cm high] was used for the study (Figure 1). Compressed filtered air supplied to the chamber was at ambient temperature. Airflow through the chamber was determined with a manometer, which measured the pressure drop across a calibrated orifice plate and was maintained at approximately 30 litres per minute, which was sufficient to provide the normal concentration of oxygen to the animals and approximately 43 air changes per hour. The manometer was calibrated with a gas meter prior to the start of the study. The chamber was operated at a slightly positive pressure relative to the surrounding area and was contained within a secondary vented area. Chamber and exposure room temperature were recorded from two thermocouples attached to an electronic digital thermometer, one thermocouple extended into the exposure chamber and the second was stationed next to the chamber. Chamber relative humidity was monitored by a hygrometer stationed in the interior of the chamber.
Based on the 30 litre per minute flow rate, the theoretical equilibrium time to 99 % (T99) of the target concentration was 6.4 minutes. The animals were placed on the chamber after the T99 had elapsed and were removed after 240 minutes of exposure.

GENERATION SYSTEM
A liquid aerosol of test material was generated by metering the test material with an FMI pump into a stainless steel spray nozzle. The test material was mixed with compressed air in the spray nozzle and the aerosol was sprayed into the chamber. Since the formulation contained materials of varying vapour pressures, the test material was not recycled.

EXPOSURE CONDITIONS
Exposure room temperature, chamber temperature, humidity and airflow were monitored continuously and recorded approximately every 30 minutes during the exposure period.

EXPOSURE CONCENTRATION
The mass concentration of aerosol present in the chamber was determined gravimetrically three times during the exposure period. Each gravimetric sample was taken by drawing air samples, at 1 L/minute, through a sampling probe located in the breathing zone of the animals (Figure 1). Aerosol particles were collected on pre-weighed 0.45 µm PTFE laminated 47 mm filters. A substantial portion of the exposure chamber atmosphere consisted of vapour (primarily the solvent vehicle); therefore, vapour samples were collected using two silica sorbent tubes in-line with the PTFE filter. Background measurements of water vapour in the chamber were taken approximately 45 minutes after placing the animals on the chamber. Chamber concentration of the formulation was calculated using only the net weight of the dry filter (24-hour drying time) and the percent active ingredient in the formulation.
The nominal concentration was calculated based on the amount of test material fed into the generation system divided by the total chamber airflow during the exposure period.

PARTICLE SIZE DETERMINATION
The aerodynamic particle size was determined twice during the exposure period through a multi-stage cascade impactor (Figure 1). The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD; σg) were determined for each sample as well as the average of both samples.
A sorbent tube was placed in-line with the cascade impactor to trap vapours to prevent contamination of the pump used to draw the samples.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

3.51 mg/L

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
A cage-side examination was conducted at least once a day, approximately at the same time each day (usually in the morning). This examination was typically performed with the animals in their cages and was designed to detect significant clinical abnormalities that were clearly visible upon a limited examination, and to monitor the general health of the animals. The animals were not hand-held for these observations unless deemed necessary. Significant abnormalities that could be observed include, but are not limited to: decreased/increased activity, repetitive behaviour, vocalisation, incoordination/limping, injury, neuromuscular function (convulsion, fasciculation, tremor, twitches), altered respiration, blue/pale skin and mucous membranes, severe eye injury (rupture), alterations in faecal consistency, and faecal/urinary quantity. In addition, all animals were observed for morbidity, mortality, and the availability of feed and water at least twice daily. Animals were weighed and examined prior to exposure to the test material and observed at least every 30 minutes during the exposure period. All rats were weighed on test days 2, 4, 8, 11, and 15 during the two-week post-exposure period.
- Necropsy of survivors performed: yes
All rats were submitted for a complete gross necropsy examination on test day 15. The rats were anaesthetised by inhalation of carbon dioxide and euthanised. The necropsy included examination of the eyes with a microscope slide using fluorescent illumination. Tissues were not saved and no histopathologic examination was performed.
- Other examinations performed: yes (detailed clinical observations)
Detailed clinical observations (DCO) were conducted on all animals pre-exposure and daily following the start of treatment. The DCO was conducted on all animals, at approximately the same time each day. The examination included cage-side, hand-held and open-field observations that were recorded categorically or using explicitly defined scales.

