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EXPOSURE TO METHYL ISOCYANATE (MIC) IN PREGNANCY

Date of issue: September 2023, Version: 1.3

Methyl isocyanate (MIC) is a clear, colourless, pungent liquid with lacrimatory properties formed as a chemical intermediate during the production of carbamate insecticides. It is also used in the production of rubber, polyurethane foams, plastics and adhesives.

The available published data regarding MIC exposure during pregnancy relates to women exposed during the Bhopal disaster of 1984. This limited information does not indicate an increased risk of congenital malformation in the offspring of women who lived in the affected area but is insufficient to exclude any increased risk. Exposure to MIC was associated with an increased incidence of miscarriage, neonatal mortality, and lower birth and placental weight. It is unclear whether this is as a consequence of maternal toxicity or due to maternal stress that may have occurred in the aftermath of the disaster.

In experimental studies, placental weight was reduced in mice exposed to MIC. Together with the findings from Bhopal, this may suggest a possible mechanism for interruption of normal fetal growth.

In the event of MIC exposure in a pregnant patient, maternal toxicity is likely to be a major determinant of risk to the fetus. There are no guidelines regarding the treatment of MIC poisoning during pregnancy. Where management is required, treatment should be the same as for a non-pregnant patient. For current guidelines on the management of MIC poisoning please consult TOXBASE or contact UKTIS.

Where exposure to MIC has occurred, whether or not there is associated maternal toxicity, close monitoring of fetal growth is warranted. Discussion with UKTIS is recommended.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

Disclaimer: Every effort has been made to ensure that this monograph was accurate and up-to-date at the time of writing, however it cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes of the measures recommended. The final decision regarding which treatment is used for an individual patient remains the clinical responsibility of the prescriber. This material may be freely reproduced for education and not for profit purposes within the UK National Health Service, however no linking to this website or reproduction by or for commercial organisations is permitted without the express written permission of this service. This document is regularly reviewed and updated. Only use UKTIS monographs downloaded directly from UKTIS.org to ensure you are using the most up-to-date version.