Pidolic acid

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 January 2017 to 22 February 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

2009

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

1998

GLP compliance:

yes (incl. QA statement)

Test type:

traditional method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Pidolic acid

EC Number:

202-700-3

EC Name:

Pidolic acid

Cas Number:

98-79-3

Molecular formula:

C5H7NO3

IUPAC Name:

5-oxo-L-proline

Test material form:

solid: particulate/powder

Details on test material:

white solid crystalline powder

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material:
- Batch Number: 20140124
- Purity: 99.92%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: white crystalline solid, room temperature in the dark.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing (e.g. warming, grinding): In order to facilitate aerosolisation and reduce particle size, the test item was ground using a Retsch Planetary Ball Mill (Retsch (UK) Ltd, UK) prior to use. The absorption of the test item was not determined.

FORM AS APPLIED IN THE TEST (if different from that of starting material)
- Specify the relevant form characteristics if different from those in the starting material, such as state of aggregation, shape of particles or particle size distribution: Aerosol

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: male and female RccHan : WIST strain rats were supplied by Envigo RMS (UK) Limited Oxon, UK.
- Females (if applicable) nulliparous and non-pregnant: Yes
- Age at study initiation: 8 to 12 weeks old
- Weight at study initiation: 200 - 350 g
- Housing: The animals were housed in groups of up to five by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes.
- Diet (e.g. ad libitum): With the exception tot he exposure period, free access to mains drinking water and food was allowed throughout the study.
- Water (e.g. ad libitum): With the exception tot he exposure period, free access to mains drinking water and food was allowed throughout the study.
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- The temperature and relative humidity were set to achieve limits of 19 to 25 degrees and 30 - 70% respectively. The rate of air exchange was at least fifteen changes per hour and the lighting was controlled by a time switch to give 12 hours continuous light and 12 hours continuous dark. The animals were retained in this accommodation at all times except during the exposure period.

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

3.65 µm

Geometric standard deviation (GSD):

3.06

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: A dust atmosphere was produced from the test item using a SAG 410 Solid Aerosol Generator (TOPAS GmbH, Dresden, Germany) located adjacent to the exposure chamber. The SAG 410 was connected to a metered compressed air supply.
- Exposure chamber volume: The cylindrical exposure chamber has a volume of approximately 30 liters.
- Method of holding animals in test chamber: individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber and sealed by means of a rubber O ring.
- Source and rate of air (airflow): Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the SAG 410.
- Method of conditioning air: Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the SAG 410.
- System of generating particulates/aerosols: A dust atmosphere was produced from the test item using a SAG 410 Solid Aerosol Generator (TOPAS GmbH, Dresden, Germany) located adjacent to the exposure chamber.
- Method of particle size determination: The particle size of the generated atmosphere inside the exposure chamber was determined three times during the exposure period using a Marple Personal Cascade Impactor (Wetech IS Ltd, Beds., UK).
- Treatment of exhaust air: the extract from the exposure chamber passed through a scrubber tap and was connected with a high efficiency filter to a metered exhaust system. The chamber was maintained under negative pressure.
- Temperature, humidity, pressure in air chamber: The temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter located in a vacant port in the animals breathing zone of the chamber and recorded every 30 minutes throughout the 4-hour exposure period.

TEST ATMOSPHERE
- Brief description of analytical method and equipment used: The actual chamber concentration was measured at regular intervals during each exposure period. The gravimetric method used glass fiber filters placed in a filter holder.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: the proportion percentage of aerosol less than 10.4, 7.7, 4.1, 1.3, 0.9 and 0.56 um um was calculated.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): MMAD was determined (as the 50% point). GSD was calculated.

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

4 h

Concentrations:

5.00 mg/L

No. of animals per sex per dose:

10 (5 males, 5 females)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days or 35 days
- Frequency of observations and weighing: at hourly intervals during exposure, 1 hour after termination of exposure and subsequently once daily for 14 or 35 days
- Necropsy of survivors performed: yes
- Clinical signs including body weight: Individual body weights were recorded on arrival, prior to treatment on the day of exposure and on days 1, 3, 7 and 14 (all animals) and days 28 and 35 (males only)
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: all animals were observed for clinical signs at hourly intervals during exposure immediately on removal from the restraining tubes at the end of exposure, 1 hour after termination of exposure and subsequently once daily for 14 or 35 days. During necropsy, the respiratory tract was subjected to a detailed macroscopic examination for signs of irritancy or local toxicity.

Results and discussion

Effect levels

Effect levels 1

Key result

Sex:

female

Dose descriptor:

LC50

Effect level:

> 5 mg/L air (nominal)

Based on:

test mat. (dissolved fraction)

Exp. duration:

4 h

Effect levels 2

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

> 5 mg/L air (nominal)

Based on:

test mat. (dissolved fraction)

Exp. duration:

4 h

Mortality:

None. All animals survived until termination

Clinical signs:

irregular respiration

Remarks:

decreased respiration, noisy respiration

Body weight:

- other body weight observations:
all males and two females showed body weigh loss 1 day after dosing. Incidents of body weight loss or no gain in body weight were noted between days 1 to 14. One male showed no gain in bod weight from Day 28 to 35.

Gross pathology:

Dark patches on the lungs were noted at necropsy of one female. No macroscopic abnormalities were noted at necropsy of the remaining animals.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The acute inhalation median lethal concentration (LC50) of the test item in the Wistar strain rat was estimated to be greater than 5.00 mg/L.

Executive summary:

A study was performed to assess the acute inhalation toxicity of the test item in the Wistar strain rat. A troup of ten rates (five males and five females) were exposed to a dust atmosphere (5mg/L) of the test item for 4 hours using a nose only exposure system, followed by a 14 or 35 days observation period. Clinical signs and body weight development were monitored during the study. All animals were subjected to gross necropsy. There were no deaths. The acute inhalation median lethal concentration (LC50) of the test item in the Wistar strain rat was estimated to be greater than 5.00 mg/L.