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EC number: 201-162-7
CAS number: 78-96-6
Acute toxicity data indicate low toxicity: In rats the oral LD50 was
2813 mg/kg bw, in rabbits the dermal LD50 was approximately 1851 mg/kg
bw. An acute inhalation according to OECD403 is not available, but the
endpoint is assessed from the available toxicological data in rats and
mice (WoE). An acute inhalatory exposure study in rats for 6 hours at a
concentration of 1126 ppm (3460 mg/m3) failed to cause any deaths in
rats (LC50 was not determined).
Table 1: Mortality observed in animals during the study.
The 3 surviving animals of the
3104 mg/kg bw group were sacrificed on day 7.
In an acute oral toxicity study, comparable to OECD TG 401, US-rats
(5/sex/dose) were administered MIPA at 194-6208 mg/kg bw by single dose
(gavage) followed by a 14-days observation period. Clinical signs
included restlessness, stagger, creep, slight abdominal position,
anemia, mouth discharge, compulsive chewing, dyspnoea, apathy,
tonic-clonic convulsions, and overnight exitus. Surviving animals
recovered slowly and showed apathy, dyspnoea, partly slight stagger and
decelerated motion. Findings at necropsy included red discoloration of
abdominal viscus (6208 mg/kg bw dose group), reddish livid discoloration
of the abdominal viscus (at 3104 mg/kg bw), bowel irritation and
dilation of the stomach (at 2425 mg/kg bw), bronchitis, and
bronchiectasia. The LD50 was 2813 mg/kg bw.
In a second study, 6 male CDF albino rats were orally gavaged with test
substance given in the vehicle corn oil at doses of 500, 2000, 3500
mg/kg. The observation period was 2 weeks. Examination parameters were
mortality, clinical signs, body weight and macroscopically observations.
Lethargy, diarrhea and rough hair coats were observed in all rats. One
death occurred in the 2000 mg/kg exposure group and all animals died in
the 3500 mg/kg exposure group. There were no adverse effects observed
for animal body weights or for pathological observations.
Due to its relatively low volatility, there is a lack of data
documenting the acute inhalation toxicity. Hence, the endpoint is
assessed in a weight of evidence approach from the available
toxicological data. According to REACH annex XI, section 1 a testing
does not appear scientifically necessary, using the available
toxicological data with MIPA.
One report describes a study with Fischer F344 rats that inhaled 1126
ppm (3460 mg/m3) of the test substance ad an aerosol for 6 hours with a
14 day observation period. There were no animals found dead and no
clinical effects were described. In 2/6 animals, only slightly enlarged
livers were observed at the end of the study period. Deficiencies in the
data entry contradict the approach of a key study and in the weight of
evidence approach, two further studies are consulted. One report stated
that whole-body exposure of rats to a saturated MIPA atmosphere
(concentration not given) at 20°C for 8 hours failed to cause any
deaths, therefore no LC50 value has been determined for this compound.
Besides, neither clinical nor pathological effects were observed during
the study. In a third study on respiratory irritation, Swiss webster
mice were exposed to an aerosol with concentrations of 230 to 1005 mg/m3MIPA.
The 3-hour exposure caused sensory irritation (immediate onset) and
little pulmonary irritation (delayed onset). No mortality was observed.
Post-exposure recovery of the breathing frequency was moderate to good.
In an acute percutaneous absorption test in rabbits, MIPA was applied at
doses of 630 - 5000 mg/kg bw. Marked redness, moderate swelling, and
marked necrosis of the skin were observed. At all doses, rabbits were
lethargic. At doses of 630 and 1300 mg/kg bw, anorexia was observed, and
at a dose of 1300 mg/kg bw, diarrhea was observed. At necropsy at the
end of a 2-week observation period, no treatment-related changes were
noted. The LD50 was 1851 mg/kg bw.
The available experimental test data for acute oral and inhalation
toxicity studies are reliable and suitable for classification purposes
under Regulation 1272/2008, as amended for the tenth time in
Regulation (EU) No 2017/776. As a result the substance is not
considered to be classified for oral and inhalatory acute toxicity under
Regulation (EC) No. 1272/2008.
The limited available dermal acute toxicity data warrants
classification with Cat. 4; H312 according to the EU Classification,
Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC)
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