4-methylpentan-2-ol

Endpoint summary

Description of key information

Studies with experimental animals indicate that MIBC is of low toxicity by the oral, dermal and inhalation routes of exposure.  MIBC has typical organic solvent effects in rats following acute inhalation exposures with anesthetic effects occurring at 10 mg/L (2360 ppm). The 4-h LC50 was greater than 16000 mg/m3 in rats.  The acute oral and dermal LD50 values for MIBC are 2590 mg/kg in rats and 2870 mg/kg in rabbits, respectively. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 590 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

discriminating conc.

Value:

16 000 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 870 mg/kg bw

Additional information

Acute Toxicity: Oral

The potential acute oral toxicity of methyl i-butylcarbinol was assessed in rats by Smyth et al, (1951). Although this study is lacking in methodological details, the work of this group pre-dates range finding toxicity guidelines and provided much of the basis for their development. Their results are cited by many subsequent authoritative review bodies and are often found in SIDS and SIAR documents via secondary references. Therefore, the results reported by this group are deemed reliable. In their investigation, Smyth et al. (1951) determined the LD50 of methyl i-butylcarbinol in rats to be 2590 mg/kg body weight as assessed following oral gavage administration of a range of methyl i-butylcarbinol doses (reported as 10, 1, 0.1, etc. g/kg body weight). 

  

Acute Toxicity: Dermal

The potential acute dermal toxicity of methyl i-butylcarbinol was assessed in rabbits (Smyth, 1951). As this test was conducted by the same investigators as discussed above, the results are deemed reliable, despite the lack of methodological details. The dermal LD50 of methyl i-butylcarbinol in rabbits was reported to be 3.56 mL/kg (2870 mg/kg) body weight.

 

Acute Toxicity: Inhalation

 

The potential acute inhalation toxicity of methyl i-butylcarbinol was assessed in Wistar rats in a study similar in methodology to OECD guidelines for the Testing of Chemicals No. 403 (Blair, 1981). Groups of 5 male and 5 female Wistar rats were exposed to 10000 or 16000 mg/m3 for 4 hours (whole-body exposure). The test atmosphere was generated using a wick-type saturator and was supplied to two identical glass inhalation chambers. The test atmosphere was passed through each chamber at a volume of 7 liters. The animals were observed for toxic signs continuously for the first 30 minutes and thereafter at 15 minute intervals throughout the exposure period. Over the following 14 days, animals were observed twice daily. Body weights were recorded initially and after 7 and 14 days. One female animal exposed to 16000 mg/m3 died at termination of exposure. All animals were anaesthetized within the first hour of exposure and all regained consciousness within half an hour in the 10000 mg/m3 group and all but one animal (a female that died) regained consciousness within 2 hours in the 16000 mg/m3 group. Body weights were normal and there were no signs of toxicity over the 14-day observation period in surviving animals. The inhalation LC50 of methyl i-butylcarbinol was determined to be greater than 16000 mg/m3.

Smyth et al (1951) reported that 5 out 6 rats died following inhalation exposure to 2000 ppm of methyl i-butylcarbinol for 8 hours. No other details were provided; however the work of Symth et al. (1951) has been deemed reliable.

Justification for classification or non-classification

The substance does not meet the criteria for classification and labelling for this endpoint, as set out in Regulation (EC) NO. 1272/2008.