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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Description of key information

No specific test data for skin sensitisation are available for the registered substance, 3-(trimethoxysilyl)propyl isocyanate. However, isocyanates are known skin sensitisers with many references in the open literature (see for example HSDB database). It is therefore reasonable to conclude that 3-(trimethoxysilyl)propyl isocyanate could cause skin sensitisation.

There is good evidence to indicate that isocyanates: cause chemical bronchitis/pneumonitis; are potent pulmonary sensitizers capable of causing “isocyanate asthma”; cause nonspecific airways disease, including chronic bronchitis; can induce a general asthmatic state; and can cause hypersensitivity pneumonitis. Similar dose-response relationships are seen for both acute and chronic effects (Musk et al., 1988).


Musk et al., 1988. American Journal of Industrial Medicine, Vol 13, Issue 3, pages 331-349

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
skin sensitisation: in vitro
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

Isocyanates cause asthma. The symptoms of asthma include coughing, shortness of breath, wheezing, and chest tightness. Symptoms can occur soon after exposure or several hours later. Isocyanates can also cause hypersensitivity pneumonitis, a lung disease whose symptoms include fever, body aches, shortness of breath, and cough with phlegm or sputum. About one out of twenty people who work with isocyanates becomes "sensitized" to them. Being "sensitized" to isocyanates means that you may have an asthma attack any time you are exposed to them, even to extremely small amounts. Sensitivity to isocyanates can be permanent. Also, continuing to work with isocyanates after you become sensitized can cause asthma itself to become permanent, so that attacks can occur even without any further exposure to isocyanates. Once you become sensitized, you cannot continue to work in any job where you could be exposed to isocyanates. You can become sensitized to isocyanates without ever having had any other symptoms of overexposure. There is no evidence that people with other allergies are more likely to become sensitized to isocyanates. Daily exposure to levels of isocyanates too low to sensitize you or cause asthma or pneumonitis may still cause a reduction in lung capacity and function ((

Skin sensitisation data for the hydrolysis product, 3-(trimethoxysilyl)propylamine (CAS 13822-56-5), have been added to the dataset as supporting information. The skin and respiratory sensitisation are determined by the isocyanate group. The hydrolysis product data support this conclusion as the skin sensitisation test does not lead to classification for skin sensitisation for the hydrolysis product, which lacks an isocyanide group. Therefore, supports the use of OEL for isocyanates for DNEL derivation.

Justification for classification or non-classification

Based on data for isocyanates, 3-(trimethoxysilyl) isocyanate is classified for skin sensitisation Cat. 1A and respiratory sensitisation Cat. 1 with hazard statements 'H317: May cause an allergic skin reaction' and 'H334: May cause allergy or asthma symptoms or breathing difficulties if inhaled' according to Regulation (EC) No 1272/2008.