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Description of key information

The acute toxicity of DMT has been investigated by various routes of exposure and using various species.  The substance is of very low acute toxicity by all routes investigated.  Oral LD50 values of >3200->7500 mg/kg bw are reported.  Dermal LD50 values of >2000->5000 mg/kg bw are reported.  A 2-hour inhalation LC50 of 6 mg/L is reported.  Acute intraperitoneal LD50 values 1600-3200 mg/kg bw are reported.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
7 500 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
Value:
3 000 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
Value:
5 000 mg/kg bw

Additional information

Acute oral toxicity

A number of acute oral toxicity studies are consistent in demonstrating very low toxicity, with no mortalities and only limited clinical signs reported at dose levels of up to 7500 mg/kg bw.

Perry (1957) gavaged groups of 5 rats with a single dose of DMT (in corn oil) at dose levels of 200 -3200 mg/kg bw and observed for 14 days. No deaths occurred; signs of toxicity were limited to weakness and ataxia. Bodyweights were unaffected by treatment. The acute oral LD50 of DMT in the rat was therefore found to be >3200 mg/kg bw under the conditions of this study.

Shaw (1958) gavaged groups of 5 rats and 5 mice were gavaged with a single dose of DMT (in corn oil) at dose levels of 200 -3200 mg/kg bw and observed for 14 days. No deaths occurred; signs of toxicity were limited to weakness. Bodyweights were unaffected by treatment. The acute oral LD50 of DMT in the rat and mouse was therefore found to be >3200 mg/kg bw under the conditions of this study.

Krasavage et al (1973) administered doses of 3000, 3900, 5020 and 6590 mg/kg dimethyl terephthalate (20% in corn oil) were administered orally to male Long-Evans rats (3-6 per group) to determine the median lethal dose. All groups were observed for signs of toxicity for 14 days. At the end of the test, the survivors were autopsied and examined for gross and micropathology. The acute oral toxicity of Dimethyl terephthalate is of a low order. The LD50 was determined to be >6590 mg/kg bw under the conditions of this study.

A further limited study (DuPont, 1955) confirms the low acute oral toxicity of dimethyl terephthalate. The largest oral dose that was given to a single rat, 7500 mg/kg bw, failed to kill and produced only transient discomfort and weight loss. Gross and microscopic examination of the tissues revealed no organic injury.

In 1961 BASF administered dimethyl terephthalate at doses of 200, 1600, 3200, 6400 and 10000 mg/kg bw in Tragacanth suspension. There were no treatment related mortalities recorded and no abnormalites due to adminiatration of the test substance observed. The LD50was determined to be >10000 mg/kg.

Acute dermal toxicity

In two studies, moistened solid dimethyl terephthalate was held in contact with the depilated skin of guinea pigs, for 24 hours. The exposures resulted in slight skin irritation. The LD50 values were reported to be >2000 mg/kg bw (Perry, 1957) and >5000 mg/kg bw (Shaw, 1958).

Acute inhalation toxicity

In a published acute inhalation toxicity study, a group of 12 rats was exposed (whole body) to DMT vapour at a concentration of 6 mg/L for 2 hours (Sanina & Kochetkova, 1963). During the exposure to condensation aerosol and vapours of dimethyl terephthalate a pronounced irritating effect on the conjunctiva and respiratory tract accompanied by moderate hemodynamic disorders was observed. The 2 -hour LC50 was estimated to be greater than 6 mg/L, estimated to be equivalent to a 4 -hour LC50 of >3 mg/L.

Acute intraperitoneal toxicity

In two studies, the acute intraperitoneal LD50 of dimethyl terephthalate in rats was found to be greater than 3200 mg/kg (Perry, 1957; Shaw, 1958). In mice an i.p. dose of 3200 mg/kg bw was fatal, and the LD50 was estimated to be 1600 to 3200 mg/kg bw (Perry, 1957; Shaw, 1958). Krasavage et al (1973) administered i.p. doses of dimethyl terephthalate (20% in corn oil) up to 6590 mg/kg to male Long-Evans rat (3 -6 per group). Deaths occurred within 48 hours, and gross pathology revealed peritoneal irritation. The acute LD50 was found to be 3900 mg/kg bw.

Justification for classification or non-classification

It can be concluded based on results of the studies above, that dimethyl terephthalate is of a low order of toxicity by the oral, dermal, inhalation and intraperitoneal routes. Dimethyl terephthalate does not warrant classification according to Regulation (EC) No. 1272/2008.