EXPOSURE TO DIESEL FUEL IN PREGNANCY

Diesel fuel (petroleum distillate) is a complex mixture of saturated and aromatic hydrocarbons produced from the distillation of crude oil and is thus distinguishable from biodiesel which is produced from vegetable or animal lipids. Under normal conditions it is a liquid with a characteristic odour. A craving for diesel fumes is a common non-food related pica experienced by pregnant women.

There are very limited data on pregnancy outcome following exposure to diesel in human pregnancy. No studies have investigated pregnancy outcome following exposure as a consequence of pica. Individual studies have found an increased risk of autism spectrum disorder in male (but not female) offspring, preterm delivery, childhood wheezing in infants of younger women (<25), possible deficits in school performance by age 8 to 9, and childhood brain tumour following environmental diesel exposure in pregnancy. Paternal exposure has been associated with an increased risk of cryptorchidism. The clinical  significance of these findings is unclear as some of the associations, in some instances observed only at high levels of exposure, have not yet been replicated and the number of diesel exposures in each of these studies is low and based on assumed rather than confirmed exposure to diesel exhaust. The effect of maternal diesel exposure on other pregnancy outcomes (spontaneous abortion, intrauterine death, neonatal complications) have not been investigated.

As with all chemicals, unnecessary exposure to diesel should be avoided and pregnant women advised to avoid behaviours in response to pica that increase exposure to diesel. Where occupational exposure is considered unavoidable then precautions, such as use of PPE and appropriate ventilation, should be taken to ensure that exposure is not associated with toxic symptoms. An occupational health assessment is recommended where a pregnancy is planned or as soon as pregnancy is recognised if occupational exposure is likely.

There are no published guidelines concerning the management of diesel poisoning during pregnancy. Maternal toxicity as a result of acute exposure in pregnancy is likely to be a major determinant of the risk posed to the developing fetus. It is therefore important to treat the mother appropriately to reduce the risks of maternal and, as a consequence, fetal toxicity. Pregnant women should be managed as for the non-pregnant patient but may require additional fetal monitoring or intervention. For current guidelines on the management of diesel poisoning readers are advised to consult TOXBASE or contact UKTIS.

Due to limitations in the available data, it is not currently possible to state that an absence of maternal toxicity excludes the possibility of adverse pregnancy outcomes. Additionally, 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. Discussion with UKTIS is recommended in all cases.