Elsevier

Reproductive Toxicology

Volume 30, Issue 3, November 2010, Pages 409-413
Reproductive Toxicology

Pregnancy outcome after risk assessment of occupational exposure to organic solvents: A prospective cohort study

https://doi.org/10.1016/j.reprotox.2010.06.004Get rights and content

Abstract

A rational medical, occupational and toxicological approach is instrumental to select objectively among pregnant women exposed to chemicals at the workplace those who should be withdrawn or benefit from improvements of working conditions. Risk assessment is based on a comprehensive review of compounds’ hazards and a thorough evaluation of the actual exposure including biomonitoring whenever as possible. Since 1996, the Lyon Poison Center has been conducting a prospective follow-up of pregnant women exposed to chemicals at the workplace. Of these, 206 exposed to organic solvents since conception were selected and matched with 206 exposed to a non-embryotoxic agent. Total withdrawal from the workplace was recommended in 22% of cases, but exposure was not considered to be hazardous to pregnancy in 51%. Overall, no increase in adverse outcomes was found. Maintaining pregnant women at their workplace, particularly most of the laboratory technicians, is reasonably possible after careful toxicological risk assessment.

Introduction

Many women of childbearing age are occupationally exposed to chemicals and thus may become concerned with ensuing risks when pregnant. Although an ideal situation would be to enquire about the potential adverse fetal consequences of occupational chemical exposure(s) prior to the undertaking of pregnancy, in most cases exposure predates conception and actually goes on when pregnancy is discovered. In France, risk assessment of drugs and medications in pregnant women is of primary concern for physicians and pharmacists, but not the chemicals handled at the workplace. Nevertheless, due to its long-standing activity in the field of occupational toxicology, the Toxicovigilance unit of Lyon Poison Center is often requested to assess risk from or about women exposed to chemicals at the workplace [1]. For the medical toxicologist, issues to be addressed include the most likely outcome of the pregnancy and the management of risks from an occupational health point of view, ranging from total withdrawal from the workplace to improvements of working hygiene or unmodified ongoing activity.

In France as in other industrial countries, organic solvents are the main source of chemical exposure in the occupational setting [2]. The most frequently used industrial solvents are petroleum hydrocarbons, chlorinated solvents and oxygenated hydrocarbons (i.e. ketones, esters, ethers and alcohols). All these compounds are volatile liquids that share common physical (liposolubility), toxicokinetic (absorption via the respiratory tract, but also the dermal route) and toxicodynamic (primarily central neurotoxicity) properties. They all easily cross the placenta and thus can reach the embryo. Therefore, they are usually considered as a single group of chemicals. Moreover, solvents are often used as mixtures and not as a single compound.

Some solvents have shown clearly dose-dependent embryotoxic and teratogenic effects in rodents [3]. However, high doses and/or administration routes used in animal studies are most often not suitable for risk assessment in occupationally or environmentally exposed women. This is why epidemiological data are absolutely essential for pregnant women's counselling in the real working life. Many studies, mainly retrospective, have been conducted in women occupationally exposed to solvents. In 1998, a metaanalysis concluded that heavy exposure during the first trimester of pregnancy may increase the risk of spontaneous abortions and major malformations in the offspring [4]. No specific pattern of congenital malformation(s) has so far been described, but oral clefts have been pointed out in some studies [4], [5], [6].

The present work describes the principles of individual risk assessment that are believed to be necessarily applied in pregnant women or in women wishing to undertake pregnancy while exposed to organic solvents at the workplace. Results of the prospective follow-up of 206 exposed pregnant women will then be presented with the aim to determine if the intervention had an influence on the outcome.

Section snippets

Study population

Between 1996 and 2008, the Lyon Poison Center received 578 reproductive risk assessment requests about women exposed to chemicals. They came from gynecologists in 49% of cases, general practitioners in 16%, occupational physicians in 12%, and from the working women themselves in 23%. Requests not included in the analysis concerned possible causal relationship between occupational exposure and the occurrence of miscarriage or malformation(s) in the newborn (n = 47), preventive advice in view of

Results

From a total of 578 risk assessment requests received by the Lyon Poison Center between 1996 and 2008, 206 pregnancies in women occupationally exposed to organic solvents with a prospective follow-up of the outcome were included for subsequent analysis. A sub-group of 66 pregnant laboratory technicians was individualized. In all women, exposure predated conception and was still present at inclusion, usually close to the diagnosis of pregnancy.

The mother's age at inclusion was 28.33 ± 4.36 years;

Discussion

In 22.3% of the women from this cohort, occupational exposure to organic solvents was considered to be hazardous to pregnancy in terms of increased risk of abortion or malformations: this was essentially due to high exposure levels and/or exposure to compounds of concern (e.g. glycol ethers, trichloroethylene…). Consequently, withdrawal from the workplace was highly recommended. However, in more than 50% of cases, no measurable risk for pregnancy was found after in-depth assessment: this was

Conclusion

This study demonstrates the feasibility and the utility of risk assessment at the individual level in pregnant women occupationally exposed to chemicals. Women who should be withdrawn, or benefit from improvements at the workplace can be objectively selected using a rational occupational and toxicological approach. No risk for pregnancy was assessed to be present in one-half of our cases, essentially because of very low solvent exposure levels, as in laboratory technicians. The prospective

Conflict of interest statement

The authors declare no conflicts of interest.

Acknowledgement

No specific grants supported the present study.

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