Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

A number older studies are available, which investigate the potential of DMT to cause skin sensitisation in the guinea-pig using various study designs. Although the results of the studies are not uniformly negative (two studies report a borderline response with findings in a single animal only), the weight of evidence from these studies (taken in conjunction with an absence of any reported cases of sensitisation in exposed workers - no medical records or case histories were available indicating occupational contact hypersensitivity) leads to the conclusion that DMT does not have the potential to induce skin sensitisation.

For further confirmation, a LLNA study was conducted, wherein there was no indication that a stimulation index (SI) of 3 or greater was achieved, at concentrations of up to 50%. No evidence of skin sensitization was seen in a cuff-rub-on-cuff method (EKC, 1958) using a 24 -hour induction application of approximately 0.5 mL of a 10% suspension of dimethyl terephthalate in corn oil under occlusive conditions followed by ten consecutive daily applications of a 10% suspension of DMT in corn oil (0.5 mL). Following a 3 -week rest period, no reactions were noted to a 24 -hour occlusive application of the substance.

In a study of similar design (EKC, 1957) using a 50% solution of DMT for the induction and challenge exposures, a positive response was reported in one of the five guinea pigs investigated. The authors of the study concluded that DMT has a slight potential to induce sensitisation.

In a further study using the Kodak Drop-on Method (EKC, 1971), a group of ten guinea pigs was treated with multiple topical applications of 0.5 mL of a 1.0% solution of DMT in acetone + dioxane + guinea pig fat (7:2:1). After a three-week rest period, the animals were treated again with the solution on one shoulder and one week later, on the other shoulder . The final observations were compared to the initial observations to determine potential sensitization by the test material. A group of five control guinea pigs was treated with only the solvent mixture. Twenty-four and forty-eight hours after challenge, the reactions in the control and test groups were similar. Based on the results of this study it was determined that dimethyl terephthalate was a not a dermal sensitizer.

In an additional study using the Footpad Method, a group of ten guinea pigs was induced by injection in the footpad with 0.05 mL of a 1.0% solution of the test substance in heparinized whole rabbit blood. One week later, the animals were challenged with a 1% solution of DMT in acetone: dioxane: guinea pig fat (7:2:1). The 1.0% solution was used since a 1% solution of the test substance in the same solvent was found to be non-irritating in the preliminary irritation study. Twenty-four hours after challenge, the average score (erythema + oedema) was 1.4, and 48 hours after challenge the average score was 1.6. Although the scores were slightly higher in the test group when compared to the irritation control group, the sensitization response was, at most, minimal. The authors stated that the results were indicative of sensitization in only 1/10 animals, which is below a response that is considered statistically significant. The lack of a significant sensitization response in this study was reaffirmed in a subsequent publication.  Based on the results of this study, it was determined that dimethyl terephthalate was a not a dermal sensitizer.

In a study conducted in 1955, the test substance dimethyl terephthalate was tested for its ability to cause skin sensitization reactions when tested on guinea pigs.The animals were observed at 1, 24 and 48 hours after administration. When tested as a 50% water paste, dimethyl terephthalate did not produce an allergic skin sensitization reaction.


Migrated from Short description of key information:
The results of the five available skin sensitisation studies are not uniformly negative as two studies report a borderline response with findings in a single animal only. However the weight of evidence from these studies (in conjunction with an absence of reported cases of sensitisation in exposed workers) leads to the conclusion that DMT is not a skin sensitiser. There is no evidence of respiratory sensitisation in animal studies or from exposed workers.
For further confirmation, a LLNA study was conducted, wherein there was no indication that a stimulation index (SI) of 3 or greater was achieved, at concentrations of up to 50%.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

No animal data are available (no validated model is available). However there is no evidence of respiratory sensitisation in exposed workers - as indicated by the absence of any available medical reporting, case histories or occupational health unit records linking occupational exposure to DMT to any respiratory dysfunction.


Migrated from Short description of key information:
No animal data are available. No case records or medical histories were available to indicate any incidence of human respiratory sensitisation in exposed workers.

Justification for classification or non-classification

The results of the five available skin sensitistaion studies are not uniformly negative as two studies report a borderline response with findings in a single animal only. However the weight of evidence from these studies and the absence of reports of sensitisation in exposed workers leads to the conclusion that DMT is not a skin sensitiser. There are no medical records, case histories or adverse reporting records from occupational health units to indicate any evidence of respiratory sensitisation in exposed workers. For further confirmation, a LLNA study was conducted, wherein there was no indication that a stimulation index (SI) of 3 or greater was achieved, at concentrations of up to 50%.