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Date of issue: November 2018
Version: 3

This is a UKTIS monograph for use by health care professionals. For case-specific advice please contact UKTIS on 0344 892 0909. To report an exposure please download and complete a pregnancy reporting form. Please encourage all women to complete an online reporting form.


Benomyl is a benzimidazole carbamate fungicide and ascaricide used widely in agriculture and gardening. The available data concerning benomyl exposure in human pregnancy are highly limited and potentially confounded, mainly by exposure estimations being based on occupation or residential location.

No studies have assessed the overall risk of congenital malformation. A possible association between benzimidazole pesticide exposure and an increased risk of spina bifida has been suggested in a single study. Additional data are required before conclusions regarding this specific risk can be provided. A possible clustering of infants with eye malformations in which benomyl exposure was causally implicated was reported in the 1990s. Two subsequent epidemiological studies did not provide evidence of an association but suffered a number of methodological limitations and therefore an association cannot currently be excluded.

No studies have investigated the risk of spontaneous abortion, preterm delivery, growth restriction, intrauterine death, offspring neurodevelopmental impairment or cancer following maternal exposure in pregnancy.

As with all chemicals, unnecessary exposure to benomyl should be avoided during pregnancy. However, where occupational exposure is unavoidable, adequate health and safety precautions should be taken to ensure that exposure is well within the recommended exposure limits and not associated with maternal symptoms of toxicity.

Inadvertent exposure to benomyl at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy. However, other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments. Where exposure to benomyl has occurred, even in cases which did not result in maternal toxicity, enhanced fetal monitoring may be warranted. Discussion with UKTIS is recommended.

Note: This product is no longer commercially available in the UK, therefore this document will not be routinely updated. If up-to-date information is required please contact UKTIS.

This document is regularly reviewed and updated. Only use full UKTIS monographs downloaded directly from to be sure you are using the most up-to-date version. The summaries of these monographs are openly available on

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 health care professionals at

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 or to ensure you are using the most up-to-date version.