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Toxicological information

Neurotoxicity

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Description of key information

A supportive GLP, oral, developmental neurotoxicity study with isopropanol (IPA) conducted according to OECD Guideline 426 in Sprague-Dawley rats reported a NOAEL of 700 mg/kg bw  for maternal toxicity effects, and a developmental neurotoxicity NOAEL of 1,200 mg/kg bw (the highest dose tested).  A supportive 9 to 13-week inhalational toxicity study in rats (comparable to OECD Guideline 413) did not report a NOAEL at the only concentration level tested (5000 ppm).

Key value for chemical safety assessment

Effect on neurotoxicity: via oral route

Endpoint conclusion
Dose descriptor:
NOAEL
700 mg/kg bw/day

Additional information

The neurotoxicity of isopropanol (IPA) was evaluated in a supportive GLP, oral developmental neurotoxicity study, in Sprague-Dawley rats (Bates and de Serres, 1991). This study was conducted according to OECD Guideline 426. Pregnant rats were exposed to 200, 700, or 1200 mg/kg bw/day from gestation days 6 through 21. Dams were allowed to undergo parturition and selected offspring were assessed for motor activity, auditory startle reflex habituation, and habituation tests. One subset of animals was sacrificed on post natal day 22 for neuropathological and brain weight measurements. One dam in the 1200 mg/kg group died on post natal Day 15. There were no significant findings in any of the assessed parameters. The NOAEL for developmental neurotoxicity was the highest dose tested, 1200 mg/kg bw. The NOAEL for maternal toxicity was 700 mg/kg bw due to the death of 1 dam at the 1200 mg/kg bw dose level.

 

A supportive 9 to 13-week inhalational toxicity study conducted according to OECD Guideline 413 did not report a NOAEL at the only IPA concentration level tested (5000 ppm) (Burleigh-Flayer and Hurley, 1994). Findings at the 5000 ppm dose level included hypoactivity and lack of startle activity in some rats, transient changes in body weight, and recoverable increases in mean cumulative motor activity. An acute inhalation study available in the public domain (Gill et al., J appl Toxicol 1995; see chapter 7.2.2), reported acute transient concentration-related narcosis and/or sedation and minor decreases in motor function after IPA treatment. This would lead to classification as STOT 3, H336. In addition, IPA is classified STOT3/H336 in Annex V1 (index #: 603-117-00-0)

Justification for classification or non-classification

According to CLP classification criteria, the substance does meet the criteria for classification and labelling for this endpoint (STOT single exposure category 3, H336 - May cause drowsiness or dizziness), as set out in Regulation (EC) No. 1272/2008.