N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine

Endpoint summary

Description of key information

The oral acute toxicity is moderate indicated by oral LD50 values in rats of 1005 mg/kg bw for males and 893 mg/kg bw for females (Hatano Research Institute 1999). The dermal acute toxicity is low indicated by a dermal LD50 in rabbits higher than 3000 mg/kg bw (Monsanto Co. 1962, 1973, Randall and Bannister, 1990).

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP and guideline study; original reference in Japanese, compilation of data from English summary and tables

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

corn oil

Doses:

0, 250, 500, 1000, 2000 mg/kg bw

No. of animals per sex per dose:

5 per sex and dose

Control animals:

yes

Sex:

male

Dose descriptor:

LD50

Effect level:

1 005 mg/kg bw

95% CL:

711 - 1 604

Remarks on result:

other: clinical signs, pathological lesions in digestive organs and respiratory

Sex:

female

Dose descriptor:

LD50

Effect level:

893 mg/kg bw

95% CL:

634 - 1 346

Remarks on result:

other: clinical signs, pathological lesions in digestive organs and respiratory

RS-Freetext:
LD50: 1005 mg/kg (95% confidence limit: 711-1604 mg/kg)

MORTALITY:
-Time of death: day 2-4 p.a.
-Number of deaths at each dose males : 0/5, 0/5, 0/5, 2/5, 5/5

-Number of deaths at each dose females: 0/5, 0/5, 0/5, 3/5, 5/5

CLINICAL SIGNS:
from 500 mg/kg males and females: reduced volume of feces; 
from 1000 mg/kg: hypoactivity, diarrhea, bradypnea,
hypothermia, prone position;
2000 mg/kg males: abnormal gait

2000 mg/kg: lacrimation, weakness of limbs

NECROPSY FINDINGS:
pathological lesions in digestive organs and respiratory
system

POTENTIAL TARGET ORGANS:
not reported

SEX-SPECIFIC DIFFERENCES:
male rats were less sensitive than female rats

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

893 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles, data from summary without detailed documentation, acceptable for assessment

Principles of method if other than guideline:

Method: other acute dermal toxicity study

GLP compliance:

no

Test type:

other: acute toxicity study

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Type of coverage:

semiocclusive

Vehicle:

other: undiluted (warmed to 115°F to liquefy)

Duration of exposure:

24 h

Doses:

3160, 5010, 7940 mg/kg bw

No. of animals per sex per dose:

1 to 2

Control animals:

not required

Sex:

not specified

Dose descriptor:

LD50

Effect level:

> 7 940 mg/kg bw

Remarks on result:

other: reduced appetite and activity three to seven days

RS-Freetext:
MORTALITY:
-Number of deaths at each dose: no deaths

CLINICAL SIGNS:
reduced appetite and activity for 3-7 days

NECROPSY FINDINGS:
viscera appeared normal

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

7 940 mg/kg bw

Quality of whole database:

Two studies are available; LD50 > 3100 in both studies.

Additional information

Acute toxicity: oral

The acute oral toxicity of 6PPD was evaluated in a GLP and OECD guideline study (TG 401) (Hatano Research Institute 1999). In this OECD study 5 male and 5 female rats were dosed with 0, 250, 500, 1000 and 2000 mg 6PPD/kg bw in corn oil by gavage. Deaths occurred at day 2 to 4 p. a. at 1000 mg/kg (2/5 males and 3/5 females) and at 2000 mg/kg (all animals), resulting in LD50 values between 1000 - 2000 mg/kg for male rats and 500 - 1000 mg/kg for female rats. Signs of intoxication were hypoactivity, diarrhea, bradypnea, hypothermia and a prone position in the 1000 mg/kg or higher dosed groups, abnormal gait in 2000 mg/kg males, and lacrimation and weakness of limbs in 2000 mg/kg females. Pathological lesions were observed in digestive organs and the respiratory system (Hatano Research Institute, 1999).

Based on data from this study an oral LD50 value for male rats of 1005 mg/kg bw and an oral LD50 of 893 mg/kg bw for female rats were calculated (OECD SIDS 2005).

In another acute oral toxicity study (Monsanto Co., 1991a) done under GLP according to EPA OTS 798.1175 (Acute Oral Toxicity) Sprague-Dawley rats were dosed with warmed 6PPD. The solid test substance was warmed to 55°C to produce a liquid and then allowed to cool to 50°C for dosing. The density of the liquid test article was determined to be 1.00 g/ml. A dose-rage finding study was done up to 5000 mg/kg bw with one animal per dose and sex. One male died at 5000 mg/kg bw; whereas no death occurred in treated females up to 5000 mg/kg bw. Following the range-finding test, a limit test was performed in which one group of five male and five female rats received a single oral dose of the test substance at a dose of 5000 mg/kg bw. Following dosing, the rats were observed daily and weighed weekly. A gross necropsy examination was performed on all animals at the scheduled sacrifice (day 15). Death occurred in 2/5 males and in 1/5 females. The most notable clinical signs included decreased fecal output, fecal/urine stains, rough coat, piloerection, diarrhea/soft stools and dark material around the facial area. Body weight loss was noted in one surviving male and three surviving females during the test period. Body weight gain was exhibited by all other surviving animals during the study. The most notable internal necropsy finding consisted of black, hard (rock-like) material contents in the stomach. This finding occurred in the surviving animals as well as in those that died. Additional findings which occurred in the animals that died included black/yellow-green mucoid contents throughout the digestive tract eroded areas with perforations of the stomach and reddened mucosa/dark red foci of the stomach. Based on findings from this study an acute oral LD50 greater than 5000 mg/kg bw was estimated.

