Dimethyl sulfoxide

Endpoint summary

Description of key information

The acute inhalation toxicity of DMSO in rats has been investigated in studies compliant with OECD guidelines and also in non-guideline studies. For the oral and dermal routes, only non-guideline studies are available. 
DMSO is of low acute toxicity. In non-guideline studies, LD50 in rats are generally higher than 20,000 mg/kg bw and 40,000 mg/kg bw by the oral and dermal routes, respectively. In an acute inhalation study performed following the OECD guideline # 403, the 4h-LC50 in rats was higher than 5330 mg/m3.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

28 300 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

discriminating conc.

Value:

5 330 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

40 000 mg/kg bw

Additional information

Acute Oral toxicity

Willson et al. (1965) has determined two LD50 for DMSO after oral administration: 28300 mg/kg in rats and 21400 (17100-26900) mg/kg in mice

Acute inhalation toxicity

In a key study, the acute inhalation toxicity of DMSO was evaluated in a 4-hour, single-exposure study in rats according to OECD Guideline 403 (May 12th 1981) (Jackson, 1998). DMSO was initially administered to a single group of five male and five female Sprague Dawley rats via nose only vapor exposure at concentrations of 0, 0.9 or 5.33 mg/l. Rats were held for exposure in nose-only molded polycarbonate restraining tubes which were attached to a central exposure chamber. Rats were observed continuously for reaction to the test atmosphere during exposure, at one and two hour after exposure, and at least twice daily during the post-exposure interval. Body weight, and food and water consumption were measured daily for all rats, from day of delivery until the end of the observation interval. Rats were sacrificed and subjected to a detailed macroscopic examination at the end of the 14-day observation interval. Lungs were processed and examined microscopically.

There were no deaths during or following exposure to DMSO. There were no clinical signs related to exposure to DMSO during exposure. Soiling of the fur with excreta, as a consequence of the method of restraint, was seen in all test and control rats during and immediately after exposure. Normal appearance and behaviour was observed in all animals during the 14-day observation interval. Rate of body weight gain, and food and water consumption in rats exposed to DMSO were similar to controls. There were no macroscopic abnormalities in test or control rats. Based on the results of this study, the LC0 of DMSO was higher than 5.3 mg/l when male and female Sprague Dawley rats were exposed nose-only to a vapor of the test article for a single, 4-hour period.

In a supporting study, Fishman et al.’s studies (1969) on rats allowed to determine a LC0 higher than 1.6 mg/l (4-hour exposure), 2.9 mg/l (24-hour exposure) and 2.0 mg/l (40-hour exposure) after an exposure to a mixture of vapours and aerosols of DMSO.

Acute dermal

Two studies from Smyth et al. (1968) allowed determining LD50 of 40000 mg/kg in rats and a LD50 of 50000 mg/kg in mice.

Other routes

Willson et al. (1965) has calculated an intravenous LD50 of 5360 mg/kg in rats and an intravenous LD50 of 5750 mg/ kg in mice. Fishman et al. (1969) determined a LD50 of 3100 (2700-3500) mg/kg in mice.

Justification for classification or non-classification

No classification for acute toxicity has to be applied for DMSO according to EU Directive 67/584/EEC and EU regulation (EC) No 1272/2008 (CLP).

oral LD50 = 28300 mg/kg in rats and 21400 mg/kg in mice

4h inhalation LC0 > 5.3 mg/l in rats

dermal LD50 ca. 40000 mg/kg in rats and ca. 50000 mg/kg in mice