Dimethyl Sulfoxide (DMSO)

SECTION 2: Hazards identification

CANADIAN WHMIS SYMBOLS EMERGENCY OVERVIEW RISK HARMFUL - May cause lung damage if swallowed. Irritating to eyes, respiratory system and skin.

Potential Acute Health Effects

SWALLOWED ■ Swallowing of the liquid may cause aspiration into the lungs with the risk of chemical pneumonitis; serious consequences may result. (ICSC13733). ■ Accidental ingestion of the material may be damaging to the health of the individual. ■ DMSO has shows very few toxic symptoms in humans. The most common are nausea, skin rashes and an unusual garlic- onion-oyster smell on body and breath. Ingestion of large quantities of DMSO may cause nausea, vomiting, diarrhoea, cramps, chills and drowsiness. EYE ■ Evidence exists, or practical experience predicts, that the material may cause eye irritation in a substantial number of individuals. Prolonged eye contact may cause inflammation characterized by a temporary redness of the conjunctiva (similar to windburn). ■ Direct contact with aqueous solutions containing 75-90% DMSO produce irritation with temporary stinging and burning. Lower concentrations do not appear to cause injury and are tolerated well. Application, full strength to rabbit eye, produces pain, moderate discharge, corneal epithelium injury and dilation of the conjunctival blood vessels with haemorrhage. The effects are reversed within 2 days. SKIN ■ The material may cause mild but significant inflammation of the skin either following direct contact or after a delay of some time. Repeated exposure can cause contact dermatitis which is characterized by redness, swelling and blistering. ■ Skin contact with the material may damage the health of the individual; systemic effects may result following absorption. ■ Stinging and burning of the skin as well as rashes and vesicles have been seen. A heat reaction may occur if applied to wet skin Absorption through the skin may produce a garlic-like odour on the breath as a result of conversion within the body to mercaptans. Other effects of absorption include transient disturbances of colour vision, photophobia, headache, diarrhoea, anaesthesia, lethargy, drowsiness, chills, chest pains, burning and aching eyes. Topical application is often employed to increase dermal absorption of many chemicals including drugs and allergens of moderate molecular weight. Skin contact with concentrated solutions may produce erythema, itching, scaling, a transient burning sensation, and possible blistering. Histamine release may result in urticarial wheal and flare. Transient haemolysis with haemoglobinuria has also been reported. Occluded patch testing has produced enhanced irritation, epidermal vesiculation, histological evidence of dermal death, and perivascular dermal infiltrates. Occasional hypersensitivity reactions, including anaphylaxis, have been described Avoid contact with DMSO solutions containing toxic material or materials whose toxicological properties are not known. DMSO easily penetrates the skin and may enhance the rate of skin absorption of skin-permeable substances. But because of DMSO's low toxicity and its inability to carry less-permeable substances with it through the skin, it can be concluded that DMSO does not pose a significant threat by skin absorption. ■ Open cuts, abraded or irritated skin should not be exposed to this material. ■ Entry into the blood-stream, through, for example, cuts, abrasions or lesions, may produce systemic injury with harmful effects. Examine the skin prior to the use of the material and ensure that any external damage is suitably protected. INHALED ■ The material can cause respiratory irritation in some persons. The body's response to such irritation can cause further lung damage. ■ Inhalation hazard is increased at higher temperatures. ■ Inhalation of aerosols/ vapours of may result in coughing or burning sensation. High concentrations may produce systemic effects such as nausea, vomiting, chills, cramps, headache, dizziness, and lethargy. Allergic respiratory reactions may also occur. The lethal dose for rabbits is reportedly 1600 mg/m3/4hours. Animals subject to DMSO spray for 5 minutes, 10 times over 15 days showed liver damage and bronchopneumonia. Histamine release may produce bronchoconstriction, wheezing.

Potential chronic health

Long-term exposure to respiratory irritants may result in disease of the airways involving difficult breathing and related systemic problems. Limited evidence suggests that repeated or long-term occupational exposure may produce cumulative health effects involving organs or biochemical systems. There is some evidence that inhaling this product is more likely to cause a sensitization reaction in some persons compared to the general population. There is limited evidence that, skin contact with this product is more likely to cause a sensitization reaction in some persons compared to the general population. When 90 ml of 90% DMSO were applied to the entire trunk of 20 men daily for 6 months, bad breath, transient erythema, burning and stinging were apparent. Dermatitis, accompanied by moderate inflammation, regressed as treatment continued. Continuous applications under an occluding membrane produced hardening of the skin within a month. Crystalline lens alterations, resembling juvenile nuclear sclerosis, has been produced in test animals, but not in man, following chronic dermal exposure. Rabbits exposed to DMSO mists for 5 months developed chemical pneumonia, cloudy swelling of the liver and signs of renal toxicity. Reproductive effects have been reported in animals.