1-butyl-2,3-dicyclohexyl-1-methylguanidine

Endpoint summary

Description of key information

Acute toxicity: Oral: LD50 females comprised between 50 and 300 mg mg/kg bw (K, Reliability 2)
Acute toxicity: Dermal: not applicable as the substance is classified as corrosive

Additional information

Acute toxicity: oral

In an acute oral toxicity study (Gerbeix, 2008), performed according to the test guidelines OECD No. 423 and EC 96/54, B.1 ter and in compliance with GLP, groups of fasted Sprague-Dawley female rats were administered a single oral dose of test substance in corn oil by gavage. The animals were observed for mortality, clinical signs and body weight for 14 days and then necropsied for macroscopic observations.

Three animals were first given an oral dose of 300 mg/kg bw. Death occurred in 1/3 females 2 hours after treatment. Hypoactivity then sedation, and dyspnea were observed prior to its death. Another female was found dead on day 13. Hypoactivity, piloerection, dyspnea, swollen abdomen, chromodacryorrhea, soft faeces and body weight loss were observed. In the surviving animal, hypoactivity, dyspnea and rhinorrhea were noted between day 1 and day 3. Dyspnea persisted until day 6.When compared to historical control animals, a slightly lower body weight gain was noted in the surviving female between day 1 and day 8 (returning to normal thereafter).

Three animals were then given an oral dose of 300 mg/kg bw in a confirmatory assay. Death occurred in 1/3 animals on day 2. Hypoactivity, piloerection and dyspnea were noted prior to its death. In the surviving animals, hypoactivity, piloerection and dyspnea were observed on day 1 only. A body weight loss was noted in 1/2 surviving animals between day 8 and day 15.At necropsy, no apparent abnormalities were observed in any animal.

As mortality and clinical signs occurred at 300 mg/kg bw, a lower dose was tested. Two independent and successive groups of 3 female rats each were given the dose of 50 mg/kg bw. No deaths and no clinical signs were observed at this dose-level. When compared to historical control animals, a slightly lower body weight gain was noted in 1/6 females between day 1 and day 8 (returning to normal thereafter). The body weight gain of the other animals was not affected by treatment with the test item.At necropsy, no apparent abnormalities were observed in any animal.

The oral LD₅₀of the test item was comprised between 50 and 300 mg/kg bw in female rats. This study is considered as acceptable as it satisfied the criteria of OECD guidelines for the acute toxicity.

Acute toxicity: dermal

In accordance with column 2 of REACH Annex VIII, the acute dermal toxicity study (required in section 8.5.3) does not need to be conducted as the substance is classified as corrosive to the skin based on the results of the in vitro membrane barrier test for skin corrosion (Heppenheimer, 2010). However, at low non irritating doses corresponding to lower doses of classification (< 50 mg/kg bw), no mortality (from systemic effect) is expected to occur after dermal exposure.

Acute toxicity: inhalation

In accordance with column 2 of REACH Annex VIII, the acute toxicity study by inhalation (required in section 8.5.3) does not need to be conducted as the substance is classified as corrosive to the skin based on the results of the in vitro membrane barrier test for skin corrosion (Heppenheimer, 2010). Moreover, the test item is a liquid with low vapour pressure (see §4). Therefore, no significant volatilisation is expected under environmental conditions such as the workplace.

At low non irritating concentrations corresponding to lower concentrations of classification (< 20 mg/L), no mortality from systemic effect is expected to occur by inhalation.

Justification for classification or non-classification

Based on the results of the key study, the substance is classified for acute oral toxicity as:

- Acute oral Category 3 (H301; Toxic if swallowed) according to the criteria of the Regulation (EC) No. 1272/2008 (CLP)

- Toxic if swallowed (T; R25) according to the criteria of the Council Directive 67/548/EEC (and subsequent adaptations).

The substance is not classified for acute toxicity by dermal route and by inhalation.