Statistics:

Means and standard deviations were calculated for descriptive purposes for chamber concentration (mean only), animal body weights, exposure room temperature and chamber temperature, humidity, and airflow.

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 3.51 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Effect levels 2

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 0.63 mg/L air

Based on:

act. ingr.

Exp. duration:

4 h

Remarks on result:

other: This value was not quoted in the study report; it was calculated using the concentration (percentage weight) of the active ingredient.

Mortality:

All animals survived the four-hour exposure to the test material as well as the two week post-exposure period.

Clinical signs:

other: There were no clinical effects noted during the four-hour exposure. There were also no in-life observations noted during the two-week observation period.

Body weight:

Mean body weight losses of 0.6 and 1.8 % were noted for male and female rats, respectively, on test day 2. Pre-exposure mean body weight values were exceeded on test day 4.

Gross pathology:

There were no treatment-related visible lesions noted in any of the rats exposed to test material at the test day 15-scheduled necropsy.

Any other information on results incl. tables

Chamber Summary Data

The resulting time-weighted average (TWA) concentration was 3.51 mg/L; the nominal concentration was 91.0 mg/L. Although the TWA concentration was below the target exposure concentration of 5 mg/L, it was the highest attainable stable aerosol concentration with a respirable particle size. The difference between the gravimetric and the nominal concentration was due to the loss of test material coating the walls of the generation apparatus and exposure chamber and the inefficiency of the generation system employed.

The average chamber temperature and relative humidity were 22.7 ± 0.9 °C and 63.8 ± 4.7 %, respectively. The average exposure room temperature was 19.1 ± 0.3 °C. Airflow was maintained at 30 litres per minute.

Based on two determinations, the mean MMAD of the particles was 2.84 µm with an average geometric standard deviation of 2.65. Approximately 23 % of the particle mass was contained in a size fraction with an aerodynamic diameter less than 1.3 µm. Approximately 76 % of the particulate mass was present in size fractions with an aerodynamic diameter less than 6.1 µm.

Applicant's summary and conclusion

Interpretation of results:

not classified

Conclusions:

Under the conditions of the study the acute inhalation LC50 of the test material was determined to be in excess of 3.51 mg/L for male and female rats.

Executive summary:

The acute inhalation toxicity of the test material was investigated in a study which was conducted under GLP conditions and in accordance with the standardised guidelines EPA OPPTS 870.1300, OECD 403, EU Method B.4 and the JMAFF guideline for acute inhalation toxicity.

During the study groups of five F344/DuCrl rats per sex were exposed for four hours, using a nose-only inhalation exposure system, to a time-weighted average chamber concentration of 3.51 mg test material per litre of air. The mass median aerodynamic diameter (MMAD) of particulate test material present in the exposure chamber test atmosphere averaged 2.84 µm with an average geometric standard deviation of 2.65. Approximately 23 % of the particle mass was contained in a size fraction with an aerodynamic diameter less than 1.3 µm. Approximately 76 % of the particulate mass was present in size fractions with an aerodynamic diameter less than 6.1 µm.

All animals survived the four-hour exposure to the test material as well as the two-week post-exposure period. There were no clinical effects noted during the four-hour exposure period or during the two-week observation period post-exposure. Mean body weight losses of 0.6 and 1.8 % were noted for male and female rats, respectively, on test day 2. Pre-exposure mean body weight values were exceeded on test day 4. There were no visible treatment-related lesions noted in any of the rats exposed to test material at the test day 15-scheduled necropsy.

Under the conditions of the study the acute inhalation LC50 of the test material was determined to be in excess of 3.51 mg/L for male and female rats.