3-methylpyridine

Endpoint summary

Description of key information

This substance, along with other pyridines of similar structure, has moderate acute oral, dermal and inhalation toxicity.

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:

1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well conducted study similar to OECD 401 protocol. The study was done prior to implementation of GLPs.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Doses:

320, 630, 1,300, 2,000, 3,200, 5,000 mg/kg

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Daily
- Necropsy of survivors performed: no
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: Clinical signs

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

630 mg/kg bw

Based on:

test mat.

Mortality:

320 mg/kg - 0/3
630 mg/kg - 1/3
1,300 mg/kg - 3/3
2,000 mg/kg - 3/3
3,200 mg/kg - 3/3
5,000 mg/kg - 3/3

Clinical signs:

other: 320 mg/kg = lethargy and watery eyes 630, 1,300 and 2,000 mg/kg = lethargy, watery eyes, loss of motor coordination, excessive salivation, rapid shallow breathing and unconsciousness 3,200 mg/kg = watery eyes, excessive salivation, rapid shallow breathing

Interpretation of results:

Toxicity Category IV

Remarks:

Migrated information meets criteria of 300 mg/kg bw < LD50 < 2000 mg/kg bw. Criteria used for interpretation of results: EU

Conclusions:

The oral LD50 of b-picoline in male Fisher rats was approximately 630 mg/kg. This meets the criteria for classification as Category 4 according to Regulation EC No. 1272/2008.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

630 mg/kg bw

Quality of whole database:

adequate

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Reliable with restrictions; acceptable, well-documented publication/study report which meets basic scientific principles.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Rats were exposed (nose-only) to vapours of test material for a single 4 hour period. Clinical signs were note. Lethality and weight gain was followed for 14 days after exposure to determine levels associated with acute lethality.

GLP compliance:

not specified

Test type:

standard acute method

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

Rats were 8 weeks of age, weighing between 237 and 279 g.

Route of administration:

inhalation: vapour

Type of inhalation exposure:

nose only

Vehicle:

not specified

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gas chromatography

Duration of exposure:

4 h

Concentrations:

1300 and 3300 ppm, equivalent to about 5000 mg/m3 and 12,500 mg/m3, respectively

No. of animals per sex per dose:

6 rats/sex/group

Control animals:

no

Details on study design:

Rats were weighed prior to exposure and observed during exposure. Surviving rats were weighed and observed daily for 14 days post exposure, weekends excluded except when deemed necessary by the rats’ condition. Except during exposure, feed and water were available ad libitum.

Sex:

male

Dose descriptor:

LC50

Effect level:

> 1 300 - < 3 300 ppm

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Deaths at 1300 ppm: 0/6, Deaths at 3300 ppm: 6/6.

Mortality:

Deaths at 1300 ppm: 0/6,
Deaths at 3300 ppm: 6/6.

Interpretation of results:

Toxicity Category IV

Remarks:

Migrated information 2500 < LC50 <10000 ppm. Criteria used for interpretation of results: EU

Conclusions:

The lethality of inhalation exposure to 3-picoline (3-methylpyridine) was investigated in male rats. The LC50 was between 1300 ppm and 3300 ppm, which spans 2 hazard categories. No deaths were observed at the low concentration of 1300 ppm. A middle value of 2500 ppm is chosen as the LD50, equivalent to 9521 mg/m3 or 9.5 mg/L, which is at the threshold between two classification categories. Considering the consistent behaviour of this substance with other category members, and the fact that two other category members show inhalation lethality at ranges above 10 mg/L, this substance is placed in GHS category 4.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

9 521 mg/m³ air

Quality of whole database:

adequate

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:

1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well-conducted study similar to OECD 402 protocol.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rabbit

Strain:

New Zealand White

Sex:

not specified

Type of coverage:

not specified

Vehicle:

unchanged (no vehicle)

Duration of exposure:

24 Hours

Doses:

200, 800, 2000 mg/kg

No. of animals per sex per dose:

2/dose

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Observations - daily
- Necropsy of survivors performed: no
- Other examinations performed: clinical signs, body weight

Sex:

not specified

Dose descriptor:

LD50

Effect level:

> 800 - < 2 000 mg/kg bw

Based on:

test mat.

Mortality:

200 mg/kg -0/2
800 mg/kg - 0/2
2,000 mg/kg - 2/2

Clinical signs:

other: 200 mg/kg - lethargy 800 mg/kg - lethargy, apparent loss of appetite and semi-consciousness 2,000 mg/kg - semi-consciousness, watery eyes and rapid shallow breathing

Moderate redness, slight to moderate swelling and moderate necrosis were observed on the application sites of surviving rabbits 24 hours post exposure.

Interpretation of results:

Toxicity Category IV

Remarks:

Migrated information Meets criteria of 300 mg/kg bw < LD50 < 2000 mg/kg bw. Criteria used for interpretation of results: EU

Conclusions:

The dermal LD50 of b-picoline in rabbits was > 800 and < 2000 mg/kg bw. The substance is classified as Category 4 according to Regulation EC No. 1272/2008.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

1 000 mg/kg bw

Quality of whole database:

adequate

Additional information

The acute oral toxicity LD50 value for 3-methylpyridine is 630 mg/kg bw.  The acute inhalation LD50 is greater than 1300 but less than 3300 ppm, and the value of 2500 ppm is selected as a midpoint value. This corresponds to an LC50 of 9521 mg/m3.

The acute dermal LD50 is greater than 400 mg/kg bw, a value where there were no deaths among 5 exposed rats (Oley, 2008). The value selected for the dermal LD50 is 1000 mg/kg bw, based on the findings in rabbits of Fitzgerald et.al, 1991, where the LD50 was less than 1000 mg/kg bw, and Carreon, 1982, where the LD50 in rabbits was > 1000 and < 2000 mg/kg bw.

Justification for selection of acute toxicity – oral endpoint
Experimental value

Justification for selection of acute toxicity – inhalation endpoint
Experimental value

Justification for selection of acute toxicity – dermal endpoint
experimental value in rabbits

Justification for classification or non-classification

3 -Methylpyridine shows acute toxicity LD50 values of 630 mg/kg via the oral route, placing it in Category 4 (between 300 and 2000 mg/kg). For the inhalation route, the LC50 is 2500 ppm or 9.52 mg/L (9521 mg/m3), at the threshold between two categories. Considering that other members of the chemical category (pyridine, 2 -methylpyridine and 4 -methylpyridine) show LC50 values of generally greater than 10, this substance is also placed in Category 4 (between 2500 and 20000 ppm or 10 -20 mg/L). Lastly, the dermal LD50 is greater than 400 mg/kg in rats. A value of 1000 mg/kg bw has been selected as the most appropriate single value based on experimental data in rabbits, placing the substance in Category 3. These classifications are comparable to or more conservative than those for the other members of the pyridine and methylpyridine category, according to Regulation (EC) No. 1272/2008.