Studies from 1962 and 1973 reported oral LD50 values in the range of 3340 - 3580 mg/kg bw.

In the study from 1962 groups of 5 Sprague-Dawley rats were fed undiluted 6PPD by stomach tube in dosages of 2510, 3160, 3980 (3 females and 2 males each) and 5010 mg/kg bw (4 males and 1 female). Deaths occurred within 2-5 days. Number of deaths for the 4 dose groups were 1/3 females, 1/3 females and 1/2 males, 3/3 females as well as 5/5 in the highest dose group. Signs of intoxication were collapse within 15 - 30 minutes after application, which in some cases was followed by recovery after several hours; severe diarrhea, loss of appetite, salivation and dyspnea were also noted. Necropsy revealed an inflammation of the gastric mucosa as well as renal and liver congestion (Monsanto Co.1962). Gavage application of 6PPD (undiluted test substance warmed to 115°F to liquefy) in doses of 2510, 3160, 3980, 5010 and 6310 mg/kg bw resulted in death of 1, 2, 3, 3 or 4 of the 5 rats/dose (males and females mixed) (Monsanto Co 1973, Randall and Bannister, 1990). Clinical signs included reduced appetite and activity (lasting 2 to 5 days in survivors), increasing weakness, diarrhea, ocular discharge, collapse and death. Autopsy of decedents showed hemorrhagic lungs, liver discoloration (jaundiced) and acute gastrointestinal inflammation. Slight liver discoloration was found at sacrifice in some survivors (Monsanto Co. 1973, Randall and Bannister, 1990).

The inconsistent range of oral LD50 values can be explained by the substance preparation which influences the bioavailability after oral application. According to the OECD guideline in the study of Ohara (Hatano Research Institute 1999) 6PPD as a lipophilic substance was dissolved in corn oil as a suitable vehicle whereas other studies either applied undissolved (Monsanto Co. 1962) or undiluted test substance warmed to 46CF to liquefy 6PPD (Monsanto Co. 1973, Randall and Bannister, 1990, Monsanto Co. 1991a).

Acute toxicity: dermal

There are no studies according to the current OECD guideline but there are 2 older studies which give sufficient information to evaluate this endpoint. No mortality was observed after a 24-hour semi-occlusive application of 3160, 5010 or 7940 mg 6PPD/kg bw to the clipped intact skin of 2 rabbits/dose (LD50 > 7940 mg/kg bw). Reduced appetite and activity for 3-7 days were the only clinical signs, whereas the viscera appeared normal (Monsanto Co. 1973, Randall and Bannister, 1990). In a second study 6PPD was applied at doses of 798, 1260, 2000, 3160, 5010, 7980 mg/kg bw (1 rabbit/dose) under a dressing of plastic strips. Doses of>5010 mg/kg bw caused mortality after 10-11 days accompanied by loss of appetite, lethargy and gradual wasting. Gross autopsy yielded liver discoloration and pulmonary hyperemia. According to this study the lethal dose is in the range between 3160 and 5010 mg/kg bw (Monsanto Co. 1962).

Conclusion:

Oral

The acute oral toxicity of 6PPD was evaluated in a GLP and OECD guideline study (TG 401) (Hatano Research Institute 1999). The rats dosed with 0, 250, 500, 1000 and 2000 mg 6PPD/kg bw in corn oil by gavage. Deaths occurred at 1000 mg/kg (2/5 males and 3/5 females) and at 2000 mg/kg (all animals). Clinical signs observed included decreased fecal output, fecal/urine stains, rough coat, piloerection, diarrhea/soft stools and dark material around the facial area. An oral LD50 value of 1005 mg/kg bw for males and 893 mg/kg bw for females were calculated (OECD SIDS 2005).

In another GLP and guideline study (EPA OTS 798.1175) Sprague-Dawley rats were orally dosed with warmed 6PPD (Monsanto Co. 1991a). Following a range-finding test, a limit test was performed with 5000 mg 6PPD/kg bw. Death occurred in 2/5 males and in 1/5 females. The most notable clinical signs included decreased fecal output, fecal/urine stains, rough coat, piloerection, diarrhea/soft stools and dark material around the facial area. Based on findings from this study an acute oral LD50 greater than 5000 mg/kg bw was estimated. Earlier studies from 1962 and 1973 reported oral LD50 values in the range of 3340 - 3580 mg/kg bw (Monsanto Co. 1962, 1973).

It is suggested that the findings from the Hatano Research Institute (1999) are the most relevant because of the higher bioavailability. Based on the calculated oral LD50 of 893 mg/kg 6PPD should be classified as harmful if swallowed.

Dermal

There are no studies according to the current OECD guideline but there are 2 older studies which give sufficient information to evaluate this endpoint. The dermal LD50 in rabbits was > 3000 mg/kg bw (Monsanto Co. 1962, 1973, Randall 1990). Signs of intoxication were reduced food consumption, hypoactivity and lethargy.

Justification for classification or non-classification

Based on the findings of the above mentioned GLP and OECD guideline study (Hatano Research Institute 1999, LD50 893 mg/kg bw) the test substance 6PPD is classified as harmful if swallowed to the classification criteria 67/548/EEC and regulation no. 1272/2008 (GHS).