EXPOSURE TO ETHYLENETHIOUREA IN PREGNANCY

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(Date of issue: April 2020, 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.

Summary

Ethylenethiourea (ETU) is used in the rubber industry and in the production of some fungicides. 

Data relating to pregnancy outcomes following ETU exposure are scarce. No increased risk of malformation was observed in a retrospective case-series investigating the offspring of women who worked in the rubber industry and a prospective cohort study found no significant differences in neurodevelopmental outcomes between exposed infants and population norms. However, due to the extremely limited data an evidence-based assessment of fetal risk following either acute or chronic exposure to ethylenethiourea during pregnancy is not possible. 

Teratogenicity has been observed in some (but not all) animal species following in utero ethylenethiourea exposure. Various structural malformations, growth restriction, thyrotoxicity, hepatotoxicity and behavioural abnormalities have been reported in rats. Ethylenethiourea consistently induces anorectal malformations in a high percentage of rat embryos and is therefore used as a positive control for teratogenicity in preclinical studies.  It is not known whether there are similar risks to the human fetus.

As with all chemicals, unnecessary exposure to ethylenethiourea should be avoided during pregnancy. Where occupational exposure is unavoidable, precautions should be taken to ensure that exposure is well within the recommended exposure limits and not associated with toxic symptoms.

Following ethylenethiourea exposure in a pregnant woman, maternal toxicity is likely to be a major determinant of risk to the fetus. However, due to a lack of data relating to the human teratogenicity of ethylenethiourea, it is not currently possible to state that an absence of maternal toxicity excludes the possibility of adverse events occurring in the developing fetus.

There are no published guidelines on the management of poisoning with ethylenethiourea compounds during pregnancy and pregnant patients should be managed as for non-pregnant patients. Thiourea compounds can interfere with thyroid function and maternal thyroid status should be checked following any exposure to ethylenethiourea.

Exposure to ethylenethiourea at any stage in pregnancy may also confer a risk to the fetus. The need for additional fetal monitoring following maternal exposure to ethylenethiourea needs to be assessed on a case-by-case basis. A detailed fetal anomaly scan to include assessment of the fetal thyroid should be considered. Thyroid and liver function should be checked in all exposed neonates at birth. Other risk factors may also 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. Discussion with UKTIS is recommended in all cases.

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

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 www.toxbase.org.

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