Dimethyl terephthalate

Endpoint summary

Description of key information

No evidence of skin irritation was seen in a modern, guideline-compliant study; findings are supported by evidence from a number of non-standard studies.  No evidence of eye irritation was seen in four non-standard studies.   In the absence of any effects on the skin or eye, it is considered unlikely that DMT is a respiratory irritant.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Skin irritation

The irritant potential of Dimethyl terephthalate (DMT) was determined according to ES EPA guidelines (and comparable to OECD 404). A single 4 hour, semi-occluded application of DMT to the skin of six male New Zealand White rabbits produced no evidence of skin irritation. The test material produced a primary index of 0.0 and is not classified as irritating to rabbit skin (Anonymous, 1989).

The dermal irritation of DMT has been further investigated in a number of non-standard older studies, however the results are largely consistent and do not demonstrate that the substance is a skin irritant. Findings in a study in which guinea pigs were exposed to mositened DMT at a level of 1 and 2 g/kg for 24 hours under occlusive conditions were limited to very slight skin irritation (Perry, 1957). In a further non-standard study, DMT moistened with water (0.1 -5 g/kg bw) was applied for 24 hours under occlusive conditions to the skin of groups of guinea pigs. One animal died as a consequence of the application procedure. No findings were observed with the exception of 'erythematous pits' caused by embossed particles in the skin. At one week, hairloss and 'very little' desquamation was reported. The application site was reported to be normal at 2 weeks (Shaw, 1958). In a non-standard study in rats and mice (Sanina & Kocketkova, 1963), DMT (5% starch) was applied to the rabbit's shorn skin for two hours. For the mice, the tails were immersed into a test tube filled with a suspension of terephthalate in 5% starch. A single exposure lasted two hours. The application was repeated ten times. In rabbits, reddening of the skin was observed on the third application, followed by a change in pigmentation on day 10. By 12 days the skin was back to normal. A similar reaction was seen in mice. Repeated application resulted in slight hyperaemia after the third exposure. Behavioural changes were also noted. Again, by day 12 the skin and behaviour had returned to normal. In a 1961 study conducted by BASF, the test susbtance dimethyl terephthalate (DMT) was tested in Vienna White rabbits. The test substance was applied at a concentration of approximately 2g in 50% solution in water, occlusively to the dorsal region and the ear of each rabbit. There were no treatment related abnormalities observed following treatment with the test susbtance at any of the time points examined.

Eye irritation

In a guideline-compliant study, a single dose of 50 mg DMT was instilled into the conjunctival sac one eye of 8 rabbits. The eyes were washed with water after five minutes or 24 hours. No evidence of ocular irritation was reported. Three further eye irritation studies are available. They do not follow standard methodology however they contain some useful information regarding the eye irritant properties and clearly indicate that the substance is not irritating to eyes. Perry (1957) found that one drop of an aqueous slurry of the test substance instilled into the conjunctival sac of a single rabbit's eye caused no irritation or damage. In another study conducted at the same laboratory, Shaw (1958) found that one drop of an aqueous slurry placed into the conjunctival sac of the rabbit's eye resulted in only a slight immediate discomfort. No signs of pathology or signs of continued irritation were noted in the eye. In a published study by Sanina and Kochetkova (1963), a suspension of two drops of dimethyl terephthalate in 5% starch was placed into the conjunctival sac of four rabbits. The rabbits were observed for signs of irritation for 2 days. The test substance caused reddening of the conjunctiva immediately after administration, all signs of irritation had disappeared by the next day. It is also notable that the toxicokinetic study of Moffit et al (1975) did not identify any local effects following installation of DMT.

In a study conducted by BASF in 1961, 50 mg of the test substance was applied to the right eye of each of 2 test rabbits of the Vienna White strain. The left eye of each animal served as the control and talcum was applied. The test substance resulted in slight redness of the treated eye in both animals 10 minutes post application. After examination at 3 hours, redness was still present. Slight swelling was noted in 1 animal after 3 hours. Within 24 hours of application, all observed symptoms had completely reversed in both test animals.

Respiratory irritation

No data are available. In the absence of any effects on the skin or eye, it is considered unlikely that DMT is a respiratory irritant.

Justification for classification or non-classification

In a GLP guideline study, there was no evidence that dimethyl terephthalate was irritating to the skin or rabbits; no evidence of marked irritation is reported in a number of non-standard studies. The available eye irritation studies do not report any notable irritation. DMT therefore does not warrant classification as a skin or eye irritant according to Regulation (EC) No. 1272/2008.